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glsl: Add "built-in" functions to do fp32_to_fp64(fp32)

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Signed-off-by: Elie Tournier <elie.tournier@collabora.com>
This commit is contained in:
Elie Tournier
2017-08-09 23:11:08 +01:00
committed by Matt Turner
parent 407bd1bbf9
commit cad58fc5e7
1 changed files with 38 additions and 0 deletions
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38
src/compiler/glsl/float64.glsl
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@@ -1045,3 +1045,41 @@ __fp64_to_fp32(uint64_t __a)
zFrac = mix(zFrac, zFrac | 0x40000000u, aExp != 0);
return __roundAndPackFloat32(aSign, aExp - 0x381, zFrac);
}
/* Returns the result of converting the single-precision floating-point value
* `a' to the double-precision floating-point format.
*/
uint64_t
__fp32_to_fp64(float f)
{
uint a = floatBitsToUint(f);
uint aFrac = a & 0x007FFFFFu;
int aExp = int((a>>23) & 0xFFu);
uint aSign = a>>31;
uint zFrac0 = 0u;
uint zFrac1 = 0u;
if (aExp == 0xFF) {
if (aFrac != 0u) {
uint nanLo = 0u;
uint nanHi = a<<9;
__shift64Right(nanHi, nanLo, 12, nanHi, nanLo);
nanHi |= ((aSign<<31) | 0x7FF80000u);
return packUint2x32(uvec2(nanLo, nanHi));
}
return __packFloat64(aSign, 0x7FF, 0u, 0u);
}
if (aExp == 0) {
if (aFrac == 0u)
return __packFloat64(aSign, 0, 0u, 0u);
/* Normalize subnormal */
int shiftCount = __countLeadingZeros32(aFrac) - 8;
aFrac <<= shiftCount;
aExp = 1 - shiftCount;
--aExp;
}
__shift64Right(aFrac, 0u, 3, zFrac0, zFrac1);
return __packFloat64(aSign, aExp + 0x380, zFrac0, zFrac1);
}