zstd/compress/zstd_lazy.c

758 /* Constants for row-based hash */
759 #define ZSTD_ROW_HASH_TAG_OFFSET 16     /* byte offset of hashes in the match state's tagTable from the beginning of a row */
762 #define ZSTD_ROW_HASH_MAX_ENTRIES 64    /* absolute maximum number of entries per row, for all configurations */
823  * Returns the next index to insert at within a tagTable row, and updates the "head"
824  * value to reflect the update. Essentially cycles backwards from [0, {entries per row})
841  * Performs prefetching for the hashTable and tagTable at a given row.
854     assert(ZSTD_isAligned(hashTable + relRow, 64));                 /* prefetched hash row always 64-byte aligned */
874         U32 const row = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
875         ZSTD_row_prefetch(hashTable, tagTable, row, rowLog);
894     U32 const row = (newHash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
895     ZSTD_row_prefetch(hashTable, tagTable, row, rowLog);
920         U32* const row = hashTable + relRow;
922                                                        Explicit cast allows us to get exact desired position within each row */
927         row[pos] = updateStartIdx;
998  * the hash at the nth position in a row of the tagTable.
999  * Each row is a circular buffer beginning at the value of "head". So we must rotate the "matches" bitfield
1104 /* The high-level approach of the SIMD row based match finder is as follows:
1108  *        which row to insert into.
1109  *      - Determine the correct position within the row to insert the entry into. Each row of 16 or 32 can
1111  *      - Also insert the "tag" into the equivalent row and position in the tagTable.
1112  *          - Note: The tagTable has 17 or 33 1-byte entries per row, due to 16 or 32 tags, and 1 "head" entry.
1145     const U32 cappedSearchLog = MIN(cParams->searchLog, rowLog); /* nb of searches is capped at nb entries per row */
1182     {   /* Get the hash for ip, compute the appropriate row */
1186         U32* const row = hashTable + relRow;
1197             U32 const matchIndex = row[matchPos];
1214             row[pos] = ms->nextToUpdate++;
1378 /* Generate row search fns for each combination of (dictMode, mls, rowLog) */
1441  * @param rowLog The row log (if applicable), in the range [4, 6].