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Merge pull request #317 from namar0x0309/master

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Fix for 64bit builds btSqrt and USE_APPROXIMATION
This commit is contained in:
erwincoumans
2015-02-12 13:34:22 -08:00
parent 078afee015 e9c7f3a0d2
commit 5a91c9ea3c
1 changed files with 22 additions and 11 deletions
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33
src/LinearMath/btScalar.h
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@@ -418,19 +418,30 @@ SIMD_FORCE_INLINE btScalar btFmod(btScalar x,btScalar y) { return fmod(x,y); }
SIMD_FORCE_INLINE btScalar btSqrt(btScalar y)
{
#ifdef USE_APPROXIMATION
#ifdef __LP64__
float xhalf = 0.5f*y;
int i = *(int*)&y;
i = 0x5f375a86 - (i>>1);
y = *(float*)&i;
y = y*(1.5f - xhalf*y*y);
y = y*(1.5f - xhalf*y*y);
y = y*(1.5f - xhalf*y*y);
y=1/y;
return y;
#else
double x, z, tempf;
unsigned long *tfptr = ((unsigned long *)&tempf) + 1;
tempf = y;
*tfptr = (0xbfcdd90a - *tfptr)>>1; /* estimate of 1/sqrt(y) */
x = tempf;
z = y*btScalar(0.5);
x = (btScalar(1.5)*x)-(x*x)*(x*z); /* iteration formula */
x = (btScalar(1.5)*x)-(x*x)*(x*z);
x = (btScalar(1.5)*x)-(x*x)*(x*z);
x = (btScalar(1.5)*x)-(x*x)*(x*z);
x = (btScalar(1.5)*x)-(x*x)*(x*z);
return x*y;
tempf = y;
*tfptr = (0xbfcdd90a - *tfptr)>>1; /* estimate of 1/sqrt(y) */
x = tempf;
z = y*btScalar(0.5);
x = (btScalar(1.5)*x)-(x*x)*(x*z); /* iteration formula */
x = (btScalar(1.5)*x)-(x*x)*(x*z);
x = (btScalar(1.5)*x)-(x*x)*(x*z);
x = (btScalar(1.5)*x)-(x*x)*(x*z);
x = (btScalar(1.5)*x)-(x*x)*(x*z);
return x*y;
#endif
#else
return sqrtf(y);
#endif