| // 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+4(FP), DX // high word |
| MOVL f+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+8(FP) |
| MOVL DX, int+12(FP) |
| MOVL AX, frac+16(FP) |
| MOVL DX, frac+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 |
