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/* $NetBSD: fpeadd.S,v 1.2 1996/03/18 19:58:12 mark Exp $ */
/*
* Copyright (c) 1995 Mark Brinicombe.
* Copyright (c) 1995 Neil Carson.
* 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 RiscBSD kernel team.
* 4. The name of the company nor the name of the author may be used to
* endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``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 AUTHORS 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.
*
* RiscBSD kernel project
*
* fpeadd.S
*
* FP addition
*
* Created : 11/02/95
*/
/* std. registers
*/
sp .req r13
lr .req r14
pc .req r15
.global _nc_fp_add
mant1 .req r2
xp1 .req r3
mant2 .req r4
xp2 .req r5
wrk1 .req r14
_nc_fp_add:
stmfd r13!,{r2-r5,r14}
mov xp1,r0,lsr #23 /* get exponent+sign */
bic mant1,r0,xp1,lsl #23 /* get mantissa */
cmp r0,#0
orrne mant1,mant1,#1<<23 /* set on bit to left of point */
and xp1,xp1,#255 /* remove sign */
mov xp2,r1,lsr #23 /* get exponent+sign */
bic mant2,r1,xp2,lsl #23 /* get mantissa */
cmp r1,#0
orrne mant2,mant2,#1<<23 /* set on bit to left of point */
and xp2,xp2,#255 /* remove sign */
eors wrk1,r0,r1 /* both +ve/-ve? */
bmi fp_add_neg /* no, unequal signs */
subs wrk1,xp1,xp2 /* exp. difference */
addpl mant1,mant1,mant2,lsr wrk1 /* xp1>exp2, round mant2 down */
rsbmi wrk1,wrk1,#0 /* as +ve difference */
addmi mant1,mant2,mant1,lsr wrk1 /* xp1<exp2, round mant1 down */
movmi xp1,xp2 /* exponent of result */
and r0,r0,#1<<31 /* set sign of result */
/* normalise mantissa & exponent */
fp_add_rounddown:
cmp mant1,#1<<24
blt fp_add_normexit
add xp1,xp1,#1
mov mant1,mant1,lsr #1
b fp_add_rounddown
/* r0 or r1 is -ve */
fp_add_neg:
subs wrk1,xp1,xp2 /* exp. difference */
movpl mant2,mant2,lsr wrk1 /* exp1>xp2, round mant2 */
rsbmi wrk1,wrk1,#0 /* as +ve difference */
movmi mant1,mant1,lsr wrk1 /* exp1<exp2, round mant1 */
movmi xp1,xp2 /* exponent of result */
tst r0,#1<<31 /* r0 -ve? */
subeq mant1,mant1,mant2 /* no, r0=r0-r1 */
subne mant1,mant2,mant1 /* yes, r0=r1-r0 */
cmp mant1,#0
rsbmi mant1,mant1,#0 /* +ve mantissa */
movmi r0,#1<<31 /* -ve result */
movpl r0,#0 /* +ve result */
/* normalise result - adjust mantissa & exponent */
cmp mant1,#0 /* check for 0 - special case */
moveq r0,#0
beq fp_add_exit
fp_add_roundup:
tst mant1,#1<<23
bne fp_add_normexit
sub xp1,xp1,#1
mov mant1,mant1,lsl #1
b fp_add_roundup
/* combine result */
fp_add_normexit:
orr r0,r0,xp1,lsl #23 /* set exponent */
bic mant1,mant1,#1<<23 /* clear hi-order */
orr r0,r0,mant1 /* full result */
fp_add_exit:
ldmfd r13!,{r2-r5,pc}
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