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/* $OpenBSD: __divqu.S,v 1.1 2007/11/25 18:25:34 deraadt Exp $ */
/* $NetBSD: divrem.m4,v 1.5 1996/10/17 04:26:25 cgd Exp $ */
/*
* Copyright (c) 1994, 1995 Carnegie-Mellon University.
* All rights reserved.
*
* Author: Chris G. Demetriou
*
* Permission to use, copy, modify and distribute this software and
* its documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*/
/*
* Division and remainder.
*
* The use of m4 is modeled after the sparc code, but the algorithm is
* simple binary long division.
*
* Note that the loops could probably benefit from unrolling.
*/
/*
* M4 Parameters
* __divqu name of function to generate
* div div=div: t10 / t11 -> t12; div=rem: t10 % t11 -> t12
* false false=true: signed; false=false: unsigned
* 64 total number of bits
*/
#include <machine/asm.h>
LEAF(__divqu, 0) /* XXX */
lda sp, -64(sp)
stq t0, 0(sp)
stq t1, 8(sp)
stq t2, 16(sp)
stq t3, 24(sp)
stq t10, 40(sp)
stq t11, 48(sp)
mov zero, t12 /* Initialize result to zero */
/* kill the special cases. */
beq t11, Ldotrap /* division by zero! */
cmpult t10, t11, t2 /* t10 < t11? */
/* t12 is already zero, from above. t10 is untouched. */
bne t2, Lret_result
cmpeq t10, t11, t2 /* t10 == t11? */
cmovne t2, 1, t12
cmovne t2, zero, t10
bne t2, Lret_result
/*
* Find out how many bits of zeros are at the beginning of the divisor.
*/
LBbits:
ldiq t3, 1 /* t1 = 0; t0 = 1<<64-1 */
mov zero, t1
sll t3, 64-1, t0
LBloop:
and t11, t0, t2 /* if bit in t11 is set, done. */
bne t2, LAbits
addq t1, 1, t1 /* increment t1, bit */
srl t0, 1, t0
cmplt t1, 64-1, t2 /* if t1 leaves one bit, done. */
bne t2, LBloop
LAbits:
beq t1, Ldodiv /* If t1 = 0, divide now. */
ldiq t3, 1 /* t0 = 1<<64-1 */
sll t3, 64-1, t0
LAloop:
and t10, t0, t2 /* if bit in t10 is set, done. */
bne t2, Ldodiv
subq t1, 1, t1 /* decrement t1, bit */
srl t0, 1, t0
bne t1, LAloop /* If t1 != 0, loop again */
Ldodiv:
sll t11, t1, t11 /* t11 <<= i */
ldiq t3, 1
sll t3, t1, t0
Ldivloop:
cmpult t10, t11, t2
or t12, t0, t3
cmoveq t2, t3, t12
subq t10, t11, t3
cmoveq t2, t3, t10
srl t0, 1, t0
srl t11, 1, t11
beq t10, Lret_result
bne t0, Ldivloop
Lret_result:
ldq t0, 0(sp)
ldq t1, 8(sp)
ldq t2, 16(sp)
ldq t3, 24(sp)
ldq t10, 40(sp)
ldq t11, 48(sp)
lda sp, 64(sp)
ret zero, (t9), 1
Ldotrap:
ldiq a0, -2 /* This is the signal to SIGFPE! */
call_pal PAL_gentrap
br zero, Lret_result
END(__divqu)
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