n_cabs.S revision 1.3
1 /* $NetBSD: n_cabs.S,v 1.3 2000/07/14 04:50:58 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 21:09:56 GMT 2025