Dima353/openal-soft
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Fix overflow issues when converting float to int

Browse Source 
32-bit floats can only reach between -16777215...+16777215 (25 bits) before it
starts losing whole-number accuracy. Some compiler optimizations may break
trying to multiply a float by 2147483647.0 when the result is given right to a
float parameter, causing it instead to multiply by the nearest representable
float value, 2147483648.0.
This commit is contained in:
Chris Robinson
2013-04-22 00:52:50 -07:00
parent 43b406ad9b
commit 563f16dc2a
1 changed files with 10 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files
Alc/ALu.c
+10 -7
View File
@@ -912,24 +912,27 @@ ALvoid CalcSourceParams(ALsource *ALSource, const ALCcontext *ALContext)
}
static __inline ALfloat aluF2F(ALfloat val)
{ return val; }
static __inline ALint aluF2I(ALfloat val)
static __inline ALint aluF2I25(ALfloat val)
{
/* Clamp the value between -1 and +1. This handles that with only a single branch. */
if(fabsf(val) > 1.0f)
val = (ALfloat)((0.0f < val) - (val < 0.0f));
/* Convert to a signed integer, between -2147483647 and +2147483647. */
return fastf2i((ALfloat)(val*2147483647.0));
/* Convert to a signed integer, between -16777215 and +16777215. */
return fastf2i(val*16777215.0f);
}
static __inline ALfloat aluF2F(ALfloat val)
{ return val; }
static __inline ALint aluF2I(ALfloat val)
{ return aluF2I25(val)<<7; }
static __inline ALuint aluF2UI(ALfloat val)
{ return aluF2I(val)+2147483648u; }
static __inline ALshort aluF2S(ALfloat val)
{ return aluF2I(val)>>16; }
{ return aluF2I25(val)>>9; }
static __inline ALushort aluF2US(ALfloat val)
{ return aluF2S(val)+32768; }
static __inline ALbyte aluF2B(ALfloat val)
{ return aluF2I(val)>>24; }
{ return aluF2I25(val)>>17; }
static __inline ALubyte aluF2UB(ALfloat val)
{ return aluF2B(val)+128; }