// 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 archHypot(p, q float64) float64

TEXT ·archHypot(SB),NOSPLIT,$0

// test bits for not-finite

MOVL p_hi+4(FP), AX // high word p

ANDL $0x7ff00000, AX

CMPL AX, $0x7ff00000

JEQ not_finite

MOVL q_hi+12(FP), AX // high word q

ANDL $0x7ff00000, AX

CMPL AX, $0x7ff00000

JEQ not_finite

FMOVD p+0(FP), F0 // F0=p

FABS // F0=|p|

FMOVD q+8(FP), F0 // F0=q, F1=|p|

FABS // F0=|q|, F1=|p|

FUCOMI F0, F1 // compare F0 to F1

JCC 2(PC) // jump if F0 >= F1

FXCHD F0, F1 // F0=|p| (larger), F1=|q| (smaller)

FTST // compare F0 to 0

FSTSW AX

ANDW $0x4000, AX

JNE 10(PC) // jump if F0 = 0

FXCHD F0, F1 // F0=q (smaller), F1=p (larger)

FDIVD F1, F0 // F0=q(=q/p), F1=p

FMULD F0, F0 // F0=q*q, F1=p

FLD1 // F0=1, F1=q*q, F2=p

FADDDP F0, F1 // F0=1+q*q, F1=p

FSQRT // F0=sqrt(1+q*q), F1=p

FMULDP F0, F1 // F0=p*sqrt(1+q*q)

FMOVDP F0, ret+16(FP)

RET

FMOVDP F0, F1 // F0=0

FMOVDP F0, ret+16(FP)

RET

not_finite:

// test bits for -Inf or +Inf

MOVL p_hi+4(FP), AX // high word p

ORL p_lo+0(FP), AX // low word p

ANDL $0x7fffffff, AX

CMPL AX, $0x7ff00000

JEQ is_inf

MOVL q_hi+12(FP), AX // high word q

ORL q_lo+8(FP), AX // low word q

ANDL $0x7fffffff, AX

CMPL AX, $0x7ff00000

JEQ is_inf

MOVL $0x7ff80000, ret_hi+20(FP) // return NaN = 0x7FF8000000000001

MOVL $0x00000001, ret_lo+16(FP)

RET

is_inf:

MOVL AX, ret_hi+20(FP) // return +Inf = 0x7FF0000000000000

MOVL $0x00000000, ret_lo+16(FP)

RET