103 lines
4.0 KiB
ArmAsm
103 lines
4.0 KiB
ArmAsm
/* $NetBSD: fpediv.S,v 1.1 1996/01/31 23:21:14 mark Exp $ */
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/*
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* Copyright (c) 1995 Mark Brinicombe.
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* Copyright (c) 1995 Neil Carson.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the RiscBSD kernel team.
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* 4. The name of the company nor the name of the author may be used to
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* endorse or promote products derived from this software without specific
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* prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* RiscBSD kernel project
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*
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* fpediv.S
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*
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* FP divide
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*
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* Created : 11/02/95
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* Last updated : 28/08/95
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*
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* $Id: fpediv.S,v 1.1 1996/01/31 23:21:14 mark Exp $
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*/
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.global _nc_fp_div
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pc .req r15
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mant1 .req r2
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xp1 .req r3
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mant2 .req r4
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xp2 .req r14
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q .req r1
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p .req r14
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_nc_fp_div:
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stmfd r13!,{r2-r4,r14}
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/* check for null result */
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cmp r0,#0
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cmpne r1,#0
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moveq r0,#0
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beq fp_div_exit
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mov xp1,r0,lsr #23 /* get exponent+sign */
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bic mant1,r0,xp1,lsl #23 /* get mantissa */
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orr mant1,mant1,#1<<23 /* set on bit to left of point */
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and xp1,xp1,#255 /* remove sign */
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mov xp2,r1,lsr #23 /* get exponent+sign */
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bic mant2,r1,xp2,lsl #23 /* get mantissa */
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orr mant2,mant2,#1<<23 /* set on bit to left of point */
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and xp2,xp2,#255 /* remove sign */
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sub xp1,xp1,xp2
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adds xp1,xp1,#127 /* exponent result */
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movmi r0,#0 /* underflow */
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bmi fp_div_exit
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eor r0,r0,r1 /* sign of result */
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and r0,r0,#1<<31 /* clear rest of result */
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/* do the divide to full precision */
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mov q,#0 /* quotient */
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mov p,#1<<23 /* number binary places to do */
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fp_divloop: /* do binary places */
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cmp mant1,mant2 /* number>divisor? */
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orrcs q,q,p /* yes - set bit in binary place */
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subcs mant1,mant1,mant2 /* discard accounted value */
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movs mant1,mant1,lsl #1 /* shift up remainder, if any */
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movnes p,p,lsr#1 /* next binary place, if remainder */
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bne fp_divloop /* next place if any */
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cmp q,#1<<23 /* normalise? */
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sublt xp1,xp1,#1 /* yes, adjust exponent */
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movlt q,q,lsl #1 /* & mantissa */
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/* combine result */
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orr r0,r0,xp1,lsl #23 /* set exponent */
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bic q,q,#1<<23 /* clear hi-order */
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orr r0,r0,q /* result */
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fp_div_exit:
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ldmfd r13!,{r2-r4,pc}
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