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Clarify comments in zstd.h some more

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This commit is contained in:
senhuang42
2020-10-28 09:53:09 -04:00
parent 3163909d14
commit 3ed5d053d8
3 changed files with 17 additions and 10 deletions
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lib/zstd.h
+15 -6
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@@ -1114,20 +1114,25 @@ ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);
typedef struct ZSTD_CCtx_params_s ZSTD_CCtx_params;
typedef struct {
unsigned int offset; /* The offset of the match.
* If offset == 0 and matchLength == 0,
* then this sequence represents last literals in the block of litLength size.
unsigned int offset; /* The offset of the match. (NOT the same as the offset code)
* If offset == 0 and matchLength == 0, this sequence represents the last
* literals in the block of litLength size.
*/
unsigned int litLength; /* Literal length of the sequence. */
unsigned int matchLength; /* Match length of the sequence. */
/* Note: Users of this API may provide a sequence with matchLength == litLength == offset == 0.
* In this case, we will treat the "sequence" as a marker for a block boundary.
* In this case, we will treat the sequence as a marker for a block boundary.
*/
unsigned int rep; /* Represents which repeat offset is used. Ranges from [0, 3].
* If rep == 0, then this sequence does not contain a repeat offset.
unsigned int rep; /* Represents which repeat offset is represented by the field 'offset'.
* Ranges from [0, 3].
*
* Repeat offsets are essentially previous offsets from previous sequences sorted in
* recency order. For more detail, see doc/zstd_compression_format.md
*
* If rep == 0, then 'offset' does not contain a repeat offset.
* If rep > 0:
* If litLength != 0:
* rep == 1 --> offset == repeat_offset_1
@@ -1137,6 +1142,10 @@ typedef struct {
* rep == 1 --> offset == repeat_offset_2
* rep == 2 --> offset == repeat_offset_3
* rep == 3 --> offset == repeat_offset_1 - 1
*
* Note: This field is optional. ZSTD_getSequence() will calculate the value of
* 'rep', but repeat offsets do not necessarily need to be calculated from an external
* sequence provider's perspective.
*/
} ZSTD_Sequence;