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Fix for 64bit builds btSqrt

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Fix issue with btSqrt with macro USE_APPROXIMATION turned on.
This commit is contained in:
Nassim Amar 2015-02-01 05:41:07 -08:00
parent 76b80ca71b
commit cf705d6fa4
1 changed files with 23 additions and 12 deletions
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35
src/LinearMath/btScalar.h
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@ -418,21 +418,32 @@ SIMD_FORCE_INLINE btScalar btFmod(btScalar x,btScalar y) { return fmod(x,y); }
SIMD_FORCE_INLINE btScalar btSqrt(btScalar y)
{
#ifdef USE_APPROXIMATION
#ifdef __arm__
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;
#elif __arm64__
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;
#endif
#else
return sqrtf(y);
return sqrtf(y);
#endif
}
SIMD_FORCE_INLINE btScalar btFabs(btScalar x) { return fabsf(x); }