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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 Exp2(x float64) float64
TEXT ·Exp2(SB),NOSPLIT,$0
// test bits for not-finite
MOVL x_hi+4(FP), AX
ANDL $0x7ff00000, AX
CMPL AX, $0x7ff00000
JEQ not_finite
FMOVD x+0(FP), F0 // F0=x
FMOVD F0, F1 // F0=x, F1=x
FRNDINT // F0=int(x), F1=x
FSUBD F0, F1 // F0=int(x), F1=x-int(x)
FXCHD F0, F1 // F0=x-int(x), F1=int(x)
F2XM1 // F0=2**(x-int(x))-1, F1=int(x)
FLD1 // F0=1, F1=2**(x-int(x))-1, F2=int(x)
FADDDP F0, F1 // F0=2**(x-int(x)), F1=int(x)
FSCALE // F0=2**x, F1=int(x)
FMOVDP F0, F1 // F0=2**x
FMOVDP F0, ret+8(FP)
RET
not_finite:
// test bits for -Inf
MOVL x_hi+4(FP), BX
MOVL x_lo+0(FP), CX
CMPL BX, $0xfff00000
JNE not_neginf
CMPL CX, $0
JNE not_neginf
MOVL $0, ret_lo+8(FP)
MOVL $0, ret_hi+12(FP)
RET
not_neginf:
MOVL CX, ret_lo+8(FP)
MOVL BX, ret_hi+12(FP)
RET
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