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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 Frexp(f float64) (frac float64, exp int)
+TEXT ·Frexp(SB),NOSPLIT,$0
+ FMOVD f+0(FP), F0 // F0=f
+ FXAM
+ FSTSW AX
+ SAHF
+ JNP nan_zero_inf
+ JCS nan_zero_inf
+ FXTRACT // F0=f (0<=f<1), F1=e
+ FMULD $(0.5), F0 // F0=f (0.5<=f<1), F1=e
+ FMOVDP F0, frac+8(FP) // F0=e
+ FLD1 // F0=1, F1=e
+ FADDDP F0, F1 // F0=e+1
+ FMOVLP F0, exp+16(FP) // (int=int32)
+ RET
+nan_zero_inf:
+ FMOVDP F0, frac+8(FP) // F0=e
+ MOVL $0, exp+16(FP) // exp=0
+ RET