root/src/pkg/math/exp2_386.s

// 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 "../../cmd/ld/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