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/* $NetBSD: n_cabs.S,v 1.7 2014/10/10 20:58:09 martin Exp $ */
/*
* Copyright (c) 1985, 1993
* The 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. 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.
*
* @(#)cabs.s 8.1 (Berkeley) 6/4/93
*/
#include <machine/asm.h>
.globl _C_LABEL(__libm_dsqrt_r5)
/*
* 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(%ap)
* argument for cabs and hypot (C fcns) by value, 4(%ap)
* output is in %r0:%r1 (error less than 0.86 ulps)
*/
/* entry for c functions cabs and hypot */
#ifdef WEAK_ALIAS
WEAK_ALIAS(hypotf, _hypotf)
#endif
ENTRY(_hypotf, 0)
cvtfd 4(%ap),-(%sp)
calls $2,_C_LABEL(_hypot)
cvtdf %r0,%r0
ret
#ifdef WEAK_ALIAS
WEAK_ALIAS(hypot, _hypot)
WEAK_ALIAS(hypotl, _hypot)
WEAK_ALIAS(_hypotl, _hypot)
#endif
ALTENTRY(cabs)
ENTRY(_hypot, 0x8040) # save %r6, enable floating overflow
movq 4(%ap),%r0 # %r0:1 = x
movq 12(%ap),%r2 # %r2:3 = y
jbr cabs2
/* entry for Fortran use, call by: d = abs(z) */
ENTRY(z_abs, 0x8040) # save %r6, enable floating overflow
movl 4(%ap),%r2 # indirect addressing is necessary here
movq (%r2)+,%r0 # %r0:1 = x
movq (%r2),%r2 # %r2:3 = y
cabs2:
bicw3 $0x7f,%r0,%r4 # %r4 has signed biased exp of x
cmpw $0x8000,%r4
jeql return # x is a reserved operand, so return it
bicw3 $0x7f,%r2,%r5 # %r5 has signed biased exp of y
cmpw $0x8000,%r5
jneq cont /* y isn't a reserved operand */
movq %r2,%r0 /* return y if it's reserved */
ret
cont:
bsbb regs_set # %r0:1 = dsqrt(x^2+y^2)/2^%r6
addw2 %r6,%r0 # unscaled cdabs in %r0:1
jvc return # unless it overflows
subw2 $0x80,%r0 # halve %r0 to get meaningful overflow
addd2 %r0,%r0 # overflow; %r0 is half of true abs value
return:
ret
ENTRY(__libm_cdabs_r6,0) # ENTRY POINT for cdsqrt
# calculates a scaled (factor in %r6)
# complex absolute value
movq (%r4)+,%r0 # %r0:%r1 = x via indirect addressing
movq (%r4),%r2 # %r2:%r3 = y via indirect addressing
bicw3 $0x7f,%r0,%r5 # %r5 has signed biased exp of x
cmpw $0x8000,%r5
jeql cdreserved # x is a reserved operand
bicw3 $0x7f,%r2,%r5 # %r5 has signed biased exp of y
cmpw $0x8000,%r5
jneq regs_set /* y isn't a reserved operand either? */
cdreserved:
movl *4(%ap),%r4 # %r4 -> (u,v), if x or y is reserved
movq %r0,(%r4)+ # copy u and v as is and return
movq %r2,(%r4) # (again addressing is indirect)
ret
regs_set:
bicw2 $0x8000,%r0 # %r0:%r1 = dabs(x)
bicw2 $0x8000,%r2 # %r2:%r3 = dabs(y)
cmpw %r0,%r2
jgeq ordered
movq %r0,%r4
movq %r2,%r0
movq %r4,%r2 # force y's exp <= x's exp
ordered:
bicw3 $0x7f,%r0,%r6 # %r6 = exponent(x) + bias(129)
jeql retsb # if x = y = 0 then cdabs(x,y) = 0
subw2 $0x4780,%r6 # %r6 = exponent(x) - 14
subw2 %r6,%r0 # 2^14 <= scaled x < 2^15
bitw $0xff80,%r2
jeql retsb # if y = 0 return dabs(x)
subw2 %r6,%r2
cmpw $0x3780,%r2 # if scaled y < 2^-18
jgtr retsb # return dabs(x)
emodd %r0,$0,%r0,%r4,%r0 # %r4 + %r0:1 = scaled x^2
emodd %r2,$0,%r2,%r5,%r2 # %r5 + %r2:3 = scaled y^2
addd2 %r2,%r0
addl2 %r5,%r4
cvtld %r4,%r2
addd2 %r2,%r0 # %r0:1 = scaled x^2 + y^2
jmp _C_LABEL(__libm_dsqrt_r5)+2
# %r0:1 = dsqrt(x^2+y^2)/2^%r6
retsb:
rsb # error < 0.86 ulp
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