1*61310Sbostic# Copyright (c) 1987, 1993 2*61310Sbostic# The Regents of the University of California. All rights reserved. 332004Szliu# 445306Sbostic# %sccs.include.redist.sh% 534128Sbostic# 6*61310Sbostic# @(#)cabs.s 8.1 (Berkeley) 06/04/93 734128Sbostic# 832004Szliu .data 932004Szliu .align 2 1032004Szliu_sccsid: 11*61310Sbostic.asciz "@(#)cabs.s 8.1 8.1 (ucb.elefunt) 06/04/93" 1232004Szliu 1332004Szliu# double precision complex absolute value 1432004Szliu# CABS by W. Kahan, 9/7/80. 1532004Szliu# Revised for reserved operands by E. LeBlanc, 8/18/82 1632004Szliu# argument for complex absolute value by reference, *4(fp) 1732004Szliu# argument for cabs and hypot (C fcns) by value, 4(fp) 1832004Szliu# output is in r0:r1 1932004Szliu 2032004Szliu .text 2132004Szliu .align 2 2232004Szliu .globl _cabs 2332004Szliu .globl _hypot 2432004Szliu .globl _z_abs 2532004Szliu 2632004Szliu# entry for c functions cabs and hypot 2732004Szliu_cabs: 2832004Szliu_hypot: 2932004Szliu .word 0x807c # save r2-r6, enable floating overflow 3032004Szliu movl 16(fp),r3 3132004Szliu movl 12(fp),r2 # r2:3 = y 3232004Szliu movl 8(fp),r1 3332004Szliu movl 4(fp),r0 # r0:1 = x 3432004Szliu brb 1f 3532004Szliu# entry for Fortran use, call by: d = abs(z) 3632004Szliu_z_abs: 3732004Szliu .word 0x807c # save r2-r6, enable floating overflow 3832004Szliu movl 4(fp),r4 # indirect addressing is necessary here 3932004Szliu movl 12(r4),r3 # 4032004Szliu movl 8(r4),r2 # r2:3 = y 4132004Szliu movl 4(r4),r1 # 4232004Szliu movl (r4),r0 # r0:1 = x 4332004Szliu1: andl3 $0xff800000,r0,r4 # r4 has signed biased exp of x 4432004Szliu cmpl $0x80000000,r4 4532004Szliu beql 2f # x is a reserved operand, so return it 4632004Szliu andl3 $0xff800000,r2,r5 # r5 has signed biased exp of y 4732004Szliu cmpl $0x80000000,r5 4832004Szliu bneq 3f # y isn't a reserved operand 4932004Szliu movl r3,r1 5032004Szliu movl r2,r0 # return y if it's reserved 5132004Szliu2: ret 5232004Szliu 5332004Szliu3: callf $4,regs_set # r0:1 = dsqrt(x^2+y^2)/2^r6 5432004Szliu addl2 r6,r0 # unscaled cdabs in r0:1 5532004Szliu jvc 2b # unless it overflows 5632004Szliu subl2 $0x800000,r0 # halve r0 to get meaningful overflow 5732004Szliu ldd r0 5832004Szliu addd r0 # overflow; r0 is half of true abs value 5932004Szliu ret 6032004Szliu 6132004Szliuregs_set: 6232004Szliu .word 0x0000 6332004Szliu andl2 $0x7fffffff,r0 # r0:r1 = dabs(x) 6432004Szliu andl2 $0x7fffffff,r2 # r2:r3 = dabs(y) 6532004Szliu cmpl r0,r2 6632004Szliu bgeq 4f 6732004Szliu movl r1,r5 6832004Szliu movl r0,r4 6932004Szliu movl r3,r1 7032004Szliu movl r2,r0 7132004Szliu movl r5,r3 7232004Szliu movl r4,r2 # force y's exp <= x's exp 7332004Szliu4: andl3 $0xff800000,r0,r6 # r6 = exponent(x) + bias(129) 7432004Szliu beql 5f # if x = y = 0 then cdabs(x,y) = 0 7532004Szliu subl2 $0x47800000,r6 # r6 = exponent(x) - 14 7632004Szliu subl2 r6,r0 # 2^14 <= scaled x < 2^15 7732004Szliu bitl $0xff800000,r2 7832004Szliu beql 5f # if y = 0 return dabs(x) 7932004Szliu subl2 r6,r2 8032004Szliu cmpl $0x37800000,r2 # if scaled y < 2^-18 8132004Szliu bgtr 5f # return dabs(x) 8232004Szliu ldd r0 8332004Szliu muld r0 8432004Szliu std r0 # r0:1 = scaled x^2 8532004Szliu ldd r2 8632004Szliu muld r2 # acc = scaled y^2 8732004Szliu addd r0 8832004Szliu std r0 8932004Szliu pushl r1 9032004Szliu pushl r0 9132004Szliu callf $12,_sqrt # r0:1 = dsqrt(x^2+y^2)/2^r6 9232004Szliu5: ret 93