n_cabs.S revision 1.4
1 /* $NetBSD: n_cabs.S,v 1.4 2002/02/24 01:06:21 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 #include <machine/asm.h> 38 39 .globl _C_LABEL(__libm_dsqrt_r5) 40 /* 41 * double precision complex absolute value 42 * CABS by W. Kahan, 9/7/80. 43 * Revised for reserved operands by E. LeBlanc, 8/18/82 44 * argument for complex absolute value by reference, *4(%ap) 45 * argument for cabs and hypot (C fcns) by value, 4(%ap) 46 * output is in %r0:%r1 (error less than 0.86 ulps) 47 */ 48 49 /* entry for c functions cabs and hypot */ 50 ALTENTRY(cabs) 51 ENTRY(hypot, 0x8040) # save %r6, enable floating overflow 52 movq 4(%ap),%r0 # %r0:1 = x 53 movq 12(%ap),%r2 # %r2:3 = y 54 jbr cabs2 55 56 /* entry for Fortran use, call by: d = abs(z) */ 57 ENTRY(z_abs, 0x8040) # save %r6, enable floating overflow 58 movl 4(%ap),%r2 # indirect addressing is necessary here 59 movq (%r2)+,%r0 # %r0:1 = x 60 movq (%r2),%r2 # %r2:3 = y 61 62 cabs2: 63 bicw3 $0x7f,%r0,%r4 # %r4 has signed biased exp of x 64 cmpw $0x8000,%r4 65 jeql return # x is a reserved operand, so return it 66 bicw3 $0x7f,%r2,%r5 # %r5 has signed biased exp of y 67 cmpw $0x8000,%r5 68 jneq cont /* y isn't a reserved operand */ 69 movq %r2,%r0 /* return y if it's reserved */ 70 ret 71 72 cont: 73 bsbb regs_set # %r0:1 = dsqrt(x^2+y^2)/2^%r6 74 addw2 %r6,%r0 # unscaled cdabs in %r0:1 75 jvc return # unless it overflows 76 subw2 $0x80,%r0 # halve %r0 to get meaningful overflow 77 addd2 %r0,%r0 # overflow; %r0 is half of true abs value 78 return: 79 ret 80 81 ENTRY(__libm_cdabs_r6,0) # ENTRY POINT for cdsqrt 82 # calculates a scaled (factor in %r6) 83 # complex absolute value 84 85 movq (%r4)+,%r0 # %r0:%r1 = x via indirect addressing 86 movq (%r4),%r2 # %r2:%r3 = y via indirect addressing 87 88 bicw3 $0x7f,%r0,%r5 # %r5 has signed biased exp of x 89 cmpw $0x8000,%r5 90 jeql cdreserved # x is a reserved operand 91 bicw3 $0x7f,%r2,%r5 # %r5 has signed biased exp of y 92 cmpw $0x8000,%r5 93 jneq regs_set /* y isn't a reserved operand either? */ 94 95 cdreserved: 96 movl *4(%ap),%r4 # %r4 -> (u,v), if x or y is reserved 97 movq %r0,(%r4)+ # copy u and v as is and return 98 movq %r2,(%r4) # (again addressing is indirect) 99 ret 100 101 regs_set: 102 bicw2 $0x8000,%r0 # %r0:%r1 = dabs(x) 103 bicw2 $0x8000,%r2 # %r2:%r3 = dabs(y) 104 cmpw %r0,%r2 105 jgeq ordered 106 movq %r0,%r4 107 movq %r2,%r0 108 movq %r4,%r2 # force y's exp <= x's exp 109 ordered: 110 bicw3 $0x7f,%r0,%r6 # %r6 = exponent(x) + bias(129) 111 jeql retsb # if x = y = 0 then cdabs(x,y) = 0 112 subw2 $0x4780,%r6 # %r6 = exponent(x) - 14 113 subw2 %r6,%r0 # 2^14 <= scaled x < 2^15 114 bitw $0xff80,%r2 115 jeql retsb # if y = 0 return dabs(x) 116 subw2 %r6,%r2 117 cmpw $0x3780,%r2 # if scaled y < 2^-18 118 jgtr retsb # return dabs(x) 119 emodd %r0,$0,%r0,%r4,%r0 # %r4 + %r0:1 = scaled x^2 120 emodd %r2,$0,%r2,%r5,%r2 # %r5 + %r2:3 = scaled y^2 121 addd2 %r2,%r0 122 addl2 %r5,%r4 123 cvtld %r4,%r2 124 addd2 %r2,%r0 # %r0:1 = scaled x^2 + y^2 125 jmp _C_LABEL(__libm_dsqrt_r5)+2 126 # %r0:1 = dsqrt(x^2+y^2)/2^%r6 127 retsb: 128 rsb # error < 0.86 ulp 129
Indexes created Mon Sep 29 18:09:42 GMT 2025