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Diffstat (limited to 'src/math/expm1_386.s')
| -rw-r--r-- | src/math/expm1_386.s | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/src/math/expm1_386.s b/src/math/expm1_386.s new file mode 100644 index 0000000..d020296 --- /dev/null +++ b/src/math/expm1_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. + +#include "textflag.h" + +// func Expm1(x float64) float64 +TEXT ·Expm1(SB),NOSPLIT,$0 + FLDLN2 // F0=log(2) = 1/log2(e) ~ 0.693147 + FMOVD x+0(FP), F0 // F0=x, F1=1/log2(e) + FABS // F0=|x|, F1=1/log2(e) + FUCOMPP F0, F1 // compare F0 to F1 + FSTSW AX + SAHF + JCC use_exp // jump if F0 >= F1 + FLDL2E // F0=log2(e) + FMULD x+0(FP), F0 // F0=x*log2(e) (-1<F0<1) + F2XM1 // F0=e**x-1 = 2**(x*log2(e))-1 + FMOVDP F0, ret+8(FP) + RET +use_exp: +// test bits for not-finite + MOVL x_hi+4(FP), AX + ANDL $0x7ff00000, AX + CMPL AX, $0x7ff00000 + JEQ not_finite + FLDL2E // F0=log2(e) + FMULD x+0(FP), F0 // F0=x*log2(e) + FMOVD F0, F1 // F0=x*log2(e), F1=x*log2(e) + FRNDINT // F0=int(x*log2(e)), F1=x*log2(e) + FSUBD F0, F1 // F0=int(x*log2(e)), F1=x*log2(e)-int(x*log2(e)) + FXCHD F0, F1 // F0=x*log2(e)-int(x*log2(e)), F1=int(x*log2(e)) + F2XM1 // F0=2**(x*log2(e)-int(x*log2(e)))-1, F1=int(x*log2(e)) + FLD1 // F0=1, F1=2**(x*log2(e)-int(x*log2(e)))-1, F2=int(x*log2(e)) + FADDDP F0, F1 // F0=2**(x*log2(e)-int(x*log2(e))), F1=int(x*log2(e)) + FSCALE // F0=e**x, F1=int(x*log2(e)) + FMOVDP F0, F1 // F0=e**x + FLD1 // F0=1, F1=e**x + FSUBDP F0, F1 // F0=e**x-1 + FMOVDP F0, ret+8(FP) + RET +not_finite: +// test bits for -Inf + MOVL x_hi+4(FP), BX + MOVL x_lo+0(FP), CX + CMPL BX, $0xfff00000 + JNE not_neginf + CMPL CX, $0 + JNE not_neginf + FLD1 // F0=1 + FCHS // F0=-1 + FMOVDP F0, ret+8(FP) + RET +not_neginf: + MOVL CX, ret_lo+8(FP) + MOVL BX, ret_hi+12(FP) + RET |