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/* $NetBSD: fpemul.S,v 1.2 1996/03/18 19:58:16 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
*
* fpemul.S
*
* FP multiply
*
* Created : 11/02/95
*/
.global _nc_fp_mul
pc .req r15
mant1 .req r2
xp1 .req r3
mant2 .req r1
xp2 .req r4
wrk1 .req r14
reshigh .req r4
_nc_fp_mul:
stmfd r13!,{r2-r4,r14}
/* check for null result - bloody lucky but you never know... */
cmp r0,#0
cmpne r1,#0
moveq r0,#0
beq fp_mul_exit
mov xp1,r0,lsr #23 /* get exponent+sign */
bic mant1,r0,xp1,lsl #23 /* get mantissa */
orr mant1,mant1,#1<<23 /* set on bit to left of point */
and xp1,xp1,#255 /* remove sign */
eor r0,r0,r1 /* sign of result */
and r0,r0,#1<<31 /* clear rest of result */
mov xp2,r1,lsr #23 /* get exponent+sign */
bic mant2,r1,xp2,lsl #23 /* get mantissa */
orr mant2,mant2,#1<<23 /* set on bit to left of point */
and xp2,xp2,#255 /* remove sign */
add xp1,xp1,xp2
subs xp1,xp1,#127 /* exponent result */
movmi r0,#0 /* underflow */
bmi fp_mul_exit
/* do the multiply to 30 bits precision */
mov wrk1,mant1,lsr#9 /* top 15 bits */
mov reshigh,mant2,lsr#9 /* top 15 bits */
bic mant1,mant1,wrk1,lsl#9 /* low 9 bits */
bic mant2,mant2,reshigh,lsl#9 /* low 9 bits */
mul mant2,wrk1,mant2 /* top*low */
mul mant1,reshigh,mant1 /* low*top */
mul reshigh,wrk1,reshigh /* top*top */
add reshigh,reshigh,mant1,lsr#9 /* top + middle bit1 */
add reshigh,reshigh,mant2,lsr#9 /* top + middle bit2 */
/* adjust for carry */
tst reshigh,#1<<29
addne xp1,xp1,#1 /* adjust exponent */
movne reshigh,reshigh,lsr#1 /* shift result right */
/* combine result */
orr r0,r0,xp1,lsl #23 /* set exponent */
bic reshigh,reshigh,#1<<28 /* clear hi-order */
orr r0,r0,reshigh,lsr #5 /* top 23 bits */
fp_mul_exit:
ldmfd r13!,{r2-r4,pc}
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