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minor behavior refinements

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specifically, there is no obligation to start streaming compression with pos=0.
stableSrc mode is now compatible with this setup.
This commit is contained in:
Yann Collet
2022-01-26 10:31:24 -08:00
parent 37b87add7a
commit 27d336b099
3 changed files with 21 additions and 15 deletions
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lib/compress/zstd_compress.c
+8 -4
View File
@@ -5630,6 +5630,8 @@ static size_t ZSTD_CCtx_init_compressStream2(ZSTD_CCtx* cctx,
return 0;
}
/* @return provides a minimum amount of data remaining to be flushed from internal buffers
*/
size_t ZSTD_compressStream2( ZSTD_CCtx* cctx,
ZSTD_outBuffer* output,
ZSTD_inBuffer* input,
@@ -5644,13 +5646,15 @@ size_t ZSTD_compressStream2( ZSTD_CCtx* cctx,
/* transparent initialization stage */
if (cctx->streamStage == zcss_init) {
size_t const inputSize = input->size - input->pos; /* no obligation to start from pos==0 */
if ( (cctx->requestedParams.inBufferMode == ZSTD_bm_stable) /* input is presumed stable, across invocations */
&& (endOp == ZSTD_e_continue) /* more to come */
&& (input->pos < ZSTD_BLOCKSIZE_MAX) ) { /* not even reached one block yet */
&& (endOp == ZSTD_e_continue) /* no flush requested, more input to come */
&& (inputSize < ZSTD_BLOCKSIZE_MAX) ) { /* not even reached one block yet */
/* just wait, allows lazy adaptation of compression parameters */
cctx->expectedInBuffer = *input;
return (ZSTD_BLOCKSIZE_MAX - input->pos); /* don't do anything : allows lazy adaptation of compression parameters */
return ZSTD_FRAMEHEADERSIZE_MIN(cctx->requestedParams.format); /* at least some header to produce */
}
FORWARD_IF_ERROR(ZSTD_CCtx_init_compressStream2(cctx, endOp, input->size), "CompressStream2 initialization failed");
FORWARD_IF_ERROR(ZSTD_CCtx_init_compressStream2(cctx, endOp, inputSize), "CompressStream2 initialization failed");
ZSTD_setBufferExpectations(cctx, output, input); /* Set initial buffer expectations now that we've initialized */
}
/* end of transparent initialization stage */
lib/zstd.h
+1 -1
View File
@@ -1851,7 +1851,7 @@ ZSTDLIB_STATIC_API size_t ZSTD_CCtx_refPrefix_advanced(ZSTD_CCtx* cctx, const vo
* memory. However, compression WILL fail if conditions are not respected.
*
* WARNING: The data in the ZSTD_inBuffer in the range [src, src + pos) MUST
* not be modified during compression or it sill result in data corruption.
* not be modified during compression or it will result in data corruption.
* This is because zstd needs to reference data in the ZSTD_inBuffer to find
* matches. Normally zstd maintains its own window buffer for this purpose,
* but passing this flag tells zstd to rely on user provided buffer instead.