n_cabs.S revision 1.2
1 /* $NetBSD: n_cabs.S,v 1.2 1998/10/31 02:06:02 matt Exp $ */ 2 /* 3 * Copyright (c) 1985, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by the University of 17 * California, Berkeley and its contributors. 18 * 4. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)cabs.s 8.1 (Berkeley) 6/4/93 35 */ 36 37 /* 38 * double precision complex absolute value 39 * CABS by W. Kahan, 9/7/80. 40 * Revised for reserved operands by E. LeBlanc, 8/18/82 41 * argument for complex absolute value by reference, *4(ap) 42 * argument for cabs and hypot (C fcns) by value, 4(ap) 43 * output is in r0:r1 (error less than 0.86 ulps) 44 */ 45 46 .text 47 .align 1 48 .globl _cabs 49 .type _cabs,@function 50 .globl _hypot 51 .type _hypot,@function 52 .globl _z_abs 53 .type _z_abs,@function 54 .globl libm$cdabs_r6 55 .type libm$cdabs_r6,@label 56 .globl libm$dsqrt_r5 57 .type libm$dsqrt_r5,@label 58 59 /* entry for c functions cabs and hypot */ 60 _cabs: 61 _hypot: 62 .word 0x807c # save r2-r6, enable floating overflow 63 movq 4(ap),r0 # r0:1 = x 64 movq 12(ap),r2 # r2:3 = y 65 jmp cabs2 66 /* entry for Fortran use, call by: d = abs(z) */ 67 _z_abs: 68 .word 0x807c # save r2-r6, enable floating overflow 69 movl 4(ap),r2 # indirect addressing is necessary here 70 movq (r2)+,r0 # r0:1 = x 71 movq (r2),r2 # r2:3 = y 72 73 cabs2: 74 bicw3 $0x7f,r0,r4 # r4 has signed biased exp of x 75 cmpw $0x8000,r4 76 jeql return # x is a reserved operand, so return it 77 bicw3 $0x7f,r2,r5 # r5 has signed biased exp of y 78 cmpw $0x8000,r5 79 jneq cont /* y isn't a reserved operand */ 80 movq r2,r0 /* return y if it's reserved */ 81 ret 82 83 cont: 84 bsbb regs_set # r0:1 = dsqrt(x^2+y^2)/2^r6 85 addw2 r6,r0 # unscaled cdabs in r0:1 86 jvc return # unless it overflows 87 subw2 $0x80,r0 # halve r0 to get meaningful overflow 88 addd2 r0,r0 # overflow; r0 is half of true abs value 89 return: 90 ret 91 92 libm$cdabs_r6: # ENTRY POINT for cdsqrt 93 # calculates a scaled (factor in r6) 94 # complex absolute value 95 96 movq (r4)+,r0 # r0:r1 = x via indirect addressing 97 movq (r4),r2 # r2:r3 = y via indirect addressing 98 99 bicw3 $0x7f,r0,r5 # r5 has signed biased exp of x 100 cmpw $0x8000,r5 101 jeql cdreserved # x is a reserved operand 102 bicw3 $0x7f,r2,r5 # r5 has signed biased exp of y 103 cmpw $0x8000,r5 104 jneq regs_set /* y isn't a reserved operand either? */ 105 106 cdreserved: 107 movl *4(ap),r4 # r4 -> (u,v), if x or y is reserved 108 movq r0,(r4)+ # copy u and v as is and return 109 movq r2,(r4) # (again addressing is indirect) 110 ret 111 112 regs_set: 113 bicw2 $0x8000,r0 # r0:r1 = dabs(x) 114 bicw2 $0x8000,r2 # r2:r3 = dabs(y) 115 cmpw r0,r2 116 jgeq ordered 117 movq r0,r4 118 movq r2,r0 119 movq r4,r2 # force y's exp <= x's exp 120 ordered: 121 bicw3 $0x7f,r0,r6 # r6 = exponent(x) + bias(129) 122 jeql retsb # if x = y = 0 then cdabs(x,y) = 0 123 subw2 $0x4780,r6 # r6 = exponent(x) - 14 124 subw2 r6,r0 # 2^14 <= scaled x < 2^15 125 bitw $0xff80,r2 126 jeql retsb # if y = 0 return dabs(x) 127 subw2 r6,r2 128 cmpw $0x3780,r2 # if scaled y < 2^-18 129 jgtr retsb # return dabs(x) 130 emodd r0,$0,r0,r4,r0 # r4 + r0:1 = scaled x^2 131 emodd r2,$0,r2,r5,r2 # r5 + r2:3 = scaled y^2 132 addd2 r2,r0 133 addl2 r5,r4 134 cvtld r4,r2 135 addd2 r2,r0 # r0:1 = scaled x^2 + y^2 136 jmp libm$dsqrt_r5 # r0:1 = dsqrt(x^2+y^2)/2^r6 137 retsb: 138 rsb # error < 0.86 ulp 139
Indexes created Tue Sep 30 17:09:57 GMT 2025