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math: special cases for Modf, Frexp and Ldexp; added Modf_386

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Also moved Modf from bits.go into modf.go and added timing tests.

R=rsc
CC=golang-dev
https://golang.org/cl/202042
This commit is contained in:
Charles L. Dorian 2010-02-05 00:41:30 -08:00 committed by Russ Cox
parent db3ec4f239
commit 04217ee54e
6 changed files with 188 additions and 26 deletions
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2
src/pkg/math/Makefile
View File

@ -18,6 +18,7 @@ OFILES_386=\
fmod_386.$O\
hypot_386.$O\
log_386.$O\
modf_386.$O\
sin_386.$O\
sqrt_386.$O\
tan_386.$O\
@ -44,6 +45,7 @@ ALLGOFILES=\
hypot.go\
log.go\
log1p.go\
modf.go\
pow.go\
pow10.go\
sin.go\

114
src/pkg/math/all_test.go
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@ -1,4 +1,4 @@
// Copyright 2009-2010 The Go Authors. All rights reserved.
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
@ -220,6 +220,25 @@ var fmod = []float64{
8.734595415957246977711748e-01,
1.314075231424398637614104e+00,
}
type fi struct {
f float64
i int
}
var frexp = []fi{
fi{6.2237649061045918750e-01, 3},
fi{9.6735905932226306250e-01, 3},
fi{-5.5376011438400318000e-01, -1},
fi{-6.2632545228388436250e-01, 3},
fi{6.02268356699901081250e-01, 4},
fi{7.3159430981099115000e-01, 2},
fi{6.5363542893241332500e-01, 3},
fi{6.8198497760900255000e-01, 2},
fi{9.1265404584042750000e-01, 1},
fi{-5.4287029803597508250e-01, 4},
}
var log = []float64{
1.605231462693062999102599e+00,
2.0462560018708770653153909e+00,
@ -256,6 +275,18 @@ var log1p = []float64{
1.8088493239630770262045333e-02,
-9.0865245631588989681559268e-02,
}
var modf = [][2]float64{
[2]float64{4.0000000000000000e+00, 9.7901192488367350108546816e-01},
[2]float64{7.0000000000000000e+00, 7.3887247457810456552351752e-01},
[2]float64{0.0000000000000000e+00, -2.7688005719200159404635997e-01},
[2]float64{-5.0000000000000000e+00, -1.060361827107492160848778e-02},
[2]float64{9.0000000000000000e+00, 6.3629370719841737980004837e-01},
[2]float64{2.0000000000000000e+00, 9.2637723924396464525443662e-01},
[2]float64{5.0000000000000000e+00, 2.2908343145930665230025625e-01},
[2]float64{2.0000000000000000e+00, 7.2793991043601025126008608e-01},
[2]float64{1.0000000000000000e+00, 8.2530809168085506044576505e-01},
[2]float64{-8.0000000000000000e+00, -6.8592476857560136238589621e-01},
}
var pow = []float64{
9.5282232631648411840742957e+04,
5.4811599352999901232411871e+07,
@ -516,6 +547,19 @@ var fmodSC = []float64{
NaN(),
}
var vffrexpSC = []float64{
Inf(-1),
0,
Inf(1),
NaN(),
}
var frexpSC = []fi{
fi{Inf(-1), 0},
fi{0, 0},
fi{Inf(1), 0},
fi{NaN(), 0},
}
var vfhypotSC = [][2]float64{
[2]float64{Inf(-1), Inf(-1)},
[2]float64{Inf(-1), 0},
@ -581,6 +625,17 @@ var log1pSC = []float64{
NaN(),
}
var vfmodfSC = []float64{
Inf(-1),
Inf(1),
NaN(),
}
var modfSC = [][2]float64{
[2]float64{Inf(-1), NaN()},
[2]float64{Inf(1), NaN()},
[2]float64{NaN(), NaN()},
}
var vfpowSC = [][2]float64{
[2]float64{-Pi, Pi},
[2]float64{-Pi, -Pi},
@ -919,6 +974,19 @@ func TestFmod(t *testing.T) {
}
}
func TestFrexp(t *testing.T) {
for i := 0; i < len(vf); i++ {
if f, j := Frexp(vf[i]); !veryclose(frexp[i].f, f) || frexp[i].i != j {
t.Errorf("Frexp(%g) = %g, %d, want %g, %d\n", vf[i], f, j, frexp[i].f, frexp[i].i)
}
}
for i := 0; i < len(vffrexpSC); i++ {
if f, j := Frexp(vffrexpSC[i]); !alike(frexpSC[i].f, f) || frexpSC[i].i != j {
t.Errorf("Frexp(%g) = %g, %d, want %g, %d\n", vffrexpSC[i], f, j, frexpSC[i].f, frexpSC[i].i)
}
}
}
func TestHypot(t *testing.T) {
for i := 0; i < len(vf); i++ {
a := Fabs(1e200 * tanh[i] * Sqrt(2))
@ -933,6 +1001,19 @@ func TestHypot(t *testing.T) {
}
}
func TestLdexp(t *testing.T) {
for i := 0; i < len(vf); i++ {
if f := Ldexp(frexp[i].f, frexp[i].i); !veryclose(vf[i], f) {
t.Errorf("Ldexp(%g, %d) = %g, want %g\n", frexp[i].f, frexp[i].i, f, vf[i])
}
}
for i := 0; i < len(vffrexpSC); i++ {
if f := Ldexp(frexpSC[i].f, frexpSC[i].i); !alike(vffrexpSC[i], f) {
t.Errorf("Ldexp(%g, %d) = %g, want %g\n", frexpSC[i].f, frexpSC[i].i, f, vffrexpSC[i])
}
}
}
func TestLog(t *testing.T) {
for i := 0; i < len(vf); i++ {
a := Fabs(vf[i])
@ -985,6 +1066,19 @@ func TestLog1p(t *testing.T) {
}
}
func TestModf(t *testing.T) {
for i := 0; i < len(vf); i++ {
if f, g := Modf(vf[i]); !veryclose(modf[i][0], f) || !veryclose(modf[i][1], g) {
t.Errorf("Modf(%g) = %g, %g, want %g, %g\n", vf[i], f, g, modf[i][0], modf[i][1])
}
}
for i := 0; i < len(vfmodfSC); i++ {
if f, g := Modf(vfmodfSC[i]); !alike(modfSC[i][0], f) || !alike(modfSC[i][1], g) {
t.Errorf("Modf(%g) = %g, %g, want %g, %g\n", vfmodfSC[i], f, g, modfSC[i][0], modfSC[i][1])
}
}
}
func TestPow(t *testing.T) {
for i := 0; i < len(vf); i++ {
if f := Pow(10, vf[i]); !close(pow[i], f) {
@ -1220,12 +1314,24 @@ func BenchmarkFmod(b *testing.B) {
}
}
func BenchmarkFrexp(b *testing.B) {
for i := 0; i < b.N; i++ {
Frexp(8)
}
}
func BenchmarkHypot(b *testing.B) {
for i := 0; i < b.N; i++ {
Hypot(3, 4)
}
}
func BenchmarkLdexp(b *testing.B) {
for i := 0; i < b.N; i++ {
Ldexp(.5, 2)
}
}
func BenchmarkLog(b *testing.B) {
for i := 0; i < b.N; i++ {
Log(.5)
@ -1244,6 +1350,12 @@ func BenchmarkLog1p(b *testing.B) {
}
}
func BenchmarkModf(b *testing.B) {
for i := 0; i < b.N; i++ {
Modf(1.5)
}
}
func BenchmarkPowInt(b *testing.B) {
for i := 0; i < b.N; i++ {
Pow(2, 2)

39
src/pkg/math/bits.go
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@ -53,7 +53,14 @@ func IsInf(f float64, sign int) bool {
// It returns frac and exp satisfying f == frac × 2<sup>exp</sup>,
// with the absolute value of frac in the interval [½, 1).
func Frexp(f float64) (frac float64, exp int) {
if f == 0 {
// TODO(rsc): Remove manual inlining of IsNaN, IsInf
// when compiler does it for us
// special cases
switch {
case f == 0:
return
case f < -MaxFloat64 || f > MaxFloat64 || f != f: // IsInf(f, 0) || IsNaN(f):
frac = f
return
}
x := Float64bits(f)
@ -67,6 +74,12 @@ func Frexp(f float64) (frac float64, exp int) {
// Ldexp is the inverse of Frexp.
// It returns frac × 2<sup>exp</sup>.
func Ldexp(frac float64, exp int) float64 {
// TODO(rsc): Remove manual inlining of IsNaN, IsInf
// when compiler does it for us
// special cases
if frac != frac { // IsNaN(frac)
return NaN()
}
x := Float64bits(frac)
exp += int(x>>shift) & mask
if exp <= 0 {
@ -82,27 +95,3 @@ func Ldexp(frac float64, exp int) float64 {
x |= uint64(exp) << shift
return Float64frombits(x)
}
// Modf returns integer and fractional floating-point numbers
// that sum to f.
// Integer and frac have the same sign as f.
func Modf(f float64) (int float64, frac float64) {
if f < 1 {
if f < 0 {
int, frac = Modf(-f)
return -int, -frac
}
return 0, f
}
x := Float64bits(f)
e := uint(x>>shift)&mask - bias
// Keep the top 11+e bits, the integer part; clear the rest.
if e < 64-11 {
x &^= 1<<(64-11-e) - 1
}
int = Float64frombits(x)
frac = f - int
return
}

33
src/pkg/math/modf.go Normal file
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@ -0,0 +1,33 @@
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package math
// Modf returns integer and fractional floating-point numbers
// that sum to f. Both values have the same sign as f.
//
// Special cases are:
// Modf(+Inf) = +Inf, NaN
// Modf(-Inf) = -Inf, NaN
// Modf(NaN) = NaN, NaN
func Modf(f float64) (int float64, frac float64) {
if f < 1 {
if f < 0 {
int, frac = Modf(-f)
return -int, -frac
}
return 0, f
}
x := Float64bits(f)
e := uint(x>>shift)&mask - bias
// Keep the top 11+e bits, the integer part; clear the rest.
if e < 64-11 {
x &^= 1<<(64-11-e) - 1
}
int = Float64frombits(x)
frac = f - int
return
}

19
src/pkg/math/modf_386.s Normal file
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@ -0,0 +1,19 @@
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// func Modf(x float64) (int float64, frac float64)
TEXT ·Modf(SB),7,$0
FMOVD x+0(FP), F0 // F0=x
FMOVD F0, F1 // F0=x, F1=x
FSTCW -2(SP) // save old Control Word
MOVW -2(SP), AX
ORW $0x0c00, AX // Rounding Control set to truncate
MOVW AX, -4(SP) // store new Control Word
FLDCW -4(SP) // load new Control Word
FRNDINT // F0=trunc(x), F1=x
FLDCW -2(SP) // load old Control Word
FSUBD F0, F1 // F0=trunc(x), F1=x-trunc(x)
FMOVDP F0, i+8(FP) // F0=x-trunc(x)
FMOVDP F0, f+16(FP)
RET

7
src/pkg/math/modf_decl.go Normal file
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@ -0,0 +1,7 @@
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package math
func Modf(f float64) (int float64, frac float64)