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      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 #define PosInf 0x7FF0000000000000
      8 #define NaN 0x7FF8000000000001
      9 
     10 // func Hypot(p, q float64) float64
     11 TEXT Hypot(SB),NOSPLIT,$0
     12 	// test bits for special cases
     13 	MOVQ    p+0(FP), BX
     14 	MOVQ    $~(1<<63), AX
     15 	ANDQ    AX, BX // p = |p|
     16 	MOVQ    q+8(FP), CX
     17 	ANDQ    AX, CX // q = |q|
     18 	MOVQ    $PosInf, AX
     19 	CMPQ    AX, BX
     20 	JLE     isInfOrNaN
     21 	CMPQ    AX, CX
     22 	JLE     isInfOrNaN
     23 	// hypot = max * sqrt(1 + (min/max)**2)
     24 	MOVQ    BX, X0
     25 	MOVQ    CX, X1
     26 	ORQ     CX, BX
     27 	JEQ     isZero
     28 	MOVAPD  X0, X2
     29 	MAXSD   X1, X0
     30 	MINSD   X2, X1
     31 	DIVSD   X0, X1
     32 	MULSD   X1, X1
     33 	ADDSD   $1.0, X1
     34 	SQRTSD  X1, X1
     35 	MULSD   X1, X0
     36 	MOVSD   X0, ret+16(FP)
     37 	RET
     38 isInfOrNaN:
     39 	CMPQ    AX, BX
     40 	JEQ     isInf
     41 	CMPQ    AX, CX
     42 	JEQ     isInf
     43 	MOVQ    $NaN, AX
     44 	MOVQ    AX, ret+16(FP) // return NaN
     45 	RET
     46 isInf:
     47 	MOVQ    AX, ret+16(FP) // return +Inf
     48 	RET
     49 isZero:
     50 	MOVQ    $0, AX
     51 	MOVQ    AX, ret+16(FP) // return 0
     52 	RET
     53