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decodecorpus.c
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/*
* 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.
*/
#include <limits.h>
#include <math.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h> /* time(), for seed random initialization */
#include "util.h"
#include "timefn.h" /* UTIL_clockSpanMicro, SEC_TO_MICRO, UTIL_TIME_INITIALIZER */
#include "zstd.h"
#include "zstd_internal.h"
#include "mem.h"
#define ZDICT_STATIC_LINKING_ONLY
#include "zdict.h"
/* Direct access to internal compression functions is required */
#include "compress/zstd_compress.c" /* ZSTD_resetSeqStore, ZSTD_storeSeq, *_TO_OFFBASE, HIST_countFast_wksp, HIST_isError */
#include "decompress/zstd_decompress_block.h" /* ZSTD_decompressBlock_deprecated */
#define XXH_STATIC_LINKING_ONLY
#include "xxhash.h" /* XXH64 */
#if !(defined (__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */))
# define inline /* disable */
#endif
/*-************************************
* DISPLAY Macros
**************************************/
#define DISPLAY(...) fprintf(stderr, __VA_ARGS__)
#define DISPLAYLEVEL(l, ...) if (g_displayLevel>=l) { DISPLAY(__VA_ARGS__); }
static U32 g_displayLevel = 2;
#define DISPLAYUPDATE(...) \
do { \
if ((UTIL_clockSpanMicro(g_displayClock) > g_refreshRate) || \
(g_displayLevel >= 4)) { \
g_displayClock = UTIL_getTime(); \
DISPLAY(__VA_ARGS__); \
if (g_displayLevel >= 4) fflush(stderr); \
} \
} while (0)
static const U64 g_refreshRate = SEC_TO_MICRO / 6;
static UTIL_time_t g_displayClock = UTIL_TIME_INITIALIZER;
#define CHECKERR(code) \
do { \
if (ZSTD_isError(code)) { \
DISPLAY("Error occurred while generating data: %s\n", \
ZSTD_getErrorName(code)); \
exit(1); \
} \
} while (0)
/*-*******************************************************
* Random function
*********************************************************/
static U32 RAND(U32* src)
{
#define RAND_rotl32(x,r) ((x << r) | (x >> (32 - r)))
static const U32 prime1 = 2654435761U;
static const U32 prime2 = 2246822519U;
U32 rand32 = *src;
rand32 *= prime1;
rand32 += prime2;
rand32 = RAND_rotl32(rand32, 13);
*src = rand32;
return RAND_rotl32(rand32, 27);
#undef RAND_rotl32
}
#define DISTSIZE (8192)
/* Write `size` bytes into `ptr`, all of which are less than or equal to `maxSymb` */
static void RAND_bufferMaxSymb(U32* seed, void* ptr, size_t size, int maxSymb)
{
size_t i;
BYTE* op = ptr;
for (i = 0; i < size; i++) {
op[i] = (BYTE) (RAND(seed) % (maxSymb + 1));
}
}
/* Write `size` random bytes into `ptr` */
static void RAND_buffer(U32* seed, void* ptr, size_t size)
{
size_t i;
BYTE* op = ptr;
for (i = 0; i + 4 <= size; i += 4) {
MEM_writeLE32(op + i, RAND(seed));
}
for (; i < size; i++) {
op[i] = RAND(seed) & 0xff;
}
}
/* Write `size` bytes into `ptr` following the distribution `dist` */
static void RAND_bufferDist(U32* seed, BYTE* dist, void* ptr, size_t size)
{
size_t i;
BYTE* op = ptr;
for (i = 0; i < size; i++) {
op[i] = dist[RAND(seed) % DISTSIZE];
}
}
/* Generate a random distribution where the frequency of each symbol follows a
* geometric distribution defined by `weight`
* `dist` should have size at least `DISTSIZE` */
static void RAND_genDist(U32* seed, BYTE* dist, double weight)
{
size_t i = 0;
size_t statesLeft = DISTSIZE;
BYTE symb = (BYTE) (RAND(seed) % 256);
BYTE step = (BYTE) ((RAND(seed) % 256) | 1); /* force it to be odd so it's relatively prime to 256 */
while (i < DISTSIZE) {
size_t states = ((size_t)(weight * (double)statesLeft)) + 1;
size_t j;
for (j = 0; j < states && i < DISTSIZE; j++, i++) {
dist[i] = symb;
}
symb += step;
statesLeft -= states;
}
}
/* Generates a random number in the range [min, max) */
static inline U32 RAND_range(U32* seed, U32 min, U32 max)
{
return (RAND(seed) % (max-min)) + min;
}
#define ROUND(x) ((U32)(x + 0.5))
/* Generates a random number in an exponential distribution with mean `mean` */
static double RAND_exp(U32* seed, double mean)
{
double const u = RAND(seed) / (double) UINT_MAX;
return log(1-u) * (-mean);
}
/*-*******************************************************
* Constants and Structs
*********************************************************/
const char* BLOCK_TYPES[] = {"raw", "rle", "compressed"};
#define MAX_DECOMPRESSED_SIZE_LOG 20
#define MAX_DECOMPRESSED_SIZE (1ULL << MAX_DECOMPRESSED_SIZE_LOG)
#define MAX_WINDOW_LOG 22 /* Recommended support is 8MB, so limit to 4MB + mantissa */
#define MIN_SEQ_LEN (3)
#define MAX_NB_SEQ ((ZSTD_BLOCKSIZE_MAX + MIN_SEQ_LEN - 1) / MIN_SEQ_LEN)
#ifndef MAX_PATH
#ifdef PATH_MAX
#define MAX_PATH PATH_MAX
#else
#define MAX_PATH 256
#endif
#endif
BYTE CONTENT_BUFFER[MAX_DECOMPRESSED_SIZE];
BYTE FRAME_BUFFER[MAX_DECOMPRESSED_SIZE * 2];
BYTE LITERAL_BUFFER[ZSTD_BLOCKSIZE_MAX];
seqDef SEQUENCE_BUFFER[MAX_NB_SEQ];
BYTE SEQUENCE_LITERAL_BUFFER[ZSTD_BLOCKSIZE_MAX]; /* storeSeq expects a place to copy literals to */
BYTE SEQUENCE_LLCODE[ZSTD_BLOCKSIZE_MAX];
BYTE SEQUENCE_MLCODE[ZSTD_BLOCKSIZE_MAX];
BYTE SEQUENCE_OFCODE[ZSTD_BLOCKSIZE_MAX];
U64 WKSP[HUF_WORKSPACE_SIZE_U64];
typedef struct {
size_t contentSize; /* 0 means unknown (unless contentSize == windowSize == 0) */
unsigned windowSize; /* contentSize >= windowSize means single segment */
} frameHeader_t;
/* For repeat modes */
typedef struct {
U32 rep[ZSTD_REP_NUM];
int hufInit;
/* the distribution used in the previous block for repeat mode */
BYTE hufDist[DISTSIZE];
HUF_CElt hufTable [HUF_CTABLE_SIZE_ST(255)];
int fseInit;
FSE_CTable offcodeCTable [FSE_CTABLE_SIZE_U32(OffFSELog, MaxOff)];
FSE_CTable matchlengthCTable[FSE_CTABLE_SIZE_U32(MLFSELog, MaxML)];
FSE_CTable litlengthCTable [FSE_CTABLE_SIZE_U32(LLFSELog, MaxLL)];
/* Symbols that were present in the previous distribution, for use with
* set_repeat */
BYTE litlengthSymbolSet[36];
BYTE offsetSymbolSet[29];
BYTE matchlengthSymbolSet[53];
} cblockStats_t;
typedef struct {
void* data;
void* dataStart;
void* dataEnd;
void* src;
void* srcStart;
void* srcEnd;
frameHeader_t header;
cblockStats_t stats;
cblockStats_t oldStats; /* so they can be rolled back if uncompressible */
} frame_t;
typedef struct {
int useDict;
U32 dictID;
size_t dictContentSize;
BYTE* dictContent;
} dictInfo;
typedef enum {
gt_frame = 0, /* generate frames */
gt_block, /* generate compressed blocks without block/frame headers */
} genType_e;
#ifndef MIN
#define MIN(a, b) ((a) < (b) ? (a) : (b))
#endif
/*-*******************************************************
* Global variables (set from command line)
*********************************************************/
U32 g_maxDecompressedSizeLog = MAX_DECOMPRESSED_SIZE_LOG; /* <= 20 */
U32 g_maxBlockSize = ZSTD_BLOCKSIZE_MAX; /* <= 128 KB */
/*-*******************************************************
* Generator Functions
*********************************************************/
struct {
int contentSize; /* force the content size to be present */
} opts; /* advanced options on generation */
/* Generate and write a random frame header */
static void writeFrameHeader(U32* seed, frame_t* frame, dictInfo info)
{
BYTE* const op = frame->data;
size_t pos = 0;
frameHeader_t fh;
BYTE windowByte = 0;
int singleSegment = 0;
int contentSizeFlag = 0;
int fcsCode = 0;
memset(&fh, 0, sizeof(fh));
/* generate window size */
{
/* Follow window algorithm from specification */
int const exponent = RAND(seed) % (MAX_WINDOW_LOG - 10);
int const mantissa = RAND(seed) % 8;
windowByte = (BYTE) ((exponent << 3) | mantissa);
fh.windowSize = (1U << (exponent + 10));
fh.windowSize += fh.windowSize / 8 * mantissa;
}
{
/* Generate random content size */
size_t highBit;
if (RAND(seed) & 7 && g_maxDecompressedSizeLog > 7) {
/* do content of at least 128 bytes */
highBit = 1ULL << RAND_range(seed, 7, g_maxDecompressedSizeLog);
} else if (RAND(seed) & 3) {
/* do small content */
highBit = 1ULL << RAND_range(seed, 0, MIN(7, 1U << g_maxDecompressedSizeLog));
} else {
/* 0 size frame */
highBit = 0;
}
fh.contentSize = highBit ? highBit + (RAND(seed) % highBit) : 0;
/* provide size sometimes */
contentSizeFlag = opts.contentSize | (RAND(seed) & 1);
if (contentSizeFlag && (fh.contentSize == 0 || !(RAND(seed) & 7))) {
/* do single segment sometimes */
fh.windowSize = (U32) fh.contentSize;
singleSegment = 1;
}
}
if (contentSizeFlag) {
/* Determine how large fcs field has to be */
int minFcsCode = (fh.contentSize >= 256) +
(fh.contentSize >= 65536 + 256) +
(fh.contentSize > 0xFFFFFFFFU);
if (!singleSegment && !minFcsCode) {
minFcsCode = 1;
}
fcsCode = minFcsCode + (RAND(seed) % (4 - minFcsCode));
if (fcsCode == 1 && fh.contentSize < 256) fcsCode++;
}
/* write out the header */
MEM_writeLE32(op + pos, ZSTD_MAGICNUMBER);
pos += 4;
{
/*
* fcsCode: 2-bit flag specifying how many bytes used to represent Frame_Content_Size (bits 7-6)
* singleSegment: 1-bit flag describing if data must be regenerated within a single continuous memory segment. (bit 5)
* contentChecksumFlag: 1-bit flag that is set if frame includes checksum at the end -- set to 1 below (bit 2)
* dictBits: 2-bit flag describing how many bytes Dictionary_ID uses -- set to 3 (bits 1-0)
* For more information: https://github.com/facebook/zstd/blob/dev/doc/zstd_compression_format.md#frame_header
*/
int const dictBits = info.useDict ? 3 : 0;
BYTE const frameHeaderDescriptor =
(BYTE) ((fcsCode << 6) | (singleSegment << 5) | (1 << 2) | dictBits);
op[pos++] = frameHeaderDescriptor;
}
if (!singleSegment) {
op[pos++] = windowByte;
}
if (info.useDict) {
MEM_writeLE32(op + pos, (U32) info.dictID);
pos += 4;
}
if (contentSizeFlag) {
switch (fcsCode) {
default: /* Impossible */
case 0: op[pos++] = (BYTE) fh.contentSize; break;
case 1: MEM_writeLE16(op + pos, (U16) (fh.contentSize - 256)); pos += 2; break;
case 2: MEM_writeLE32(op + pos, (U32) fh.contentSize); pos += 4; break;
case 3: MEM_writeLE64(op + pos, (U64) fh.contentSize); pos += 8; break;
}
}
DISPLAYLEVEL(3, " frame content size:\t%u\n", (unsigned)fh.contentSize);
DISPLAYLEVEL(3, " frame window size:\t%u\n", fh.windowSize);
DISPLAYLEVEL(3, " content size flag:\t%d\n", contentSizeFlag);
DISPLAYLEVEL(3, " single segment flag:\t%d\n", singleSegment);
frame->data = op + pos;
frame->header = fh;
}
/* Write a literal block in either raw or RLE form, return the literals size */
static size_t writeLiteralsBlockSimple(U32* seed, frame_t* frame, size_t contentSize)
{
BYTE* op = (BYTE*)frame->data;
int const type = RAND(seed) % 2;
int const sizeFormatDesc = RAND(seed) % 8;
size_t litSize;
size_t maxLitSize = MIN(contentSize, g_maxBlockSize);
if (sizeFormatDesc == 0) {
/* Size_FormatDesc = ?0 */
maxLitSize = MIN(maxLitSize, 31);
} else if (sizeFormatDesc <= 4) {
/* Size_FormatDesc = 01 */
maxLitSize = MIN(maxLitSize, 4095);
} else {
/* Size_Format = 11 */
maxLitSize = MIN(maxLitSize, 1048575);
}
litSize = RAND(seed) % (maxLitSize + 1);
if (frame->src == frame->srcStart && litSize == 0) {
litSize = 1; /* no empty literals if there's nothing preceding this block */
}
if (litSize + 3 > contentSize) {
litSize = contentSize; /* no matches shorter than 3 are allowed */
}
/* use smallest size format that fits */
if (litSize < 32) {
op[0] = (type | (0 << 2) | (litSize << 3)) & 0xff;
op += 1;
} else if (litSize < 4096) {
op[0] = (type | (1 << 2) | (litSize << 4)) & 0xff;
op[1] = (litSize >> 4) & 0xff;
op += 2;
} else {
op[0] = (type | (3 << 2) | (litSize << 4)) & 0xff;
op[1] = (litSize >> 4) & 0xff;
op[2] = (litSize >> 12) & 0xff;
op += 3;
}
if (type == 0) {
/* Raw literals */
DISPLAYLEVEL(4, " raw literals\n");
RAND_buffer(seed, LITERAL_BUFFER, litSize);
memcpy(op, LITERAL_BUFFER, litSize);
op += litSize;
} else {
/* RLE literals */
BYTE const symb = (BYTE) (RAND(seed) % 256);
DISPLAYLEVEL(4, " rle literals: 0x%02x\n", (unsigned)symb);
memset(LITERAL_BUFFER, symb, litSize);
op[0] = symb;
op++;
}
frame->data = op;
return litSize;
}
/* Generate a Huffman header for the given source */
static size_t writeHufHeader(U32* seed, HUF_CElt* hufTable, void* dst, size_t dstSize,
const void* src, size_t srcSize)
{
BYTE* const ostart = (BYTE*)dst;
BYTE* op = ostart;
unsigned huffLog = 11;
unsigned maxSymbolValue = 255;
unsigned count[HUF_SYMBOLVALUE_MAX+1];
/* Scan input and build symbol stats */
{ size_t const largest = HIST_count_wksp (count, &maxSymbolValue, (const BYTE*)src, srcSize, WKSP, sizeof(WKSP));
assert(!HIST_isError(largest));
if (largest == srcSize) { *ostart = ((const BYTE*)src)[0]; return 0; } /* single symbol, rle */
if (largest <= (srcSize >> 7)+1) return 0; /* Fast heuristic : not compressible enough */
}
/* Build Huffman Tree */
/* Max Huffman log is 11, min is highbit(maxSymbolValue)+1 */
huffLog = RAND_range(seed, ZSTD_highbit32(maxSymbolValue)+1, huffLog+1);
DISPLAYLEVEL(6, " huffman log: %u\n", huffLog);
{ size_t const maxBits = HUF_buildCTable_wksp (hufTable, count, maxSymbolValue, huffLog, WKSP, sizeof(WKSP));
CHECKERR(maxBits);
huffLog = (U32)maxBits;
}
/* Write table description header */
{ size_t const hSize = HUF_writeCTable_wksp (op, dstSize, hufTable, maxSymbolValue, huffLog, WKSP, sizeof(WKSP));
if (hSize + 12 >= srcSize) return 0; /* not useful to try compression */
op += hSize;
}
return op - ostart;
}
/* Write a Huffman coded literals block and return the literals size */
static size_t writeLiteralsBlockCompressed(U32* seed, frame_t* frame, size_t contentSize)
{
BYTE* origop = (BYTE*)frame->data;
BYTE* opend = (BYTE*)frame->dataEnd;
BYTE* op;
BYTE* const ostart = origop;
int const sizeFormat = RAND(seed) % 4;
size_t litSize;
size_t hufHeaderSize = 0;
size_t compressedSize = 0;
size_t maxLitSize = MIN(contentSize-3, g_maxBlockSize);
symbolEncodingType_e hType;
if (contentSize < 64) {
/* make sure we get reasonably-sized literals for compression */
return ERROR(GENERIC);
}
DISPLAYLEVEL(4, " compressed literals\n");
switch (sizeFormat) {
case 0: /* fall through, size is the same as case 1 */
case 1:
maxLitSize = MIN(maxLitSize, 1023);
origop += 3;
break;
case 2:
maxLitSize = MIN(maxLitSize, 16383);
origop += 4;
break;
case 3:
maxLitSize = MIN(maxLitSize, 262143);
origop += 5;
break;
default:; /* impossible */
}
do {
op = origop;
do {
litSize = RAND(seed) % (maxLitSize + 1);
} while (litSize < 32); /* avoid small literal sizes */
if (litSize + 3 > contentSize) {
litSize = contentSize; /* no matches shorter than 3 are allowed */
}
/* most of the time generate a new distribution */
if ((RAND(seed) & 3) || !frame->stats.hufInit) {
do {
if (RAND(seed) & 3) {
/* add 10 to ensure some compressibility */
double const weight = ((RAND(seed) % 90) + 10) / 100.0;
DISPLAYLEVEL(5, " distribution weight: %d%%\n",
(int)(weight * 100));
RAND_genDist(seed, frame->stats.hufDist, weight);
} else {
/* sometimes do restricted range literals to force
* non-huffman headers */
DISPLAYLEVEL(5, " small range literals\n");
RAND_bufferMaxSymb(seed, frame->stats.hufDist, DISTSIZE,
15);
}
RAND_bufferDist(seed, frame->stats.hufDist, LITERAL_BUFFER,
litSize);
/* generate the header from the distribution instead of the
* actual data to avoid bugs with symbols that were in the
* distribution but never showed up in the output */
hufHeaderSize = writeHufHeader(
seed, frame->stats.hufTable, op, opend - op,
frame->stats.hufDist, DISTSIZE);
CHECKERR(hufHeaderSize);
/* repeat until a valid header is written */
} while (hufHeaderSize == 0);
op += hufHeaderSize;
hType = set_compressed;
frame->stats.hufInit = 1;
} else {
/* repeat the distribution/table from last time */
DISPLAYLEVEL(5, " huffman repeat stats\n");
RAND_bufferDist(seed, frame->stats.hufDist, LITERAL_BUFFER,
litSize);
hufHeaderSize = 0;
hType = set_repeat;
}
do {
compressedSize =
sizeFormat == 0
? HUF_compress1X_usingCTable(
op, opend - op, LITERAL_BUFFER, litSize,
frame->stats.hufTable, /* flags */ 0)
: HUF_compress4X_usingCTable(
op, opend - op, LITERAL_BUFFER, litSize,
frame->stats.hufTable, /* flags */ 0);
CHECKERR(compressedSize);
/* this only occurs when it could not compress or similar */
} while (compressedSize <= 0);
op += compressedSize;
compressedSize += hufHeaderSize;
DISPLAYLEVEL(5, " regenerated size: %u\n", (unsigned)litSize);
DISPLAYLEVEL(5, " compressed size: %u\n", (unsigned)compressedSize);
if (compressedSize >= litSize) {
DISPLAYLEVEL(5, " trying again\n");
/* if we have to try again, reset the stats so we don't accidentally
* try to repeat a distribution we just made */
frame->stats = frame->oldStats;
} else {
break;
}
} while (1);
/* write header */
switch (sizeFormat) {
case 0: /* fall through, size is the same as case 1 */
case 1: {
U32 const header = hType | (sizeFormat << 2) | ((U32)litSize << 4) |
((U32)compressedSize << 14);
MEM_writeLE24(ostart, header);
break;
}
case 2: {
U32 const header = hType | (sizeFormat << 2) | ((U32)litSize << 4) |
((U32)compressedSize << 18);
MEM_writeLE32(ostart, header);
break;
}
case 3: {
U32 const header = hType | (sizeFormat << 2) | ((U32)litSize << 4) |
((U32)compressedSize << 22);
MEM_writeLE32(ostart, header);
ostart[4] = (BYTE)(compressedSize >> 10);
break;
}
default:; /* impossible */
}
frame->data = op;
return litSize;
}
static size_t writeLiteralsBlock(U32* seed, frame_t* frame, size_t contentSize)
{
/* only do compressed for larger segments to avoid compressibility issues */
if (RAND(seed) & 7 && contentSize >= 64) {
return writeLiteralsBlockCompressed(seed, frame, contentSize);
} else {
return writeLiteralsBlockSimple(seed, frame, contentSize);
}
}
static inline void initSeqStore(seqStore_t *seqStore) {
seqStore->maxNbSeq = MAX_NB_SEQ;
seqStore->maxNbLit = ZSTD_BLOCKSIZE_MAX;
seqStore->sequencesStart = SEQUENCE_BUFFER;
seqStore->litStart = SEQUENCE_LITERAL_BUFFER;
seqStore->llCode = SEQUENCE_LLCODE;
seqStore->mlCode = SEQUENCE_MLCODE;
seqStore->ofCode = SEQUENCE_OFCODE;
ZSTD_resetSeqStore(seqStore);
}
/* Randomly generate sequence commands */
static U32
generateSequences(U32* seed, frame_t* frame, seqStore_t* seqStore,
size_t contentSize, size_t literalsSize, dictInfo info)
{
/* The total length of all the matches */
size_t const remainingMatch = contentSize - literalsSize;
size_t excessMatch = 0;
U32 numSequences = 0;
U32 i;
const BYTE* literals = LITERAL_BUFFER;
BYTE* srcPtr = frame->src;
if (literalsSize != contentSize) {
/* each match must be at least MIN_SEQ_LEN, so this is the maximum
* number of sequences we can have */
U32 const maxSequences = (U32)remainingMatch / MIN_SEQ_LEN;
numSequences = (RAND(seed) % maxSequences) + 1;
/* the extra match lengths we have to allocate to each sequence */
excessMatch = remainingMatch - numSequences * MIN_SEQ_LEN;
}
DISPLAYLEVEL(5, " total match lengths: %u\n", (unsigned)remainingMatch);
for (i = 0; i < numSequences; i++) {
/* Generate match and literal lengths by exponential distribution to
* ensure nice numbers */
U32 matchLen =
MIN_SEQ_LEN +
ROUND(RAND_exp(seed, (double)excessMatch / (double)(numSequences - i)));
U32 literalLen =
(RAND(seed) & 7)
? ROUND(RAND_exp(seed,
(double)literalsSize /
(double)(numSequences - i)))
: 0;
/* actual offset, code to send, and point to copy up to when shifting
* codes in the repeat offsets history */
U32 offset, offBase, repIndex;
/* bounds checks */
matchLen = (U32) MIN(matchLen, excessMatch + MIN_SEQ_LEN);
literalLen = MIN(literalLen, (U32) literalsSize);
if (i == 0 && srcPtr == frame->srcStart && literalLen == 0) literalLen = 1;
if (i + 1 == numSequences) matchLen = MIN_SEQ_LEN + (U32) excessMatch;
memcpy(srcPtr, literals, literalLen);
srcPtr += literalLen;
do {
if (RAND(seed) & 7) {
/* do a normal offset */
U32 const dataDecompressed = (U32)((BYTE*)srcPtr-(BYTE*)frame->srcStart);
offset = (RAND(seed) %
MIN(frame->header.windowSize,
(size_t)((BYTE*)srcPtr - (BYTE*)frame->srcStart))) +
1;
if (info.useDict && (RAND(seed) & 1) && i + 1 != numSequences && dataDecompressed < frame->header.windowSize) {
/* need to occasionally generate offsets that go past the start */
/* including i+1 != numSequences because the last sequences has to adhere to predetermined contentSize */
U32 lenPastStart = (RAND(seed) % info.dictContentSize) + 1;
offset = (U32)((BYTE*)srcPtr - (BYTE*)frame->srcStart)+lenPastStart;
if (offset > frame->header.windowSize) {
if (lenPastStart < MIN_SEQ_LEN) {
/* when offset > windowSize, matchLen bound by end of dictionary (lenPastStart) */
/* this also means that lenPastStart must be greater than MIN_SEQ_LEN */
/* make sure lenPastStart does not go past dictionary start though */
lenPastStart = MIN(lenPastStart+MIN_SEQ_LEN, (U32)info.dictContentSize);
offset = (U32)((BYTE*)srcPtr - (BYTE*)frame->srcStart) + lenPastStart;
}
{ U32 const matchLenBound = MIN(frame->header.windowSize, lenPastStart);
matchLen = MIN(matchLen, matchLenBound);
}
}
}
offBase = OFFSET_TO_OFFBASE(offset);
repIndex = 2;
} else {
/* do a repeat offset */
U32 const randomRepIndex = RAND(seed) % 3;
offBase = REPCODE_TO_OFFBASE(randomRepIndex + 1); /* expects values between 1 & 3 */
if (literalLen > 0) {
offset = frame->stats.rep[randomRepIndex];
repIndex = randomRepIndex;
} else {
/* special case : literalLen == 0 */
offset = randomRepIndex == 2 ? frame->stats.rep[0] - 1
: frame->stats.rep[randomRepIndex + 1];
repIndex = MIN(2, randomRepIndex + 1);
}
}
} while (((!info.useDict) && (offset > (size_t)((BYTE*)srcPtr - (BYTE*)frame->srcStart))) || offset == 0);
{ BYTE* const dictEnd = info.dictContent + info.dictContentSize;
size_t j;
for (j = 0; j < matchLen; j++) {
if ((U32)((BYTE*)srcPtr - (BYTE*)frame->srcStart) < offset) {
/* copy from dictionary instead of literals */
size_t const dictOffset = offset - (srcPtr - (BYTE*)frame->srcStart);
*srcPtr = *(dictEnd - dictOffset);
}
else {
*srcPtr = *(srcPtr-offset);
}
srcPtr++;
} }
{ int r;
for (r = repIndex; r > 0; r--) {
frame->stats.rep[r] = frame->stats.rep[r - 1];
}
frame->stats.rep[0] = offset;
}
DISPLAYLEVEL(6, " LL: %5u OF: %5u ML: %5u",
(unsigned)literalLen, (unsigned)offset, (unsigned)matchLen);
DISPLAYLEVEL(7, " srcPos: %8u seqNb: %3u",
(unsigned)((BYTE*)srcPtr - (BYTE*)frame->srcStart), (unsigned)i);
DISPLAYLEVEL(6, "\n");
if (OFFBASE_IS_REPCODE(offBase)) { /* expects sumtype numeric representation of ZSTD_storeSeq() */
DISPLAYLEVEL(7, " repeat offset: %d\n", (int)repIndex);
}
/* use libzstd sequence handling */
ZSTD_storeSeq(seqStore, literalLen, literals, literals + literalLen,
offBase, matchLen);
literalsSize -= literalLen;
excessMatch -= (matchLen - MIN_SEQ_LEN);
literals += literalLen;
}
memcpy(srcPtr, literals, literalsSize);
srcPtr += literalsSize;
DISPLAYLEVEL(6, " excess literals: %5u ", (unsigned)literalsSize);
DISPLAYLEVEL(7, "srcPos: %8u ", (unsigned)((BYTE*)srcPtr - (BYTE*)frame->srcStart));
DISPLAYLEVEL(6, "\n");
return numSequences;
}
static void initSymbolSet(const BYTE* symbols, size_t len, BYTE* set, BYTE maxSymbolValue)
{
size_t i;
memset(set, 0, (size_t)maxSymbolValue+1);
for (i = 0; i < len; i++) {
set[symbols[i]] = 1;
}
}
static int isSymbolSubset(const BYTE* symbols, size_t len, const BYTE* set, BYTE maxSymbolValue)
{
size_t i;
for (i = 0; i < len; i++) {
if (symbols[i] > maxSymbolValue || !set[symbols[i]]) {
return 0;
}
}
return 1;
}
static size_t writeSequences(U32* seed, frame_t* frame, seqStore_t* seqStorePtr,
size_t nbSeq)
{
/* This code is mostly copied from ZSTD_compressSequences in zstd_compress.c */
unsigned count[MaxSeq+1];
S16 norm[MaxSeq+1];
FSE_CTable* CTable_LitLength = frame->stats.litlengthCTable;
FSE_CTable* CTable_OffsetBits = frame->stats.offcodeCTable;
FSE_CTable* CTable_MatchLength = frame->stats.matchlengthCTable;
U32 LLtype, Offtype, MLtype; /* compressed, raw or rle */
const seqDef* const sequences = seqStorePtr->sequencesStart;
const BYTE* const ofCodeTable = seqStorePtr->ofCode;
const BYTE* const llCodeTable = seqStorePtr->llCode;
const BYTE* const mlCodeTable = seqStorePtr->mlCode;
BYTE* const oend = (BYTE*)frame->dataEnd;
BYTE* op = (BYTE*)frame->data;
BYTE* seqHead;
BYTE scratchBuffer[FSE_BUILD_CTABLE_WORKSPACE_SIZE(MaxSeq, MaxFSELog)];
/* literals compressing block removed so that can be done separately */
/* Sequences Header */
if ((oend-op) < 3 /*max nbSeq Size*/ + 1 /*seqHead */) return ERROR(dstSize_tooSmall);
if (nbSeq < 0x7F) *op++ = (BYTE)nbSeq;
else if (nbSeq < LONGNBSEQ) op[0] = (BYTE)((nbSeq>>8) + 0x80), op[1] = (BYTE)nbSeq, op+=2;
else op[0]=0xFF, MEM_writeLE16(op+1, (U16)(nbSeq - LONGNBSEQ)), op+=3;
if (nbSeq==0) {
frame->data = op;
return 0;
}
/* seqHead : flags for FSE encoding type */
seqHead = op++;
/* convert length/distances into codes */
ZSTD_seqToCodes(seqStorePtr);
/* CTable for Literal Lengths */
{ unsigned max = MaxLL;
size_t const mostFrequent = HIST_countFast_wksp(count, &max, llCodeTable, nbSeq, WKSP, sizeof(WKSP)); /* cannot fail */
assert(!HIST_isError(mostFrequent));
if (frame->stats.fseInit && !(RAND(seed) & 3) &&
isSymbolSubset(llCodeTable, nbSeq,
frame->stats.litlengthSymbolSet, 35)) {
/* maybe do repeat mode if we're allowed to */
LLtype = set_repeat;
} else if (mostFrequent == nbSeq) {
/* do RLE if we have the chance */
*op++ = llCodeTable[0];
FSE_buildCTable_rle(CTable_LitLength, (BYTE)max);
LLtype = set_rle;
} else if (!(RAND(seed) & 3)) {
/* maybe use the default distribution */
CHECKERR(FSE_buildCTable_wksp(CTable_LitLength, LL_defaultNorm, MaxLL, LL_defaultNormLog, scratchBuffer, sizeof(scratchBuffer)));
LLtype = set_basic;
} else {
/* fall back on a full table */
size_t nbSeq_1 = nbSeq;
const U32 tableLog = FSE_optimalTableLog(LLFSELog, nbSeq, max);
if (count[llCodeTable[nbSeq-1]]>1) { count[llCodeTable[nbSeq-1]]--; nbSeq_1--; }
FSE_normalizeCount(norm, tableLog, count, nbSeq_1, max, nbSeq >= 2048);
{ size_t const NCountSize = FSE_writeNCount(op, oend-op, norm, max, tableLog); /* overflow protected */
if (FSE_isError(NCountSize)) return ERROR(GENERIC);
op += NCountSize; }
CHECKERR(FSE_buildCTable_wksp(CTable_LitLength, norm, max, tableLog, scratchBuffer, sizeof(scratchBuffer)));
LLtype = set_compressed;
} }
/* CTable for Offsets */
/* see Literal Lengths for descriptions of mode choices */
{ unsigned max = MaxOff;
size_t const mostFrequent = HIST_countFast_wksp(count, &max, ofCodeTable, nbSeq, WKSP, sizeof(WKSP)); /* cannot fail */
assert(!HIST_isError(mostFrequent));
if (frame->stats.fseInit && !(RAND(seed) & 3) &&
isSymbolSubset(ofCodeTable, nbSeq,
frame->stats.offsetSymbolSet, 28)) {
Offtype = set_repeat;
} else if (mostFrequent == nbSeq) {
*op++ = ofCodeTable[0];
FSE_buildCTable_rle(CTable_OffsetBits, (BYTE)max);
Offtype = set_rle;
} else if (!(RAND(seed) & 3)) {
FSE_buildCTable_wksp(CTable_OffsetBits, OF_defaultNorm, DefaultMaxOff, OF_defaultNormLog, scratchBuffer, sizeof(scratchBuffer));
Offtype = set_basic;
} else {
size_t nbSeq_1 = nbSeq;
const U32 tableLog = FSE_optimalTableLog(OffFSELog, nbSeq, max);
if (count[ofCodeTable[nbSeq-1]]>1) { count[ofCodeTable[nbSeq-1]]--; nbSeq_1--; }
FSE_normalizeCount(norm, tableLog, count, nbSeq_1, max, nbSeq >= 2048);
{ size_t const NCountSize = FSE_writeNCount(op, oend-op, norm, max, tableLog); /* overflow protected */
if (FSE_isError(NCountSize)) return ERROR(GENERIC);
op += NCountSize; }
FSE_buildCTable_wksp(CTable_OffsetBits, norm, max, tableLog, scratchBuffer, sizeof(scratchBuffer));
Offtype = set_compressed;
} }
/* CTable for MatchLengths */
/* see Literal Lengths for descriptions of mode choices */
{ unsigned max = MaxML;
size_t const mostFrequent = HIST_countFast_wksp(count, &max, mlCodeTable, nbSeq, WKSP, sizeof(WKSP)); /* cannot fail */
assert(!HIST_isError(mostFrequent));
if (frame->stats.fseInit && !(RAND(seed) & 3) &&
isSymbolSubset(mlCodeTable, nbSeq,
frame->stats.matchlengthSymbolSet, 52)) {
MLtype = set_repeat;
} else if (mostFrequent == nbSeq) {
*op++ = *mlCodeTable;
FSE_buildCTable_rle(CTable_MatchLength, (BYTE)max);
MLtype = set_rle;
} else if (!(RAND(seed) & 3)) {
/* sometimes do default distribution */
FSE_buildCTable_wksp(CTable_MatchLength, ML_defaultNorm, MaxML, ML_defaultNormLog, scratchBuffer, sizeof(scratchBuffer));
MLtype = set_basic;
} else {
/* fall back on table */
size_t nbSeq_1 = nbSeq;
const U32 tableLog = FSE_optimalTableLog(MLFSELog, nbSeq, max);
if (count[mlCodeTable[nbSeq-1]]>1) { count[mlCodeTable[nbSeq-1]]--; nbSeq_1--; }
FSE_normalizeCount(norm, tableLog, count, nbSeq_1, max, nbSeq >= 2048);
{ size_t const NCountSize = FSE_writeNCount(op, oend-op, norm, max, tableLog); /* overflow protected */
if (FSE_isError(NCountSize)) return ERROR(GENERIC);
op += NCountSize; }
FSE_buildCTable_wksp(CTable_MatchLength, norm, max, tableLog, scratchBuffer, sizeof(scratchBuffer));
MLtype = set_compressed;
} }
frame->stats.fseInit = 1;
initSymbolSet(llCodeTable, nbSeq, frame->stats.litlengthSymbolSet, 35);
initSymbolSet(ofCodeTable, nbSeq, frame->stats.offsetSymbolSet, 28);
initSymbolSet(mlCodeTable, nbSeq, frame->stats.matchlengthSymbolSet, 52);
DISPLAYLEVEL(5, " LL type: %d OF type: %d ML type: %d\n", (unsigned)LLtype, (unsigned)Offtype, (unsigned)MLtype);
*seqHead = (BYTE)((LLtype<<6) + (Offtype<<4) + (MLtype<<2));
/* Encoding Sequences */
{ BIT_CStream_t blockStream;
FSE_CState_t stateMatchLength;
FSE_CState_t stateOffsetBits;
FSE_CState_t stateLitLength;
RETURN_ERROR_IF(
ERR_isError(BIT_initCStream(&blockStream, op, oend-op)),
dstSize_tooSmall, "not enough space remaining");
/* first symbols */
FSE_initCState2(&stateMatchLength, CTable_MatchLength, mlCodeTable[nbSeq-1]);
FSE_initCState2(&stateOffsetBits, CTable_OffsetBits, ofCodeTable[nbSeq-1]);
FSE_initCState2(&stateLitLength, CTable_LitLength, llCodeTable[nbSeq-1]);
BIT_addBits(&blockStream, sequences[nbSeq-1].litLength, LL_bits[llCodeTable[nbSeq-1]]);
if (MEM_32bits()) BIT_flushBits(&blockStream);
BIT_addBits(&blockStream, sequences[nbSeq-1].mlBase, ML_bits[mlCodeTable[nbSeq-1]]);
if (MEM_32bits()) BIT_flushBits(&blockStream);
BIT_addBits(&blockStream, sequences[nbSeq-1].offBase, ofCodeTable[nbSeq-1]);
BIT_flushBits(&blockStream);
{ size_t n;
for (n=nbSeq-2 ; n<nbSeq ; n--) { /* intentional underflow */
BYTE const llCode = llCodeTable[n];
BYTE const ofCode = ofCodeTable[n];
BYTE const mlCode = mlCodeTable[n];
U32 const llBits = LL_bits[llCode];
U32 const ofBits = ofCode; /* 32b*/ /* 64b*/
U32 const mlBits = ML_bits[mlCode];
/* (7)*/ /* (7)*/
FSE_encodeSymbol(&blockStream, &stateOffsetBits, ofCode); /* 15 */ /* 15 */
FSE_encodeSymbol(&blockStream, &stateMatchLength, mlCode); /* 24 */ /* 24 */
if (MEM_32bits()) BIT_flushBits(&blockStream); /* (7)*/
FSE_encodeSymbol(&blockStream, &stateLitLength, llCode); /* 16 */ /* 33 */
if (MEM_32bits() || (ofBits+mlBits+llBits >= 64-7-(LLFSELog+MLFSELog+OffFSELog)))
BIT_flushBits(&blockStream); /* (7)*/
BIT_addBits(&blockStream, sequences[n].litLength, llBits);
if (MEM_32bits() && ((llBits+mlBits)>24)) BIT_flushBits(&blockStream);
BIT_addBits(&blockStream, sequences[n].mlBase, mlBits);
if (MEM_32bits()) BIT_flushBits(&blockStream); /* (7)*/
BIT_addBits(&blockStream, sequences[n].offBase, ofBits); /* 31 */
BIT_flushBits(&blockStream); /* (7)*/
} }
FSE_flushCState(&blockStream, &stateMatchLength);
FSE_flushCState(&blockStream, &stateOffsetBits);
FSE_flushCState(&blockStream, &stateLitLength);
{ size_t const streamSize = BIT_closeCStream(&blockStream);
if (streamSize==0) return ERROR(dstSize_tooSmall); /* not enough space */
op += streamSize;
} }
frame->data = op;
return 0;
}
static size_t writeSequencesBlock(U32* seed, frame_t* frame, size_t contentSize,
size_t literalsSize, dictInfo info)
{