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fixed very minor inefficiency (nbSeq==127)

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The nbSeq "short" format (1-byte)
is compatible with any value < 128.

However, the code would cautiously only accept values < 127.
This is not an error, because the general 2-bytes format
is compatible with small values < 128.
Hence the inefficiency never triggered any warning.

Spotted by Intel's Smita Kumar.
This commit is contained in:
Yann Collet 2019-08-15 16:41:34 +02:00
parent 87e31223e8
commit 782bfb858a
1 changed files with 10 additions and 5 deletions
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15
lib/compress/zstd_compress.c
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@ -1981,12 +1981,17 @@ ZSTD_compressSequences_internal(seqStore_t* seqStorePtr,
/* Sequences Header */
RETURN_ERROR_IF((oend-op) < 3 /*max nbSeq Size*/ + 1 /*seqHead*/,
dstSize_tooSmall);
if (nbSeq < 0x7F)
if (nbSeq < 128) {
*op++ = (BYTE)nbSeq;
else if (nbSeq < LONGNBSEQ)
op[0] = (BYTE)((nbSeq>>8) + 0x80), op[1] = (BYTE)nbSeq, op+=2;
else
op[0]=0xFF, MEM_writeLE16(op+1, (U16)(nbSeq - LONGNBSEQ)), op+=3;
} else if (nbSeq < LONGNBSEQ) {
op[0] = (BYTE)((nbSeq>>8) + 0x80);
op[1] = (BYTE)nbSeq;
op+=2;
} else {
op[0]=0xFF;
MEM_writeLE16(op+1, (U16)(nbSeq - LONGNBSEQ));
op+=3;
}
assert(op <= oend);
if (nbSeq==0) {
/* Copy the old tables over as if we repeated them */