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