1# Copyright (c) 1987 Regents of the University of California. 2# All rights reserved. 3# 4# Redistribution and use in source and binary forms are permitted 5# provided that the above copyright notice and this paragraph are 6# duplicated in all such forms and that any documentation, 7# advertising materials, and other materials related to such 8# distribution and use acknowledge that the software was developed 9# by the University of California, Berkeley. The name of the 10# University may not be used to endorse or promote products derived 11# from this software without specific prior written permission. 12# THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 13# IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 14# WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. 15# 16# All recipients should regard themselves as participants in an ongoing 17# research project and hence should feel obligated to report their 18# experiences (good or bad) with these elementary function codes, using 19# the sendbug(8) program, to the authors. 20# 21# @(#)cabs.s 5.4 (Berkeley) 06/30/88 22# 23 .data 24 .align 2 25_sccsid: 26.asciz "@(#)cabs.s 5.4 5.4 (ucb.elefunt) 06/30/88" 27 28# double precision complex absolute value 29# CABS by W. Kahan, 9/7/80. 30# Revised for reserved operands by E. LeBlanc, 8/18/82 31# argument for complex absolute value by reference, *4(fp) 32# argument for cabs and hypot (C fcns) by value, 4(fp) 33# output is in r0:r1 34 35 .text 36 .align 2 37 .globl _cabs 38 .globl _hypot 39 .globl _z_abs 40 41# entry for c functions cabs and hypot 42_cabs: 43_hypot: 44 .word 0x807c # save r2-r6, enable floating overflow 45 movl 16(fp),r3 46 movl 12(fp),r2 # r2:3 = y 47 movl 8(fp),r1 48 movl 4(fp),r0 # r0:1 = x 49 brb 1f 50# entry for Fortran use, call by: d = abs(z) 51_z_abs: 52 .word 0x807c # save r2-r6, enable floating overflow 53 movl 4(fp),r4 # indirect addressing is necessary here 54 movl 12(r4),r3 # 55 movl 8(r4),r2 # r2:3 = y 56 movl 4(r4),r1 # 57 movl (r4),r0 # r0:1 = x 581: andl3 $0xff800000,r0,r4 # r4 has signed biased exp of x 59 cmpl $0x80000000,r4 60 beql 2f # x is a reserved operand, so return it 61 andl3 $0xff800000,r2,r5 # r5 has signed biased exp of y 62 cmpl $0x80000000,r5 63 bneq 3f # y isn't a reserved operand 64 movl r3,r1 65 movl r2,r0 # return y if it's reserved 662: ret 67 683: callf $4,regs_set # r0:1 = dsqrt(x^2+y^2)/2^r6 69 addl2 r6,r0 # unscaled cdabs in r0:1 70 jvc 2b # unless it overflows 71 subl2 $0x800000,r0 # halve r0 to get meaningful overflow 72 ldd r0 73 addd r0 # overflow; r0 is half of true abs value 74 ret 75 76regs_set: 77 .word 0x0000 78 andl2 $0x7fffffff,r0 # r0:r1 = dabs(x) 79 andl2 $0x7fffffff,r2 # r2:r3 = dabs(y) 80 cmpl r0,r2 81 bgeq 4f 82 movl r1,r5 83 movl r0,r4 84 movl r3,r1 85 movl r2,r0 86 movl r5,r3 87 movl r4,r2 # force y's exp <= x's exp 884: andl3 $0xff800000,r0,r6 # r6 = exponent(x) + bias(129) 89 beql 5f # if x = y = 0 then cdabs(x,y) = 0 90 subl2 $0x47800000,r6 # r6 = exponent(x) - 14 91 subl2 r6,r0 # 2^14 <= scaled x < 2^15 92 bitl $0xff800000,r2 93 beql 5f # if y = 0 return dabs(x) 94 subl2 r6,r2 95 cmpl $0x37800000,r2 # if scaled y < 2^-18 96 bgtr 5f # return dabs(x) 97 ldd r0 98 muld r0 99 std r0 # r0:1 = scaled x^2 100 ldd r2 101 muld r2 # acc = scaled y^2 102 addd r0 103 std r0 104 pushl r1 105 pushl r0 106 callf $12,_sqrt # r0:1 = dsqrt(x^2+y^2)/2^r6 1075: ret 108