summaryrefslogtreecommitdiffstats
path: root/contrib/zstd/zstd_decompress_block.c
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-10 21:30:40 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-10 21:30:40 +0000
commit133a45c109da5310add55824db21af5239951f93 (patch)
treeba6ac4c0a950a0dda56451944315d66409923918 /contrib/zstd/zstd_decompress_block.c
parentInitial commit. (diff)
downloadrspamd-upstream.tar.xz
rspamd-upstream.zip
Adding upstream version 3.8.1.upstream/3.8.1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'contrib/zstd/zstd_decompress_block.c')
-rw-r--r--contrib/zstd/zstd_decompress_block.c2193
1 files changed, 2193 insertions, 0 deletions
diff --git a/contrib/zstd/zstd_decompress_block.c b/contrib/zstd/zstd_decompress_block.c
new file mode 100644
index 0000000..add277e
--- /dev/null
+++ b/contrib/zstd/zstd_decompress_block.c
@@ -0,0 +1,2193 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+/* zstd_decompress_block :
+ * this module takes care of decompressing _compressed_ block */
+
+/*-*******************************************************
+* Dependencies
+*********************************************************/
+#include "zstd_deps.h" /* ZSTD_memcpy, ZSTD_memmove, ZSTD_memset */
+#include "compiler.h" /* prefetch */
+#include "cpu.h" /* bmi2 */
+#include "mem.h" /* low level memory routines */
+#define FSE_STATIC_LINKING_ONLY
+#include "fse.h"
+#include "huf.h"
+#include "zstd_internal.h"
+#include "zstd_decompress_internal.h" /* ZSTD_DCtx */
+#include "zstd_ddict.h" /* ZSTD_DDictDictContent */
+#include "zstd_decompress_block.h"
+#include "bits.h" /* ZSTD_highbit32 */
+
+/*_*******************************************************
+* Macros
+**********************************************************/
+
+/* These two optional macros force the use one way or another of the two
+ * ZSTD_decompressSequences implementations. You can't force in both directions
+ * at the same time.
+ */
+#if defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
+ defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG)
+#error "Cannot force the use of the short and the long ZSTD_decompressSequences variants!"
+#endif
+
+
+/*_*******************************************************
+* Memory operations
+**********************************************************/
+static void ZSTD_copy4(void* dst, const void* src) { ZSTD_memcpy(dst, src, 4); }
+
+
+/*-*************************************************************
+ * Block decoding
+ ***************************************************************/
+
+/*! ZSTD_getcBlockSize() :
+ * Provides the size of compressed block from block header `src` */
+size_t ZSTD_getcBlockSize(const void* src, size_t srcSize,
+ blockProperties_t* bpPtr)
+{
+ RETURN_ERROR_IF(srcSize < ZSTD_blockHeaderSize, srcSize_wrong, "");
+
+ { U32 const cBlockHeader = MEM_readLE24(src);
+ U32 const cSize = cBlockHeader >> 3;
+ bpPtr->lastBlock = cBlockHeader & 1;
+ bpPtr->blockType = (blockType_e)((cBlockHeader >> 1) & 3);
+ bpPtr->origSize = cSize; /* only useful for RLE */
+ if (bpPtr->blockType == bt_rle) return 1;
+ RETURN_ERROR_IF(bpPtr->blockType == bt_reserved, corruption_detected, "");
+ return cSize;
+ }
+}
+
+/* Allocate buffer for literals, either overlapping current dst, or split between dst and litExtraBuffer, or stored entirely within litExtraBuffer */
+static void ZSTD_allocateLiteralsBuffer(ZSTD_DCtx* dctx, void* const dst, const size_t dstCapacity, const size_t litSize,
+ const streaming_operation streaming, const size_t expectedWriteSize, const unsigned splitImmediately)
+{
+ if (streaming == not_streaming && dstCapacity > ZSTD_BLOCKSIZE_MAX + WILDCOPY_OVERLENGTH + litSize + WILDCOPY_OVERLENGTH)
+ {
+ /* room for litbuffer to fit without read faulting */
+ dctx->litBuffer = (BYTE*)dst + ZSTD_BLOCKSIZE_MAX + WILDCOPY_OVERLENGTH;
+ dctx->litBufferEnd = dctx->litBuffer + litSize;
+ dctx->litBufferLocation = ZSTD_in_dst;
+ }
+ else if (litSize > ZSTD_LITBUFFEREXTRASIZE)
+ {
+ /* won't fit in litExtraBuffer, so it will be split between end of dst and extra buffer */
+ if (splitImmediately) {
+ /* won't fit in litExtraBuffer, so it will be split between end of dst and extra buffer */
+ dctx->litBuffer = (BYTE*)dst + expectedWriteSize - litSize + ZSTD_LITBUFFEREXTRASIZE - WILDCOPY_OVERLENGTH;
+ dctx->litBufferEnd = dctx->litBuffer + litSize - ZSTD_LITBUFFEREXTRASIZE;
+ }
+ else {
+ /* initially this will be stored entirely in dst during huffman decoding, it will partially be shifted to litExtraBuffer after */
+ dctx->litBuffer = (BYTE*)dst + expectedWriteSize - litSize;
+ dctx->litBufferEnd = (BYTE*)dst + expectedWriteSize;
+ }
+ dctx->litBufferLocation = ZSTD_split;
+ }
+ else
+ {
+ /* fits entirely within litExtraBuffer, so no split is necessary */
+ dctx->litBuffer = dctx->litExtraBuffer;
+ dctx->litBufferEnd = dctx->litBuffer + litSize;
+ dctx->litBufferLocation = ZSTD_not_in_dst;
+ }
+}
+
+/* Hidden declaration for fullbench */
+size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
+ const void* src, size_t srcSize,
+ void* dst, size_t dstCapacity, const streaming_operation streaming);
+/*! ZSTD_decodeLiteralsBlock() :
+ * Where it is possible to do so without being stomped by the output during decompression, the literals block will be stored
+ * in the dstBuffer. If there is room to do so, it will be stored in full in the excess dst space after where the current
+ * block will be output. Otherwise it will be stored at the end of the current dst blockspace, with a small portion being
+ * stored in dctx->litExtraBuffer to help keep it "ahead" of the current output write.
+ *
+ * @return : nb of bytes read from src (< srcSize )
+ * note : symbol not declared but exposed for fullbench */
+size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx,
+ const void* src, size_t srcSize, /* note : srcSize < BLOCKSIZE */
+ void* dst, size_t dstCapacity, const streaming_operation streaming)
+{
+ DEBUGLOG(5, "ZSTD_decodeLiteralsBlock");
+ RETURN_ERROR_IF(srcSize < MIN_CBLOCK_SIZE, corruption_detected, "");
+
+ { const BYTE* const istart = (const BYTE*) src;
+ symbolEncodingType_e const litEncType = (symbolEncodingType_e)(istart[0] & 3);
+
+ switch(litEncType)
+ {
+ case set_repeat:
+ DEBUGLOG(5, "set_repeat flag : re-using stats from previous compressed literals block");
+ RETURN_ERROR_IF(dctx->litEntropy==0, dictionary_corrupted, "");
+ ZSTD_FALLTHROUGH;
+
+ case set_compressed:
+ RETURN_ERROR_IF(srcSize < 5, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 2; here we need up to 5 for case 3");
+ { size_t lhSize, litSize, litCSize;
+ U32 singleStream=0;
+ U32 const lhlCode = (istart[0] >> 2) & 3;
+ U32 const lhc = MEM_readLE32(istart);
+ size_t hufSuccess;
+ size_t expectedWriteSize = MIN(ZSTD_BLOCKSIZE_MAX, dstCapacity);
+ int const flags = 0
+ | (ZSTD_DCtx_get_bmi2(dctx) ? HUF_flags_bmi2 : 0)
+ | (dctx->disableHufAsm ? HUF_flags_disableAsm : 0);
+ switch(lhlCode)
+ {
+ case 0: case 1: default: /* note : default is impossible, since lhlCode into [0..3] */
+ /* 2 - 2 - 10 - 10 */
+ singleStream = !lhlCode;
+ lhSize = 3;
+ litSize = (lhc >> 4) & 0x3FF;
+ litCSize = (lhc >> 14) & 0x3FF;
+ break;
+ case 2:
+ /* 2 - 2 - 14 - 14 */
+ lhSize = 4;
+ litSize = (lhc >> 4) & 0x3FFF;
+ litCSize = lhc >> 18;
+ break;
+ case 3:
+ /* 2 - 2 - 18 - 18 */
+ lhSize = 5;
+ litSize = (lhc >> 4) & 0x3FFFF;
+ litCSize = (lhc >> 22) + ((size_t)istart[4] << 10);
+ break;
+ }
+ RETURN_ERROR_IF(litSize > 0 && dst == NULL, dstSize_tooSmall, "NULL not handled");
+ RETURN_ERROR_IF(litSize > ZSTD_BLOCKSIZE_MAX, corruption_detected, "");
+ if (!singleStream)
+ RETURN_ERROR_IF(litSize < MIN_LITERALS_FOR_4_STREAMS, literals_headerWrong,
+ "Not enough literals (%zu) for the 4-streams mode (min %u)",
+ litSize, MIN_LITERALS_FOR_4_STREAMS);
+ RETURN_ERROR_IF(litCSize + lhSize > srcSize, corruption_detected, "");
+ RETURN_ERROR_IF(expectedWriteSize < litSize , dstSize_tooSmall, "");
+ ZSTD_allocateLiteralsBuffer(dctx, dst, dstCapacity, litSize, streaming, expectedWriteSize, 0);
+
+ /* prefetch huffman table if cold */
+ if (dctx->ddictIsCold && (litSize > 768 /* heuristic */)) {
+ PREFETCH_AREA(dctx->HUFptr, sizeof(dctx->entropy.hufTable));
+ }
+
+ if (litEncType==set_repeat) {
+ if (singleStream) {
+ hufSuccess = HUF_decompress1X_usingDTable(
+ dctx->litBuffer, litSize, istart+lhSize, litCSize,
+ dctx->HUFptr, flags);
+ } else {
+ assert(litSize >= MIN_LITERALS_FOR_4_STREAMS);
+ hufSuccess = HUF_decompress4X_usingDTable(
+ dctx->litBuffer, litSize, istart+lhSize, litCSize,
+ dctx->HUFptr, flags);
+ }
+ } else {
+ if (singleStream) {
+#if defined(HUF_FORCE_DECOMPRESS_X2)
+ hufSuccess = HUF_decompress1X_DCtx_wksp(
+ dctx->entropy.hufTable, dctx->litBuffer, litSize,
+ istart+lhSize, litCSize, dctx->workspace,
+ sizeof(dctx->workspace), flags);
+#else
+ hufSuccess = HUF_decompress1X1_DCtx_wksp(
+ dctx->entropy.hufTable, dctx->litBuffer, litSize,
+ istart+lhSize, litCSize, dctx->workspace,
+ sizeof(dctx->workspace), flags);
+#endif
+ } else {
+ hufSuccess = HUF_decompress4X_hufOnly_wksp(
+ dctx->entropy.hufTable, dctx->litBuffer, litSize,
+ istart+lhSize, litCSize, dctx->workspace,
+ sizeof(dctx->workspace), flags);
+ }
+ }
+ if (dctx->litBufferLocation == ZSTD_split)
+ {
+ ZSTD_memcpy(dctx->litExtraBuffer, dctx->litBufferEnd - ZSTD_LITBUFFEREXTRASIZE, ZSTD_LITBUFFEREXTRASIZE);
+ ZSTD_memmove(dctx->litBuffer + ZSTD_LITBUFFEREXTRASIZE - WILDCOPY_OVERLENGTH, dctx->litBuffer, litSize - ZSTD_LITBUFFEREXTRASIZE);
+ dctx->litBuffer += ZSTD_LITBUFFEREXTRASIZE - WILDCOPY_OVERLENGTH;
+ dctx->litBufferEnd -= WILDCOPY_OVERLENGTH;
+ }
+
+ RETURN_ERROR_IF(HUF_isError(hufSuccess), corruption_detected, "");
+
+ dctx->litPtr = dctx->litBuffer;
+ dctx->litSize = litSize;
+ dctx->litEntropy = 1;
+ if (litEncType==set_compressed) dctx->HUFptr = dctx->entropy.hufTable;
+ return litCSize + lhSize;
+ }
+
+ case set_basic:
+ { size_t litSize, lhSize;
+ U32 const lhlCode = ((istart[0]) >> 2) & 3;
+ size_t expectedWriteSize = MIN(ZSTD_BLOCKSIZE_MAX, dstCapacity);
+ switch(lhlCode)
+ {
+ case 0: case 2: default: /* note : default is impossible, since lhlCode into [0..3] */
+ lhSize = 1;
+ litSize = istart[0] >> 3;
+ break;
+ case 1:
+ lhSize = 2;
+ litSize = MEM_readLE16(istart) >> 4;
+ break;
+ case 3:
+ lhSize = 3;
+ RETURN_ERROR_IF(srcSize<3, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 2; here we need lhSize = 3");
+ litSize = MEM_readLE24(istart) >> 4;
+ break;
+ }
+
+ RETURN_ERROR_IF(litSize > 0 && dst == NULL, dstSize_tooSmall, "NULL not handled");
+ RETURN_ERROR_IF(expectedWriteSize < litSize, dstSize_tooSmall, "");
+ ZSTD_allocateLiteralsBuffer(dctx, dst, dstCapacity, litSize, streaming, expectedWriteSize, 1);
+ if (lhSize+litSize+WILDCOPY_OVERLENGTH > srcSize) { /* risk reading beyond src buffer with wildcopy */
+ RETURN_ERROR_IF(litSize+lhSize > srcSize, corruption_detected, "");
+ if (dctx->litBufferLocation == ZSTD_split)
+ {
+ ZSTD_memcpy(dctx->litBuffer, istart + lhSize, litSize - ZSTD_LITBUFFEREXTRASIZE);
+ ZSTD_memcpy(dctx->litExtraBuffer, istart + lhSize + litSize - ZSTD_LITBUFFEREXTRASIZE, ZSTD_LITBUFFEREXTRASIZE);
+ }
+ else
+ {
+ ZSTD_memcpy(dctx->litBuffer, istart + lhSize, litSize);
+ }
+ dctx->litPtr = dctx->litBuffer;
+ dctx->litSize = litSize;
+ return lhSize+litSize;
+ }
+ /* direct reference into compressed stream */
+ dctx->litPtr = istart+lhSize;
+ dctx->litSize = litSize;
+ dctx->litBufferEnd = dctx->litPtr + litSize;
+ dctx->litBufferLocation = ZSTD_not_in_dst;
+ return lhSize+litSize;
+ }
+
+ case set_rle:
+ { U32 const lhlCode = ((istart[0]) >> 2) & 3;
+ size_t litSize, lhSize;
+ size_t expectedWriteSize = MIN(ZSTD_BLOCKSIZE_MAX, dstCapacity);
+ switch(lhlCode)
+ {
+ case 0: case 2: default: /* note : default is impossible, since lhlCode into [0..3] */
+ lhSize = 1;
+ litSize = istart[0] >> 3;
+ break;
+ case 1:
+ lhSize = 2;
+ RETURN_ERROR_IF(srcSize<3, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 2; here we need lhSize+1 = 3");
+ litSize = MEM_readLE16(istart) >> 4;
+ break;
+ case 3:
+ lhSize = 3;
+ RETURN_ERROR_IF(srcSize<4, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 2; here we need lhSize+1 = 4");
+ litSize = MEM_readLE24(istart) >> 4;
+ break;
+ }
+ RETURN_ERROR_IF(litSize > 0 && dst == NULL, dstSize_tooSmall, "NULL not handled");
+ RETURN_ERROR_IF(litSize > ZSTD_BLOCKSIZE_MAX, corruption_detected, "");
+ RETURN_ERROR_IF(expectedWriteSize < litSize, dstSize_tooSmall, "");
+ ZSTD_allocateLiteralsBuffer(dctx, dst, dstCapacity, litSize, streaming, expectedWriteSize, 1);
+ if (dctx->litBufferLocation == ZSTD_split)
+ {
+ ZSTD_memset(dctx->litBuffer, istart[lhSize], litSize - ZSTD_LITBUFFEREXTRASIZE);
+ ZSTD_memset(dctx->litExtraBuffer, istart[lhSize], ZSTD_LITBUFFEREXTRASIZE);
+ }
+ else
+ {
+ ZSTD_memset(dctx->litBuffer, istart[lhSize], litSize);
+ }
+ dctx->litPtr = dctx->litBuffer;
+ dctx->litSize = litSize;
+ return lhSize+1;
+ }
+ default:
+ RETURN_ERROR(corruption_detected, "impossible");
+ }
+ }
+}
+
+/* Default FSE distribution tables.
+ * These are pre-calculated FSE decoding tables using default distributions as defined in specification :
+ * https://github.com/facebook/zstd/blob/release/doc/zstd_compression_format.md#default-distributions
+ * They were generated programmatically with following method :
+ * - start from default distributions, present in /lib/common/zstd_internal.h
+ * - generate tables normally, using ZSTD_buildFSETable()
+ * - printout the content of tables
+ * - pretify output, report below, test with fuzzer to ensure it's correct */
+
+/* Default FSE distribution table for Literal Lengths */
+static const ZSTD_seqSymbol LL_defaultDTable[(1<<LL_DEFAULTNORMLOG)+1] = {
+ { 1, 1, 1, LL_DEFAULTNORMLOG}, /* header : fastMode, tableLog */
+ /* nextState, nbAddBits, nbBits, baseVal */
+ { 0, 0, 4, 0}, { 16, 0, 4, 0},
+ { 32, 0, 5, 1}, { 0, 0, 5, 3},
+ { 0, 0, 5, 4}, { 0, 0, 5, 6},
+ { 0, 0, 5, 7}, { 0, 0, 5, 9},
+ { 0, 0, 5, 10}, { 0, 0, 5, 12},
+ { 0, 0, 6, 14}, { 0, 1, 5, 16},
+ { 0, 1, 5, 20}, { 0, 1, 5, 22},
+ { 0, 2, 5, 28}, { 0, 3, 5, 32},
+ { 0, 4, 5, 48}, { 32, 6, 5, 64},
+ { 0, 7, 5, 128}, { 0, 8, 6, 256},
+ { 0, 10, 6, 1024}, { 0, 12, 6, 4096},
+ { 32, 0, 4, 0}, { 0, 0, 4, 1},
+ { 0, 0, 5, 2}, { 32, 0, 5, 4},
+ { 0, 0, 5, 5}, { 32, 0, 5, 7},
+ { 0, 0, 5, 8}, { 32, 0, 5, 10},
+ { 0, 0, 5, 11}, { 0, 0, 6, 13},
+ { 32, 1, 5, 16}, { 0, 1, 5, 18},
+ { 32, 1, 5, 22}, { 0, 2, 5, 24},
+ { 32, 3, 5, 32}, { 0, 3, 5, 40},
+ { 0, 6, 4, 64}, { 16, 6, 4, 64},
+ { 32, 7, 5, 128}, { 0, 9, 6, 512},
+ { 0, 11, 6, 2048}, { 48, 0, 4, 0},
+ { 16, 0, 4, 1}, { 32, 0, 5, 2},
+ { 32, 0, 5, 3}, { 32, 0, 5, 5},
+ { 32, 0, 5, 6}, { 32, 0, 5, 8},
+ { 32, 0, 5, 9}, { 32, 0, 5, 11},
+ { 32, 0, 5, 12}, { 0, 0, 6, 15},
+ { 32, 1, 5, 18}, { 32, 1, 5, 20},
+ { 32, 2, 5, 24}, { 32, 2, 5, 28},
+ { 32, 3, 5, 40}, { 32, 4, 5, 48},
+ { 0, 16, 6,65536}, { 0, 15, 6,32768},
+ { 0, 14, 6,16384}, { 0, 13, 6, 8192},
+}; /* LL_defaultDTable */
+
+/* Default FSE distribution table for Offset Codes */
+static const ZSTD_seqSymbol OF_defaultDTable[(1<<OF_DEFAULTNORMLOG)+1] = {
+ { 1, 1, 1, OF_DEFAULTNORMLOG}, /* header : fastMode, tableLog */
+ /* nextState, nbAddBits, nbBits, baseVal */
+ { 0, 0, 5, 0}, { 0, 6, 4, 61},
+ { 0, 9, 5, 509}, { 0, 15, 5,32765},
+ { 0, 21, 5,2097149}, { 0, 3, 5, 5},
+ { 0, 7, 4, 125}, { 0, 12, 5, 4093},
+ { 0, 18, 5,262141}, { 0, 23, 5,8388605},
+ { 0, 5, 5, 29}, { 0, 8, 4, 253},
+ { 0, 14, 5,16381}, { 0, 20, 5,1048573},
+ { 0, 2, 5, 1}, { 16, 7, 4, 125},
+ { 0, 11, 5, 2045}, { 0, 17, 5,131069},
+ { 0, 22, 5,4194301}, { 0, 4, 5, 13},
+ { 16, 8, 4, 253}, { 0, 13, 5, 8189},
+ { 0, 19, 5,524285}, { 0, 1, 5, 1},
+ { 16, 6, 4, 61}, { 0, 10, 5, 1021},
+ { 0, 16, 5,65533}, { 0, 28, 5,268435453},
+ { 0, 27, 5,134217725}, { 0, 26, 5,67108861},
+ { 0, 25, 5,33554429}, { 0, 24, 5,16777213},
+}; /* OF_defaultDTable */
+
+
+/* Default FSE distribution table for Match Lengths */
+static const ZSTD_seqSymbol ML_defaultDTable[(1<<ML_DEFAULTNORMLOG)+1] = {
+ { 1, 1, 1, ML_DEFAULTNORMLOG}, /* header : fastMode, tableLog */
+ /* nextState, nbAddBits, nbBits, baseVal */
+ { 0, 0, 6, 3}, { 0, 0, 4, 4},
+ { 32, 0, 5, 5}, { 0, 0, 5, 6},
+ { 0, 0, 5, 8}, { 0, 0, 5, 9},
+ { 0, 0, 5, 11}, { 0, 0, 6, 13},
+ { 0, 0, 6, 16}, { 0, 0, 6, 19},
+ { 0, 0, 6, 22}, { 0, 0, 6, 25},
+ { 0, 0, 6, 28}, { 0, 0, 6, 31},
+ { 0, 0, 6, 34}, { 0, 1, 6, 37},
+ { 0, 1, 6, 41}, { 0, 2, 6, 47},
+ { 0, 3, 6, 59}, { 0, 4, 6, 83},
+ { 0, 7, 6, 131}, { 0, 9, 6, 515},
+ { 16, 0, 4, 4}, { 0, 0, 4, 5},
+ { 32, 0, 5, 6}, { 0, 0, 5, 7},
+ { 32, 0, 5, 9}, { 0, 0, 5, 10},
+ { 0, 0, 6, 12}, { 0, 0, 6, 15},
+ { 0, 0, 6, 18}, { 0, 0, 6, 21},
+ { 0, 0, 6, 24}, { 0, 0, 6, 27},
+ { 0, 0, 6, 30}, { 0, 0, 6, 33},
+ { 0, 1, 6, 35}, { 0, 1, 6, 39},
+ { 0, 2, 6, 43}, { 0, 3, 6, 51},
+ { 0, 4, 6, 67}, { 0, 5, 6, 99},
+ { 0, 8, 6, 259}, { 32, 0, 4, 4},
+ { 48, 0, 4, 4}, { 16, 0, 4, 5},
+ { 32, 0, 5, 7}, { 32, 0, 5, 8},
+ { 32, 0, 5, 10}, { 32, 0, 5, 11},
+ { 0, 0, 6, 14}, { 0, 0, 6, 17},
+ { 0, 0, 6, 20}, { 0, 0, 6, 23},
+ { 0, 0, 6, 26}, { 0, 0, 6, 29},
+ { 0, 0, 6, 32}, { 0, 16, 6,65539},
+ { 0, 15, 6,32771}, { 0, 14, 6,16387},
+ { 0, 13, 6, 8195}, { 0, 12, 6, 4099},
+ { 0, 11, 6, 2051}, { 0, 10, 6, 1027},
+}; /* ML_defaultDTable */
+
+
+static void ZSTD_buildSeqTable_rle(ZSTD_seqSymbol* dt, U32 baseValue, U8 nbAddBits)
+{
+ void* ptr = dt;
+ ZSTD_seqSymbol_header* const DTableH = (ZSTD_seqSymbol_header*)ptr;
+ ZSTD_seqSymbol* const cell = dt + 1;
+
+ DTableH->tableLog = 0;
+ DTableH->fastMode = 0;
+
+ cell->nbBits = 0;
+ cell->nextState = 0;
+ assert(nbAddBits < 255);
+ cell->nbAdditionalBits = nbAddBits;
+ cell->baseValue = baseValue;
+}
+
+
+/* ZSTD_buildFSETable() :
+ * generate FSE decoding table for one symbol (ll, ml or off)
+ * cannot fail if input is valid =>
+ * all inputs are presumed validated at this stage */
+FORCE_INLINE_TEMPLATE
+void ZSTD_buildFSETable_body(ZSTD_seqSymbol* dt,
+ const short* normalizedCounter, unsigned maxSymbolValue,
+ const U32* baseValue, const U8* nbAdditionalBits,
+ unsigned tableLog, void* wksp, size_t wkspSize)
+{
+ ZSTD_seqSymbol* const tableDecode = dt+1;
+ U32 const maxSV1 = maxSymbolValue + 1;
+ U32 const tableSize = 1 << tableLog;
+
+ U16* symbolNext = (U16*)wksp;
+ BYTE* spread = (BYTE*)(symbolNext + MaxSeq + 1);
+ U32 highThreshold = tableSize - 1;
+
+
+ /* Sanity Checks */
+ assert(maxSymbolValue <= MaxSeq);
+ assert(tableLog <= MaxFSELog);
+ assert(wkspSize >= ZSTD_BUILD_FSE_TABLE_WKSP_SIZE);
+ (void)wkspSize;
+ /* Init, lay down lowprob symbols */
+ { ZSTD_seqSymbol_header DTableH;
+ DTableH.tableLog = tableLog;
+ DTableH.fastMode = 1;
+ { S16 const largeLimit= (S16)(1 << (tableLog-1));
+ U32 s;
+ for (s=0; s<maxSV1; s++) {
+ if (normalizedCounter[s]==-1) {
+ tableDecode[highThreshold--].baseValue = s;
+ symbolNext[s] = 1;
+ } else {
+ if (normalizedCounter[s] >= largeLimit) DTableH.fastMode=0;
+ assert(normalizedCounter[s]>=0);
+ symbolNext[s] = (U16)normalizedCounter[s];
+ } } }
+ ZSTD_memcpy(dt, &DTableH, sizeof(DTableH));
+ }
+
+ /* Spread symbols */
+ assert(tableSize <= 512);
+ /* Specialized symbol spreading for the case when there are
+ * no low probability (-1 count) symbols. When compressing
+ * small blocks we avoid low probability symbols to hit this
+ * case, since header decoding speed matters more.
+ */
+ if (highThreshold == tableSize - 1) {
+ size_t const tableMask = tableSize-1;
+ size_t const step = FSE_TABLESTEP(tableSize);
+ /* First lay down the symbols in order.
+ * We use a uint64_t to lay down 8 bytes at a time. This reduces branch
+ * misses since small blocks generally have small table logs, so nearly
+ * all symbols have counts <= 8. We ensure we have 8 bytes at the end of
+ * our buffer to handle the over-write.
+ */
+ {
+ U64 const add = 0x0101010101010101ull;
+ size_t pos = 0;
+ U64 sv = 0;
+ U32 s;
+ for (s=0; s<maxSV1; ++s, sv += add) {
+ int i;
+ int const n = normalizedCounter[s];
+ MEM_write64(spread + pos, sv);
+ for (i = 8; i < n; i += 8) {
+ MEM_write64(spread + pos + i, sv);
+ }
+ assert(n>=0);
+ pos += (size_t)n;
+ }
+ }
+ /* Now we spread those positions across the table.
+ * The benefit of doing it in two stages is that we avoid the
+ * variable size inner loop, which caused lots of branch misses.
+ * Now we can run through all the positions without any branch misses.
+ * We unroll the loop twice, since that is what empirically worked best.
+ */
+ {
+ size_t position = 0;
+ size_t s;
+ size_t const unroll = 2;
+ assert(tableSize % unroll == 0); /* FSE_MIN_TABLELOG is 5 */
+ for (s = 0; s < (size_t)tableSize; s += unroll) {
+ size_t u;
+ for (u = 0; u < unroll; ++u) {
+ size_t const uPosition = (position + (u * step)) & tableMask;
+ tableDecode[uPosition].baseValue = spread[s + u];
+ }
+ position = (position + (unroll * step)) & tableMask;
+ }
+ assert(position == 0);
+ }
+ } else {
+ U32 const tableMask = tableSize-1;
+ U32 const step = FSE_TABLESTEP(tableSize);
+ U32 s, position = 0;
+ for (s=0; s<maxSV1; s++) {
+ int i;
+ int const n = normalizedCounter[s];
+ for (i=0; i<n; i++) {
+ tableDecode[position].baseValue = s;
+ position = (position + step) & tableMask;
+ while (UNLIKELY(position > highThreshold)) position = (position + step) & tableMask; /* lowprob area */
+ } }
+ assert(position == 0); /* position must reach all cells once, otherwise normalizedCounter is incorrect */
+ }
+
+ /* Build Decoding table */
+ {
+ U32 u;
+ for (u=0; u<tableSize; u++) {
+ U32 const symbol = tableDecode[u].baseValue;
+ U32 const nextState = symbolNext[symbol]++;
+ tableDecode[u].nbBits = (BYTE) (tableLog - ZSTD_highbit32(nextState) );
+ tableDecode[u].nextState = (U16) ( (nextState << tableDecode[u].nbBits) - tableSize);
+ assert(nbAdditionalBits[symbol] < 255);
+ tableDecode[u].nbAdditionalBits = nbAdditionalBits[symbol];
+ tableDecode[u].baseValue = baseValue[symbol];
+ }
+ }
+}
+
+/* Avoids the FORCE_INLINE of the _body() function. */
+static void ZSTD_buildFSETable_body_default(ZSTD_seqSymbol* dt,
+ const short* normalizedCounter, unsigned maxSymbolValue,
+ const U32* baseValue, const U8* nbAdditionalBits,
+ unsigned tableLog, void* wksp, size_t wkspSize)
+{
+ ZSTD_buildFSETable_body(dt, normalizedCounter, maxSymbolValue,
+ baseValue, nbAdditionalBits, tableLog, wksp, wkspSize);
+}
+
+#if DYNAMIC_BMI2
+BMI2_TARGET_ATTRIBUTE static void ZSTD_buildFSETable_body_bmi2(ZSTD_seqSymbol* dt,
+ const short* normalizedCounter, unsigned maxSymbolValue,
+ const U32* baseValue, const U8* nbAdditionalBits,
+ unsigned tableLog, void* wksp, size_t wkspSize)
+{
+ ZSTD_buildFSETable_body(dt, normalizedCounter, maxSymbolValue,
+ baseValue, nbAdditionalBits, tableLog, wksp, wkspSize);
+}
+#endif
+
+void ZSTD_buildFSETable(ZSTD_seqSymbol* dt,
+ const short* normalizedCounter, unsigned maxSymbolValue,
+ const U32* baseValue, const U8* nbAdditionalBits,
+ unsigned tableLog, void* wksp, size_t wkspSize, int bmi2)
+{
+#if DYNAMIC_BMI2
+ if (bmi2) {
+ ZSTD_buildFSETable_body_bmi2(dt, normalizedCounter, maxSymbolValue,
+ baseValue, nbAdditionalBits, tableLog, wksp, wkspSize);
+ return;
+ }
+#endif
+ (void)bmi2;
+ ZSTD_buildFSETable_body_default(dt, normalizedCounter, maxSymbolValue,
+ baseValue, nbAdditionalBits, tableLog, wksp, wkspSize);
+}
+
+
+/*! ZSTD_buildSeqTable() :
+ * @return : nb bytes read from src,
+ * or an error code if it fails */
+static size_t ZSTD_buildSeqTable(ZSTD_seqSymbol* DTableSpace, const ZSTD_seqSymbol** DTablePtr,
+ symbolEncodingType_e type, unsigned max, U32 maxLog,
+ const void* src, size_t srcSize,
+ const U32* baseValue, const U8* nbAdditionalBits,
+ const ZSTD_seqSymbol* defaultTable, U32 flagRepeatTable,
+ int ddictIsCold, int nbSeq, U32* wksp, size_t wkspSize,
+ int bmi2)
+{
+ switch(type)
+ {
+ case set_rle :
+ RETURN_ERROR_IF(!srcSize, srcSize_wrong, "");
+ RETURN_ERROR_IF((*(const BYTE*)src) > max, corruption_detected, "");
+ { U32 const symbol = *(const BYTE*)src;
+ U32 const baseline = baseValue[symbol];
+ U8 const nbBits = nbAdditionalBits[symbol];
+ ZSTD_buildSeqTable_rle(DTableSpace, baseline, nbBits);
+ }
+ *DTablePtr = DTableSpace;
+ return 1;
+ case set_basic :
+ *DTablePtr = defaultTable;
+ return 0;
+ case set_repeat:
+ RETURN_ERROR_IF(!flagRepeatTable, corruption_detected, "");
+ /* prefetch FSE table if used */
+ if (ddictIsCold && (nbSeq > 24 /* heuristic */)) {
+ const void* const pStart = *DTablePtr;
+ size_t const pSize = sizeof(ZSTD_seqSymbol) * (SEQSYMBOL_TABLE_SIZE(maxLog));
+ PREFETCH_AREA(pStart, pSize);
+ }
+ return 0;
+ case set_compressed :
+ { unsigned tableLog;
+ S16 norm[MaxSeq+1];
+ size_t const headerSize = FSE_readNCount(norm, &max, &tableLog, src, srcSize);
+ RETURN_ERROR_IF(FSE_isError(headerSize), corruption_detected, "");
+ RETURN_ERROR_IF(tableLog > maxLog, corruption_detected, "");
+ ZSTD_buildFSETable(DTableSpace, norm, max, baseValue, nbAdditionalBits, tableLog, wksp, wkspSize, bmi2);
+ *DTablePtr = DTableSpace;
+ return headerSize;
+ }
+ default :
+ assert(0);
+ RETURN_ERROR(GENERIC, "impossible");
+ }
+}
+
+size_t ZSTD_decodeSeqHeaders(ZSTD_DCtx* dctx, int* nbSeqPtr,
+ const void* src, size_t srcSize)
+{
+ const BYTE* const istart = (const BYTE*)src;
+ const BYTE* const iend = istart + srcSize;
+ const BYTE* ip = istart;
+ int nbSeq;
+ DEBUGLOG(5, "ZSTD_decodeSeqHeaders");
+
+ /* check */
+ RETURN_ERROR_IF(srcSize < MIN_SEQUENCES_SIZE, srcSize_wrong, "");
+
+ /* SeqHead */
+ nbSeq = *ip++;
+ if (!nbSeq) {
+ *nbSeqPtr=0;
+ RETURN_ERROR_IF(srcSize != 1, srcSize_wrong, "");
+ return 1;
+ }
+ if (nbSeq > 0x7F) {
+ if (nbSeq == 0xFF) {
+ RETURN_ERROR_IF(ip+2 > iend, srcSize_wrong, "");
+ nbSeq = MEM_readLE16(ip) + LONGNBSEQ;
+ ip+=2;
+ } else {
+ RETURN_ERROR_IF(ip >= iend, srcSize_wrong, "");
+ nbSeq = ((nbSeq-0x80)<<8) + *ip++;
+ }
+ }
+ *nbSeqPtr = nbSeq;
+
+ /* FSE table descriptors */
+ RETURN_ERROR_IF(ip+1 > iend, srcSize_wrong, ""); /* minimum possible size: 1 byte for symbol encoding types */
+ { symbolEncodingType_e const LLtype = (symbolEncodingType_e)(*ip >> 6);
+ symbolEncodingType_e const OFtype = (symbolEncodingType_e)((*ip >> 4) & 3);
+ symbolEncodingType_e const MLtype = (symbolEncodingType_e)((*ip >> 2) & 3);
+ ip++;
+
+ /* Build DTables */
+ { size_t const llhSize = ZSTD_buildSeqTable(dctx->entropy.LLTable, &dctx->LLTptr,
+ LLtype, MaxLL, LLFSELog,
+ ip, iend-ip,
+ LL_base, LL_bits,
+ LL_defaultDTable, dctx->fseEntropy,
+ dctx->ddictIsCold, nbSeq,
+ dctx->workspace, sizeof(dctx->workspace),
+ ZSTD_DCtx_get_bmi2(dctx));
+ RETURN_ERROR_IF(ZSTD_isError(llhSize), corruption_detected, "ZSTD_buildSeqTable failed");
+ ip += llhSize;
+ }
+
+ { size_t const ofhSize = ZSTD_buildSeqTable(dctx->entropy.OFTable, &dctx->OFTptr,
+ OFtype, MaxOff, OffFSELog,
+ ip, iend-ip,
+ OF_base, OF_bits,
+ OF_defaultDTable, dctx->fseEntropy,
+ dctx->ddictIsCold, nbSeq,
+ dctx->workspace, sizeof(dctx->workspace),
+ ZSTD_DCtx_get_bmi2(dctx));
+ RETURN_ERROR_IF(ZSTD_isError(ofhSize), corruption_detected, "ZSTD_buildSeqTable failed");
+ ip += ofhSize;
+ }
+
+ { size_t const mlhSize = ZSTD_buildSeqTable(dctx->entropy.MLTable, &dctx->MLTptr,
+ MLtype, MaxML, MLFSELog,
+ ip, iend-ip,
+ ML_base, ML_bits,
+ ML_defaultDTable, dctx->fseEntropy,
+ dctx->ddictIsCold, nbSeq,
+ dctx->workspace, sizeof(dctx->workspace),
+ ZSTD_DCtx_get_bmi2(dctx));
+ RETURN_ERROR_IF(ZSTD_isError(mlhSize), corruption_detected, "ZSTD_buildSeqTable failed");
+ ip += mlhSize;
+ }
+ }
+
+ return ip-istart;
+}
+
+
+typedef struct {
+ size_t litLength;
+ size_t matchLength;
+ size_t offset;
+} seq_t;
+
+typedef struct {
+ size_t state;
+ const ZSTD_seqSymbol* table;
+} ZSTD_fseState;
+
+typedef struct {
+ BIT_DStream_t DStream;
+ ZSTD_fseState stateLL;
+ ZSTD_fseState stateOffb;
+ ZSTD_fseState stateML;
+ size_t prevOffset[ZSTD_REP_NUM];
+} seqState_t;
+
+/*! ZSTD_overlapCopy8() :
+ * Copies 8 bytes from ip to op and updates op and ip where ip <= op.
+ * If the offset is < 8 then the offset is spread to at least 8 bytes.
+ *
+ * Precondition: *ip <= *op
+ * Postcondition: *op - *op >= 8
+ */
+HINT_INLINE void ZSTD_overlapCopy8(BYTE** op, BYTE const** ip, size_t offset) {
+ assert(*ip <= *op);
+ if (offset < 8) {
+ /* close range match, overlap */
+ static const U32 dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 }; /* added */
+ static const int dec64table[] = { 8, 8, 8, 7, 8, 9,10,11 }; /* subtracted */
+ int const sub2 = dec64table[offset];
+ (*op)[0] = (*ip)[0];
+ (*op)[1] = (*ip)[1];
+ (*op)[2] = (*ip)[2];
+ (*op)[3] = (*ip)[3];
+ *ip += dec32table[offset];
+ ZSTD_copy4(*op+4, *ip);
+ *ip -= sub2;
+ } else {
+ ZSTD_copy8(*op, *ip);
+ }
+ *ip += 8;
+ *op += 8;
+ assert(*op - *ip >= 8);
+}
+
+/*! ZSTD_safecopy() :
+ * Specialized version of memcpy() that is allowed to READ up to WILDCOPY_OVERLENGTH past the input buffer
+ * and write up to 16 bytes past oend_w (op >= oend_w is allowed).
+ * This function is only called in the uncommon case where the sequence is near the end of the block. It
+ * should be fast for a single long sequence, but can be slow for several short sequences.
+ *
+ * @param ovtype controls the overlap detection
+ * - ZSTD_no_overlap: The source and destination are guaranteed to be at least WILDCOPY_VECLEN bytes apart.
+ * - ZSTD_overlap_src_before_dst: The src and dst may overlap and may be any distance apart.
+ * The src buffer must be before the dst buffer.
+ */
+static void ZSTD_safecopy(BYTE* op, const BYTE* const oend_w, BYTE const* ip, ptrdiff_t length, ZSTD_overlap_e ovtype) {
+ ptrdiff_t const diff = op - ip;
+ BYTE* const oend = op + length;
+
+ assert((ovtype == ZSTD_no_overlap && (diff <= -8 || diff >= 8 || op >= oend_w)) ||
+ (ovtype == ZSTD_overlap_src_before_dst && diff >= 0));
+
+ if (length < 8) {
+ /* Handle short lengths. */
+ while (op < oend) *op++ = *ip++;
+ return;
+ }
+ if (ovtype == ZSTD_overlap_src_before_dst) {
+ /* Copy 8 bytes and ensure the offset >= 8 when there can be overlap. */
+ assert(length >= 8);
+ ZSTD_overlapCopy8(&op, &ip, diff);
+ length -= 8;
+ assert(op - ip >= 8);
+ assert(op <= oend);
+ }
+
+ if (oend <= oend_w) {
+ /* No risk of overwrite. */
+ ZSTD_wildcopy(op, ip, length, ovtype);
+ return;
+ }
+ if (op <= oend_w) {
+ /* Wildcopy until we get close to the end. */
+ assert(oend > oend_w);
+ ZSTD_wildcopy(op, ip, oend_w - op, ovtype);
+ ip += oend_w - op;
+ op += oend_w - op;
+ }
+ /* Handle the leftovers. */
+ while (op < oend) *op++ = *ip++;
+}
+
+/* ZSTD_safecopyDstBeforeSrc():
+ * This version allows overlap with dst before src, or handles the non-overlap case with dst after src
+ * Kept separate from more common ZSTD_safecopy case to avoid performance impact to the safecopy common case */
+static void ZSTD_safecopyDstBeforeSrc(BYTE* op, BYTE const* ip, ptrdiff_t length) {
+ ptrdiff_t const diff = op - ip;
+ BYTE* const oend = op + length;
+
+ if (length < 8 || diff > -8) {
+ /* Handle short lengths, close overlaps, and dst not before src. */
+ while (op < oend) *op++ = *ip++;
+ return;
+ }
+
+ if (op <= oend - WILDCOPY_OVERLENGTH && diff < -WILDCOPY_VECLEN) {
+ ZSTD_wildcopy(op, ip, oend - WILDCOPY_OVERLENGTH - op, ZSTD_no_overlap);
+ ip += oend - WILDCOPY_OVERLENGTH - op;
+ op += oend - WILDCOPY_OVERLENGTH - op;
+ }
+
+ /* Handle the leftovers. */
+ while (op < oend) *op++ = *ip++;
+}
+
+/* ZSTD_execSequenceEnd():
+ * This version handles cases that are near the end of the output buffer. It requires
+ * more careful checks to make sure there is no overflow. By separating out these hard
+ * and unlikely cases, we can speed up the common cases.
+ *
+ * NOTE: This function needs to be fast for a single long sequence, but doesn't need
+ * to be optimized for many small sequences, since those fall into ZSTD_execSequence().
+ */
+FORCE_NOINLINE
+size_t ZSTD_execSequenceEnd(BYTE* op,
+ BYTE* const oend, seq_t sequence,
+ const BYTE** litPtr, const BYTE* const litLimit,
+ const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd)
+{
+ BYTE* const oLitEnd = op + sequence.litLength;
+ size_t const sequenceLength = sequence.litLength + sequence.matchLength;
+ const BYTE* const iLitEnd = *litPtr + sequence.litLength;
+ const BYTE* match = oLitEnd - sequence.offset;
+ BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH;
+
+ /* bounds checks : careful of address space overflow in 32-bit mode */
+ RETURN_ERROR_IF(sequenceLength > (size_t)(oend - op), dstSize_tooSmall, "last match must fit within dstBuffer");
+ RETURN_ERROR_IF(sequence.litLength > (size_t)(litLimit - *litPtr), corruption_detected, "try to read beyond literal buffer");
+ assert(op < op + sequenceLength);
+ assert(oLitEnd < op + sequenceLength);
+
+ /* copy literals */
+ ZSTD_safecopy(op, oend_w, *litPtr, sequence.litLength, ZSTD_no_overlap);
+ op = oLitEnd;
+ *litPtr = iLitEnd;
+
+ /* copy Match */
+ if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
+ /* offset beyond prefix */
+ RETURN_ERROR_IF(sequence.offset > (size_t)(oLitEnd - virtualStart), corruption_detected, "");
+ match = dictEnd - (prefixStart - match);
+ if (match + sequence.matchLength <= dictEnd) {
+ ZSTD_memmove(oLitEnd, match, sequence.matchLength);
+ return sequenceLength;
+ }
+ /* span extDict & currentPrefixSegment */
+ { size_t const length1 = dictEnd - match;
+ ZSTD_memmove(oLitEnd, match, length1);
+ op = oLitEnd + length1;
+ sequence.matchLength -= length1;
+ match = prefixStart;
+ }
+ }
+ ZSTD_safecopy(op, oend_w, match, sequence.matchLength, ZSTD_overlap_src_before_dst);
+ return sequenceLength;
+}
+
+/* ZSTD_execSequenceEndSplitLitBuffer():
+ * This version is intended to be used during instances where the litBuffer is still split. It is kept separate to avoid performance impact for the good case.
+ */
+FORCE_NOINLINE
+size_t ZSTD_execSequenceEndSplitLitBuffer(BYTE* op,
+ BYTE* const oend, const BYTE* const oend_w, seq_t sequence,
+ const BYTE** litPtr, const BYTE* const litLimit,
+ const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd)
+{
+ BYTE* const oLitEnd = op + sequence.litLength;
+ size_t const sequenceLength = sequence.litLength + sequence.matchLength;
+ const BYTE* const iLitEnd = *litPtr + sequence.litLength;
+ const BYTE* match = oLitEnd - sequence.offset;
+
+
+ /* bounds checks : careful of address space overflow in 32-bit mode */
+ RETURN_ERROR_IF(sequenceLength > (size_t)(oend - op), dstSize_tooSmall, "last match must fit within dstBuffer");
+ RETURN_ERROR_IF(sequence.litLength > (size_t)(litLimit - *litPtr), corruption_detected, "try to read beyond literal buffer");
+ assert(op < op + sequenceLength);
+ assert(oLitEnd < op + sequenceLength);
+
+ /* copy literals */
+ RETURN_ERROR_IF(op > *litPtr && op < *litPtr + sequence.litLength, dstSize_tooSmall, "output should not catch up to and overwrite literal buffer");
+ ZSTD_safecopyDstBeforeSrc(op, *litPtr, sequence.litLength);
+ op = oLitEnd;
+ *litPtr = iLitEnd;
+
+ /* copy Match */
+ if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
+ /* offset beyond prefix */
+ RETURN_ERROR_IF(sequence.offset > (size_t)(oLitEnd - virtualStart), corruption_detected, "");
+ match = dictEnd - (prefixStart - match);
+ if (match + sequence.matchLength <= dictEnd) {
+ ZSTD_memmove(oLitEnd, match, sequence.matchLength);
+ return sequenceLength;
+ }
+ /* span extDict & currentPrefixSegment */
+ { size_t const length1 = dictEnd - match;
+ ZSTD_memmove(oLitEnd, match, length1);
+ op = oLitEnd + length1;
+ sequence.matchLength -= length1;
+ match = prefixStart;
+ }
+ }
+ ZSTD_safecopy(op, oend_w, match, sequence.matchLength, ZSTD_overlap_src_before_dst);
+ return sequenceLength;
+}
+
+HINT_INLINE
+size_t ZSTD_execSequence(BYTE* op,
+ BYTE* const oend, seq_t sequence,
+ const BYTE** litPtr, const BYTE* const litLimit,
+ const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd)
+{
+ BYTE* const oLitEnd = op + sequence.litLength;
+ size_t const sequenceLength = sequence.litLength + sequence.matchLength;
+ BYTE* const oMatchEnd = op + sequenceLength; /* risk : address space overflow (32-bits) */
+ BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH; /* risk : address space underflow on oend=NULL */
+ const BYTE* const iLitEnd = *litPtr + sequence.litLength;
+ const BYTE* match = oLitEnd - sequence.offset;
+
+ assert(op != NULL /* Precondition */);
+ assert(oend_w < oend /* No underflow */);
+
+#if defined(__aarch64__)
+ /* prefetch sequence starting from match that will be used for copy later */
+ PREFETCH_L1(match);
+#endif
+ /* Handle edge cases in a slow path:
+ * - Read beyond end of literals
+ * - Match end is within WILDCOPY_OVERLIMIT of oend
+ * - 32-bit mode and the match length overflows
+ */
+ if (UNLIKELY(
+ iLitEnd > litLimit ||
+ oMatchEnd > oend_w ||
+ (MEM_32bits() && (size_t)(oend - op) < sequenceLength + WILDCOPY_OVERLENGTH)))
+ return ZSTD_execSequenceEnd(op, oend, sequence, litPtr, litLimit, prefixStart, virtualStart, dictEnd);
+
+ /* Assumptions (everything else goes into ZSTD_execSequenceEnd()) */
+ assert(op <= oLitEnd /* No overflow */);
+ assert(oLitEnd < oMatchEnd /* Non-zero match & no overflow */);
+ assert(oMatchEnd <= oend /* No underflow */);
+ assert(iLitEnd <= litLimit /* Literal length is in bounds */);
+ assert(oLitEnd <= oend_w /* Can wildcopy literals */);
+ assert(oMatchEnd <= oend_w /* Can wildcopy matches */);
+
+ /* Copy Literals:
+ * Split out litLength <= 16 since it is nearly always true. +1.6% on gcc-9.
+ * We likely don't need the full 32-byte wildcopy.
+ */
+ assert(WILDCOPY_OVERLENGTH >= 16);
+ ZSTD_copy16(op, (*litPtr));
+ if (UNLIKELY(sequence.litLength > 16)) {
+ ZSTD_wildcopy(op + 16, (*litPtr) + 16, sequence.litLength - 16, ZSTD_no_overlap);
+ }
+ op = oLitEnd;
+ *litPtr = iLitEnd; /* update for next sequence */
+
+ /* Copy Match */
+ if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
+ /* offset beyond prefix -> go into extDict */
+ RETURN_ERROR_IF(UNLIKELY(sequence.offset > (size_t)(oLitEnd - virtualStart)), corruption_detected, "");
+ match = dictEnd + (match - prefixStart);
+ if (match + sequence.matchLength <= dictEnd) {
+ ZSTD_memmove(oLitEnd, match, sequence.matchLength);
+ return sequenceLength;
+ }
+ /* span extDict & currentPrefixSegment */
+ { size_t const length1 = dictEnd - match;
+ ZSTD_memmove(oLitEnd, match, length1);
+ op = oLitEnd + length1;
+ sequence.matchLength -= length1;
+ match = prefixStart;
+ }
+ }
+ /* Match within prefix of 1 or more bytes */
+ assert(op <= oMatchEnd);
+ assert(oMatchEnd <= oend_w);
+ assert(match >= prefixStart);
+ assert(sequence.matchLength >= 1);
+
+ /* Nearly all offsets are >= WILDCOPY_VECLEN bytes, which means we can use wildcopy
+ * without overlap checking.
+ */
+ if (LIKELY(sequence.offset >= WILDCOPY_VECLEN)) {
+ /* We bet on a full wildcopy for matches, since we expect matches to be
+ * longer than literals (in general). In silesia, ~10% of matches are longer
+ * than 16 bytes.
+ */
+ ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength, ZSTD_no_overlap);
+ return sequenceLength;
+ }
+ assert(sequence.offset < WILDCOPY_VECLEN);
+
+ /* Copy 8 bytes and spread the offset to be >= 8. */
+ ZSTD_overlapCopy8(&op, &match, sequence.offset);
+
+ /* If the match length is > 8 bytes, then continue with the wildcopy. */
+ if (sequence.matchLength > 8) {
+ assert(op < oMatchEnd);
+ ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength - 8, ZSTD_overlap_src_before_dst);
+ }
+ return sequenceLength;
+}
+
+HINT_INLINE
+size_t ZSTD_execSequenceSplitLitBuffer(BYTE* op,
+ BYTE* const oend, const BYTE* const oend_w, seq_t sequence,
+ const BYTE** litPtr, const BYTE* const litLimit,
+ const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd)
+{
+ BYTE* const oLitEnd = op + sequence.litLength;
+ size_t const sequenceLength = sequence.litLength + sequence.matchLength;
+ BYTE* const oMatchEnd = op + sequenceLength; /* risk : address space overflow (32-bits) */
+ const BYTE* const iLitEnd = *litPtr + sequence.litLength;
+ const BYTE* match = oLitEnd - sequence.offset;
+
+ assert(op != NULL /* Precondition */);
+ assert(oend_w < oend /* No underflow */);
+ /* Handle edge cases in a slow path:
+ * - Read beyond end of literals
+ * - Match end is within WILDCOPY_OVERLIMIT of oend
+ * - 32-bit mode and the match length overflows
+ */
+ if (UNLIKELY(
+ iLitEnd > litLimit ||
+ oMatchEnd > oend_w ||
+ (MEM_32bits() && (size_t)(oend - op) < sequenceLength + WILDCOPY_OVERLENGTH)))
+ return ZSTD_execSequenceEndSplitLitBuffer(op, oend, oend_w, sequence, litPtr, litLimit, prefixStart, virtualStart, dictEnd);
+
+ /* Assumptions (everything else goes into ZSTD_execSequenceEnd()) */
+ assert(op <= oLitEnd /* No overflow */);
+ assert(oLitEnd < oMatchEnd /* Non-zero match & no overflow */);
+ assert(oMatchEnd <= oend /* No underflow */);
+ assert(iLitEnd <= litLimit /* Literal length is in bounds */);
+ assert(oLitEnd <= oend_w /* Can wildcopy literals */);
+ assert(oMatchEnd <= oend_w /* Can wildcopy matches */);
+
+ /* Copy Literals:
+ * Split out litLength <= 16 since it is nearly always true. +1.6% on gcc-9.
+ * We likely don't need the full 32-byte wildcopy.
+ */
+ assert(WILDCOPY_OVERLENGTH >= 16);
+ ZSTD_copy16(op, (*litPtr));
+ if (UNLIKELY(sequence.litLength > 16)) {
+ ZSTD_wildcopy(op+16, (*litPtr)+16, sequence.litLength-16, ZSTD_no_overlap);
+ }
+ op = oLitEnd;
+ *litPtr = iLitEnd; /* update for next sequence */
+
+ /* Copy Match */
+ if (sequence.offset > (size_t)(oLitEnd - prefixStart)) {
+ /* offset beyond prefix -> go into extDict */
+ RETURN_ERROR_IF(UNLIKELY(sequence.offset > (size_t)(oLitEnd - virtualStart)), corruption_detected, "");
+ match = dictEnd + (match - prefixStart);
+ if (match + sequence.matchLength <= dictEnd) {
+ ZSTD_memmove(oLitEnd, match, sequence.matchLength);
+ return sequenceLength;
+ }
+ /* span extDict & currentPrefixSegment */
+ { size_t const length1 = dictEnd - match;
+ ZSTD_memmove(oLitEnd, match, length1);
+ op = oLitEnd + length1;
+ sequence.matchLength -= length1;
+ match = prefixStart;
+ } }
+ /* Match within prefix of 1 or more bytes */
+ assert(op <= oMatchEnd);
+ assert(oMatchEnd <= oend_w);
+ assert(match >= prefixStart);
+ assert(sequence.matchLength >= 1);
+
+ /* Nearly all offsets are >= WILDCOPY_VECLEN bytes, which means we can use wildcopy
+ * without overlap checking.
+ */
+ if (LIKELY(sequence.offset >= WILDCOPY_VECLEN)) {
+ /* We bet on a full wildcopy for matches, since we expect matches to be
+ * longer than literals (in general). In silesia, ~10% of matches are longer
+ * than 16 bytes.
+ */
+ ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength, ZSTD_no_overlap);
+ return sequenceLength;
+ }
+ assert(sequence.offset < WILDCOPY_VECLEN);
+
+ /* Copy 8 bytes and spread the offset to be >= 8. */
+ ZSTD_overlapCopy8(&op, &match, sequence.offset);
+
+ /* If the match length is > 8 bytes, then continue with the wildcopy. */
+ if (sequence.matchLength > 8) {
+ assert(op < oMatchEnd);
+ ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength-8, ZSTD_overlap_src_before_dst);
+ }
+ return sequenceLength;
+}
+
+
+static void
+ZSTD_initFseState(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD, const ZSTD_seqSymbol* dt)
+{
+ const void* ptr = dt;
+ const ZSTD_seqSymbol_header* const DTableH = (const ZSTD_seqSymbol_header*)ptr;
+ DStatePtr->state = BIT_readBits(bitD, DTableH->tableLog);
+ DEBUGLOG(6, "ZSTD_initFseState : val=%u using %u bits",
+ (U32)DStatePtr->state, DTableH->tableLog);
+ BIT_reloadDStream(bitD);
+ DStatePtr->table = dt + 1;
+}
+
+FORCE_INLINE_TEMPLATE void
+ZSTD_updateFseStateWithDInfo(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD, U16 nextState, U32 nbBits)
+{
+ size_t const lowBits = BIT_readBits(bitD, nbBits);
+ DStatePtr->state = nextState + lowBits;
+}
+
+/* We need to add at most (ZSTD_WINDOWLOG_MAX_32 - 1) bits to read the maximum
+ * offset bits. But we can only read at most STREAM_ACCUMULATOR_MIN_32
+ * bits before reloading. This value is the maximum number of bytes we read
+ * after reloading when we are decoding long offsets.
+ */
+#define LONG_OFFSETS_MAX_EXTRA_BITS_32 \
+ (ZSTD_WINDOWLOG_MAX_32 > STREAM_ACCUMULATOR_MIN_32 \
+ ? ZSTD_WINDOWLOG_MAX_32 - STREAM_ACCUMULATOR_MIN_32 \
+ : 0)
+
+typedef enum { ZSTD_lo_isRegularOffset, ZSTD_lo_isLongOffset=1 } ZSTD_longOffset_e;
+
+FORCE_INLINE_TEMPLATE seq_t
+ZSTD_decodeSequence(seqState_t* seqState, const ZSTD_longOffset_e longOffsets)
+{
+ seq_t seq;
+ /*
+ * ZSTD_seqSymbol is a structure with a total of 64 bits wide. So it can be
+ * loaded in one operation and extracted its fields by simply shifting or
+ * bit-extracting on aarch64.
+ * GCC doesn't recognize this and generates more unnecessary ldr/ldrb/ldrh
+ * operations that cause performance drop. This can be avoided by using this
+ * ZSTD_memcpy hack.
+ */
+#if defined(__aarch64__) && (defined(__GNUC__) && !defined(__clang__))
+ ZSTD_seqSymbol llDInfoS, mlDInfoS, ofDInfoS;
+ ZSTD_seqSymbol* const llDInfo = &llDInfoS;
+ ZSTD_seqSymbol* const mlDInfo = &mlDInfoS;
+ ZSTD_seqSymbol* const ofDInfo = &ofDInfoS;
+ ZSTD_memcpy(llDInfo, seqState->stateLL.table + seqState->stateLL.state, sizeof(ZSTD_seqSymbol));
+ ZSTD_memcpy(mlDInfo, seqState->stateML.table + seqState->stateML.state, sizeof(ZSTD_seqSymbol));
+ ZSTD_memcpy(ofDInfo, seqState->stateOffb.table + seqState->stateOffb.state, sizeof(ZSTD_seqSymbol));
+#else
+ const ZSTD_seqSymbol* const llDInfo = seqState->stateLL.table + seqState->stateLL.state;
+ const ZSTD_seqSymbol* const mlDInfo = seqState->stateML.table + seqState->stateML.state;
+ const ZSTD_seqSymbol* const ofDInfo = seqState->stateOffb.table + seqState->stateOffb.state;
+#endif
+ seq.matchLength = mlDInfo->baseValue;
+ seq.litLength = llDInfo->baseValue;
+ { U32 const ofBase = ofDInfo->baseValue;
+ BYTE const llBits = llDInfo->nbAdditionalBits;
+ BYTE const mlBits = mlDInfo->nbAdditionalBits;
+ BYTE const ofBits = ofDInfo->nbAdditionalBits;
+ BYTE const totalBits = llBits+mlBits+ofBits;
+
+ U16 const llNext = llDInfo->nextState;
+ U16 const mlNext = mlDInfo->nextState;
+ U16 const ofNext = ofDInfo->nextState;
+ U32 const llnbBits = llDInfo->nbBits;
+ U32 const mlnbBits = mlDInfo->nbBits;
+ U32 const ofnbBits = ofDInfo->nbBits;
+
+ assert(llBits <= MaxLLBits);
+ assert(mlBits <= MaxMLBits);
+ assert(ofBits <= MaxOff);
+ /*
+ * As gcc has better branch and block analyzers, sometimes it is only
+ * valuable to mark likeliness for clang, it gives around 3-4% of
+ * performance.
+ */
+
+ /* sequence */
+ { size_t offset;
+ #if defined(__clang__)
+ if (LIKELY(ofBits > 1)) {
+ #else
+ if (ofBits > 1) {
+ #endif
+ ZSTD_STATIC_ASSERT(ZSTD_lo_isLongOffset == 1);
+ ZSTD_STATIC_ASSERT(LONG_OFFSETS_MAX_EXTRA_BITS_32 == 5);
+ ZSTD_STATIC_ASSERT(STREAM_ACCUMULATOR_MIN_32 > LONG_OFFSETS_MAX_EXTRA_BITS_32);
+ ZSTD_STATIC_ASSERT(STREAM_ACCUMULATOR_MIN_32 - LONG_OFFSETS_MAX_EXTRA_BITS_32 >= MaxMLBits);
+ if (MEM_32bits() && longOffsets && (ofBits >= STREAM_ACCUMULATOR_MIN_32)) {
+ /* Always read extra bits, this keeps the logic simple,
+ * avoids branches, and avoids accidentally reading 0 bits.
+ */
+ U32 const extraBits = LONG_OFFSETS_MAX_EXTRA_BITS_32;
+ offset = ofBase + (BIT_readBitsFast(&seqState->DStream, ofBits - extraBits) << extraBits);
+ BIT_reloadDStream(&seqState->DStream);
+ offset += BIT_readBitsFast(&seqState->DStream, extraBits);
+ } else {
+ offset = ofBase + BIT_readBitsFast(&seqState->DStream, ofBits/*>0*/); /* <= (ZSTD_WINDOWLOG_MAX-1) bits */
+ if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream);
+ }
+ seqState->prevOffset[2] = seqState->prevOffset[1];
+ seqState->prevOffset[1] = seqState->prevOffset[0];
+ seqState->prevOffset[0] = offset;
+ } else {
+ U32 const ll0 = (llDInfo->baseValue == 0);
+ if (LIKELY((ofBits == 0))) {
+ offset = seqState->prevOffset[ll0];
+ seqState->prevOffset[1] = seqState->prevOffset[!ll0];
+ seqState->prevOffset[0] = offset;
+ } else {
+ offset = ofBase + ll0 + BIT_readBitsFast(&seqState->DStream, 1);
+ { size_t temp = (offset==3) ? seqState->prevOffset[0] - 1 : seqState->prevOffset[offset];
+ temp += !temp; /* 0 is not valid; input is corrupted; force offset to 1 */
+ if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1];
+ seqState->prevOffset[1] = seqState->prevOffset[0];
+ seqState->prevOffset[0] = offset = temp;
+ } } }
+ seq.offset = offset;
+ }
+
+ #if defined(__clang__)
+ if (UNLIKELY(mlBits > 0))
+ #else
+ if (mlBits > 0)
+ #endif
+ seq.matchLength += BIT_readBitsFast(&seqState->DStream, mlBits/*>0*/);
+
+ if (MEM_32bits() && (mlBits+llBits >= STREAM_ACCUMULATOR_MIN_32-LONG_OFFSETS_MAX_EXTRA_BITS_32))
+ BIT_reloadDStream(&seqState->DStream);
+ if (MEM_64bits() && UNLIKELY(totalBits >= STREAM_ACCUMULATOR_MIN_64-(LLFSELog+MLFSELog+OffFSELog)))
+ BIT_reloadDStream(&seqState->DStream);
+ /* Ensure there are enough bits to read the rest of data in 64-bit mode. */
+ ZSTD_STATIC_ASSERT(16+LLFSELog+MLFSELog+OffFSELog < STREAM_ACCUMULATOR_MIN_64);
+
+ #if defined(__clang__)
+ if (UNLIKELY(llBits > 0))
+ #else
+ if (llBits > 0)
+ #endif
+ seq.litLength += BIT_readBitsFast(&seqState->DStream, llBits/*>0*/);
+
+ if (MEM_32bits())
+ BIT_reloadDStream(&seqState->DStream);
+
+ DEBUGLOG(6, "seq: litL=%u, matchL=%u, offset=%u",
+ (U32)seq.litLength, (U32)seq.matchLength, (U32)seq.offset);
+
+ ZSTD_updateFseStateWithDInfo(&seqState->stateLL, &seqState->DStream, llNext, llnbBits); /* <= 9 bits */
+ ZSTD_updateFseStateWithDInfo(&seqState->stateML, &seqState->DStream, mlNext, mlnbBits); /* <= 9 bits */
+ if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); /* <= 18 bits */
+ ZSTD_updateFseStateWithDInfo(&seqState->stateOffb, &seqState->DStream, ofNext, ofnbBits); /* <= 8 bits */
+ }
+
+ return seq;
+}
+
+#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
+MEM_STATIC int ZSTD_dictionaryIsActive(ZSTD_DCtx const* dctx, BYTE const* prefixStart, BYTE const* oLitEnd)
+{
+ size_t const windowSize = dctx->fParams.windowSize;
+ /* No dictionary used. */
+ if (dctx->dictContentEndForFuzzing == NULL) return 0;
+ /* Dictionary is our prefix. */
+ if (prefixStart == dctx->dictContentBeginForFuzzing) return 1;
+ /* Dictionary is not our ext-dict. */
+ if (dctx->dictEnd != dctx->dictContentEndForFuzzing) return 0;
+ /* Dictionary is not within our window size. */
+ if ((size_t)(oLitEnd - prefixStart) >= windowSize) return 0;
+ /* Dictionary is active. */
+ return 1;
+}
+
+MEM_STATIC void ZSTD_assertValidSequence(
+ ZSTD_DCtx const* dctx,
+ BYTE const* op, BYTE const* oend,
+ seq_t const seq,
+ BYTE const* prefixStart, BYTE const* virtualStart)
+{
+#if DEBUGLEVEL >= 1
+ size_t const windowSize = dctx->fParams.windowSize;
+ size_t const sequenceSize = seq.litLength + seq.matchLength;
+ BYTE const* const oLitEnd = op + seq.litLength;
+ DEBUGLOG(6, "Checking sequence: litL=%u matchL=%u offset=%u",
+ (U32)seq.litLength, (U32)seq.matchLength, (U32)seq.offset);
+ assert(op <= oend);
+ assert((size_t)(oend - op) >= sequenceSize);
+ assert(sequenceSize <= ZSTD_BLOCKSIZE_MAX);
+ if (ZSTD_dictionaryIsActive(dctx, prefixStart, oLitEnd)) {
+ size_t const dictSize = (size_t)((char const*)dctx->dictContentEndForFuzzing - (char const*)dctx->dictContentBeginForFuzzing);
+ /* Offset must be within the dictionary. */
+ assert(seq.offset <= (size_t)(oLitEnd - virtualStart));
+ assert(seq.offset <= windowSize + dictSize);
+ } else {
+ /* Offset must be within our window. */
+ assert(seq.offset <= windowSize);
+ }
+#else
+ (void)dctx, (void)op, (void)oend, (void)seq, (void)prefixStart, (void)virtualStart;
+#endif
+}
+#endif
+
+#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
+
+
+FORCE_INLINE_TEMPLATE size_t
+DONT_VECTORIZE
+ZSTD_decompressSequences_bodySplitLitBuffer( ZSTD_DCtx* dctx,
+ void* dst, size_t maxDstSize,
+ const void* seqStart, size_t seqSize, int nbSeq,
+ const ZSTD_longOffset_e isLongOffset,
+ const int frame)
+{
+ const BYTE* ip = (const BYTE*)seqStart;
+ const BYTE* const iend = ip + seqSize;
+ BYTE* const ostart = (BYTE*)dst;
+ BYTE* const oend = ostart + maxDstSize;
+ BYTE* op = ostart;
+ const BYTE* litPtr = dctx->litPtr;
+ const BYTE* litBufferEnd = dctx->litBufferEnd;
+ const BYTE* const prefixStart = (const BYTE*) (dctx->prefixStart);
+ const BYTE* const vBase = (const BYTE*) (dctx->virtualStart);
+ const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd);
+ DEBUGLOG(5, "ZSTD_decompressSequences_bodySplitLitBuffer");
+ (void)frame;
+
+ /* Regen sequences */
+ if (nbSeq) {
+ seqState_t seqState;
+ dctx->fseEntropy = 1;
+ { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->entropy.rep[i]; }
+ RETURN_ERROR_IF(
+ ERR_isError(BIT_initDStream(&seqState.DStream, ip, iend-ip)),
+ corruption_detected, "");
+ ZSTD_initFseState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr);
+ ZSTD_initFseState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr);
+ ZSTD_initFseState(&seqState.stateML, &seqState.DStream, dctx->MLTptr);
+ assert(dst != NULL);
+
+ ZSTD_STATIC_ASSERT(
+ BIT_DStream_unfinished < BIT_DStream_completed &&
+ BIT_DStream_endOfBuffer < BIT_DStream_completed &&
+ BIT_DStream_completed < BIT_DStream_overflow);
+
+ /* decompress without overrunning litPtr begins */
+ {
+ seq_t sequence = ZSTD_decodeSequence(&seqState, isLongOffset);
+ /* Align the decompression loop to 32 + 16 bytes.
+ *
+ * zstd compiled with gcc-9 on an Intel i9-9900k shows 10% decompression
+ * speed swings based on the alignment of the decompression loop. This
+ * performance swing is caused by parts of the decompression loop falling
+ * out of the DSB. The entire decompression loop should fit in the DSB,
+ * when it can't we get much worse performance. You can measure if you've
+ * hit the good case or the bad case with this perf command for some
+ * compressed file test.zst:
+ *
+ * perf stat -e cycles -e instructions -e idq.all_dsb_cycles_any_uops \
+ * -e idq.all_mite_cycles_any_uops -- ./zstd -tq test.zst
+ *
+ * If you see most cycles served out of the MITE you've hit the bad case.
+ * If you see most cycles served out of the DSB you've hit the good case.
+ * If it is pretty even then you may be in an okay case.
+ *
+ * This issue has been reproduced on the following CPUs:
+ * - Kabylake: Macbook Pro (15-inch, 2019) 2.4 GHz Intel Core i9
+ * Use Instruments->Counters to get DSB/MITE cycles.
+ * I never got performance swings, but I was able to
+ * go from the good case of mostly DSB to half of the
+ * cycles served from MITE.
+ * - Coffeelake: Intel i9-9900k
+ * - Coffeelake: Intel i7-9700k
+ *
+ * I haven't been able to reproduce the instability or DSB misses on any
+ * of the following CPUS:
+ * - Haswell
+ * - Broadwell: Intel(R) Xeon(R) CPU E5-2680 v4 @ 2.40GH
+ * - Skylake
+ *
+ * Alignment is done for each of the three major decompression loops:
+ * - ZSTD_decompressSequences_bodySplitLitBuffer - presplit section of the literal buffer
+ * - ZSTD_decompressSequences_bodySplitLitBuffer - postsplit section of the literal buffer
+ * - ZSTD_decompressSequences_body
+ * Alignment choices are made to minimize large swings on bad cases and influence on performance
+ * from changes external to this code, rather than to overoptimize on the current commit.
+ *
+ * If you are seeing performance stability this script can help test.
+ * It tests on 4 commits in zstd where I saw performance change.
+ *
+ * https://gist.github.com/terrelln/9889fc06a423fd5ca6e99351564473f4
+ */
+#if defined(__GNUC__) && defined(__x86_64__)
+ __asm__(".p2align 6");
+# if __GNUC__ >= 7
+ /* good for gcc-7, gcc-9, and gcc-11 */
+ __asm__("nop");
+ __asm__(".p2align 5");
+ __asm__("nop");
+ __asm__(".p2align 4");
+# if __GNUC__ == 8 || __GNUC__ == 10
+ /* good for gcc-8 and gcc-10 */
+ __asm__("nop");
+ __asm__(".p2align 3");
+# endif
+# endif
+#endif
+
+ /* Handle the initial state where litBuffer is currently split between dst and litExtraBuffer */
+ for (; litPtr + sequence.litLength <= dctx->litBufferEnd; ) {
+ size_t const oneSeqSize = ZSTD_execSequenceSplitLitBuffer(op, oend, litPtr + sequence.litLength - WILDCOPY_OVERLENGTH, sequence, &litPtr, litBufferEnd, prefixStart, vBase, dictEnd);
+#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
+ assert(!ZSTD_isError(oneSeqSize));
+ if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase);
+#endif
+ if (UNLIKELY(ZSTD_isError(oneSeqSize)))
+ return oneSeqSize;
+ DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize);
+ op += oneSeqSize;
+ if (UNLIKELY(!--nbSeq))
+ break;
+ BIT_reloadDStream(&(seqState.DStream));
+ sequence = ZSTD_decodeSequence(&seqState, isLongOffset);
+ }
+
+ /* If there are more sequences, they will need to read literals from litExtraBuffer; copy over the remainder from dst and update litPtr and litEnd */
+ if (nbSeq > 0) {
+ const size_t leftoverLit = dctx->litBufferEnd - litPtr;
+ if (leftoverLit)
+ {
+ RETURN_ERROR_IF(leftoverLit > (size_t)(oend - op), dstSize_tooSmall, "remaining lit must fit within dstBuffer");
+ ZSTD_safecopyDstBeforeSrc(op, litPtr, leftoverLit);
+ sequence.litLength -= leftoverLit;
+ op += leftoverLit;
+ }
+ litPtr = dctx->litExtraBuffer;
+ litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE;
+ dctx->litBufferLocation = ZSTD_not_in_dst;
+ {
+ size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litBufferEnd, prefixStart, vBase, dictEnd);
+#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
+ assert(!ZSTD_isError(oneSeqSize));
+ if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase);
+#endif
+ if (UNLIKELY(ZSTD_isError(oneSeqSize)))
+ return oneSeqSize;
+ DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize);
+ op += oneSeqSize;
+ if (--nbSeq)
+ BIT_reloadDStream(&(seqState.DStream));
+ }
+ }
+ }
+
+ if (nbSeq > 0) /* there is remaining lit from extra buffer */
+ {
+
+#if defined(__GNUC__) && defined(__x86_64__)
+ __asm__(".p2align 6");
+ __asm__("nop");
+# if __GNUC__ != 7
+ /* worse for gcc-7 better for gcc-8, gcc-9, and gcc-10 and clang */
+ __asm__(".p2align 4");
+ __asm__("nop");
+ __asm__(".p2align 3");
+# elif __GNUC__ >= 11
+ __asm__(".p2align 3");
+# else
+ __asm__(".p2align 5");
+ __asm__("nop");
+ __asm__(".p2align 3");
+# endif
+#endif
+
+ for (; ; ) {
+ seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset);
+ size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litBufferEnd, prefixStart, vBase, dictEnd);
+#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
+ assert(!ZSTD_isError(oneSeqSize));
+ if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase);
+#endif
+ if (UNLIKELY(ZSTD_isError(oneSeqSize)))
+ return oneSeqSize;
+ DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize);
+ op += oneSeqSize;
+ if (UNLIKELY(!--nbSeq))
+ break;
+ BIT_reloadDStream(&(seqState.DStream));
+ }
+ }
+
+ /* check if reached exact end */
+ DEBUGLOG(5, "ZSTD_decompressSequences_bodySplitLitBuffer: after decode loop, remaining nbSeq : %i", nbSeq);
+ RETURN_ERROR_IF(nbSeq, corruption_detected, "");
+ RETURN_ERROR_IF(BIT_reloadDStream(&seqState.DStream) < BIT_DStream_completed, corruption_detected, "");
+ /* save reps for next block */
+ { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->entropy.rep[i] = (U32)(seqState.prevOffset[i]); }
+ }
+
+ /* last literal segment */
+ if (dctx->litBufferLocation == ZSTD_split) /* split hasn't been reached yet, first get dst then copy litExtraBuffer */
+ {
+ size_t const lastLLSize = litBufferEnd - litPtr;
+ RETURN_ERROR_IF(lastLLSize > (size_t)(oend - op), dstSize_tooSmall, "");
+ if (op != NULL) {
+ ZSTD_memmove(op, litPtr, lastLLSize);
+ op += lastLLSize;
+ }
+ litPtr = dctx->litExtraBuffer;
+ litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE;
+ dctx->litBufferLocation = ZSTD_not_in_dst;
+ }
+ { size_t const lastLLSize = litBufferEnd - litPtr;
+ RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, "");
+ if (op != NULL) {
+ ZSTD_memcpy(op, litPtr, lastLLSize);
+ op += lastLLSize;
+ }
+ }
+
+ return op-ostart;
+}
+
+FORCE_INLINE_TEMPLATE size_t
+DONT_VECTORIZE
+ZSTD_decompressSequences_body(ZSTD_DCtx* dctx,
+ void* dst, size_t maxDstSize,
+ const void* seqStart, size_t seqSize, int nbSeq,
+ const ZSTD_longOffset_e isLongOffset,
+ const int frame)
+{
+ const BYTE* ip = (const BYTE*)seqStart;
+ const BYTE* const iend = ip + seqSize;
+ BYTE* const ostart = (BYTE*)dst;
+ BYTE* const oend = dctx->litBufferLocation == ZSTD_not_in_dst ? ostart + maxDstSize : dctx->litBuffer;
+ BYTE* op = ostart;
+ const BYTE* litPtr = dctx->litPtr;
+ const BYTE* const litEnd = litPtr + dctx->litSize;
+ const BYTE* const prefixStart = (const BYTE*)(dctx->prefixStart);
+ const BYTE* const vBase = (const BYTE*)(dctx->virtualStart);
+ const BYTE* const dictEnd = (const BYTE*)(dctx->dictEnd);
+ DEBUGLOG(5, "ZSTD_decompressSequences_body: nbSeq = %d", nbSeq);
+ (void)frame;
+
+ /* Regen sequences */
+ if (nbSeq) {
+ seqState_t seqState;
+ dctx->fseEntropy = 1;
+ { U32 i; for (i = 0; i < ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->entropy.rep[i]; }
+ RETURN_ERROR_IF(
+ ERR_isError(BIT_initDStream(&seqState.DStream, ip, iend - ip)),
+ corruption_detected, "");
+ ZSTD_initFseState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr);
+ ZSTD_initFseState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr);
+ ZSTD_initFseState(&seqState.stateML, &seqState.DStream, dctx->MLTptr);
+ assert(dst != NULL);
+
+ ZSTD_STATIC_ASSERT(
+ BIT_DStream_unfinished < BIT_DStream_completed &&
+ BIT_DStream_endOfBuffer < BIT_DStream_completed &&
+ BIT_DStream_completed < BIT_DStream_overflow);
+
+#if defined(__GNUC__) && defined(__x86_64__)
+ __asm__(".p2align 6");
+ __asm__("nop");
+# if __GNUC__ >= 7
+ __asm__(".p2align 5");
+ __asm__("nop");
+ __asm__(".p2align 3");
+# else
+ __asm__(".p2align 4");
+ __asm__("nop");
+ __asm__(".p2align 3");
+# endif
+#endif
+
+ for ( ; ; ) {
+ seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset);
+ size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litEnd, prefixStart, vBase, dictEnd);
+#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
+ assert(!ZSTD_isError(oneSeqSize));
+ if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase);
+#endif
+ if (UNLIKELY(ZSTD_isError(oneSeqSize)))
+ return oneSeqSize;
+ DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize);
+ op += oneSeqSize;
+ if (UNLIKELY(!--nbSeq))
+ break;
+ BIT_reloadDStream(&(seqState.DStream));
+ }
+
+ /* check if reached exact end */
+ DEBUGLOG(5, "ZSTD_decompressSequences_body: after decode loop, remaining nbSeq : %i", nbSeq);
+ RETURN_ERROR_IF(nbSeq, corruption_detected, "");
+ RETURN_ERROR_IF(BIT_reloadDStream(&seqState.DStream) < BIT_DStream_completed, corruption_detected, "");
+ /* save reps for next block */
+ { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->entropy.rep[i] = (U32)(seqState.prevOffset[i]); }
+ }
+
+ /* last literal segment */
+ { size_t const lastLLSize = litEnd - litPtr;
+ RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, "");
+ if (op != NULL) {
+ ZSTD_memcpy(op, litPtr, lastLLSize);
+ op += lastLLSize;
+ }
+ }
+
+ return op-ostart;
+}
+
+static size_t
+ZSTD_decompressSequences_default(ZSTD_DCtx* dctx,
+ void* dst, size_t maxDstSize,
+ const void* seqStart, size_t seqSize, int nbSeq,
+ const ZSTD_longOffset_e isLongOffset,
+ const int frame)
+{
+ return ZSTD_decompressSequences_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
+}
+
+static size_t
+ZSTD_decompressSequencesSplitLitBuffer_default(ZSTD_DCtx* dctx,
+ void* dst, size_t maxDstSize,
+ const void* seqStart, size_t seqSize, int nbSeq,
+ const ZSTD_longOffset_e isLongOffset,
+ const int frame)
+{
+ return ZSTD_decompressSequences_bodySplitLitBuffer(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
+}
+#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */
+
+#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
+
+FORCE_INLINE_TEMPLATE size_t
+ZSTD_prefetchMatch(size_t prefetchPos, seq_t const sequence,
+ const BYTE* const prefixStart, const BYTE* const dictEnd)
+{
+ prefetchPos += sequence.litLength;
+ { const BYTE* const matchBase = (sequence.offset > prefetchPos) ? dictEnd : prefixStart;
+ const BYTE* const match = matchBase + prefetchPos - sequence.offset; /* note : this operation can overflow when seq.offset is really too large, which can only happen when input is corrupted.
+ * No consequence though : memory address is only used for prefetching, not for dereferencing */
+ PREFETCH_L1(match); PREFETCH_L1(match+CACHELINE_SIZE); /* note : it's safe to invoke PREFETCH() on any memory address, including invalid ones */
+ }
+ return prefetchPos + sequence.matchLength;
+}
+
+/* This decoding function employs prefetching
+ * to reduce latency impact of cache misses.
+ * It's generally employed when block contains a significant portion of long-distance matches
+ * or when coupled with a "cold" dictionary */
+FORCE_INLINE_TEMPLATE size_t
+ZSTD_decompressSequencesLong_body(
+ ZSTD_DCtx* dctx,
+ void* dst, size_t maxDstSize,
+ const void* seqStart, size_t seqSize, int nbSeq,
+ const ZSTD_longOffset_e isLongOffset,
+ const int frame)
+{
+ const BYTE* ip = (const BYTE*)seqStart;
+ const BYTE* const iend = ip + seqSize;
+ BYTE* const ostart = (BYTE*)dst;
+ BYTE* const oend = dctx->litBufferLocation == ZSTD_in_dst ? dctx->litBuffer : ostart + maxDstSize;
+ BYTE* op = ostart;
+ const BYTE* litPtr = dctx->litPtr;
+ const BYTE* litBufferEnd = dctx->litBufferEnd;
+ const BYTE* const prefixStart = (const BYTE*) (dctx->prefixStart);
+ const BYTE* const dictStart = (const BYTE*) (dctx->virtualStart);
+ const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd);
+ (void)frame;
+
+ /* Regen sequences */
+ if (nbSeq) {
+#define STORED_SEQS 8
+#define STORED_SEQS_MASK (STORED_SEQS-1)
+#define ADVANCED_SEQS STORED_SEQS
+ seq_t sequences[STORED_SEQS];
+ int const seqAdvance = MIN(nbSeq, ADVANCED_SEQS);
+ seqState_t seqState;
+ int seqNb;
+ size_t prefetchPos = (size_t)(op-prefixStart); /* track position relative to prefixStart */
+
+ dctx->fseEntropy = 1;
+ { int i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->entropy.rep[i]; }
+ assert(dst != NULL);
+ assert(iend >= ip);
+ RETURN_ERROR_IF(
+ ERR_isError(BIT_initDStream(&seqState.DStream, ip, iend-ip)),
+ corruption_detected, "");
+ ZSTD_initFseState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr);
+ ZSTD_initFseState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr);
+ ZSTD_initFseState(&seqState.stateML, &seqState.DStream, dctx->MLTptr);
+
+ /* prepare in advance */
+ for (seqNb=0; (BIT_reloadDStream(&seqState.DStream) <= BIT_DStream_completed) && (seqNb<seqAdvance); seqNb++) {
+ seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset);
+ prefetchPos = ZSTD_prefetchMatch(prefetchPos, sequence, prefixStart, dictEnd);
+ sequences[seqNb] = sequence;
+ }
+ RETURN_ERROR_IF(seqNb<seqAdvance, corruption_detected, "");
+
+ /* decompress without stomping litBuffer */
+ for (; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && (seqNb < nbSeq); seqNb++) {
+ seq_t sequence = ZSTD_decodeSequence(&seqState, isLongOffset);
+ size_t oneSeqSize;
+
+ if (dctx->litBufferLocation == ZSTD_split && litPtr + sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK].litLength > dctx->litBufferEnd)
+ {
+ /* lit buffer is reaching split point, empty out the first buffer and transition to litExtraBuffer */
+ const size_t leftoverLit = dctx->litBufferEnd - litPtr;
+ if (leftoverLit)
+ {
+ RETURN_ERROR_IF(leftoverLit > (size_t)(oend - op), dstSize_tooSmall, "remaining lit must fit within dstBuffer");
+ ZSTD_safecopyDstBeforeSrc(op, litPtr, leftoverLit);
+ sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK].litLength -= leftoverLit;
+ op += leftoverLit;
+ }
+ litPtr = dctx->litExtraBuffer;
+ litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE;
+ dctx->litBufferLocation = ZSTD_not_in_dst;
+ oneSeqSize = ZSTD_execSequence(op, oend, sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK], &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd);
+#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
+ assert(!ZSTD_isError(oneSeqSize));
+ if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK], prefixStart, dictStart);
+#endif
+ if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
+
+ prefetchPos = ZSTD_prefetchMatch(prefetchPos, sequence, prefixStart, dictEnd);
+ sequences[seqNb & STORED_SEQS_MASK] = sequence;
+ op += oneSeqSize;
+ }
+ else
+ {
+ /* lit buffer is either wholly contained in first or second split, or not split at all*/
+ oneSeqSize = dctx->litBufferLocation == ZSTD_split ?
+ ZSTD_execSequenceSplitLitBuffer(op, oend, litPtr + sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK].litLength - WILDCOPY_OVERLENGTH, sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK], &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd) :
+ ZSTD_execSequence(op, oend, sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK], &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd);
+#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
+ assert(!ZSTD_isError(oneSeqSize));
+ if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[(seqNb - ADVANCED_SEQS) & STORED_SEQS_MASK], prefixStart, dictStart);
+#endif
+ if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
+
+ prefetchPos = ZSTD_prefetchMatch(prefetchPos, sequence, prefixStart, dictEnd);
+ sequences[seqNb & STORED_SEQS_MASK] = sequence;
+ op += oneSeqSize;
+ }
+ }
+ RETURN_ERROR_IF(seqNb<nbSeq, corruption_detected, "");
+
+ /* finish queue */
+ seqNb -= seqAdvance;
+ for ( ; seqNb<nbSeq ; seqNb++) {
+ seq_t *sequence = &(sequences[seqNb&STORED_SEQS_MASK]);
+ if (dctx->litBufferLocation == ZSTD_split && litPtr + sequence->litLength > dctx->litBufferEnd)
+ {
+ const size_t leftoverLit = dctx->litBufferEnd - litPtr;
+ if (leftoverLit)
+ {
+ RETURN_ERROR_IF(leftoverLit > (size_t)(oend - op), dstSize_tooSmall, "remaining lit must fit within dstBuffer");
+ ZSTD_safecopyDstBeforeSrc(op, litPtr, leftoverLit);
+ sequence->litLength -= leftoverLit;
+ op += leftoverLit;
+ }
+ litPtr = dctx->litExtraBuffer;
+ litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE;
+ dctx->litBufferLocation = ZSTD_not_in_dst;
+ {
+ size_t const oneSeqSize = ZSTD_execSequence(op, oend, *sequence, &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd);
+#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
+ assert(!ZSTD_isError(oneSeqSize));
+ if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[seqNb&STORED_SEQS_MASK], prefixStart, dictStart);
+#endif
+ if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
+ op += oneSeqSize;
+ }
+ }
+ else
+ {
+ size_t const oneSeqSize = dctx->litBufferLocation == ZSTD_split ?
+ ZSTD_execSequenceSplitLitBuffer(op, oend, litPtr + sequence->litLength - WILDCOPY_OVERLENGTH, *sequence, &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd) :
+ ZSTD_execSequence(op, oend, *sequence, &litPtr, litBufferEnd, prefixStart, dictStart, dictEnd);
+#if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
+ assert(!ZSTD_isError(oneSeqSize));
+ if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[seqNb&STORED_SEQS_MASK], prefixStart, dictStart);
+#endif
+ if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
+ op += oneSeqSize;
+ }
+ }
+
+ /* save reps for next block */
+ { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->entropy.rep[i] = (U32)(seqState.prevOffset[i]); }
+ }
+
+ /* last literal segment */
+ if (dctx->litBufferLocation == ZSTD_split) /* first deplete literal buffer in dst, then copy litExtraBuffer */
+ {
+ size_t const lastLLSize = litBufferEnd - litPtr;
+ RETURN_ERROR_IF(lastLLSize > (size_t)(oend - op), dstSize_tooSmall, "");
+ if (op != NULL) {
+ ZSTD_memmove(op, litPtr, lastLLSize);
+ op += lastLLSize;
+ }
+ litPtr = dctx->litExtraBuffer;
+ litBufferEnd = dctx->litExtraBuffer + ZSTD_LITBUFFEREXTRASIZE;
+ }
+ { size_t const lastLLSize = litBufferEnd - litPtr;
+ RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, "");
+ if (op != NULL) {
+ ZSTD_memmove(op, litPtr, lastLLSize);
+ op += lastLLSize;
+ }
+ }
+
+ return op-ostart;
+}
+
+static size_t
+ZSTD_decompressSequencesLong_default(ZSTD_DCtx* dctx,
+ void* dst, size_t maxDstSize,
+ const void* seqStart, size_t seqSize, int nbSeq,
+ const ZSTD_longOffset_e isLongOffset,
+ const int frame)
+{
+ return ZSTD_decompressSequencesLong_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
+}
+#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */
+
+
+
+#if DYNAMIC_BMI2
+
+#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
+static BMI2_TARGET_ATTRIBUTE size_t
+DONT_VECTORIZE
+ZSTD_decompressSequences_bmi2(ZSTD_DCtx* dctx,
+ void* dst, size_t maxDstSize,
+ const void* seqStart, size_t seqSize, int nbSeq,
+ const ZSTD_longOffset_e isLongOffset,
+ const int frame)
+{
+ return ZSTD_decompressSequences_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
+}
+static BMI2_TARGET_ATTRIBUTE size_t
+DONT_VECTORIZE
+ZSTD_decompressSequencesSplitLitBuffer_bmi2(ZSTD_DCtx* dctx,
+ void* dst, size_t maxDstSize,
+ const void* seqStart, size_t seqSize, int nbSeq,
+ const ZSTD_longOffset_e isLongOffset,
+ const int frame)
+{
+ return ZSTD_decompressSequences_bodySplitLitBuffer(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
+}
+#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */
+
+#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
+static BMI2_TARGET_ATTRIBUTE size_t
+ZSTD_decompressSequencesLong_bmi2(ZSTD_DCtx* dctx,
+ void* dst, size_t maxDstSize,
+ const void* seqStart, size_t seqSize, int nbSeq,
+ const ZSTD_longOffset_e isLongOffset,
+ const int frame)
+{
+ return ZSTD_decompressSequencesLong_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
+}
+#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */
+
+#endif /* DYNAMIC_BMI2 */
+
+typedef size_t (*ZSTD_decompressSequences_t)(
+ ZSTD_DCtx* dctx,
+ void* dst, size_t maxDstSize,
+ const void* seqStart, size_t seqSize, int nbSeq,
+ const ZSTD_longOffset_e isLongOffset,
+ const int frame);
+
+#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
+static size_t
+ZSTD_decompressSequences(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize,
+ const void* seqStart, size_t seqSize, int nbSeq,
+ const ZSTD_longOffset_e isLongOffset,
+ const int frame)
+{
+ DEBUGLOG(5, "ZSTD_decompressSequences");
+#if DYNAMIC_BMI2
+ if (ZSTD_DCtx_get_bmi2(dctx)) {
+ return ZSTD_decompressSequences_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
+ }
+#endif
+ return ZSTD_decompressSequences_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
+}
+static size_t
+ZSTD_decompressSequencesSplitLitBuffer(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize,
+ const void* seqStart, size_t seqSize, int nbSeq,
+ const ZSTD_longOffset_e isLongOffset,
+ const int frame)
+{
+ DEBUGLOG(5, "ZSTD_decompressSequencesSplitLitBuffer");
+#if DYNAMIC_BMI2
+ if (ZSTD_DCtx_get_bmi2(dctx)) {
+ return ZSTD_decompressSequencesSplitLitBuffer_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
+ }
+#endif
+ return ZSTD_decompressSequencesSplitLitBuffer_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
+}
+#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */
+
+
+#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
+/* ZSTD_decompressSequencesLong() :
+ * decompression function triggered when a minimum share of offsets is considered "long",
+ * aka out of cache.
+ * note : "long" definition seems overloaded here, sometimes meaning "wider than bitstream register", and sometimes meaning "farther than memory cache distance".
+ * This function will try to mitigate main memory latency through the use of prefetching */
+static size_t
+ZSTD_decompressSequencesLong(ZSTD_DCtx* dctx,
+ void* dst, size_t maxDstSize,
+ const void* seqStart, size_t seqSize, int nbSeq,
+ const ZSTD_longOffset_e isLongOffset,
+ const int frame)
+{
+ DEBUGLOG(5, "ZSTD_decompressSequencesLong");
+#if DYNAMIC_BMI2
+ if (ZSTD_DCtx_get_bmi2(dctx)) {
+ return ZSTD_decompressSequencesLong_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
+ }
+#endif
+ return ZSTD_decompressSequencesLong_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame);
+}
+#endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */
+
+
+/**
+ * @returns The total size of the history referencable by zstd, including
+ * both the prefix and the extDict. At @p op any offset larger than this
+ * is invalid.
+ */
+static size_t ZSTD_totalHistorySize(BYTE* op, BYTE const* virtualStart)
+{
+ return (size_t)(op - virtualStart);
+}
+
+typedef struct {
+ unsigned longOffsetShare;
+ unsigned maxNbAdditionalBits;
+} ZSTD_OffsetInfo;
+
+/* ZSTD_getOffsetInfo() :
+ * condition : offTable must be valid
+ * @return : "share" of long offsets (arbitrarily defined as > (1<<23))
+ * compared to maximum possible of (1<<OffFSELog),
+ * as well as the maximum number additional bits required.
+ */
+static ZSTD_OffsetInfo
+ZSTD_getOffsetInfo(const ZSTD_seqSymbol* offTable, int nbSeq)
+{
+ ZSTD_OffsetInfo info = {0, 0};
+ /* If nbSeq == 0, then the offTable is uninitialized, but we have
+ * no sequences, so both values should be 0.
+ */
+ if (nbSeq != 0) {
+ const void* ptr = offTable;
+ U32 const tableLog = ((const ZSTD_seqSymbol_header*)ptr)[0].tableLog;
+ const ZSTD_seqSymbol* table = offTable + 1;
+ U32 const max = 1 << tableLog;
+ U32 u;
+ DEBUGLOG(5, "ZSTD_getLongOffsetsShare: (tableLog=%u)", tableLog);
+
+ assert(max <= (1 << OffFSELog)); /* max not too large */
+ for (u=0; u<max; u++) {
+ info.maxNbAdditionalBits = MAX(info.maxNbAdditionalBits, table[u].nbAdditionalBits);
+ if (table[u].nbAdditionalBits > 22) info.longOffsetShare += 1;
+ }
+
+ assert(tableLog <= OffFSELog);
+ info.longOffsetShare <<= (OffFSELog - tableLog); /* scale to OffFSELog */
+ }
+
+ return info;
+}
+
+/**
+ * @returns The maximum offset we can decode in one read of our bitstream, without
+ * reloading more bits in the middle of the offset bits read. Any offsets larger
+ * than this must use the long offset decoder.
+ */
+static size_t ZSTD_maxShortOffset(void)
+{
+ if (MEM_64bits()) {
+ /* We can decode any offset without reloading bits.
+ * This might change if the max window size grows.
+ */
+ ZSTD_STATIC_ASSERT(ZSTD_WINDOWLOG_MAX <= 31);
+ return (size_t)-1;
+ } else {
+ /* The maximum offBase is (1 << (STREAM_ACCUMULATOR_MIN + 1)) - 1.
+ * This offBase would require STREAM_ACCUMULATOR_MIN extra bits.
+ * Then we have to subtract ZSTD_REP_NUM to get the maximum possible offset.
+ */
+ size_t const maxOffbase = ((size_t)1 << (STREAM_ACCUMULATOR_MIN + 1)) - 1;
+ size_t const maxOffset = maxOffbase - ZSTD_REP_NUM;
+ assert(ZSTD_highbit32((U32)maxOffbase) == STREAM_ACCUMULATOR_MIN);
+ return maxOffset;
+ }
+}
+
+size_t
+ZSTD_decompressBlock_internal(ZSTD_DCtx* dctx,
+ void* dst, size_t dstCapacity,
+ const void* src, size_t srcSize, const int frame, const streaming_operation streaming)
+{ /* blockType == blockCompressed */
+ const BYTE* ip = (const BYTE*)src;
+ DEBUGLOG(5, "ZSTD_decompressBlock_internal (size : %u)", (U32)srcSize);
+
+ /* Note : the wording of the specification
+ * allows compressed block to be sized exactly ZSTD_BLOCKSIZE_MAX.
+ * This generally does not happen, as it makes little sense,
+ * since an uncompressed block would feature same size and have no decompression cost.
+ * Also, note that decoder from reference libzstd before < v1.5.4
+ * would consider this edge case as an error.
+ * As a consequence, avoid generating compressed blocks of size ZSTD_BLOCKSIZE_MAX
+ * for broader compatibility with the deployed ecosystem of zstd decoders */
+ RETURN_ERROR_IF(srcSize > ZSTD_BLOCKSIZE_MAX, srcSize_wrong, "");
+
+ /* Decode literals section */
+ { size_t const litCSize = ZSTD_decodeLiteralsBlock(dctx, src, srcSize, dst, dstCapacity, streaming);
+ DEBUGLOG(5, "ZSTD_decodeLiteralsBlock : cSize=%u, nbLiterals=%zu", (U32)litCSize, dctx->litSize);
+ if (ZSTD_isError(litCSize)) return litCSize;
+ ip += litCSize;
+ srcSize -= litCSize;
+ }
+
+ /* Build Decoding Tables */
+ {
+ /* Compute the maximum block size, which must also work when !frame and fParams are unset.
+ * Additionally, take the min with dstCapacity to ensure that the totalHistorySize fits in a size_t.
+ */
+ size_t const blockSizeMax = MIN(dstCapacity, (frame ? dctx->fParams.blockSizeMax : ZSTD_BLOCKSIZE_MAX));
+ size_t const totalHistorySize = ZSTD_totalHistorySize((BYTE*)dst + blockSizeMax, (BYTE const*)dctx->virtualStart);
+ /* isLongOffset must be true if there are long offsets.
+ * Offsets are long if they are larger than ZSTD_maxShortOffset().
+ * We don't expect that to be the case in 64-bit mode.
+ *
+ * We check here to see if our history is large enough to allow long offsets.
+ * If it isn't, then we can't possible have (valid) long offsets. If the offset
+ * is invalid, then it is okay to read it incorrectly.
+ *
+ * If isLongOffsets is true, then we will later check our decoding table to see
+ * if it is even possible to generate long offsets.
+ */
+ ZSTD_longOffset_e isLongOffset = (ZSTD_longOffset_e)(MEM_32bits() && (totalHistorySize > ZSTD_maxShortOffset()));
+ /* These macros control at build-time which decompressor implementation
+ * we use. If neither is defined, we do some inspection and dispatch at
+ * runtime.
+ */
+#if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
+ !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG)
+ int usePrefetchDecoder = dctx->ddictIsCold;
+#else
+ /* Set to 1 to avoid computing offset info if we don't need to.
+ * Otherwise this value is ignored.
+ */
+ int usePrefetchDecoder = 1;
+#endif
+ int nbSeq;
+ size_t const seqHSize = ZSTD_decodeSeqHeaders(dctx, &nbSeq, ip, srcSize);
+ if (ZSTD_isError(seqHSize)) return seqHSize;
+ ip += seqHSize;
+ srcSize -= seqHSize;
+
+ RETURN_ERROR_IF(dst == NULL && nbSeq > 0, dstSize_tooSmall, "NULL not handled");
+
+ /* If we could potentially have long offsets, or we might want to use the prefetch decoder,
+ * compute information about the share of long offsets, and the maximum nbAdditionalBits.
+ * NOTE: could probably use a larger nbSeq limit
+ */
+ if (isLongOffset || (!usePrefetchDecoder && (totalHistorySize > (1u << 24)) && (nbSeq > 8))) {
+ ZSTD_OffsetInfo const info = ZSTD_getOffsetInfo(dctx->OFTptr, nbSeq);
+ if (isLongOffset && info.maxNbAdditionalBits <= STREAM_ACCUMULATOR_MIN) {
+ /* If isLongOffset, but the maximum number of additional bits that we see in our table is small
+ * enough, then we know it is impossible to have too long an offset in this block, so we can
+ * use the regular offset decoder.
+ */
+ isLongOffset = ZSTD_lo_isRegularOffset;
+ }
+ if (!usePrefetchDecoder) {
+ U32 const minShare = MEM_64bits() ? 7 : 20; /* heuristic values, correspond to 2.73% and 7.81% */
+ usePrefetchDecoder = (info.longOffsetShare >= minShare);
+ }
+ }
+
+ dctx->ddictIsCold = 0;
+
+#if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
+ !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG)
+ if (usePrefetchDecoder) {
+#else
+ (void)usePrefetchDecoder;
+ {
+#endif
+#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
+ return ZSTD_decompressSequencesLong(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset, frame);
+#endif
+ }
+
+#ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
+ /* else */
+ if (dctx->litBufferLocation == ZSTD_split)
+ return ZSTD_decompressSequencesSplitLitBuffer(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset, frame);
+ else
+ return ZSTD_decompressSequences(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset, frame);
+#endif
+ }
+}
+
+
+void ZSTD_checkContinuity(ZSTD_DCtx* dctx, const void* dst, size_t dstSize)
+{
+ if (dst != dctx->previousDstEnd && dstSize > 0) { /* not contiguous */
+ dctx->dictEnd = dctx->previousDstEnd;
+ dctx->virtualStart = (const char*)dst - ((const char*)(dctx->previousDstEnd) - (const char*)(dctx->prefixStart));
+ dctx->prefixStart = dst;
+ dctx->previousDstEnd = dst;
+ }
+}
+
+
+size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx,
+ void* dst, size_t dstCapacity,
+ const void* src, size_t srcSize)
+{
+ size_t dSize;
+ ZSTD_checkContinuity(dctx, dst, dstCapacity);
+ dSize = ZSTD_decompressBlock_internal(dctx, dst, dstCapacity, src, srcSize, /* frame */ 0, not_streaming);
+ dctx->previousDstEnd = (char*)dst + dSize;
+ return dSize;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-16 23:20:35 +0000