divremu.S
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;; Copyright 2011 Free Software Foundation, Inc.
;; Contributed by Bernd Schmidt <bernds@codesourcery.com>.
;;
;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2 of the License, or
;; (at your option) any later version.
;;
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with this program; if not, write to the Free Software
;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#include <linux/linkage.h>
.text
ENTRY(__c6xabi_divremu)
;; We use a series of up to 31 subc instructions. First, we find
;; out how many leading zero bits there are in the divisor. This
;; gives us both a shift count for aligning (shifting) the divisor
;; to the, and the number of times we have to execute subc.
;; At the end, we have both the remainder and most of the quotient
;; in A4. The top bit of the quotient is computed first and is
;; placed in A2.
;; Return immediately if the dividend is zero. Setting B4 to 1
;; is a trick to allow us to leave the following insns in the jump
;; delay slot without affecting the result.
mv .s2x A4, B1
[b1] lmbd .l2 1, B4, B1
||[!b1] b .s2 B3 ; RETURN A
||[!b1] mvk .d2 1, B4
||[!b1] zero .s1 A5
mv .l1x B1, A6
|| shl .s2 B4, B1, B4
;; The loop performs a maximum of 28 steps, so we do the
;; first 3 here.
cmpltu .l1x A4, B4, A2
[!A2] sub .l1x A4, B4, A4
|| shru .s2 B4, 1, B4
|| xor .s1 1, A2, A2
shl .s1 A2, 31, A2
|| [b1] subc .l1x A4,B4,A4
|| [b1] add .s2 -1, B1, B1
[b1] subc .l1x A4,B4,A4
|| [b1] add .s2 -1, B1, B1
;; RETURN A may happen here (note: must happen before the next branch)
__divremu0:
cmpgt .l2 B1, 7, B0
|| [b1] subc .l1x A4,B4,A4
|| [b1] add .s2 -1, B1, B1
[b1] subc .l1x A4,B4,A4
|| [b1] add .s2 -1, B1, B1
|| [b0] b .s1 __divremu0
[b1] subc .l1x A4,B4,A4
|| [b1] add .s2 -1, B1, B1
[b1] subc .l1x A4,B4,A4
|| [b1] add .s2 -1, B1, B1
[b1] subc .l1x A4,B4,A4
|| [b1] add .s2 -1, B1, B1
[b1] subc .l1x A4,B4,A4
|| [b1] add .s2 -1, B1, B1
[b1] subc .l1x A4,B4,A4
|| [b1] add .s2 -1, B1, B1
;; loop backwards branch happens here
ret .s2 B3
|| mvk .s1 32, A1
sub .l1 A1, A6, A6
|| extu .s1 A4, A6, A5
shl .s1 A4, A6, A4
shru .s1 A4, 1, A4
|| sub .l1 A6, 1, A6
or .l1 A2, A4, A4
shru .s1 A4, A6, A4
nop
ENDPROC(__c6xabi_divremu)