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huf_decompress.c
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huf_decompress.c
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#ifndef USE_EXTERNAL_ZSTD
/* ******************************************************************
* huff0 huffman decoder,
* part of Finite State Entropy library
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* You can contact the author at :
* - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy
*
* 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_deps.h" /* ZSTD_memcpy, ZSTD_memset */
#include "compiler.h"
#include "bitstream.h" /* BIT_* */
#include "fse.h" /* to compress headers */
#include "huf.h"
#include "error_private.h"
#include "zstd_internal.h"
#include "bits.h" /* ZSTD_highbit32, ZSTD_countTrailingZeros64 */
/* **************************************************************
* Constants
****************************************************************/
#define HUF_DECODER_FAST_TABLELOG 11
/* **************************************************************
* Macros
****************************************************************/
#ifdef HUF_DISABLE_FAST_DECODE
# define HUF_ENABLE_FAST_DECODE 0
#else
# define HUF_ENABLE_FAST_DECODE 1
#endif
/* These two optional macros force the use one way or another of the two
* Huffman decompression implementations. You can't force in both directions
* at the same time.
*/
#if defined(HUF_FORCE_DECOMPRESS_X1) && \
defined(HUF_FORCE_DECOMPRESS_X2)
#error "Cannot force the use of the X1 and X2 decoders at the same time!"
#endif
/* When DYNAMIC_BMI2 is enabled, fast decoders are only called when bmi2 is
* supported at runtime, so we can add the BMI2 target attribute.
* When it is disabled, we will still get BMI2 if it is enabled statically.
*/
#if DYNAMIC_BMI2
# define HUF_FAST_BMI2_ATTRS BMI2_TARGET_ATTRIBUTE
#else
# define HUF_FAST_BMI2_ATTRS
#endif
#ifdef __cplusplus
# define HUF_EXTERN_C extern "C"
#else
# define HUF_EXTERN_C
#endif
#define HUF_ASM_DECL HUF_EXTERN_C
#if DYNAMIC_BMI2
# define HUF_NEED_BMI2_FUNCTION 1
#else
# define HUF_NEED_BMI2_FUNCTION 0
#endif
/* **************************************************************
* Error Management
****************************************************************/
#define HUF_isError ERR_isError
/* **************************************************************
* Byte alignment for workSpace management
****************************************************************/
#define HUF_ALIGN(x, a) HUF_ALIGN_MASK((x), (a) - 1)
#define HUF_ALIGN_MASK(x, mask) (((x) + (mask)) & ~(mask))
/* **************************************************************
* BMI2 Variant Wrappers
****************************************************************/
typedef size_t (*HUF_DecompressUsingDTableFn)(void *dst, size_t dstSize,
const void *cSrc,
size_t cSrcSize,
const HUF_DTable *DTable);
#if DYNAMIC_BMI2
#define HUF_DGEN(fn) \
\
static size_t fn##_default( \
void* dst, size_t dstSize, \
const void* cSrc, size_t cSrcSize, \
const HUF_DTable* DTable) \
{ \
return fn##_body(dst, dstSize, cSrc, cSrcSize, DTable); \
} \
\
static BMI2_TARGET_ATTRIBUTE size_t fn##_bmi2( \
void* dst, size_t dstSize, \
const void* cSrc, size_t cSrcSize, \
const HUF_DTable* DTable) \
{ \
return fn##_body(dst, dstSize, cSrc, cSrcSize, DTable); \
} \
\
static size_t fn(void* dst, size_t dstSize, void const* cSrc, \
size_t cSrcSize, HUF_DTable const* DTable, int flags) \
{ \
if (flags & HUF_flags_bmi2) { \
return fn##_bmi2(dst, dstSize, cSrc, cSrcSize, DTable); \
} \
return fn##_default(dst, dstSize, cSrc, cSrcSize, DTable); \
}
#else
#define HUF_DGEN(fn) \
static size_t fn(void* dst, size_t dstSize, void const* cSrc, \
size_t cSrcSize, HUF_DTable const* DTable, int flags) \
{ \
(void)flags; \
return fn##_body(dst, dstSize, cSrc, cSrcSize, DTable); \
}
#endif
/*-***************************/
/* generic DTableDesc */
/*-***************************/
typedef struct { BYTE maxTableLog; BYTE tableType; BYTE tableLog; BYTE reserved; } DTableDesc;
static DTableDesc HUF_getDTableDesc(const HUF_DTable* table)
{
DTableDesc dtd;
ZSTD_memcpy(&dtd, table, sizeof(dtd));
return dtd;
}
static size_t HUF_initFastDStream(BYTE const* ip) {
BYTE const lastByte = ip[7];
size_t const bitsConsumed = lastByte ? 8 - ZSTD_highbit32(lastByte) : 0;
size_t const value = MEM_readLEST(ip) | 1;
assert(bitsConsumed <= 8);
assert(sizeof(size_t) == 8);
return value << bitsConsumed;
}
/**
* The input/output arguments to the Huffman fast decoding loop:
*
* ip [in/out] - The input pointers, must be updated to reflect what is consumed.
* op [in/out] - The output pointers, must be updated to reflect what is written.
* bits [in/out] - The bitstream containers, must be updated to reflect the current state.
* dt [in] - The decoding table.
* ilowest [in] - The beginning of the valid range of the input. Decoders may read
* down to this pointer. It may be below iend[0].
* oend [in] - The end of the output stream. op[3] must not cross oend.
* iend [in] - The end of each input stream. ip[i] may cross iend[i],
* as long as it is above ilowest, but that indicates corruption.
*/
typedef struct {
BYTE const* ip[4];
BYTE* op[4];
U64 bits[4];
void const* dt;
BYTE const* ilowest;
BYTE* oend;
BYTE const* iend[4];
} HUF_DecompressFastArgs;
typedef void (*HUF_DecompressFastLoopFn)(HUF_DecompressFastArgs*);
/**
* Initializes args for the fast decoding loop.
* @returns 1 on success
* 0 if the fallback implementation should be used.
* Or an error code on failure.
*/
static size_t HUF_DecompressFastArgs_init(HUF_DecompressFastArgs* args, void* dst, size_t dstSize, void const* src, size_t srcSize, const HUF_DTable* DTable)
{
void const* dt = DTable + 1;
U32 const dtLog = HUF_getDTableDesc(DTable).tableLog;
const BYTE* const istart = (const BYTE*)src;
BYTE* const oend = ZSTD_maybeNullPtrAdd((BYTE*)dst, dstSize);
/* The fast decoding loop assumes 64-bit little-endian.
* This condition is false on x32.
*/
if (!MEM_isLittleEndian() || MEM_32bits())
return 0;
/* Avoid nullptr addition */
if (dstSize == 0)
return 0;
assert(dst != NULL);
/* strict minimum : jump table + 1 byte per stream */
if (srcSize < 10)
return ERROR(corruption_detected);
/* Must have at least 8 bytes per stream because we don't handle initializing smaller bit containers.
* If table log is not correct at this point, fallback to the old decoder.
* On small inputs we don't have enough data to trigger the fast loop, so use the old decoder.
*/
if (dtLog != HUF_DECODER_FAST_TABLELOG)
return 0;
/* Read the jump table. */
{
size_t const length1 = MEM_readLE16(istart);
size_t const length2 = MEM_readLE16(istart+2);
size_t const length3 = MEM_readLE16(istart+4);
size_t const length4 = srcSize - (length1 + length2 + length3 + 6);
args->iend[0] = istart + 6; /* jumpTable */
args->iend[1] = args->iend[0] + length1;
args->iend[2] = args->iend[1] + length2;
args->iend[3] = args->iend[2] + length3;
/* HUF_initFastDStream() requires this, and this small of an input
* won't benefit from the ASM loop anyways.
*/
if (length1 < 8 || length2 < 8 || length3 < 8 || length4 < 8)
return 0;
if (length4 > srcSize) return ERROR(corruption_detected); /* overflow */
}
/* ip[] contains the position that is currently loaded into bits[]. */
args->ip[0] = args->iend[1] - sizeof(U64);
args->ip[1] = args->iend[2] - sizeof(U64);
args->ip[2] = args->iend[3] - sizeof(U64);
args->ip[3] = (BYTE const*)src + srcSize - sizeof(U64);
/* op[] contains the output pointers. */
args->op[0] = (BYTE*)dst;
args->op[1] = args->op[0] + (dstSize+3)/4;
args->op[2] = args->op[1] + (dstSize+3)/4;
args->op[3] = args->op[2] + (dstSize+3)/4;
/* No point to call the ASM loop for tiny outputs. */
if (args->op[3] >= oend)
return 0;
/* bits[] is the bit container.
* It is read from the MSB down to the LSB.
* It is shifted left as it is read, and zeros are
* shifted in. After the lowest valid bit a 1 is
* set, so that CountTrailingZeros(bits[]) can be used
* to count how many bits we've consumed.
*/
args->bits[0] = HUF_initFastDStream(args->ip[0]);
args->bits[1] = HUF_initFastDStream(args->ip[1]);
args->bits[2] = HUF_initFastDStream(args->ip[2]);
args->bits[3] = HUF_initFastDStream(args->ip[3]);
/* The decoders must be sure to never read beyond ilowest.
* This is lower than iend[0], but allowing decoders to read
* down to ilowest can allow an extra iteration or two in the
* fast loop.
*/
args->ilowest = istart;
args->oend = oend;
args->dt = dt;
return 1;
}
static size_t HUF_initRemainingDStream(BIT_DStream_t* bit, HUF_DecompressFastArgs const* args, int stream, BYTE* segmentEnd)
{
/* Validate that we haven't overwritten. */
if (args->op[stream] > segmentEnd)
return ERROR(corruption_detected);
/* Validate that we haven't read beyond iend[].
* Note that ip[] may be < iend[] because the MSB is
* the next bit to read, and we may have consumed 100%
* of the stream, so down to iend[i] - 8 is valid.
*/
if (args->ip[stream] < args->iend[stream] - 8)
return ERROR(corruption_detected);
/* Construct the BIT_DStream_t. */
assert(sizeof(size_t) == 8);
bit->bitContainer = MEM_readLEST(args->ip[stream]);
bit->bitsConsumed = ZSTD_countTrailingZeros64(args->bits[stream]);
bit->start = (const char*)args->ilowest;
bit->limitPtr = bit->start + sizeof(size_t);
bit->ptr = (const char*)args->ip[stream];
return 0;
}
/* Calls X(N) for each stream 0, 1, 2, 3. */
#define HUF_4X_FOR_EACH_STREAM(X) \
do { \
X(0); \
X(1); \
X(2); \
X(3); \
} while (0)
/* Calls X(N, var) for each stream 0, 1, 2, 3. */
#define HUF_4X_FOR_EACH_STREAM_WITH_VAR(X, var) \
do { \
X(0, (var)); \
X(1, (var)); \
X(2, (var)); \
X(3, (var)); \
} while (0)
#ifndef HUF_FORCE_DECOMPRESS_X2
/*-***************************/
/* single-symbol decoding */
/*-***************************/
typedef struct { BYTE nbBits; BYTE byte; } HUF_DEltX1; /* single-symbol decoding */
/**
* Packs 4 HUF_DEltX1 structs into a U64. This is used to lay down 4 entries at
* a time.
*/
static U64 HUF_DEltX1_set4(BYTE symbol, BYTE nbBits) {
U64 D4;
if (MEM_isLittleEndian()) {
D4 = (U64)((symbol << 8) + nbBits);
} else {
D4 = (U64)(symbol + (nbBits << 8));
}
assert(D4 < (1U << 16));
D4 *= 0x0001000100010001ULL;
return D4;
}
/**
* Increase the tableLog to targetTableLog and rescales the stats.
* If tableLog > targetTableLog this is a no-op.
* @returns New tableLog
*/
static U32 HUF_rescaleStats(BYTE* huffWeight, U32* rankVal, U32 nbSymbols, U32 tableLog, U32 targetTableLog)
{
if (tableLog > targetTableLog)
return tableLog;
if (tableLog < targetTableLog) {
U32 const scale = targetTableLog - tableLog;
U32 s;
/* Increase the weight for all non-zero probability symbols by scale. */
for (s = 0; s < nbSymbols; ++s) {
huffWeight[s] += (BYTE)((huffWeight[s] == 0) ? 0 : scale);
}
/* Update rankVal to reflect the new weights.
* All weights except 0 get moved to weight + scale.
* Weights [1, scale] are empty.
*/
for (s = targetTableLog; s > scale; --s) {
rankVal[s] = rankVal[s - scale];
}
for (s = scale; s > 0; --s) {
rankVal[s] = 0;
}
}
return targetTableLog;
}
typedef struct {
U32 rankVal[HUF_TABLELOG_ABSOLUTEMAX + 1];
U32 rankStart[HUF_TABLELOG_ABSOLUTEMAX + 1];
U32 statsWksp[HUF_READ_STATS_WORKSPACE_SIZE_U32];
BYTE symbols[HUF_SYMBOLVALUE_MAX + 1];
BYTE huffWeight[HUF_SYMBOLVALUE_MAX + 1];
} HUF_ReadDTableX1_Workspace;
size_t HUF_readDTableX1_wksp(HUF_DTable* DTable, const void* src, size_t srcSize, void* workSpace, size_t wkspSize, int flags)
{
U32 tableLog = 0;
U32 nbSymbols = 0;
size_t iSize;
void* const dtPtr = DTable + 1;
HUF_DEltX1* const dt = (HUF_DEltX1*)dtPtr;
HUF_ReadDTableX1_Workspace* wksp = (HUF_ReadDTableX1_Workspace*)workSpace;
DEBUG_STATIC_ASSERT(HUF_DECOMPRESS_WORKSPACE_SIZE >= sizeof(*wksp));
if (sizeof(*wksp) > wkspSize) return ERROR(tableLog_tooLarge);
DEBUG_STATIC_ASSERT(sizeof(DTableDesc) == sizeof(HUF_DTable));
/* ZSTD_memset(huffWeight, 0, sizeof(huffWeight)); */ /* is not necessary, even though some analyzer complain ... */
iSize = HUF_readStats_wksp(wksp->huffWeight, HUF_SYMBOLVALUE_MAX + 1, wksp->rankVal, &nbSymbols, &tableLog, src, srcSize, wksp->statsWksp, sizeof(wksp->statsWksp), flags);
if (HUF_isError(iSize)) return iSize;
/* Table header */
{ DTableDesc dtd = HUF_getDTableDesc(DTable);
U32 const maxTableLog = dtd.maxTableLog + 1;
U32 const targetTableLog = MIN(maxTableLog, HUF_DECODER_FAST_TABLELOG);
tableLog = HUF_rescaleStats(wksp->huffWeight, wksp->rankVal, nbSymbols, tableLog, targetTableLog);
if (tableLog > (U32)(dtd.maxTableLog+1)) return ERROR(tableLog_tooLarge); /* DTable too small, Huffman tree cannot fit in */
dtd.tableType = 0;
dtd.tableLog = (BYTE)tableLog;
ZSTD_memcpy(DTable, &dtd, sizeof(dtd));
}
/* Compute symbols and rankStart given rankVal:
*
* rankVal already contains the number of values of each weight.
*
* symbols contains the symbols ordered by weight. First are the rankVal[0]
* weight 0 symbols, followed by the rankVal[1] weight 1 symbols, and so on.
* symbols[0] is filled (but unused) to avoid a branch.
*
* rankStart contains the offset where each rank belongs in the DTable.
* rankStart[0] is not filled because there are no entries in the table for
* weight 0.
*/
{ int n;
U32 nextRankStart = 0;
int const unroll = 4;
int const nLimit = (int)nbSymbols - unroll + 1;
for (n=0; n<(int)tableLog+1; n++) {
U32 const curr = nextRankStart;
nextRankStart += wksp->rankVal[n];
wksp->rankStart[n] = curr;
}
for (n=0; n < nLimit; n += unroll) {
int u;
for (u=0; u < unroll; ++u) {
size_t const w = wksp->huffWeight[n+u];
wksp->symbols[wksp->rankStart[w]++] = (BYTE)(n+u);
}
}
for (; n < (int)nbSymbols; ++n) {
size_t const w = wksp->huffWeight[n];
wksp->symbols[wksp->rankStart[w]++] = (BYTE)n;
}
}
/* fill DTable
* We fill all entries of each weight in order.
* That way length is a constant for each iteration of the outer loop.
* We can switch based on the length to a different inner loop which is
* optimized for that particular case.
*/
{ U32 w;
int symbol = wksp->rankVal[0];
int rankStart = 0;
for (w=1; w<tableLog+1; ++w) {
int const symbolCount = wksp->rankVal[w];
int const length = (1 << w) >> 1;
int uStart = rankStart;
BYTE const nbBits = (BYTE)(tableLog + 1 - w);
int s;
int u;
switch (length) {
case 1:
for (s=0; s<symbolCount; ++s) {
HUF_DEltX1 D;
D.byte = wksp->symbols[symbol + s];
D.nbBits = nbBits;
dt[uStart] = D;
uStart += 1;
}
break;
case 2:
for (s=0; s<symbolCount; ++s) {
HUF_DEltX1 D;
D.byte = wksp->symbols[symbol + s];
D.nbBits = nbBits;
dt[uStart+0] = D;
dt[uStart+1] = D;
uStart += 2;
}
break;
case 4:
for (s=0; s<symbolCount; ++s) {
U64 const D4 = HUF_DEltX1_set4(wksp->symbols[symbol + s], nbBits);
MEM_write64(dt + uStart, D4);
uStart += 4;
}
break;
case 8:
for (s=0; s<symbolCount; ++s) {
U64 const D4 = HUF_DEltX1_set4(wksp->symbols[symbol + s], nbBits);
MEM_write64(dt + uStart, D4);
MEM_write64(dt + uStart + 4, D4);
uStart += 8;
}
break;
default:
for (s=0; s<symbolCount; ++s) {
U64 const D4 = HUF_DEltX1_set4(wksp->symbols[symbol + s], nbBits);
for (u=0; u < length; u += 16) {
MEM_write64(dt + uStart + u + 0, D4);
MEM_write64(dt + uStart + u + 4, D4);
MEM_write64(dt + uStart + u + 8, D4);
MEM_write64(dt + uStart + u + 12, D4);
}
assert(u == length);
uStart += length;
}
break;
}
symbol += symbolCount;
rankStart += symbolCount * length;
}
}
return iSize;
}
FORCE_INLINE_TEMPLATE BYTE
HUF_decodeSymbolX1(BIT_DStream_t* Dstream, const HUF_DEltX1* dt, const U32 dtLog)
{
size_t const val = BIT_lookBitsFast(Dstream, dtLog); /* note : dtLog >= 1 */
BYTE const c = dt[val].byte;
BIT_skipBits(Dstream, dt[val].nbBits);
return c;
}
#define HUF_DECODE_SYMBOLX1_0(ptr, DStreamPtr) \
do { *ptr++ = HUF_decodeSymbolX1(DStreamPtr, dt, dtLog); } while (0)
#define HUF_DECODE_SYMBOLX1_1(ptr, DStreamPtr) \
do { \
if (MEM_64bits() || (HUF_TABLELOG_MAX<=12)) \
HUF_DECODE_SYMBOLX1_0(ptr, DStreamPtr); \
} while (0)
#define HUF_DECODE_SYMBOLX1_2(ptr, DStreamPtr) \
do { \
if (MEM_64bits()) \
HUF_DECODE_SYMBOLX1_0(ptr, DStreamPtr); \
} while (0)
HINT_INLINE size_t
HUF_decodeStreamX1(BYTE* p, BIT_DStream_t* const bitDPtr, BYTE* const pEnd, const HUF_DEltX1* const dt, const U32 dtLog)
{
BYTE* const pStart = p;
/* up to 4 symbols at a time */
if ((pEnd - p) > 3) {
while ((BIT_reloadDStream(bitDPtr) == BIT_DStream_unfinished) & (p < pEnd-3)) {
HUF_DECODE_SYMBOLX1_2(p, bitDPtr);
HUF_DECODE_SYMBOLX1_1(p, bitDPtr);
HUF_DECODE_SYMBOLX1_2(p, bitDPtr);
HUF_DECODE_SYMBOLX1_0(p, bitDPtr);
}
} else {
BIT_reloadDStream(bitDPtr);
}
/* [0-3] symbols remaining */
if (MEM_32bits())
while ((BIT_reloadDStream(bitDPtr) == BIT_DStream_unfinished) & (p < pEnd))
HUF_DECODE_SYMBOLX1_0(p, bitDPtr);
/* no more data to retrieve from bitstream, no need to reload */
while (p < pEnd)
HUF_DECODE_SYMBOLX1_0(p, bitDPtr);
return (size_t)(pEnd-pStart);
}
FORCE_INLINE_TEMPLATE size_t
HUF_decompress1X1_usingDTable_internal_body(
void* dst, size_t dstSize,
const void* cSrc, size_t cSrcSize,
const HUF_DTable* DTable)
{
BYTE* op = (BYTE*)dst;
BYTE* const oend = ZSTD_maybeNullPtrAdd(op, dstSize);
const void* dtPtr = DTable + 1;
const HUF_DEltX1* const dt = (const HUF_DEltX1*)dtPtr;
BIT_DStream_t bitD;
DTableDesc const dtd = HUF_getDTableDesc(DTable);
U32 const dtLog = dtd.tableLog;
CHECK_F( BIT_initDStream(&bitD, cSrc, cSrcSize) );
HUF_decodeStreamX1(op, &bitD, oend, dt, dtLog);
if (!BIT_endOfDStream(&bitD)) return ERROR(corruption_detected);
return dstSize;
}
/* HUF_decompress4X1_usingDTable_internal_body():
* Conditions :
* @dstSize >= 6
*/
FORCE_INLINE_TEMPLATE size_t
HUF_decompress4X1_usingDTable_internal_body(
void* dst, size_t dstSize,
const void* cSrc, size_t cSrcSize,
const HUF_DTable* DTable)
{
/* Check */
if (cSrcSize < 10) return ERROR(corruption_detected); /* strict minimum : jump table + 1 byte per stream */
if (dstSize < 6) return ERROR(corruption_detected); /* stream 4-split doesn't work */
{ const BYTE* const istart = (const BYTE*) cSrc;
BYTE* const ostart = (BYTE*) dst;
BYTE* const oend = ostart + dstSize;
BYTE* const olimit = oend - 3;
const void* const dtPtr = DTable + 1;
const HUF_DEltX1* const dt = (const HUF_DEltX1*)dtPtr;
/* Init */
BIT_DStream_t bitD1;
BIT_DStream_t bitD2;
BIT_DStream_t bitD3;
BIT_DStream_t bitD4;
size_t const length1 = MEM_readLE16(istart);
size_t const length2 = MEM_readLE16(istart+2);
size_t const length3 = MEM_readLE16(istart+4);
size_t const length4 = cSrcSize - (length1 + length2 + length3 + 6);
const BYTE* const istart1 = istart + 6; /* jumpTable */
const BYTE* const istart2 = istart1 + length1;
const BYTE* const istart3 = istart2 + length2;
const BYTE* const istart4 = istart3 + length3;
const size_t segmentSize = (dstSize+3) / 4;
BYTE* const opStart2 = ostart + segmentSize;
BYTE* const opStart3 = opStart2 + segmentSize;
BYTE* const opStart4 = opStart3 + segmentSize;
BYTE* op1 = ostart;
BYTE* op2 = opStart2;
BYTE* op3 = opStart3;
BYTE* op4 = opStart4;
DTableDesc const dtd = HUF_getDTableDesc(DTable);
U32 const dtLog = dtd.tableLog;
U32 endSignal = 1;
if (length4 > cSrcSize) return ERROR(corruption_detected); /* overflow */
if (opStart4 > oend) return ERROR(corruption_detected); /* overflow */
assert(dstSize >= 6); /* validated above */
CHECK_F( BIT_initDStream(&bitD1, istart1, length1) );
CHECK_F( BIT_initDStream(&bitD2, istart2, length2) );
CHECK_F( BIT_initDStream(&bitD3, istart3, length3) );
CHECK_F( BIT_initDStream(&bitD4, istart4, length4) );
/* up to 16 symbols per loop (4 symbols per stream) in 64-bit mode */
if ((size_t)(oend - op4) >= sizeof(size_t)) {
for ( ; (endSignal) & (op4 < olimit) ; ) {
HUF_DECODE_SYMBOLX1_2(op1, &bitD1);
HUF_DECODE_SYMBOLX1_2(op2, &bitD2);
HUF_DECODE_SYMBOLX1_2(op3, &bitD3);
HUF_DECODE_SYMBOLX1_2(op4, &bitD4);
HUF_DECODE_SYMBOLX1_1(op1, &bitD1);
HUF_DECODE_SYMBOLX1_1(op2, &bitD2);
HUF_DECODE_SYMBOLX1_1(op3, &bitD3);
HUF_DECODE_SYMBOLX1_1(op4, &bitD4);
HUF_DECODE_SYMBOLX1_2(op1, &bitD1);
HUF_DECODE_SYMBOLX1_2(op2, &bitD2);
HUF_DECODE_SYMBOLX1_2(op3, &bitD3);
HUF_DECODE_SYMBOLX1_2(op4, &bitD4);
HUF_DECODE_SYMBOLX1_0(op1, &bitD1);
HUF_DECODE_SYMBOLX1_0(op2, &bitD2);
HUF_DECODE_SYMBOLX1_0(op3, &bitD3);
HUF_DECODE_SYMBOLX1_0(op4, &bitD4);
endSignal &= BIT_reloadDStreamFast(&bitD1) == BIT_DStream_unfinished;
endSignal &= BIT_reloadDStreamFast(&bitD2) == BIT_DStream_unfinished;
endSignal &= BIT_reloadDStreamFast(&bitD3) == BIT_DStream_unfinished;
endSignal &= BIT_reloadDStreamFast(&bitD4) == BIT_DStream_unfinished;
}
}
/* check corruption */
/* note : should not be necessary : op# advance in lock step, and we control op4.
* but curiously, binary generated by gcc 7.2 & 7.3 with -mbmi2 runs faster when >=1 test is present */
if (op1 > opStart2) return ERROR(corruption_detected);
if (op2 > opStart3) return ERROR(corruption_detected);
if (op3 > opStart4) return ERROR(corruption_detected);
/* note : op4 supposed already verified within main loop */
/* finish bitStreams one by one */
HUF_decodeStreamX1(op1, &bitD1, opStart2, dt, dtLog);
HUF_decodeStreamX1(op2, &bitD2, opStart3, dt, dtLog);
HUF_decodeStreamX1(op3, &bitD3, opStart4, dt, dtLog);
HUF_decodeStreamX1(op4, &bitD4, oend, dt, dtLog);
/* check */
{ U32 const endCheck = BIT_endOfDStream(&bitD1) & BIT_endOfDStream(&bitD2) & BIT_endOfDStream(&bitD3) & BIT_endOfDStream(&bitD4);
if (!endCheck) return ERROR(corruption_detected); }
/* decoded size */
return dstSize;
}
}
#if HUF_NEED_BMI2_FUNCTION
static BMI2_TARGET_ATTRIBUTE
size_t HUF_decompress4X1_usingDTable_internal_bmi2(void* dst, size_t dstSize, void const* cSrc,
size_t cSrcSize, HUF_DTable const* DTable) {
return HUF_decompress4X1_usingDTable_internal_body(dst, dstSize, cSrc, cSrcSize, DTable);
}
#endif
static
size_t HUF_decompress4X1_usingDTable_internal_default(void* dst, size_t dstSize, void const* cSrc,
size_t cSrcSize, HUF_DTable const* DTable) {
return HUF_decompress4X1_usingDTable_internal_body(dst, dstSize, cSrc, cSrcSize, DTable);
}
#if ZSTD_ENABLE_ASM_X86_64_BMI2
HUF_ASM_DECL void HUF_decompress4X1_usingDTable_internal_fast_asm_loop(HUF_DecompressFastArgs* args) ZSTDLIB_HIDDEN;
#endif
static HUF_FAST_BMI2_ATTRS
void HUF_decompress4X1_usingDTable_internal_fast_c_loop(HUF_DecompressFastArgs* args)
{
U64 bits[4];
BYTE const* ip[4];
BYTE* op[4];
U16 const* const dtable = (U16 const*)args->dt;
BYTE* const oend = args->oend;
BYTE const* const ilowest = args->ilowest;
/* Copy the arguments to local variables */
ZSTD_memcpy(&bits, &args->bits, sizeof(bits));
ZSTD_memcpy((void*)(&ip), &args->ip, sizeof(ip));
ZSTD_memcpy(&op, &args->op, sizeof(op));
assert(MEM_isLittleEndian());
assert(!MEM_32bits());
for (;;) {
BYTE* olimit;
int stream;
/* Assert loop preconditions */
#ifndef NDEBUG
for (stream = 0; stream < 4; ++stream) {
assert(op[stream] <= (stream == 3 ? oend : op[stream + 1]));
assert(ip[stream] >= ilowest);
}
#endif
/* Compute olimit */
{
/* Each iteration produces 5 output symbols per stream */
size_t const oiters = (size_t)(oend - op[3]) / 5;
/* Each iteration consumes up to 11 bits * 5 = 55 bits < 7 bytes
* per stream.
*/
size_t const iiters = (size_t)(ip[0] - ilowest) / 7;
/* We can safely run iters iterations before running bounds checks */
size_t const iters = MIN(oiters, iiters);
size_t const symbols = iters * 5;
/* We can simply check that op[3] < olimit, instead of checking all
* of our bounds, since we can't hit the other bounds until we've run
* iters iterations, which only happens when op[3] == olimit.
*/
olimit = op[3] + symbols;
/* Exit fast decoding loop once we reach the end. */
if (op[3] == olimit)
break;
/* Exit the decoding loop if any input pointer has crossed the
* previous one. This indicates corruption, and a precondition
* to our loop is that ip[i] >= ip[0].
*/
for (stream = 1; stream < 4; ++stream) {
if (ip[stream] < ip[stream - 1])
goto _out;
}
}
#ifndef NDEBUG
for (stream = 1; stream < 4; ++stream) {
assert(ip[stream] >= ip[stream - 1]);
}
#endif
#define HUF_4X1_DECODE_SYMBOL(_stream, _symbol) \
do { \
int const index = (int)(bits[(_stream)] >> 53); \
int const entry = (int)dtable[index]; \
bits[(_stream)] <<= (entry & 0x3F); \
op[(_stream)][(_symbol)] = (BYTE)((entry >> 8) & 0xFF); \
} while (0)
#define HUF_4X1_RELOAD_STREAM(_stream) \
do { \
int const ctz = ZSTD_countTrailingZeros64(bits[(_stream)]); \
int const nbBits = ctz & 7; \
int const nbBytes = ctz >> 3; \
op[(_stream)] += 5; \
ip[(_stream)] -= nbBytes; \
bits[(_stream)] = MEM_read64(ip[(_stream)]) | 1; \
bits[(_stream)] <<= nbBits; \
} while (0)
/* Manually unroll the loop because compilers don't consistently
* unroll the inner loops, which destroys performance.
*/
do {
/* Decode 5 symbols in each of the 4 streams */
HUF_4X_FOR_EACH_STREAM_WITH_VAR(HUF_4X1_DECODE_SYMBOL, 0);
HUF_4X_FOR_EACH_STREAM_WITH_VAR(HUF_4X1_DECODE_SYMBOL, 1);
HUF_4X_FOR_EACH_STREAM_WITH_VAR(HUF_4X1_DECODE_SYMBOL, 2);
HUF_4X_FOR_EACH_STREAM_WITH_VAR(HUF_4X1_DECODE_SYMBOL, 3);
HUF_4X_FOR_EACH_STREAM_WITH_VAR(HUF_4X1_DECODE_SYMBOL, 4);
/* Reload each of the 4 the bitstreams */
HUF_4X_FOR_EACH_STREAM(HUF_4X1_RELOAD_STREAM);
} while (op[3] < olimit);
#undef HUF_4X1_DECODE_SYMBOL
#undef HUF_4X1_RELOAD_STREAM
}
_out:
/* Save the final values of each of the state variables back to args. */
ZSTD_memcpy(&args->bits, &bits, sizeof(bits));
ZSTD_memcpy((void*)(&args->ip), &ip, sizeof(ip));
ZSTD_memcpy(&args->op, &op, sizeof(op));
}
/**
* @returns @p dstSize on success (>= 6)
* 0 if the fallback implementation should be used
* An error if an error occurred
*/
static HUF_FAST_BMI2_ATTRS
size_t
HUF_decompress4X1_usingDTable_internal_fast(
void* dst, size_t dstSize,
const void* cSrc, size_t cSrcSize,
const HUF_DTable* DTable,
HUF_DecompressFastLoopFn loopFn)
{
void const* dt = DTable + 1;
BYTE const* const ilowest = (BYTE const*)cSrc;
BYTE* const oend = ZSTD_maybeNullPtrAdd((BYTE*)dst, dstSize);
HUF_DecompressFastArgs args;
{ size_t const ret = HUF_DecompressFastArgs_init(&args, dst, dstSize, cSrc, cSrcSize, DTable);
FORWARD_IF_ERROR(ret, "Failed to init fast loop args");
if (ret == 0)
return 0;
}
assert(args.ip[0] >= args.ilowest);
loopFn(&args);
/* Our loop guarantees that ip[] >= ilowest and that we haven't
* overwritten any op[].
*/
assert(args.ip[0] >= ilowest);
assert(args.ip[0] >= ilowest);
assert(args.ip[1] >= ilowest);
assert(args.ip[2] >= ilowest);
assert(args.ip[3] >= ilowest);
assert(args.op[3] <= oend);
assert(ilowest == args.ilowest);
assert(ilowest + 6 == args.iend[0]);
(void)ilowest;
/* finish bit streams one by one. */
{ size_t const segmentSize = (dstSize+3) / 4;
BYTE* segmentEnd = (BYTE*)dst;
int i;
for (i = 0; i < 4; ++i) {
BIT_DStream_t bit;
if (segmentSize <= (size_t)(oend - segmentEnd))
segmentEnd += segmentSize;
else
segmentEnd = oend;
FORWARD_IF_ERROR(HUF_initRemainingDStream(&bit, &args, i, segmentEnd), "corruption");
/* Decompress and validate that we've produced exactly the expected length. */
args.op[i] += HUF_decodeStreamX1(args.op[i], &bit, segmentEnd, (HUF_DEltX1 const*)dt, HUF_DECODER_FAST_TABLELOG);
if (args.op[i] != segmentEnd) return ERROR(corruption_detected);
}
}
/* decoded size */
assert(dstSize != 0);
return dstSize;
}
HUF_DGEN(HUF_decompress1X1_usingDTable_internal)
static size_t HUF_decompress4X1_usingDTable_internal(void* dst, size_t dstSize, void const* cSrc,
size_t cSrcSize, HUF_DTable const* DTable, int flags)
{
HUF_DecompressUsingDTableFn fallbackFn = HUF_decompress4X1_usingDTable_internal_default;
HUF_DecompressFastLoopFn loopFn = HUF_decompress4X1_usingDTable_internal_fast_c_loop;
#if DYNAMIC_BMI2
if (flags & HUF_flags_bmi2) {
fallbackFn = HUF_decompress4X1_usingDTable_internal_bmi2;
# if ZSTD_ENABLE_ASM_X86_64_BMI2
if (!(flags & HUF_flags_disableAsm)) {
loopFn = HUF_decompress4X1_usingDTable_internal_fast_asm_loop;
}
# endif
} else {
return fallbackFn(dst, dstSize, cSrc, cSrcSize, DTable);
}
#endif
#if ZSTD_ENABLE_ASM_X86_64_BMI2 && defined(__BMI2__)
if (!(flags & HUF_flags_disableAsm)) {
loopFn = HUF_decompress4X1_usingDTable_internal_fast_asm_loop;
}
#endif
if (HUF_ENABLE_FAST_DECODE && !(flags & HUF_flags_disableFast)) {
size_t const ret = HUF_decompress4X1_usingDTable_internal_fast(dst, dstSize, cSrc, cSrcSize, DTable, loopFn);
if (ret != 0)
return ret;
}
return fallbackFn(dst, dstSize, cSrc, cSrcSize, DTable);
}
static size_t HUF_decompress4X1_DCtx_wksp(HUF_DTable* dctx, void* dst, size_t dstSize,
const void* cSrc, size_t cSrcSize,
void* workSpace, size_t wkspSize, int flags)
{
const BYTE* ip = (const BYTE*) cSrc;
size_t const hSize = HUF_readDTableX1_wksp(dctx, cSrc, cSrcSize, workSpace, wkspSize, flags);
if (HUF_isError(hSize)) return hSize;
if (hSize >= cSrcSize) return ERROR(srcSize_wrong);
ip += hSize; cSrcSize -= hSize;
return HUF_decompress4X1_usingDTable_internal(dst, dstSize, ip, cSrcSize, dctx, flags);
}
#endif /* HUF_FORCE_DECOMPRESS_X2 */
#ifndef HUF_FORCE_DECOMPRESS_X1
/* *************************/
/* double-symbols decoding */
/* *************************/
typedef struct { U16 sequence; BYTE nbBits; BYTE length; } HUF_DEltX2; /* double-symbols decoding */
typedef struct { BYTE symbol; } sortedSymbol_t;
typedef U32 rankValCol_t[HUF_TABLELOG_MAX + 1];
typedef rankValCol_t rankVal_t[HUF_TABLELOG_MAX];
/**
* Constructs a HUF_DEltX2 in a U32.
*/
static U32 HUF_buildDEltX2U32(U32 symbol, U32 nbBits, U32 baseSeq, int level)
{
U32 seq;
DEBUG_STATIC_ASSERT(offsetof(HUF_DEltX2, sequence) == 0);
DEBUG_STATIC_ASSERT(offsetof(HUF_DEltX2, nbBits) == 2);
DEBUG_STATIC_ASSERT(offsetof(HUF_DEltX2, length) == 3);
DEBUG_STATIC_ASSERT(sizeof(HUF_DEltX2) == sizeof(U32));
if (MEM_isLittleEndian()) {
seq = level == 1 ? symbol : (baseSeq + (symbol << 8));
return seq + (nbBits << 16) + ((U32)level << 24);
} else {
seq = level == 1 ? (symbol << 8) : ((baseSeq << 8) + symbol);
return (seq << 16) + (nbBits << 8) + (U32)level;
}
}
/**
* Constructs a HUF_DEltX2.
*/
static HUF_DEltX2 HUF_buildDEltX2(U32 symbol, U32 nbBits, U32 baseSeq, int level)
{
HUF_DEltX2 DElt;
U32 const val = HUF_buildDEltX2U32(symbol, nbBits, baseSeq, level);
DEBUG_STATIC_ASSERT(sizeof(DElt) == sizeof(val));
ZSTD_memcpy(&DElt, &val, sizeof(val));
return DElt;
}
/**
* Constructs 2 HUF_DEltX2s and packs them into a U64.
*/
static U64 HUF_buildDEltX2U64(U32 symbol, U32 nbBits, U16 baseSeq, int level)
{
U32 DElt = HUF_buildDEltX2U32(symbol, nbBits, baseSeq, level);
return (U64)DElt + ((U64)DElt << 32);
}
/**
* Fills the DTable rank with all the symbols from [begin, end) that are each