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GPU: Clean up float conversion functions

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This commit is contained in:
Yuri Kunde Schlesner 2015-09-05 16:55:45 -03:00
parent 11a5001f33
commit 407dcd141d
1 changed files with 54 additions and 29 deletions
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83
libctru/source/gpu/gpu.c
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@ -229,40 +229,65 @@ void GPU_SetFloatUniform(GPU_SHADER_TYPE type, u32 startreg, u32* data, u32 numr
GPUCMD_AddWrites(GPUREG_VSH_FLOATUNIFORM_DATA+regOffset, data, numreg*4);
}
//TODO : fix
u32 f32tof24(float f)
// f24 has:
// - 1 sign bit
// - 7 exponent bits
// - 16 mantissa bits
static u32 f32tof24(float f)
{
if(!f)return 0;
u32 v=*((u32*)&f);
u8 s=v>>31;
u32 exp=((v>>23)&0xFF)-0x40;
u32 man=(v>>7)&0xFFFF;
u32 i;
memcpy(&i, &f, 4);
if(exp>=0)return man|(exp<<16)|(s<<23);
else return s<<23;
u32 mantissa = (i << 9) >> 9;
s32 exponent = (i << 1) >> 24;
u32 sign = (i << 0) >> 31;
// Truncate mantissa
mantissa >>= 7;
// Re-bias exponent
exponent = exponent - 127 + 63;
if (exponent < 0)
{
// Underflow: flush to zero
return sign << 23;
}
else if (exponent > 0x7F)
{
// Overflow: saturate to infinity
return sign << 23 | 0x7F << 16;
}
return sign << 23 | exponent << 16 | mantissa;
}
u32 computeInvValue(u32 val)
// f31 has:
// - 1 sign bit
// - 7 exponent bits
// - 23 mantissa bits
static u32 f32tof31(float f)
{
//usual values
if(val==240)return 0x38111111;
if(val==480)return 0x37111111;
if(val==400)return 0x3747ae14;
//but let's not limit ourselves to the usual
float fval=2.0/val;
u32 tmp1,tmp2;
u32 tmp3=*((u32*)&fval);
tmp1=(tmp3<<9)>>9;
tmp2=tmp3&(~0x80000000);
if(tmp2)
u32 i;
memcpy(&i, &f, 4);
u32 mantissa = (i << 9) >> 9;
s32 exponent = (i << 1) >> 24;
u32 sign = (i << 0) >> 31;
// Re-bias exponent
exponent = exponent - 127 + 63;
if (exponent < 0)
{
tmp1=(tmp3<<9)>>9;
int tmp=((tmp3<<1)>>24)-0x40;
if(tmp<0)return ((tmp3>>31)<<30)<<1;
else tmp2=tmp;
// Underflow: flush to zero
return sign << 30;
}
tmp3>>=31;
return (tmp1|(tmp2<<23)|(tmp3<<30))<<1;
else if (exponent > 0x7F)
{
// Overflow: saturate to infinity
return sign << 30 | 0x7F << 23;
}
return sign << 30 | exponent << 23 | mantissa;
}
//takes PAs as arguments
@ -288,9 +313,9 @@ void GPU_SetViewport(u32* depthBuffer, u32* colorBuffer, u32 x, u32 y, u32 w, u3
GPUCMD_AddWrite(GPUREG_011B, 0x00000000); //?
param[0x0]=f32tof24(fw/2);
param[0x1]=computeInvValue(fw);
param[0x1]=f32tof31(2.0f / fw) << 1;
param[0x2]=f32tof24(fh/2);
param[0x3]=computeInvValue(fh);
param[0x3]=f32tof31(2.0f / fh) << 1;
GPUCMD_AddIncrementalWrites(GPUREG_0041, param, 0x00000004);
GPUCMD_AddWrite(GPUREG_0068, (y<<16)|(x&0xFFFF));