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aee1434193
Added tests and benchmarks for Exp2 (special cases same as Exp). Log1p also enhances speed of inverse hyperbolics. R=rsc CC=golang-dev https://golang.org/cl/206058
26 lines
828 B
ArmAsm
26 lines
828 B
ArmAsm
// 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 Log1p(x float64) float64
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TEXT ·Log1p(SB),7,$0
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FMOVD $(2.928932188134524e-01), F0
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FMOVD x+0(FP), F0 // F0=x, F1=1-sqrt(2)/2 = 0.29289321881345247559915564
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FABS // F0=|x|, F1=1-sqrt(2)/2
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FUCOMPP F0, F1 // compare F0 to F1
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FSTSW AX
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FLDLN2 // F0=log(2)
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ANDW $0x0100, AX
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JEQ use_fyl2x // jump if F0 >= F1
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FMOVD x+0(FP), F0 // F0=x, F1=log(2)
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FYL2XP1 // F0=log(1+x)=log2(1+x)*log(2)
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FMOVDP F0, r+8(FP)
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RET
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use_fyl2x:
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FLD1 // F0=1, F2=log(2)
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FADDD x+0(FP), F0 // F0=1+x, F1=log(2)
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FYL2X // F0=log(1+x)=log2(1+x)*log(2)
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FMOVDP F0, r+8(FP)
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RET
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