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-rw-r--r--lib/lz4.c70
-rw-r--r--lib/lz4.h14
2 files changed, 65 insertions, 19 deletions
diff --git a/lib/lz4.c b/lib/lz4.c
index dde27e9..40cac94 100644
--- a/lib/lz4.c
+++ b/lib/lz4.c
@@ -448,7 +448,7 @@ static const U32 LZ4_skipTrigger = 6; /* Increase this value ==> compression ru
typedef enum { notLimited = 0, limitedOutput = 1 } limitedOutput_directive;
typedef enum { unusedTable = 0, byPtr = 1, byU32 = 2, byU16 = 3 } tableType_t;
-typedef enum { noDict = 0, withPrefix64k, usingExtDict } dict_directive;
+typedef enum { noDict = 0, withPrefix64k, usingExtDict, usingExtDictCtx } dict_directive;
typedef enum { noDictIssue = 0, dictSmall } dictIssue_directive;
typedef enum { endOnOutputSize = 0, endOnInputSize = 1 } endCondition_directive;
@@ -533,7 +533,7 @@ LZ4_FORCE_INLINE int LZ4_compress_generic(
const int maxOutputSize,
const limitedOutput_directive outputLimited,
const tableType_t tableType,
- const dict_directive dict,
+ const dict_directive dictDirective,
const dictIssue_directive dictIssue,
const U32 acceleration)
{
@@ -553,15 +553,27 @@ LZ4_FORCE_INLINE int LZ4_compress_generic(
!resetTable) ? cctx->currentOffset : 1;
const BYTE* base = (const BYTE*) source - currentOffset;
const BYTE* lowLimit;
- const BYTE* const lowRefLimit = ip - cctx->dictSize;
- const BYTE* const dictionary = cctx->dictionary;
- const BYTE* const dictEnd = dictionary + cctx->dictSize;
- const ptrdiff_t dictDelta = dictEnd - (const BYTE*)source;
+
+ const LZ4_stream_t_internal* dictCtx = (const LZ4_stream_t_internal*) cctx->dictCtx;
+ const BYTE* const dictionary =
+ (dictDirective == usingExtDictCtx ? dictCtx : cctx)->dictionary;
+ const U32 dictSize =
+ (dictDirective == usingExtDictCtx ? dictCtx : cctx)->dictSize;
+
+ const BYTE* const lowRefLimit = (const BYTE*) source - dictSize;
+ const BYTE* const dictEnd = dictionary + dictSize;
const BYTE* anchor = (const BYTE*) source;
const BYTE* const iend = ip + inputSize;
const BYTE* const mflimitPlusOne = iend - MFLIMIT + 1;
const BYTE* const matchlimit = iend - LASTLITERALS;
+ /* the dictCtx currentOffset is indexed on the start of the dictionary,
+ * while a dictionary in the current context precedes the currentOffset */
+ const BYTE* dictBase = dictDirective == usingExtDictCtx ?
+ (const BYTE*) source - dictCtx->currentOffset :
+ (const BYTE*) source - dictSize - currentOffset;
+ const ptrdiff_t dictDelta = dictionary ? dictEnd - (const BYTE*) source : 0;
+
BYTE* op = (BYTE*) dest;
BYTE* const olimit = op + maxOutputSize;
@@ -574,17 +586,19 @@ LZ4_FORCE_INLINE int LZ4_compress_generic(
/* Init conditions */
if ((U32)inputSize > (U32)LZ4_MAX_INPUT_SIZE) return 0; /* Unsupported inputSize, too large (or negative) */
- switch(dict)
+ switch(dictDirective)
{
case noDict:
default:
lowLimit = (const BYTE*)source;
break;
case withPrefix64k:
- lowLimit = (const BYTE*)source - cctx->dictSize;
+ lowLimit = (const BYTE*)source - dictSize;
break;
case usingExtDict:
- base = (const BYTE*)source - cctx->currentOffset;
+ lowLimit = (const BYTE*)source;
+ break;
+ case usingExtDictCtx:
lowLimit = (const BYTE*)source;
break;
}
@@ -622,8 +636,19 @@ LZ4_FORCE_INLINE int LZ4_compress_generic(
assert(ip < mflimitPlusOne);
match = LZ4_getPositionOnHash(h, cctx->hashTable, tableType, base);
- if (dict==usingExtDict) {
+ if (dictDirective == usingExtDictCtx) {
if (match < (const BYTE*)source) {
+ /* there was no match, try the dictionary */
+ /* TODO: use precalc-ed hash? */
+ match = LZ4_getPosition(ip, dictCtx->hashTable, byU32, dictBase);
+ refDelta = dictDelta;
+ lowLimit = dictionary;
+ } else {
+ refDelta = 0;
+ lowLimit = (const BYTE*)source;
+ }
+ } else if (dictDirective==usingExtDict) {
+ if (match < (const BYTE*)source && dictionary != NULL) {
refDelta = dictDelta;
lowLimit = dictionary;
} else {
@@ -667,7 +692,7 @@ _next_match:
/* Encode MatchLength */
{ unsigned matchCode;
- if ((dict==usingExtDict) && (lowLimit==dictionary)) {
+ if ((dictDirective==usingExtDict || dictDirective==usingExtDictCtx) && (dictionary != NULL) && (lowLimit==dictionary)) {
const BYTE* limit;
match += refDelta;
limit = ip + (dictEnd-match);
@@ -712,8 +737,19 @@ _next_match:
/* Test next position */
match = LZ4_getPosition(ip, cctx->hashTable, tableType, base);
- if (dict==usingExtDict) {
+ if (dictDirective == usingExtDictCtx) {
if (match < (const BYTE*)source) {
+ /* there was no match, try the dictionary */
+ /* TODO: use precalc-ed hash? */
+ match = LZ4_getPosition(ip, dictCtx->hashTable, byU32, dictBase);
+ refDelta = dictDelta;
+ lowLimit = dictionary;
+ } else {
+ refDelta = 0;
+ lowLimit = (const BYTE*)source;
+ }
+ } else if (dictDirective==usingExtDict) {
+ if (match < (const BYTE*)source && dictionary != NULL) {
refDelta = dictDelta;
lowLimit = dictionary;
} else {
@@ -751,8 +787,15 @@ _last_literals:
retval = (((char*)op)-dest);
_clean_up:
+ if (dictDirective == usingExtDictCtx) {
+ /* Subsequent linked blocks can't use the dictionary. */
+ /* Instead, they use the block we just compressed. */
+ cctx->dictCtx = NULL;
+ cctx->dictSize = (U32)inputSize;
+ } else {
+ cctx->dictSize += (U32)inputSize;
+ }
cctx->currentOffset += (U32)inputSize;
- cctx->dictSize += (U32)inputSize;
cctx->tableType = tableType;
/* End */
@@ -773,6 +816,7 @@ int LZ4_compress_fast_safeExtState(void* state, const char* source, char* dest,
if (acceleration < 1) acceleration = ACCELERATION_DEFAULT;
ctx->dictionary = NULL;
ctx->dictSize = 0;
+ ctx->dictCtx = NULL;
if (maxOutputSize >= LZ4_compressBound(inputSize)) {
if (inputSize < LZ4_64Klimit)
diff --git a/lib/lz4.h b/lib/lz4.h
index 0013ffe..58a1e39 100644
--- a/lib/lz4.h
+++ b/lib/lz4.h
@@ -365,15 +365,16 @@ LZ4LIB_API int LZ4_decompress_fast_usingDict (const char* src, char* dst, int or
#if defined(__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */)
#include <stdint.h>
-typedef struct {
+typedef struct LZ4_stream_t_internal LZ4_stream_t_internal;
+struct LZ4_stream_t_internal {
uint32_t hashTable[LZ4_HASH_SIZE_U32];
uint32_t currentOffset;
uint16_t initCheck;
uint16_t tableType;
const uint8_t* dictionary;
- uint8_t* bufferStart; /* obsolete, used for slideInputBuffer */
+ const LZ4_stream_t_internal* dictCtx;
uint32_t dictSize;
-} LZ4_stream_t_internal;
+};
typedef struct {
const uint8_t* externalDict;
@@ -384,15 +385,16 @@ typedef struct {
#else
-typedef struct {
+typedef struct LZ4_stream_t_internal LZ4_stream_t_internal;
+struct LZ4_stream_t_internal {
unsigned int hashTable[LZ4_HASH_SIZE_U32];
unsigned int currentOffset;
unsigned short initCheck;
unsigned short tableType;
const unsigned char* dictionary;
- unsigned char* bufferStart; /* obsolete, used for slideInputBuffer */
+ const LZ4_stream_t_internal* dictCtx;
unsigned int dictSize;
-} LZ4_stream_t_internal;
+};
typedef struct {
const unsigned char* externalDict;
generated by cgit v0.12 at 2024-11-03 08:57:44 (GMT)