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glsl: Add "built-in" functions to do int_to_fp64(int)

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v2: use mix
Signed-off-by: Elie Tournier <elie.tournier@collabora.com>
This commit is contained in:
Elie Tournier 2017-08-09 17:39:23 +01:00 • committed by Matt Turner
parent 773190f281
commit f499942b31
1 changed files with 23 additions and 0 deletions
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23
src/compiler/glsl/float64.glsl
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@ -921,3 +921,26 @@ __fp64_to_int(uint64_t a)
int nan = mix(0x7FFFFFFF, 0x80000000, bool(aSign));
return mix(z, nan, bool(aSign ^ uint(z < 0)) && bool(z));
}
/* Returns the result of converting the 32-bit two's complement integer `a'
* to the double-precision floating-point format. The conversion is performed
* according to the IEEE Standard for Floating-Point Arithmetic.
*/
uint64_t
__int_to_fp64(int a)
{
uint zFrac0 = 0u;
uint zFrac1 = 0u;
if (a==0)
return __packFloat64(0u, 0, 0u, 0u);
uint zSign = uint(a < 0);
uint absA = mix(uint(a), uint(-a), a < 0);
int shiftCount = __countLeadingZeros32(absA) - 11;
if (0 <= shiftCount) {
zFrac0 = absA << shiftCount;
zFrac1 = 0u;
} else {
__shift64Right(absA, 0u, -shiftCount, zFrac0, zFrac1);
}
return __packFloat64(zSign, 0x412 - shiftCount, zFrac0, zFrac1);
}