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Add math.pow2_f{16,32,64}, fast floating point 2^x where x is an integer.

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This commit is contained in:
Jeroen van Rijn
2023-11-04 22:14:44 +01:00
parent 5edb2c5688
commit 6201280468
4 changed files with 122 additions and 4 deletions
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49
core/math/math.odin
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@@ -203,7 +203,54 @@ pow10_f64 :: proc "contextless" (n: f64) -> f64 {
return 0
}
pow2_f64 :: proc(#any_int exp: int) -> (res: f64) {
switch {
case exp >= -1022 && exp <= 1023: // Normal
return transmute(f64)(u64(exp + F64_BIAS) << F64_SHIFT)
case exp < -1075: // Underflow
return f64(0)
case exp == -1075: // Underflow
return 0h00000000_00000001
case exp < -1022: // Denormal
x := u64(exp + (F64_SHIFT + 1) + F64_BIAS) << F64_SHIFT
return f64(1) / (1 << (F64_SHIFT + 1)) * transmute(f64)x
case exp > 1023: // Overflow, +Inf
return 0h7ff00000_00000000
}
unreachable()
}
pow2_f32 :: proc(#any_int exp: int) -> (res: f32) {
switch {
case exp >= -126 && exp <= 127: // Normal
return transmute(f32)(u32(exp + F32_BIAS) << F32_SHIFT)
case exp < -151: // Underflow
return f32(0)
case exp < -126: // Denormal
x := u32(exp + (F32_SHIFT + 1) + F32_BIAS) << F32_SHIFT
return f32(1) / (1 << (F32_SHIFT + 1)) * transmute(f32)x
case exp > 127: // Overflow, +Inf
return 0h7f80_0000
}
unreachable()
}
pow2_f16 :: proc(#any_int exp: int) -> (res: f16) {
switch {
case exp >= -14 && exp <= 15: // Normal
return transmute(f16)(u16(exp + F16_BIAS) << F16_SHIFT)
case exp < -25: // Underflow
return 0h0000
case exp == -25: // Underflow
return 0h0001
case exp < -14: // Denormal
x := u16(exp + (F16_SHIFT + 1) + F16_BIAS) << F16_SHIFT
return f16(1) / (1 << (F16_SHIFT + 1)) * transmute(f16)x
case exp > 15: // Overflow, +Inf
return 0h7c00
}
unreachable()
}
@(require_results)
ldexp_f64 :: proc "contextless" (val: f64, exp: int) -> f64 {
@@ -2302,4 +2349,4 @@ INF_F64 :: f64(0h7FF0_0000_0000_0000)
NEG_INF_F64 :: f64(0hFFF0_0000_0000_0000)
SNAN_F64 :: f64(0h7FF0_0000_0000_0001)
QNAN_F64 :: f64(0h7FF8_0000_0000_0001)
QNAN_F64 :: f64(0h7FF8_0000_0000_0001)