NetBSD/lib/libm/tahoe/cabs.S

119 lines
3.9 KiB
ArmAsm

# Copyright (c) 1987 Regents of the University of California.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
# 3. All advertising materials mentioning features or use of this software
# must display the following acknowledgement:
# This product includes software developed by the University of
# California, Berkeley and its contributors.
# 4. Neither the name of the University nor the names of its contributors
# may be used to endorse or promote products derived from this software
# without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
.data
.align 2
;_sccsid:
;.asciz "from: @(#)cabs.s 5.5 5.5 (ucb.elefunt) 10/9/90"
_rcsid:
.asciz "$Id: cabs.S,v 1.1 1993/08/14 13:43:57 mycroft Exp $"
# double precision complex absolute value
# CABS by W. Kahan, 9/7/80.
# Revised for reserved operands by E. LeBlanc, 8/18/82
# argument for complex absolute value by reference, *4(fp)
# argument for cabs and hypot (C fcns) by value, 4(fp)
# output is in r0:r1
.text
.align 2
.globl _cabs
.globl _hypot
.globl _z_abs
# entry for c functions cabs and hypot
_cabs:
_hypot:
.word 0x807c # save r2-r6, enable floating overflow
movl 16(fp),r3
movl 12(fp),r2 # r2:3 = y
movl 8(fp),r1
movl 4(fp),r0 # r0:1 = x
brb 1f
# entry for Fortran use, call by: d = abs(z)
_z_abs:
.word 0x807c # save r2-r6, enable floating overflow
movl 4(fp),r4 # indirect addressing is necessary here
movl 12(r4),r3 #
movl 8(r4),r2 # r2:3 = y
movl 4(r4),r1 #
movl (r4),r0 # r0:1 = x
1: andl3 $0xff800000,r0,r4 # r4 has signed biased exp of x
cmpl $0x80000000,r4
beql 2f # x is a reserved operand, so return it
andl3 $0xff800000,r2,r5 # r5 has signed biased exp of y
cmpl $0x80000000,r5
bneq 3f # y isn't a reserved operand
movl r3,r1
movl r2,r0 # return y if it's reserved
2: ret
3: callf $4,regs_set # r0:1 = dsqrt(x^2+y^2)/2^r6
addl2 r6,r0 # unscaled cdabs in r0:1
jvc 2b # unless it overflows
subl2 $0x800000,r0 # halve r0 to get meaningful overflow
ldd r0
addd r0 # overflow; r0 is half of true abs value
ret
regs_set:
.word 0x0000
andl2 $0x7fffffff,r0 # r0:r1 = dabs(x)
andl2 $0x7fffffff,r2 # r2:r3 = dabs(y)
cmpl r0,r2
bgeq 4f
movl r1,r5
movl r0,r4
movl r3,r1
movl r2,r0
movl r5,r3
movl r4,r2 # force y's exp <= x's exp
4: andl3 $0xff800000,r0,r6 # r6 = exponent(x) + bias(129)
beql 5f # if x = y = 0 then cdabs(x,y) = 0
subl2 $0x47800000,r6 # r6 = exponent(x) - 14
subl2 r6,r0 # 2^14 <= scaled x < 2^15
bitl $0xff800000,r2
beql 5f # if y = 0 return dabs(x)
subl2 r6,r2
cmpl $0x37800000,r2 # if scaled y < 2^-18
bgtr 5f # return dabs(x)
ldd r0
muld r0
std r0 # r0:1 = scaled x^2
ldd r2
muld r2 # acc = scaled y^2
addd r0
std r0
pushl r1
pushl r0
callf $12,_sqrt # r0:1 = dsqrt(x^2+y^2)/2^r6
5: ret