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// 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 Hypot(p, q float64) float64
TEXT ·Hypot(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
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