hypot_386.s

     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
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