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/* 32 and 64-bit millicode, original author Hewlett-Packard
adapted for gcc by Paul Bame <bame@debian.org>
and Alan Modra <alan@linuxcare.com.au>.
Copyright 2001, 2002, 2003 Free Software Foundation, Inc.
This file is part of GCC and is released under the terms of
of the GNU General Public License as published by the Free Software
Foundation; either version 2, or (at your option) any later version.
See the file COPYING in the top-level GCC source directory for a copy
of the license. */
#include "milli.h"
#ifdef L_divU
/* ROUTINE: $$divU
.
. Single precision divide for unsigned integers.
.
. Quotient is truncated towards zero.
. Traps on divide by zero.
INPUT REGISTERS:
. arg0 == dividend
. arg1 == divisor
. mrp == return pc
. sr0 == return space when called externally
OUTPUT REGISTERS:
. arg0 = undefined
. arg1 = undefined
. ret1 = quotient
OTHER REGISTERS AFFECTED:
. r1 = undefined
SIDE EFFECTS:
. Causes a trap under the following conditions:
. divisor is zero
. Changes memory at the following places:
. NONE
PERMISSIBLE CONTEXT:
. Unwindable.
. Does not create a stack frame.
. Suitable for internal or external millicode.
. Assumes the special millicode register conventions.
DISCUSSION:
. Branchs to other millicode routines using BE:
. $$divU_# for 3,5,6,7,9,10,12,14,15
.
. For selected small divisors calls the special divide by constant
. routines written by Karl Pettis. These are: 3,5,6,7,9,10,12,14,15. */
RDEFINE(temp,r1)
RDEFINE(retreg,ret1) /* r29 */
RDEFINE(temp1,arg0)
SUBSPA_MILLI_DIV
ATTR_MILLI
.export $$divU,millicode
.import $$divU_3,millicode
.import $$divU_5,millicode
.import $$divU_6,millicode
.import $$divU_7,millicode
.import $$divU_9,millicode
.import $$divU_10,millicode
.import $$divU_12,millicode
.import $$divU_14,millicode
.import $$divU_15,millicode
.proc
.callinfo millicode
.entry
GSYM($$divU)
/* The subtract is not nullified since it does no harm and can be used
by the two cases that branch back to "normal". */
ldo -1(arg1),temp /* is there at most one bit set ? */
and,= arg1,temp,r0 /* if so, denominator is power of 2 */
b LREF(regular_seq)
addit,= 0,arg1,0 /* trap for zero dvr */
copy arg0,retreg
extru,= arg1,15,16,temp /* test denominator with 0xffff0000 */
extru retreg,15,16,retreg /* retreg = retreg >> 16 */
or arg1,temp,arg1 /* arg1 = arg1 | (arg1 >> 16) */
ldi 0xcc,temp1 /* setup 0xcc in temp1 */
extru,= arg1,23,8,temp /* test denominator with 0xff00 */
extru retreg,23,24,retreg /* retreg = retreg >> 8 */
or arg1,temp,arg1 /* arg1 = arg1 | (arg1 >> 8) */
ldi 0xaa,temp /* setup 0xaa in temp */
extru,= arg1,27,4,r0 /* test denominator with 0xf0 */
extru retreg,27,28,retreg /* retreg = retreg >> 4 */
and,= arg1,temp1,r0 /* test denominator with 0xcc */
extru retreg,29,30,retreg /* retreg = retreg >> 2 */
and,= arg1,temp,r0 /* test denominator with 0xaa */
extru retreg,30,31,retreg /* retreg = retreg >> 1 */
MILLIRETN
nop
LSYM(regular_seq)
comib,>= 15,arg1,LREF(special_divisor)
subi 0,arg1,temp /* clear carry, negate the divisor */
ds r0,temp,r0 /* set V-bit to 1 */
LSYM(normal)
add arg0,arg0,retreg /* shift msb bit into carry */
ds r0,arg1,temp /* 1st divide step, if no carry */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 2nd divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 3rd divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 4th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 5th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 6th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 7th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 8th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 9th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 10th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 11th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 12th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 13th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 14th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 15th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 16th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 17th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 18th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 19th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 20th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 21st divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 22nd divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 23rd divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 24th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 25th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 26th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 27th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 28th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 29th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 30th divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 31st divide step */
addc retreg,retreg,retreg /* shift retreg with/into carry */
ds temp,arg1,temp /* 32nd divide step, */
MILLIRET
addc retreg,retreg,retreg /* shift last retreg bit into retreg */
/* Handle the cases where divisor is a small constant or has high bit on. */
LSYM(special_divisor)
/* blr arg1,r0 */
/* comib,>,n 0,arg1,LREF(big_divisor) ; nullify previous instruction */
/* Pratap 8/13/90. The 815 Stirling chip set has a bug that prevents us from
generating such a blr, comib sequence. A problem in nullification. So I
rewrote this code. */
#if defined(CONFIG_64BIT)
/* Clear the upper 32 bits of the arg1 register. We are working with
small divisors (and 32-bit unsigned integers) We must not be mislead
by "1" bits left in the upper 32 bits. */
depd %r0,31,32,%r25
#endif
comib,> 0,arg1,LREF(big_divisor)
nop
blr arg1,r0
nop
LSYM(zero_divisor) /* this label is here to provide external visibility */
addit,= 0,arg1,0 /* trap for zero dvr */
nop
MILLIRET /* divisor == 1 */
copy arg0,retreg
MILLIRET /* divisor == 2 */
extru arg0,30,31,retreg
MILLI_BEN($$divU_3) /* divisor == 3 */
nop
MILLIRET /* divisor == 4 */
extru arg0,29,30,retreg
MILLI_BEN($$divU_5) /* divisor == 5 */
nop
MILLI_BEN($$divU_6) /* divisor == 6 */
nop
MILLI_BEN($$divU_7) /* divisor == 7 */
nop
MILLIRET /* divisor == 8 */
extru arg0,28,29,retreg
MILLI_BEN($$divU_9) /* divisor == 9 */
nop
MILLI_BEN($$divU_10) /* divisor == 10 */
nop
b LREF(normal) /* divisor == 11 */
ds r0,temp,r0 /* set V-bit to 1 */
MILLI_BEN($$divU_12) /* divisor == 12 */
nop
b LREF(normal) /* divisor == 13 */
ds r0,temp,r0 /* set V-bit to 1 */
MILLI_BEN($$divU_14) /* divisor == 14 */
nop
MILLI_BEN($$divU_15) /* divisor == 15 */
nop
/* Handle the case where the high bit is on in the divisor.
Compute: if( dividend>=divisor) quotient=1; else quotient=0;
Note: dividend>==divisor iff dividend-divisor does not borrow
and not borrow iff carry. */
LSYM(big_divisor)
sub arg0,arg1,r0
MILLIRET
addc r0,r0,retreg
.exit
.procend
.end
#endif
|
