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      1 // Copyright 2010 The Go Authors.  All rights reserved.
      2 // Use of this source code is governed by a BSD-style
      3 // license that can be found in the LICENSE file.
      4 
      5 #include "textflag.h"
      6 
      7 // func Modf(f float64) (int float64, frac float64)
      8 TEXT Modf(SB),NOSPLIT,$0
      9 	FMOVD   f+0(FP), F0  // F0=f
     10 	FMOVD   F0, F1       // F0=f, F1=f
     11 	FSTCW   -2(SP)       // save old Control Word
     12 	MOVW    -2(SP), AX
     13 	ORW     $0x0c00, AX  // Rounding Control set to truncate
     14 	MOVW    AX, -4(SP)   // store new Control Word
     15 	FLDCW   -4(SP)       // load new Control Word
     16 	FRNDINT              // F0=trunc(f), F1=f
     17 	FLDCW   -2(SP)       // load old Control Word
     18 	FSUBD   F0, F1       // F0=trunc(f), F1=f-trunc(f)
     19 	FMOVDP  F0, int+8(FP)  // F0=f-trunc(f)
     20 	FMOVDP  F0, frac+16(FP)
     21 	RET
     22