1*34128Sbostic# 232004Szliu# Copyright (c) 1987 Regents of the University of California. 3*34128Sbostic# All rights reserved. 432004Szliu# 5*34128Sbostic# Redistribution and use in source and binary forms are permitted 6*34128Sbostic# provided that this notice is preserved and that due credit is given 7*34128Sbostic# to the University of California at Berkeley. The name of the University 8*34128Sbostic# may not be used to endorse or promote products derived from this 9*34128Sbostic# software without specific prior written permission. This software 10*34128Sbostic# is provided ``as is'' without express or implied warranty. 11*34128Sbostic# 12*34128Sbostic# All recipients should regard themselves as participants in an ongoing 13*34128Sbostic# research project and hence should feel obligated to report their 14*34128Sbostic# experiences (good or bad) with these elementary function codes, using 15*34128Sbostic# the sendbug(8) program, to the authors. 16*34128Sbostic# 17*34128Sbostic# @(#)cabs.s 5.3 (Berkeley) 04/29/88 18*34128Sbostic# 1932004Szliu .data 2032004Szliu .align 2 2132004Szliu_sccsid: 22*34128Sbostic.asciz "@(#)cabs.s 5.3 5.3 (ucb.elefunt) 04/29/88" 2332004Szliu 2432004Szliu# double precision complex absolute value 2532004Szliu# CABS by W. Kahan, 9/7/80. 2632004Szliu# Revised for reserved operands by E. LeBlanc, 8/18/82 2732004Szliu# argument for complex absolute value by reference, *4(fp) 2832004Szliu# argument for cabs and hypot (C fcns) by value, 4(fp) 2932004Szliu# output is in r0:r1 3032004Szliu 3132004Szliu .text 3232004Szliu .align 2 3332004Szliu .globl _cabs 3432004Szliu .globl _hypot 3532004Szliu .globl _z_abs 3632004Szliu 3732004Szliu# entry for c functions cabs and hypot 3832004Szliu_cabs: 3932004Szliu_hypot: 4032004Szliu .word 0x807c # save r2-r6, enable floating overflow 4132004Szliu movl 16(fp),r3 4232004Szliu movl 12(fp),r2 # r2:3 = y 4332004Szliu movl 8(fp),r1 4432004Szliu movl 4(fp),r0 # r0:1 = x 4532004Szliu brb 1f 4632004Szliu# entry for Fortran use, call by: d = abs(z) 4732004Szliu_z_abs: 4832004Szliu .word 0x807c # save r2-r6, enable floating overflow 4932004Szliu movl 4(fp),r4 # indirect addressing is necessary here 5032004Szliu movl 12(r4),r3 # 5132004Szliu movl 8(r4),r2 # r2:3 = y 5232004Szliu movl 4(r4),r1 # 5332004Szliu movl (r4),r0 # r0:1 = x 5432004Szliu1: andl3 $0xff800000,r0,r4 # r4 has signed biased exp of x 5532004Szliu cmpl $0x80000000,r4 5632004Szliu beql 2f # x is a reserved operand, so return it 5732004Szliu andl3 $0xff800000,r2,r5 # r5 has signed biased exp of y 5832004Szliu cmpl $0x80000000,r5 5932004Szliu bneq 3f # y isn't a reserved operand 6032004Szliu movl r3,r1 6132004Szliu movl r2,r0 # return y if it's reserved 6232004Szliu2: ret 6332004Szliu 6432004Szliu3: callf $4,regs_set # r0:1 = dsqrt(x^2+y^2)/2^r6 6532004Szliu addl2 r6,r0 # unscaled cdabs in r0:1 6632004Szliu jvc 2b # unless it overflows 6732004Szliu subl2 $0x800000,r0 # halve r0 to get meaningful overflow 6832004Szliu ldd r0 6932004Szliu addd r0 # overflow; r0 is half of true abs value 7032004Szliu ret 7132004Szliu 7232004Szliuregs_set: 7332004Szliu .word 0x0000 7432004Szliu andl2 $0x7fffffff,r0 # r0:r1 = dabs(x) 7532004Szliu andl2 $0x7fffffff,r2 # r2:r3 = dabs(y) 7632004Szliu cmpl r0,r2 7732004Szliu bgeq 4f 7832004Szliu movl r1,r5 7932004Szliu movl r0,r4 8032004Szliu movl r3,r1 8132004Szliu movl r2,r0 8232004Szliu movl r5,r3 8332004Szliu movl r4,r2 # force y's exp <= x's exp 8432004Szliu4: andl3 $0xff800000,r0,r6 # r6 = exponent(x) + bias(129) 8532004Szliu beql 5f # if x = y = 0 then cdabs(x,y) = 0 8632004Szliu subl2 $0x47800000,r6 # r6 = exponent(x) - 14 8732004Szliu subl2 r6,r0 # 2^14 <= scaled x < 2^15 8832004Szliu bitl $0xff800000,r2 8932004Szliu beql 5f # if y = 0 return dabs(x) 9032004Szliu subl2 r6,r2 9132004Szliu cmpl $0x37800000,r2 # if scaled y < 2^-18 9232004Szliu bgtr 5f # return dabs(x) 9332004Szliu ldd r0 9432004Szliu muld r0 9532004Szliu std r0 # r0:1 = scaled x^2 9632004Szliu ldd r2 9732004Szliu muld r2 # acc = scaled y^2 9832004Szliu addd r0 9932004Szliu std r0 10032004Szliu pushl r1 10132004Szliu pushl r0 10232004Szliu callf $12,_sqrt # r0:1 = dsqrt(x^2+y^2)/2^r6 10332004Szliu5: ret 104