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-rw-r--r--lib/zstd/compress/zstd_compress_literals.c158
1 files changed, 158 insertions, 0 deletions
diff --git a/lib/zstd/compress/zstd_compress_literals.c b/lib/zstd/compress/zstd_compress_literals.c
new file mode 100644
index 000000000..655bcda4d
--- /dev/null
+++ b/lib/zstd/compress/zstd_compress_literals.c
@@ -0,0 +1,158 @@
+/*
+ * Copyright (c) Yann Collet, Facebook, Inc.
+ * 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.
+ */
+
+ /*-*************************************
+ * Dependencies
+ ***************************************/
+#include "zstd_compress_literals.h"
+
+size_t ZSTD_noCompressLiterals (void* dst, size_t dstCapacity, const void* src, size_t srcSize)
+{
+ BYTE* const ostart = (BYTE*)dst;
+ U32 const flSize = 1 + (srcSize>31) + (srcSize>4095);
+
+ RETURN_ERROR_IF(srcSize + flSize > dstCapacity, dstSize_tooSmall, "");
+
+ switch(flSize)
+ {
+ case 1: /* 2 - 1 - 5 */
+ ostart[0] = (BYTE)((U32)set_basic + (srcSize<<3));
+ break;
+ case 2: /* 2 - 2 - 12 */
+ MEM_writeLE16(ostart, (U16)((U32)set_basic + (1<<2) + (srcSize<<4)));
+ break;
+ case 3: /* 2 - 2 - 20 */
+ MEM_writeLE32(ostart, (U32)((U32)set_basic + (3<<2) + (srcSize<<4)));
+ break;
+ default: /* not necessary : flSize is {1,2,3} */
+ assert(0);
+ }
+
+ ZSTD_memcpy(ostart + flSize, src, srcSize);
+ DEBUGLOG(5, "Raw literals: %u -> %u", (U32)srcSize, (U32)(srcSize + flSize));
+ return srcSize + flSize;
+}
+
+size_t ZSTD_compressRleLiteralsBlock (void* dst, size_t dstCapacity, const void* src, size_t srcSize)
+{
+ BYTE* const ostart = (BYTE*)dst;
+ U32 const flSize = 1 + (srcSize>31) + (srcSize>4095);
+
+ (void)dstCapacity; /* dstCapacity already guaranteed to be >=4, hence large enough */
+
+ switch(flSize)
+ {
+ case 1: /* 2 - 1 - 5 */
+ ostart[0] = (BYTE)((U32)set_rle + (srcSize<<3));
+ break;
+ case 2: /* 2 - 2 - 12 */
+ MEM_writeLE16(ostart, (U16)((U32)set_rle + (1<<2) + (srcSize<<4)));
+ break;
+ case 3: /* 2 - 2 - 20 */
+ MEM_writeLE32(ostart, (U32)((U32)set_rle + (3<<2) + (srcSize<<4)));
+ break;
+ default: /* not necessary : flSize is {1,2,3} */
+ assert(0);
+ }
+
+ ostart[flSize] = *(const BYTE*)src;
+ DEBUGLOG(5, "RLE literals: %u -> %u", (U32)srcSize, (U32)flSize + 1);
+ return flSize+1;
+}
+
+size_t ZSTD_compressLiterals (ZSTD_hufCTables_t const* prevHuf,
+ ZSTD_hufCTables_t* nextHuf,
+ ZSTD_strategy strategy, int disableLiteralCompression,
+ void* dst, size_t dstCapacity,
+ const void* src, size_t srcSize,
+ void* entropyWorkspace, size_t entropyWorkspaceSize,
+ const int bmi2)
+{
+ size_t const minGain = ZSTD_minGain(srcSize, strategy);
+ size_t const lhSize = 3 + (srcSize >= 1 KB) + (srcSize >= 16 KB);
+ BYTE* const ostart = (BYTE*)dst;
+ U32 singleStream = srcSize < 256;
+ symbolEncodingType_e hType = set_compressed;
+ size_t cLitSize;
+
+ DEBUGLOG(5,"ZSTD_compressLiterals (disableLiteralCompression=%i srcSize=%u)",
+ disableLiteralCompression, (U32)srcSize);
+
+ /* Prepare nextEntropy assuming reusing the existing table */
+ ZSTD_memcpy(nextHuf, prevHuf, sizeof(*prevHuf));
+
+ if (disableLiteralCompression)
+ return ZSTD_noCompressLiterals(dst, dstCapacity, src, srcSize);
+
+ /* small ? don't even attempt compression (speed opt) */
+# define COMPRESS_LITERALS_SIZE_MIN 63
+ { size_t const minLitSize = (prevHuf->repeatMode == HUF_repeat_valid) ? 6 : COMPRESS_LITERALS_SIZE_MIN;
+ if (srcSize <= minLitSize) return ZSTD_noCompressLiterals(dst, dstCapacity, src, srcSize);
+ }
+
+ RETURN_ERROR_IF(dstCapacity < lhSize+1, dstSize_tooSmall, "not enough space for compression");
+ { HUF_repeat repeat = prevHuf->repeatMode;
+ int const preferRepeat = strategy < ZSTD_lazy ? srcSize <= 1024 : 0;
+ if (repeat == HUF_repeat_valid && lhSize == 3) singleStream = 1;
+ cLitSize = singleStream ?
+ HUF_compress1X_repeat(
+ ostart+lhSize, dstCapacity-lhSize, src, srcSize,
+ HUF_SYMBOLVALUE_MAX, HUF_TABLELOG_DEFAULT, entropyWorkspace, entropyWorkspaceSize,
+ (HUF_CElt*)nextHuf->CTable, &repeat, preferRepeat, bmi2) :
+ HUF_compress4X_repeat(
+ ostart+lhSize, dstCapacity-lhSize, src, srcSize,
+ HUF_SYMBOLVALUE_MAX, HUF_TABLELOG_DEFAULT, entropyWorkspace, entropyWorkspaceSize,
+ (HUF_CElt*)nextHuf->CTable, &repeat, preferRepeat, bmi2);
+ if (repeat != HUF_repeat_none) {
+ /* reused the existing table */
+ DEBUGLOG(5, "Reusing previous huffman table");
+ hType = set_repeat;
+ }
+ }
+
+ if ((cLitSize==0) | (cLitSize >= srcSize - minGain) | ERR_isError(cLitSize)) {
+ ZSTD_memcpy(nextHuf, prevHuf, sizeof(*prevHuf));
+ return ZSTD_noCompressLiterals(dst, dstCapacity, src, srcSize);
+ }
+ if (cLitSize==1) {
+ ZSTD_memcpy(nextHuf, prevHuf, sizeof(*prevHuf));
+ return ZSTD_compressRleLiteralsBlock(dst, dstCapacity, src, srcSize);
+ }
+
+ if (hType == set_compressed) {
+ /* using a newly constructed table */
+ nextHuf->repeatMode = HUF_repeat_check;
+ }
+
+ /* Build header */
+ switch(lhSize)
+ {
+ case 3: /* 2 - 2 - 10 - 10 */
+ { U32 const lhc = hType + ((!singleStream) << 2) + ((U32)srcSize<<4) + ((U32)cLitSize<<14);
+ MEM_writeLE24(ostart, lhc);
+ break;
+ }
+ case 4: /* 2 - 2 - 14 - 14 */
+ { U32 const lhc = hType + (2 << 2) + ((U32)srcSize<<4) + ((U32)cLitSize<<18);
+ MEM_writeLE32(ostart, lhc);
+ break;
+ }
+ case 5: /* 2 - 2 - 18 - 18 */
+ { U32 const lhc = hType + (3 << 2) + ((U32)srcSize<<4) + ((U32)cLitSize<<22);
+ MEM_writeLE32(ostart, lhc);
+ ostart[4] = (BYTE)(cLitSize >> 10);
+ break;
+ }
+ default: /* not possible : lhSize is {3,4,5} */
+ assert(0);
+ }
+ DEBUGLOG(5, "Compressed literals: %u -> %u", (U32)srcSize, (U32)(lhSize+cLitSize));
+ return lhSize+cLitSize;
+}