minor code doc update

facebook · Jan 8, 2025 · 60ae6de · 60ae6de
1 parent daf8e8f
commit 60ae6de
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Showing 2 changed files with 8 additions and 7 deletions.
diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
@@ -7196,8 +7196,8 @@ size_t convertSequences_noRepcodes(
         __m256i vadd = _mm256_add_epi32(vin, addition);
 
         /* Check for long length */
-        __m256i cmp  = _mm256_cmpgt_epi32(vadd, limit);  // 0xFFFFFFFF for element > 65535
-        int cmp_res  = _mm256_movemask_epi8(cmp);
+        __m256i ll_cmp  = _mm256_cmpgt_epi32(vadd, limit);  /* 0xFFFFFFFF for element > 65535 */
+        int ll_res  = _mm256_movemask_epi8(ll_cmp);
 
         /* Shuffle bytes so each half gives us the 8 bytes we need */
         __m256i vshf = _mm256_shuffle_epi8(vadd, mask);
@@ -7228,7 +7228,7 @@ size_t convertSequences_noRepcodes(
          * indices for lengths correspond to bits [4..7], [8..11], [20..23], [24..27]
          * => combined mask = 0x0FF00FF0
          */
-        if (UNLIKELY((cmp_res & 0x0FF00FF0) != 0)) {
+        if (UNLIKELY((ll_res & 0x0FF00FF0) != 0)) {
             /* long length detected: let's figure out which one*/
             if (inSeqs[i].matchLength > 65535+MINMATCH) {
                 assert(longLen == 0);
@@ -7251,12 +7251,12 @@ size_t convertSequences_noRepcodes(
 
     /* Handle leftover if @nbSequences is odd */
     if (i < nbSequences) {
-        /* Fallback: process last sequence */
+        /* process last sequence */
         assert(i == nbSequences - 1);
         dstSeqs[i].offBase = OFFSET_TO_OFFBASE(inSeqs[i].offset);
-        /* note: doesn't work if one length is > 65535 */
         dstSeqs[i].litLength = (U16)inSeqs[i].litLength;
         dstSeqs[i].mlBase = (U16)(inSeqs[i].matchLength - MINMATCH);
+        /* check (unlikely) long lengths > 65535 */
         if (UNLIKELY(inSeqs[i].matchLength > 65535+MINMATCH)) {
             assert(longLen == 0);
             longLen = i + 1;

diff --git a/lib/zstd.h b/lib/zstd.h
@@ -1696,15 +1696,16 @@ ZSTD_compressSequences(ZSTD_CCtx* cctx,
  * - Not compatible with frame checksum, which must be disabled
  * - If any block is incompressible, will fail and return an error
  * - @litSize must be == sum of all @.litLength fields in @inSeqs. Any discrepancy will generate an error.
- * - the buffer @literals must have a size @litCapacity which is larger than @litSize by at least 8 bytes.
+ * - @litBufCapacity is the size of the underlying buffer into which literals are written, starting at address @literals.
+ *   @litBufCapacity must be at least 8 bytes larger than @litSize.
  * - @decompressedSize must be correct, and correspond to the sum of all Sequences. Any discrepancy will generate an error.
  * @return : final compressed size, or a ZSTD error code.
  */
 ZSTDLIB_STATIC_API size_t
 ZSTD_compressSequencesAndLiterals(ZSTD_CCtx* cctx,
                                   void* dst, size_t dstCapacity,
                             const ZSTD_Sequence* inSeqs, size_t nbSequences,
-                            const void* literals, size_t litSize, size_t litCapacity,
+                            const void* literals, size_t litSize, size_t litBufCapacity,
                             size_t decompressedSize);