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baby-step towards solving flexArray issue #3785

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the flexArray in structure FSE_DecompressWksp
is just a way to derive a pointer easily,
without risk/complexity of calculating it manually.

Not sure if this change is good enough to avoid ubsan warnings though.
This commit is contained in:
Yann Collet
2023-10-18 16:21:39 -07:00
parent 69036dffe5
commit d988e00a7f
2 changed files with 21 additions and 20 deletions
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lib/compress/fse_compress.c
+7 -6
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@@ -225,8 +225,8 @@ size_t FSE_NCountWriteBound(unsigned maxSymbolValue, unsigned tableLog)
size_t const maxHeaderSize = (((maxSymbolValue+1) * tableLog
+ 4 /* bitCount initialized at 4 */
+ 2 /* first two symbols may use one additional bit each */) / 8)
+ 1 /* round up to whole nb bytes */
+ 2 /* additional two bytes for bitstream flush */;
+ 1 /* round up to whole nb bytes */
+ 2 /* additional two bytes for bitstream flush */;
return maxSymbolValue ? maxHeaderSize : FSE_NCOUNTBOUND; /* maxSymbolValue==0 ? use default */
}
@@ -255,7 +255,7 @@ FSE_writeNCount_generic (void* header, size_t headerBufferSize,
/* Init */
remaining = tableSize+1; /* +1 for extra accuracy */
threshold = tableSize;
nbBits = tableLog+1;
nbBits = (int)tableLog+1;
while ((symbol < alphabetSize) && (remaining>1)) { /* stops at 1 */
if (previousIs0) {
@@ -274,7 +274,7 @@ FSE_writeNCount_generic (void* header, size_t headerBufferSize,
}
while (symbol >= start+3) {
start+=3;
bitStream += 3 << bitCount;
bitStream += 3U << bitCount;
bitCount += 2;
}
bitStream += (symbol-start) << bitCount;
@@ -294,7 +294,7 @@ FSE_writeNCount_generic (void* header, size_t headerBufferSize,
count++; /* +1 for extra accuracy */
if (count>=threshold)
count += max; /* [0..max[ [max..threshold[ (...) [threshold+max 2*threshold[ */
bitStream += count << bitCount;
bitStream += (U32)count << bitCount;
bitCount += nbBits;
bitCount -= (count<max);
previousIs0 = (count==1);
@@ -322,7 +322,8 @@ FSE_writeNCount_generic (void* header, size_t headerBufferSize,
out[1] = (BYTE)(bitStream>>8);
out+= (bitCount+7) /8;
return (out-ostart);
assert(out >= ostart);
return (size_t)(out-ostart);
}