NetBSD/lib/libm/vax/cbrt.S

101 lines
3.7 KiB
ArmAsm

# Copyright (c) 1985 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: @(#)cbrt.s 1.1 (Berkeley) 5/23/85; 5.4 (ucb.elefunt) 10/9/90"
_rcsid:
.asciz "$Id: cbrt.S,v 1.1 1993/08/14 13:44:10 mycroft Exp $"
# double cbrt(double arg)
# W. Kahan, 10/13/80. revised 1/13/84 for keeping sign symmetry
# error check by E LeBlanc, 8/18/82
# Revised and tested by K.C. Ng, 5/2/85
# Max error less than 0.667 ulps (unit in the last places)
.globl _cbrt
.globl _d_cbrt
.globl _dcbrt_
.text
.align 1
_cbrt:
_d_cbrt:
.word 0x00fc # save r2 to r7
movq 4(ap),r0 # r0 = argument x
jmp dcbrt2
_dcbrt_:
.word 0x00fc # save r2 to r7
movq *4(ap),r0 # r0 = argument x
dcbrt2: bicw3 $0x807f,r0,r2 # biased exponent of x
jeql return # dcbrt(0)=0 dcbrt(res)=res. operand
bicw3 $0x7fff,r0,ap # ap has sign(x)
xorw2 ap,r0 # r0 is abs(x)
movl r0,r2 # r2 has abs(x)
rotl $16,r2,r2 # r2 = |x| with bits unscrambled
divl2 $3,r2 # rough dcbrt with bias/3
addl2 B,r2 # restore bias, diminish fraction
rotl $16,r2,r2 # r2=|q|=|dcbrt| to 5 bits
mulf3 r2,r2,r3 # r3 =qq
divf2 r0,r3 # r3 = qq/x
mulf2 r2,r3
addf2 C,r3 # r3 = s = C + qqq/x
divf3 r3,D,r4 # r4 = D/s
addf2 E,r4
addf2 r4,r3 # r3 = s + E + D/s
divf3 r3,F,r3 # r3 = F / (s + E + D/s)
addf2 G,r3 # r3 = G + F / (s + E + D/s)
mulf2 r3,r2 # r2 = qr3 = new q to 23 bits
clrl r3 # r2:r3 = q as double float
muld3 r2,r2,r4 # r4:r5 = qq exactly
divd2 r4,r0 # r0:r1 = x/(q*q) rounded
subd3 r2,r0,r6 # r6:r7 = x/(q*q) - q exactly
movq r2,r4 # r4:r5 = q
addw2 $0x80,r4 # r4:r5 = 2 * q
addd2 r0,r4 # r4:r5 = 2*q + x/(q*q)
divd2 r4,r6 # r6:r7 = (x/(q*q)-q)/(2*q+x/(q*q))
muld2 r2,r6 # r6:r7 = q*(x/(q*q)-q)/(2*q+x/(q*q))
addd3 r6,r2,r0 # r0:r1 = q + r6:r7
bisw2 ap,r0 # restore the sign bit
return:
ret # error less than 0.667 ulps
.data
.align 2
B : .long 721142941 # (86-0.03306235651)*(2^23)
C : .float 0f0.5428571429 # 19/35
D : .float 0f-0.7053061224 # -864/1225
E : .float 0f1.414285714 # 99/70
F : .float 0f1.607142857 # 45/28
G : .float 0f0.3571428571 # 5/14