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intfloat_readwrite: fix signed addition overflows

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These additions might overflow the signed range for large
input values.  Converting to unsigned before the addition
rather than after avoids such undefined behaviour.  The
result under normal two's complement wraparound remains
unchanged.

Signed-off-by: Mans Rullgard <mans@mansr.com>
This commit is contained in:
Mans Rullgard 2011-10-08 02:16:29 +01:00
parent 30c3d976f1
commit 88d1e2b2b0
1 changed files with 2 additions and 2 deletions
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4
libavutil/intfloat_readwrite.c
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@ -30,13 +30,13 @@
#include "intfloat_readwrite.h" #include "intfloat_readwrite.h"
double av_int2dbl(int64_t v){ double av_int2dbl(int64_t v){
if(v+v > 0xFFEULL<<52) if((uint64_t)v+v > 0xFFEULL<<52)
return NAN; return NAN;
return ldexp(((v&((1LL<<52)-1)) + (1LL<<52)) * (v>>63|1), (v>>52&0x7FF)-1075); return ldexp(((v&((1LL<<52)-1)) + (1LL<<52)) * (v>>63|1), (v>>52&0x7FF)-1075);
} }
float av_int2flt(int32_t v){ float av_int2flt(int32_t v){
if(v+v > 0xFF000000U) if((uint32_t)v+v > 0xFF000000U)
return NAN; return NAN;
return ldexp(((v&0x7FFFFF) + (1<<23)) * (v>>31|1), (v>>23&0xFF)-150); return ldexp(((v&0x7FFFFF) + (1<<23)) * (v>>31|1), (v>>23&0xFF)-150);
} }