hypot_386.s raw

   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 archHypot(p, q float64) float64
   8  TEXT ·archHypot(SB),NOSPLIT,$0
   9  // test bits for not-finite
  10  	MOVL    p_hi+4(FP), AX   // high word p
  11  	ANDL    $0x7ff00000, AX
  12  	CMPL    AX, $0x7ff00000
  13  	JEQ     not_finite
  14  	MOVL    q_hi+12(FP), AX   // high word q
  15  	ANDL    $0x7ff00000, AX
  16  	CMPL    AX, $0x7ff00000
  17  	JEQ     not_finite
  18  	FMOVD   p+0(FP), F0  // F0=p
  19  	FABS                 // F0=|p|
  20  	FMOVD   q+8(FP), F0  // F0=q, F1=|p|
  21  	FABS                 // F0=|q|, F1=|p|
  22  	FUCOMI  F0, F1       // compare F0 to F1
  23  	JCC     2(PC)        // jump if F0 >= F1
  24  	FXCHD   F0, F1       // F0=|p| (larger), F1=|q| (smaller)
  25  	FTST                 // compare F0 to 0
  26  	FSTSW	AX
  27  	ANDW    $0x4000, AX
  28  	JNE     10(PC)       // jump if F0 = 0
  29  	FXCHD   F0, F1       // F0=q (smaller), F1=p (larger)
  30  	FDIVD   F1, F0       // F0=q(=q/p), F1=p
  31  	FMULD   F0, F0       // F0=q*q, F1=p
  32  	FLD1                 // F0=1, F1=q*q, F2=p
  33  	FADDDP  F0, F1       // F0=1+q*q, F1=p
  34  	FSQRT                // F0=sqrt(1+q*q), F1=p
  35  	FMULDP  F0, F1       // F0=p*sqrt(1+q*q)
  36  	FMOVDP  F0, ret+16(FP)
  37  	RET
  38  	FMOVDP  F0, F1       // F0=0
  39  	FMOVDP  F0, ret+16(FP)
  40  	RET
  41  not_finite:
  42  // test bits for -Inf or +Inf
  43  	MOVL    p_hi+4(FP), AX  // high word p
  44  	ORL     p_lo+0(FP), AX  // low word p
  45  	ANDL    $0x7fffffff, AX
  46  	CMPL    AX, $0x7ff00000
  47  	JEQ     is_inf
  48  	MOVL    q_hi+12(FP), AX  // high word q
  49  	ORL     q_lo+8(FP), AX   // low word q
  50  	ANDL    $0x7fffffff, AX
  51  	CMPL    AX, $0x7ff00000
  52  	JEQ     is_inf
  53  	MOVL    $0x7ff80000, ret_hi+20(FP)  // return NaN = 0x7FF8000000000001
  54  	MOVL    $0x00000001, ret_lo+16(FP)
  55  	RET
  56  is_inf:
  57  	MOVL    AX, ret_hi+20(FP)  // return +Inf = 0x7FF0000000000000
  58  	MOVL    $0x00000000, ret_lo+16(FP)
  59  	RET
  60