math: 386 FPU functions
sin, cos, tan, asin, acos, atan, exp, log, log10,
floor, ceil, and fabs
R=rsc
CC=golang-dev
https://golang.org/cl/189083
2010-01-15 14:21:36 -07:00
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// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// func Exp(x float64) float64
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2010-01-25 19:52:55 -07:00
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TEXT ·Exp(SB),7,$0
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math: 386 FPU functions
sin, cos, tan, asin, acos, atan, exp, log, log10,
floor, ceil, and fabs
R=rsc
CC=golang-dev
https://golang.org/cl/189083
2010-01-15 14:21:36 -07:00
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// test bits for not-finite
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MOVL x+4(FP), AX
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ANDL $0x7ff00000, AX
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CMPL AX, $0x7ff00000
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JEQ not_finite
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FLDL2E // F0=log2(e)
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FMOVD x+0(FP), F0 // F0=x, F1=log2(e)
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FMULDP F0, F1 // F0=x*log2(e)
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FMOVD F0, F1 // F0=x*log2(e), F1=x*log2(e)
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FRNDINT // F0=int(x*log2(e)), F1=x*log2(e)
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FSUBD F0, F1 // F0=int(x*log2(e)), F1=x*log2(e)-int(x*log2(e))
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FXCHD F0, F1 // F0=x*log2(e)-int(x*log2(e)), F1=int(x*log2(e))
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F2XM1 // F0=2**(x*log2(e)-int(x*log2(e)))-1, F1=int(x*log2(e))
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FLD1 // F0=1, F1=2**(x*log2(e)-int(x*log2(e)))-1, F2=int(x*log2(e))
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FADDDP F0, F1 // F0=2**(x*log2(e)-int(x*log2(e))), F1=int(x*log2(e))
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FSCALE // F0=e**x, F1=int(x*log2(e))
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FMOVDP F0, F1 // F0=e**x
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FMOVDP F0, r+8(FP)
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RET
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not_finite:
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// test bits for -Inf
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MOVL x+4(FP), BX
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MOVL x+0(FP), CX
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CMPL BX, $0xfff00000
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JNE not_neginf
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CMPL CX, $0
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JNE not_neginf
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MOVL $0, r+8(FP)
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MOVL $0, r+12(FP)
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RET
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not_neginf:
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MOVL CX, r+8(FP)
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MOVL BX, r+12(FP)
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RET
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