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 Exp(x float64) float64 8 TEXT Exp(SB),NOSPLIT,$0 9 // test bits for not-finite 10 MOVL x_hi+4(FP), AX 11 ANDL $0x7ff00000, AX 12 CMPL AX, $0x7ff00000 13 JEQ not_finite 14 FLDL2E // F0=log2(e) 15 FMULD x+0(FP), F0 // F0=x*log2(e) 16 FMOVD F0, F1 // F0=x*log2(e), F1=x*log2(e) 17 FRNDINT // F0=int(x*log2(e)), F1=x*log2(e) 18 FSUBD F0, F1 // F0=int(x*log2(e)), F1=x*log2(e)-int(x*log2(e)) 19 FXCHD F0, F1 // F0=x*log2(e)-int(x*log2(e)), F1=int(x*log2(e)) 20 F2XM1 // F0=2**(x*log2(e)-int(x*log2(e)))-1, F1=int(x*log2(e)) 21 FLD1 // F0=1, F1=2**(x*log2(e)-int(x*log2(e)))-1, F2=int(x*log2(e)) 22 FADDDP F0, F1 // F0=2**(x*log2(e)-int(x*log2(e))), F1=int(x*log2(e)) 23 FSCALE // F0=e**x, F1=int(x*log2(e)) 24 FMOVDP F0, F1 // F0=e**x 25 FMOVDP F0, ret+8(FP) 26 RET 27 not_finite: 28 // test bits for -Inf 29 MOVL x_hi+4(FP), BX 30 MOVL x_lo+0(FP), CX 31 CMPL BX, $0xfff00000 32 JNE not_neginf 33 CMPL CX, $0 34 JNE not_neginf 35 FLDZ // F0=0 36 FMOVDP F0, ret+8(FP) 37 RET 38 not_neginf: 39 MOVL CX, ret_lo+8(FP) 40 MOVL BX, ret_hi+12(FP) 41 RET 42
