// 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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#include "textflag.h"
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// func Modf(f float64) (int float64, frac float64)
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TEXT ·Modf(SB),NOSPLIT,$0
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// special case for f == -0.0
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MOVL f_hi+4(FP), DX // high word
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MOVL f_lo+0(FP), AX // low word
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CMPL DX, $(1<<31) // beginning of -0.0
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JNE notNegativeZero
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CMPL AX, $0 // could be denormalized
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JNE notNegativeZero
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MOVL AX, int_lo+8(FP)
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MOVL DX, int_hi+12(FP)
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MOVL AX, frac_lo+16(FP)
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MOVL DX, frac_hi+20(FP)
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RET
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notNegativeZero:
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FMOVD f+0(FP), F0 // F0=f
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FMOVD F0, F1 // F0=f, F1=f
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FSTCW -2(SP) // save old Control Word
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MOVW -2(SP), AX
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ORW $0x0c00, AX // Rounding Control set to truncate
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MOVW AX, -4(SP) // store new Control Word
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FLDCW -4(SP) // load new Control Word
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FRNDINT // F0=trunc(f), F1=f
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FLDCW -2(SP) // load old Control Word
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FSUBD F0, F1 // F0=trunc(f), F1=f-trunc(f)
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FMOVDP F0, int+8(FP) // F0=f-trunc(f)
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FMOVDP F0, frac+16(FP)
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RET
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