| // 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" |
| |
| #define PosInf 0x7FF0000000000000 |
| #define NaN 0x7FF8000000000001 |
| |
| // func Hypot(p, q float64) float64 |
| TEXT ·Hypot(SB),NOSPLIT,$0 |
| // test bits for special cases |
| MOVQ p+0(FP), BX |
| MOVQ $~(1<<63), AX |
| ANDQ AX, BX // p = |p| |
| MOVQ q+8(FP), CX |
| ANDQ AX, CX // q = |q| |
| MOVQ $PosInf, AX |
| CMPQ AX, BX |
| JLE isInfOrNaN |
| CMPQ AX, CX |
| JLE isInfOrNaN |
| // hypot = max * sqrt(1 + (min/max)**2) |
| MOVQ BX, X0 |
| MOVQ CX, X1 |
| ORQ CX, BX |
| JEQ isZero |
| MOVAPD X0, X2 |
| MAXSD X1, X0 |
| MINSD X2, X1 |
| DIVSD X0, X1 |
| MULSD X1, X1 |
| ADDSD $1.0, X1 |
| SQRTSD X1, X1 |
| MULSD X1, X0 |
| MOVSD X0, ret+16(FP) |
| RET |
| isInfOrNaN: |
| CMPQ AX, BX |
| JEQ isInf |
| CMPQ AX, CX |
| JEQ isInf |
| MOVQ $NaN, AX |
| MOVQ AX, ret+16(FP) // return NaN |
| RET |
| isInf: |
| MOVQ AX, ret+16(FP) // return +Inf |
| RET |
| isZero: |
| MOVQ $0, AX |
| MOVQ AX, ret+16(FP) // return 0 |
| RET |
