math: 386 FPU hypot
Added 386 FPU version of Hypot; modified all_test.go to test
Hypot with large arguments. Also edited sqrt.go to remove
Sqrt(0) as a special case.
R=rsc
CC=golang-dev
https://golang.org/cl/186180
diff --git a/src/pkg/math/Makefile b/src/pkg/math/Makefile
index be9b6ff..b10df65 100644
--- a/src/pkg/math/Makefile
+++ b/src/pkg/math/Makefile
@@ -15,6 +15,7 @@
exp_386.$O\
fabs_386.$O\
floor_386.$O\
+ hypot_386.$O\
log_386.$O\
sin_386.$O\
sqrt_386.$O\
diff --git a/src/pkg/math/all_test.go b/src/pkg/math/all_test.go
index 15d289b..97c52d3 100644
--- a/src/pkg/math/all_test.go
+++ b/src/pkg/math/all_test.go
@@ -585,9 +585,9 @@
func TestHypot(t *testing.T) {
for i := 0; i < len(vf); i++ {
- a := Fabs(tanh[i] * Sqrt(2))
- if f := Hypot(tanh[i], tanh[i]); a != f {
- t.Errorf("Hypot(%g, %g) = %g, want %g\n", tanh[i], tanh[i], f, a)
+ a := Fabs(1e200 * tanh[i] * Sqrt(2))
+ if f := Hypot(1e200*tanh[i], 1e200*tanh[i]); !veryclose(a, f) {
+ t.Errorf("Hypot(%g, %g) = %g, want %g\n", 1e200*tanh[i], 1e200*tanh[i], f, a)
}
}
for i := 0; i < len(vfhypotSC); i++ {
diff --git a/src/pkg/math/hypot_386.s b/src/pkg/math/hypot_386.s
new file mode 100644
index 0000000..73e4f57
--- /dev/null
+++ b/src/pkg/math/hypot_386.s
@@ -0,0 +1,57 @@
+// 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 Hypot(x, y float64) float64
+TEXT ·Hypot(SB),7,$0
+// test bits for not-finite
+ MOVL xh+4(FP), AX // high word x
+ ANDL $0x7ff00000, AX
+ CMPL AX, $0x7ff00000
+ JEQ not_finite
+ MOVL yh+12(FP), AX // high word y
+ ANDL $0x7ff00000, AX
+ CMPL AX, $0x7ff00000
+ JEQ not_finite
+ FMOVD x+0(FP), F0 // F0=x
+ FABS // F0=|x|
+ FMOVD y+8(FP), F0 // F0=y, F1=|x|
+ FABS // F0=|y|, F1=|x|
+ FUCOMI F0, F1 // compare F0 to F1
+ JCC 2(PC) // jump if F0 < F1
+ FXCHD F0, F1 // F0=|x| (larger), F1=|y| (smaller)
+ FTST // compare F0 to 0
+ FSTSW AX
+ ANDW $0x4000, AX
+ JNE 10(PC) // jump if F0 = 0
+ FXCHD F0, F1 // F0=y (smaller), F1=x (larger)
+ FDIVD F1, F0 // F0=y(=y/x), F1=x
+ FMULD F0, F0 // F0=y*y, F1=x
+ FLD1 // F0=1, F1=y*y, F2=x
+ FADDDP F0, F1 // F0=1+y*y, F1=x
+ FSQRT // F0=sqrt(1+y*y), F1=x
+ FMULDP F0, F1 // F0=x*sqrt(1+y*y)
+ FMOVDP F0, r+16(FP)
+ RET
+ FMOVDP F0, F1 // F0=0
+ FMOVDP F0, r+16(FP)
+ RET
+not_finite:
+// test bits for -Inf or +Inf
+ MOVL xh+4(FP), AX // high word x
+ ORL xl+0(FP), AX // low word x
+ ANDL $0x7fffffff, AX
+ CMPL AX, $0x7ff00000
+ JEQ is_inf
+ MOVL yh+12(FP), AX // high word y
+ ORL yl+8(FP), AX // low word y
+ ANDL $0x7fffffff, AX
+ CMPL AX, $0x7ff00000
+ JEQ is_inf
+ MOVL $0x7ff00000, rh+20(FP) // return NaN = 0x7FF0000000000001
+ MOVL $0x00000001, rl+16(FP)
+ RET
+is_inf:
+ MOVL AX, rh+20(FP) // return +Inf = 0x7FF0000000000000
+ MOVL $0x00000000, rl+16(FP)
+ RET
diff --git a/src/pkg/math/hypot_decl.go b/src/pkg/math/hypot_decl.go
new file mode 100644
index 0000000..72603c5
--- /dev/null
+++ b/src/pkg/math/hypot_decl.go
@@ -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 Hypot(x, y float64) float64
diff --git a/src/pkg/math/sqrt.go b/src/pkg/math/sqrt.go
index f12e487..e6bc468 100644
--- a/src/pkg/math/sqrt.go
+++ b/src/pkg/math/sqrt.go
@@ -8,7 +8,6 @@
//
// Special cases are:
// Sqrt(+Inf) = +Inf
-// Sqrt(0) = 0
// Sqrt(x < 0) = NaN
// Sqrt(NaN) = NaN
func Sqrt(x float64) float64 { return sqrtGo(x) }
