contrib/zstd/lib/common/bitstream.h in extzstd-0.1.1 vs contrib/zstd/lib/common/bitstream.h in extzstd-0.2
- old
+ new
@@ -1,10 +1,10 @@
/* ******************************************************************
bitstream
Part of FSE library
header file (to include)
- Copyright (C) 2013-2016, Yann Collet.
+ Copyright (C) 2013-2017, Yann Collet.
BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
@@ -37,11 +37,10 @@
#if defined (__cplusplus)
extern "C" {
#endif
-
/*
* This API consists of small unitary functions, which must be inlined for best performance.
* Since link-time-optimization is not available for all compilers,
* these functions are defined into a .h to be included.
*/
@@ -51,10 +50,22 @@
******************************************/
#include "mem.h" /* unaligned access routines */
#include "error_private.h" /* error codes and messages */
+/*-*************************************
+* Debug
+***************************************/
+#if defined(BIT_DEBUG) && (BIT_DEBUG>=1)
+# include <assert.h>
+#else
+# ifndef assert
+# define assert(condition) ((void)0)
+# endif
+#endif
+
+
/*=========================================
* Target specific
=========================================*/
#if defined(__BMI__) && defined(__GNUC__)
# include <immintrin.h> /* support for bextr (experimental) */
@@ -62,21 +73,22 @@
#define STREAM_ACCUMULATOR_MIN_32 25
#define STREAM_ACCUMULATOR_MIN_64 57
#define STREAM_ACCUMULATOR_MIN ((U32)(MEM_32bits() ? STREAM_ACCUMULATOR_MIN_32 : STREAM_ACCUMULATOR_MIN_64))
+
/*-******************************************
* bitStream encoding API (write forward)
********************************************/
/* bitStream can mix input from multiple sources.
-* A critical property of these streams is that they encode and decode in **reverse** direction.
-* So the first bit sequence you add will be the last to be read, like a LIFO stack.
-*/
+ * A critical property of these streams is that they encode and decode in **reverse** direction.
+ * So the first bit sequence you add will be the last to be read, like a LIFO stack.
+ */
typedef struct
{
size_t bitContainer;
- int bitPos;
+ unsigned bitPos;
char* startPtr;
char* ptr;
char* endPtr;
} BIT_CStream_t;
@@ -110,10 +122,11 @@
{
size_t bitContainer;
unsigned bitsConsumed;
const char* ptr;
const char* start;
+ const char* limitPtr;
} BIT_DStream_t;
typedef enum { BIT_DStream_unfinished = 0,
BIT_DStream_endOfBuffer = 1,
BIT_DStream_completed = 2,
@@ -152,144 +165,182 @@
/*-**************************************************************
* Internal functions
****************************************************************/
-MEM_STATIC unsigned BIT_highbit32 (register U32 val)
+MEM_STATIC unsigned BIT_highbit32 (U32 val)
{
+ assert(val != 0);
+ {
# if defined(_MSC_VER) /* Visual */
- unsigned long r=0;
- _BitScanReverse ( &r, val );
- return (unsigned) r;
+ unsigned long r=0;
+ _BitScanReverse ( &r, val );
+ return (unsigned) r;
# elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */
- return 31 - __builtin_clz (val);
+ return 31 - __builtin_clz (val);
# else /* Software version */
- static const unsigned DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30, 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 };
- U32 v = val;
- v |= v >> 1;
- v |= v >> 2;
- v |= v >> 4;
- v |= v >> 8;
- v |= v >> 16;
- return DeBruijnClz[ (U32) (v * 0x07C4ACDDU) >> 27];
+ static const unsigned DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29,
+ 11, 14, 16, 18, 22, 25, 3, 30,
+ 8, 12, 20, 28, 15, 17, 24, 7,
+ 19, 27, 23, 6, 26, 5, 4, 31 };
+ U32 v = val;
+ v |= v >> 1;
+ v |= v >> 2;
+ v |= v >> 4;
+ v |= v >> 8;
+ v |= v >> 16;
+ return DeBruijnClz[ (U32) (v * 0x07C4ACDDU) >> 27];
# endif
+ }
}
/*===== Local Constants =====*/
-static const unsigned BIT_mask[] = { 0, 1, 3, 7, 0xF, 0x1F, 0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF, 0x1FFFF, 0x3FFFF, 0x7FFFF, 0xFFFFF, 0x1FFFFF, 0x3FFFFF, 0x7FFFFF, 0xFFFFFF, 0x1FFFFFF, 0x3FFFFFF }; /* up to 26 bits */
+static const unsigned BIT_mask[] = {
+ 0, 1, 3, 7, 0xF, 0x1F,
+ 0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF,
+ 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF, 0x1FFFF,
+ 0x3FFFF, 0x7FFFF, 0xFFFFF, 0x1FFFFF, 0x3FFFFF, 0x7FFFFF,
+ 0xFFFFFF, 0x1FFFFFF, 0x3FFFFFF, 0x7FFFFFF, 0xFFFFFFF, 0x1FFFFFFF,
+ 0x3FFFFFFF, 0x7FFFFFFF}; /* up to 31 bits */
+#define BIT_MASK_SIZE (sizeof(BIT_mask) / sizeof(BIT_mask[0]))
-
/*-**************************************************************
* bitStream encoding
****************************************************************/
/*! BIT_initCStream() :
- * `dstCapacity` must be > sizeof(void*)
+ * `dstCapacity` must be > sizeof(size_t)
* @return : 0 if success,
- otherwise an error code (can be tested using ERR_isError() ) */
-MEM_STATIC size_t BIT_initCStream(BIT_CStream_t* bitC, void* startPtr, size_t dstCapacity)
+ * otherwise an error code (can be tested using ERR_isError()) */
+MEM_STATIC size_t BIT_initCStream(BIT_CStream_t* bitC,
+ void* startPtr, size_t dstCapacity)
{
bitC->bitContainer = 0;
bitC->bitPos = 0;
bitC->startPtr = (char*)startPtr;
bitC->ptr = bitC->startPtr;
- bitC->endPtr = bitC->startPtr + dstCapacity - sizeof(bitC->ptr);
- if (dstCapacity <= sizeof(bitC->ptr)) return ERROR(dstSize_tooSmall);
+ bitC->endPtr = bitC->startPtr + dstCapacity - sizeof(bitC->bitContainer);
+ if (dstCapacity <= sizeof(bitC->bitContainer)) return ERROR(dstSize_tooSmall);
return 0;
}
/*! BIT_addBits() :
- can add up to 26 bits into `bitC`.
- Does not check for register overflow ! */
-MEM_STATIC void BIT_addBits(BIT_CStream_t* bitC, size_t value, unsigned nbBits)
+ * can add up to 31 bits into `bitC`.
+ * Note : does not check for register overflow ! */
+MEM_STATIC void BIT_addBits(BIT_CStream_t* bitC,
+ size_t value, unsigned nbBits)
{
+ MEM_STATIC_ASSERT(BIT_MASK_SIZE == 32);
+ assert(nbBits < BIT_MASK_SIZE);
+ assert(nbBits + bitC->bitPos < sizeof(bitC->bitContainer) * 8);
bitC->bitContainer |= (value & BIT_mask[nbBits]) << bitC->bitPos;
bitC->bitPos += nbBits;
}
/*! BIT_addBitsFast() :
* works only if `value` is _clean_, meaning all high bits above nbBits are 0 */
-MEM_STATIC void BIT_addBitsFast(BIT_CStream_t* bitC, size_t value, unsigned nbBits)
+MEM_STATIC void BIT_addBitsFast(BIT_CStream_t* bitC,
+ size_t value, unsigned nbBits)
{
+ assert((value>>nbBits) == 0);
+ assert(nbBits + bitC->bitPos < sizeof(bitC->bitContainer) * 8);
bitC->bitContainer |= value << bitC->bitPos;
bitC->bitPos += nbBits;
}
/*! BIT_flushBitsFast() :
+ * assumption : bitContainer has not overflowed
* unsafe version; does not check buffer overflow */
MEM_STATIC void BIT_flushBitsFast(BIT_CStream_t* bitC)
{
size_t const nbBytes = bitC->bitPos >> 3;
+ assert(bitC->bitPos < sizeof(bitC->bitContainer) * 8);
MEM_writeLEST(bitC->ptr, bitC->bitContainer);
bitC->ptr += nbBytes;
+ assert(bitC->ptr <= bitC->endPtr);
bitC->bitPos &= 7;
- bitC->bitContainer >>= nbBytes*8; /* if bitPos >= sizeof(bitContainer)*8 --> undefined behavior */
+ bitC->bitContainer >>= nbBytes*8;
}
/*! BIT_flushBits() :
+ * assumption : bitContainer has not overflowed
* safe version; check for buffer overflow, and prevents it.
- * note : does not signal buffer overflow. This will be revealed later on using BIT_closeCStream() */
+ * note : does not signal buffer overflow.
+ * overflow will be revealed later on using BIT_closeCStream() */
MEM_STATIC void BIT_flushBits(BIT_CStream_t* bitC)
{
size_t const nbBytes = bitC->bitPos >> 3;
+ assert(bitC->bitPos < sizeof(bitC->bitContainer) * 8);
MEM_writeLEST(bitC->ptr, bitC->bitContainer);
bitC->ptr += nbBytes;
if (bitC->ptr > bitC->endPtr) bitC->ptr = bitC->endPtr;
bitC->bitPos &= 7;
- bitC->bitContainer >>= nbBytes*8; /* if bitPos >= sizeof(bitContainer)*8 --> undefined behavior */
+ bitC->bitContainer >>= nbBytes*8;
}
/*! BIT_closeCStream() :
* @return : size of CStream, in bytes,
- or 0 if it could not fit into dstBuffer */
+ * or 0 if it could not fit into dstBuffer */
MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC)
{
BIT_addBitsFast(bitC, 1, 1); /* endMark */
BIT_flushBits(bitC);
-
- if (bitC->ptr >= bitC->endPtr) return 0; /* doesn't fit within authorized budget : cancel */
-
+ if (bitC->ptr >= bitC->endPtr) return 0; /* overflow detected */
return (bitC->ptr - bitC->startPtr) + (bitC->bitPos > 0);
}
/*-********************************************************
-* bitStream decoding
+* bitStream decoding
**********************************************************/
/*! BIT_initDStream() :
-* Initialize a BIT_DStream_t.
-* `bitD` : a pointer to an already allocated BIT_DStream_t structure.
-* `srcSize` must be the *exact* size of the bitStream, in bytes.
-* @return : size of stream (== srcSize) or an errorCode if a problem is detected
-*/
+ * Initialize a BIT_DStream_t.
+ * `bitD` : a pointer to an already allocated BIT_DStream_t structure.
+ * `srcSize` must be the *exact* size of the bitStream, in bytes.
+ * @return : size of stream (== srcSize), or an errorCode if a problem is detected
+ */
MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, size_t srcSize)
{
if (srcSize < 1) { memset(bitD, 0, sizeof(*bitD)); return ERROR(srcSize_wrong); }
+ bitD->start = (const char*)srcBuffer;
+ bitD->limitPtr = bitD->start + sizeof(bitD->bitContainer);
+
if (srcSize >= sizeof(bitD->bitContainer)) { /* normal case */
- bitD->start = (const char*)srcBuffer;
bitD->ptr = (const char*)srcBuffer + srcSize - sizeof(bitD->bitContainer);
bitD->bitContainer = MEM_readLEST(bitD->ptr);
{ BYTE const lastByte = ((const BYTE*)srcBuffer)[srcSize-1];
bitD->bitsConsumed = lastByte ? 8 - BIT_highbit32(lastByte) : 0; /* ensures bitsConsumed is always set */
if (lastByte == 0) return ERROR(GENERIC); /* endMark not present */ }
} else {
- bitD->start = (const char*)srcBuffer;
bitD->ptr = bitD->start;
bitD->bitContainer = *(const BYTE*)(bitD->start);
switch(srcSize)
{
- case 7: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[6]) << (sizeof(bitD->bitContainer)*8 - 16);
- case 6: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[5]) << (sizeof(bitD->bitContainer)*8 - 24);
- case 5: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[4]) << (sizeof(bitD->bitContainer)*8 - 32);
- case 4: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[3]) << 24;
- case 3: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[2]) << 16;
- case 2: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[1]) << 8;
- default:;
+ case 7: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[6]) << (sizeof(bitD->bitContainer)*8 - 16);
+ /* fall-through */
+
+ case 6: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[5]) << (sizeof(bitD->bitContainer)*8 - 24);
+ /* fall-through */
+
+ case 5: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[4]) << (sizeof(bitD->bitContainer)*8 - 32);
+ /* fall-through */
+
+ case 4: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[3]) << 24;
+ /* fall-through */
+
+ case 3: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[2]) << 16;
+ /* fall-through */
+
+ case 2: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[1]) << 8;
+ /* fall-through */
+
+ default: break;
}
- { BYTE const lastByte = ((const BYTE*)srcBuffer)[srcSize-1];
- bitD->bitsConsumed = lastByte ? 8 - BIT_highbit32(lastByte) : 0;
- if (lastByte == 0) return ERROR(GENERIC); /* endMark not present */ }
+ { BYTE const lastByte = ((const BYTE*)srcBuffer)[srcSize-1];
+ bitD->bitsConsumed = lastByte ? 8 - BIT_highbit32(lastByte) : 0;
+ if (lastByte == 0) return ERROR(corruption_detected); /* endMark not present */
+ }
bitD->bitsConsumed += (U32)(sizeof(bitD->bitContainer) - srcSize)*8;
}
return srcSize;
}
@@ -307,105 +358,108 @@
return _bextr_u64(bitContainer, start, nbBits);
else
# endif
return _bextr_u32(bitContainer, start, nbBits);
#else
+ assert(nbBits < BIT_MASK_SIZE);
return (bitContainer >> start) & BIT_mask[nbBits];
#endif
}
MEM_STATIC size_t BIT_getLowerBits(size_t bitContainer, U32 const nbBits)
{
+ assert(nbBits < BIT_MASK_SIZE);
return bitContainer & BIT_mask[nbBits];
}
/*! BIT_lookBits() :
* Provides next n bits from local register.
* local register is not modified.
* On 32-bits, maxNbBits==24.
* On 64-bits, maxNbBits==56.
- * @return : value extracted
- */
- MEM_STATIC size_t BIT_lookBits(const BIT_DStream_t* bitD, U32 nbBits)
+ * @return : value extracted */
+MEM_STATIC size_t BIT_lookBits(const BIT_DStream_t* bitD, U32 nbBits)
{
#if defined(__BMI__) && defined(__GNUC__) /* experimental; fails if bitD->bitsConsumed + nbBits > sizeof(bitD->bitContainer)*8 */
return BIT_getMiddleBits(bitD->bitContainer, (sizeof(bitD->bitContainer)*8) - bitD->bitsConsumed - nbBits, nbBits);
#else
- U32 const bitMask = sizeof(bitD->bitContainer)*8 - 1;
- return ((bitD->bitContainer << (bitD->bitsConsumed & bitMask)) >> 1) >> ((bitMask-nbBits) & bitMask);
+ U32 const regMask = sizeof(bitD->bitContainer)*8 - 1;
+ return ((bitD->bitContainer << (bitD->bitsConsumed & regMask)) >> 1) >> ((regMask-nbBits) & regMask);
#endif
}
/*! BIT_lookBitsFast() :
-* unsafe version; only works only if nbBits >= 1 */
+ * unsafe version; only works if nbBits >= 1 */
MEM_STATIC size_t BIT_lookBitsFast(const BIT_DStream_t* bitD, U32 nbBits)
{
- U32 const bitMask = sizeof(bitD->bitContainer)*8 - 1;
- return (bitD->bitContainer << (bitD->bitsConsumed & bitMask)) >> (((bitMask+1)-nbBits) & bitMask);
+ U32 const regMask = sizeof(bitD->bitContainer)*8 - 1;
+ assert(nbBits >= 1);
+ return (bitD->bitContainer << (bitD->bitsConsumed & regMask)) >> (((regMask+1)-nbBits) & regMask);
}
MEM_STATIC void BIT_skipBits(BIT_DStream_t* bitD, U32 nbBits)
{
bitD->bitsConsumed += nbBits;
}
/*! BIT_readBits() :
* Read (consume) next n bits from local register and update.
* Pay attention to not read more than nbBits contained into local register.
- * @return : extracted value.
- */
+ * @return : extracted value. */
MEM_STATIC size_t BIT_readBits(BIT_DStream_t* bitD, U32 nbBits)
{
size_t const value = BIT_lookBits(bitD, nbBits);
BIT_skipBits(bitD, nbBits);
return value;
}
/*! BIT_readBitsFast() :
-* unsafe version; only works only if nbBits >= 1 */
+ * unsafe version; only works only if nbBits >= 1 */
MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, U32 nbBits)
{
size_t const value = BIT_lookBitsFast(bitD, nbBits);
+ assert(nbBits >= 1);
BIT_skipBits(bitD, nbBits);
return value;
}
/*! BIT_reloadDStream() :
-* Refill `bitD` from buffer previously set in BIT_initDStream() .
-* This function is safe, it guarantees it will not read beyond src buffer.
-* @return : status of `BIT_DStream_t` internal register.
- if status == BIT_DStream_unfinished, internal register is filled with >= (sizeof(bitD->bitContainer)*8 - 7) bits */
+ * Refill `bitD` from buffer previously set in BIT_initDStream() .
+ * This function is safe, it guarantees it will not read beyond src buffer.
+ * @return : status of `BIT_DStream_t` internal register.
+ * when status == BIT_DStream_unfinished, internal register is filled with at least 25 or 57 bits */
MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD)
{
- if (bitD->bitsConsumed > (sizeof(bitD->bitContainer)*8)) /* should not happen => corruption detected */
- return BIT_DStream_overflow;
+ if (bitD->bitsConsumed > (sizeof(bitD->bitContainer)*8)) /* overflow detected, like end of stream */
+ return BIT_DStream_overflow;
- if (bitD->ptr >= bitD->start + sizeof(bitD->bitContainer)) {
+ if (bitD->ptr >= bitD->limitPtr) {
bitD->ptr -= bitD->bitsConsumed >> 3;
bitD->bitsConsumed &= 7;
bitD->bitContainer = MEM_readLEST(bitD->ptr);
return BIT_DStream_unfinished;
}
if (bitD->ptr == bitD->start) {
if (bitD->bitsConsumed < sizeof(bitD->bitContainer)*8) return BIT_DStream_endOfBuffer;
return BIT_DStream_completed;
}
+ /* start < ptr < limitPtr */
{ U32 nbBytes = bitD->bitsConsumed >> 3;
BIT_DStream_status result = BIT_DStream_unfinished;
if (bitD->ptr - nbBytes < bitD->start) {
nbBytes = (U32)(bitD->ptr - bitD->start); /* ptr > start */
result = BIT_DStream_endOfBuffer;
}
bitD->ptr -= nbBytes;
bitD->bitsConsumed -= nbBytes*8;
- bitD->bitContainer = MEM_readLEST(bitD->ptr); /* reminder : srcSize > sizeof(bitD) */
+ bitD->bitContainer = MEM_readLEST(bitD->ptr); /* reminder : srcSize > sizeof(bitD->bitContainer), otherwise bitD->ptr == bitD->start */
return result;
}
}
/*! BIT_endOfDStream() :
-* @return Tells if DStream has exactly reached its end (all bits consumed).
-*/
+ * @return : 1 if DStream has _exactly_ reached its end (all bits consumed).
+ */
MEM_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t* DStream)
{
return ((DStream->ptr == DStream->start) && (DStream->bitsConsumed == sizeof(DStream->bitContainer)*8));
}