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Diffstat (limited to '')
-rw-r--r-- | src/zstd/tests/seqgen.c | 260 |
1 files changed, 260 insertions, 0 deletions
diff --git a/src/zstd/tests/seqgen.c b/src/zstd/tests/seqgen.c new file mode 100644 index 000000000..29c0c4054 --- /dev/null +++ b/src/zstd/tests/seqgen.c @@ -0,0 +1,260 @@ +/* + * Copyright (c) 2017-2020, 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. + */ + +#include "seqgen.h" +#include "mem.h" +#include <string.h> + +#define MIN(a, b) ((a) < (b) ? (a) : (b)) + +static const size_t kMatchBytes = 128; + +#define SEQ_rotl32(x,r) ((x << r) | (x >> (32 - r))) +static BYTE SEQ_randByte(unsigned* src) +{ + static const U32 prime1 = 2654435761U; + static const U32 prime2 = 2246822519U; + U32 rand32 = *src; + rand32 *= prime1; + rand32 ^= prime2; + rand32 = SEQ_rotl32(rand32, 13); + *src = rand32; + return (BYTE)(rand32 >> 5); +} + +SEQ_stream SEQ_initStream(unsigned seed) +{ + SEQ_stream stream; + stream.state = 0; + XXH64_reset(&stream.xxh, 0); + stream.seed = seed; + return stream; +} + +/* Generates a single guard byte, then match length + 1 of a different byte, + * then another guard byte. + */ +static size_t SEQ_gen_matchLength(SEQ_stream* stream, unsigned value, + SEQ_outBuffer* out) +{ + typedef enum { + ml_first_byte = 0, + ml_match_bytes, + ml_last_byte, + } ml_state; + BYTE* const ostart = (BYTE*)out->dst; + BYTE* const oend = ostart + out->size; + BYTE* op = ostart + out->pos; + + switch ((ml_state)stream->state) { + case ml_first_byte: + /* Generate a single byte and pick a different byte for the match */ + if (op >= oend) { + stream->bytesLeft = 1; + break; + } + *op = SEQ_randByte(&stream->seed) & 0xFF; + do { + stream->saved = SEQ_randByte(&stream->seed) & 0xFF; + } while (*op == stream->saved); + ++op; + /* State transition */ + stream->state = ml_match_bytes; + stream->bytesLeft = value + 1; + /* fall-through */ + case ml_match_bytes: { + /* Copy matchLength + 1 bytes to the output buffer */ + size_t const setLength = MIN(stream->bytesLeft, (size_t)(oend - op)); + if (setLength > 0) { + memset(op, stream->saved, setLength); + op += setLength; + stream->bytesLeft -= setLength; + } + if (stream->bytesLeft > 0) + break; + /* State transition */ + stream->state = ml_last_byte; + } + /* fall-through */ + case ml_last_byte: + /* Generate a single byte and pick a different byte for the match */ + if (op >= oend) { + stream->bytesLeft = 1; + break; + } + do { + *op = SEQ_randByte(&stream->seed) & 0xFF; + } while (*op == stream->saved); + ++op; + /* State transition */ + /* fall-through */ + default: + stream->state = 0; + stream->bytesLeft = 0; + break; + } + XXH64_update(&stream->xxh, ostart + out->pos, (op - ostart) - out->pos); + out->pos = op - ostart; + return stream->bytesLeft; +} + +/* Saves the current seed then generates kMatchBytes random bytes >= 128. + * Generates literal length - kMatchBytes random bytes < 128. + * Generates another kMatchBytes using the saved seed to generate a match. + * This way the match is easy to find for the compressors. + */ +static size_t SEQ_gen_litLength(SEQ_stream* stream, unsigned value, SEQ_outBuffer* out) +{ + typedef enum { + ll_start = 0, + ll_run_bytes, + ll_literals, + ll_run_match, + } ll_state; + BYTE* const ostart = (BYTE*)out->dst; + BYTE* const oend = ostart + out->size; + BYTE* op = ostart + out->pos; + + switch ((ll_state)stream->state) { + case ll_start: + stream->state = ll_run_bytes; + stream->saved = stream->seed; + stream->bytesLeft = MIN(kMatchBytes, value); + /* fall-through */ + case ll_run_bytes: + while (stream->bytesLeft > 0 && op < oend) { + *op++ = SEQ_randByte(&stream->seed) | 0x80; + --stream->bytesLeft; + } + if (stream->bytesLeft > 0) + break; + /* State transition */ + stream->state = ll_literals; + stream->bytesLeft = value - MIN(kMatchBytes, value); + /* fall-through */ + case ll_literals: + while (stream->bytesLeft > 0 && op < oend) { + *op++ = SEQ_randByte(&stream->seed) & 0x7F; + --stream->bytesLeft; + } + if (stream->bytesLeft > 0) + break; + /* State transition */ + stream->state = ll_run_match; + stream->bytesLeft = MIN(kMatchBytes, value); + /* fall-through */ + case ll_run_match: { + while (stream->bytesLeft > 0 && op < oend) { + *op++ = SEQ_randByte(&stream->saved) | 0x80; + --stream->bytesLeft; + } + if (stream->bytesLeft > 0) + break; + } + /* fall-through */ + default: + stream->state = 0; + stream->bytesLeft = 0; + break; + } + XXH64_update(&stream->xxh, ostart + out->pos, (op - ostart) - out->pos); + out->pos = op - ostart; + return stream->bytesLeft; +} + +/* Saves the current seed then generates kMatchBytes random bytes >= 128. + * Generates offset - kMatchBytes of zeros to get a large offset without + * polluting the hash tables. + * Generates another kMatchBytes using the saved seed to generate a with the + * required offset. + */ +static size_t SEQ_gen_offset(SEQ_stream* stream, unsigned value, SEQ_outBuffer* out) +{ + typedef enum { + of_start = 0, + of_run_bytes, + of_offset, + of_run_match, + } of_state; + BYTE* const ostart = (BYTE*)out->dst; + BYTE* const oend = ostart + out->size; + BYTE* op = ostart + out->pos; + + switch ((of_state)stream->state) { + case of_start: + stream->state = of_run_bytes; + stream->saved = stream->seed; + stream->bytesLeft = MIN(value, kMatchBytes); + /* fall-through */ + case of_run_bytes: { + while (stream->bytesLeft > 0 && op < oend) { + *op++ = SEQ_randByte(&stream->seed) | 0x80; + --stream->bytesLeft; + } + if (stream->bytesLeft > 0) + break; + /* State transition */ + stream->state = of_offset; + stream->bytesLeft = value - MIN(value, kMatchBytes); + } + /* fall-through */ + case of_offset: { + /* Copy matchLength + 1 bytes to the output buffer */ + size_t const setLength = MIN(stream->bytesLeft, (size_t)(oend - op)); + if (setLength > 0) { + memset(op, 0, setLength); + op += setLength; + stream->bytesLeft -= setLength; + } + if (stream->bytesLeft > 0) + break; + /* State transition */ + stream->state = of_run_match; + stream->bytesLeft = MIN(value, kMatchBytes); + } + /* fall-through */ + case of_run_match: { + while (stream->bytesLeft > 0 && op < oend) { + *op++ = SEQ_randByte(&stream->saved) | 0x80; + --stream->bytesLeft; + } + if (stream->bytesLeft > 0) + break; + } + /* fall-through */ + default: + stream->state = 0; + stream->bytesLeft = 0; + break; + } + XXH64_update(&stream->xxh, ostart + out->pos, (op - ostart) - out->pos); + out->pos = op - ostart; + return stream->bytesLeft; +} + +/* Returns the number of bytes left to generate. + * Must pass the same type/value until it returns 0. + */ +size_t SEQ_gen(SEQ_stream* stream, SEQ_gen_type type, unsigned value, SEQ_outBuffer* out) +{ + switch (type) { + case SEQ_gen_ml: return SEQ_gen_matchLength(stream, value, out); + case SEQ_gen_ll: return SEQ_gen_litLength(stream, value, out); + case SEQ_gen_of: return SEQ_gen_offset(stream, value, out); + case SEQ_gen_max: /* fall-through */ + default: return 0; + } +} + +/* Returns the xxhash of the data produced so far */ +XXH64_hash_t SEQ_digest(SEQ_stream const* stream) +{ + return XXH64_digest(&stream->xxh); +} |