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/***************************************************************************
* Copyright (C) 2010 by Spencer Oliver *
* spen@spen-soft.co.uk *
* *
* 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. *
***************************************************************************/
/*
parameters:
r0 - address in - crc out
r1 - char count
*/
.text
.syntax unified
.cpu cortex-m0
.thumb
.thumb_func
.align 2
_start:
main:
mov r2, r0
movs r0, #0
mvns r0, r0
ldr r6, CRC32XOR
mov r3, r1
movs r4, #0
b ncomp
nbyte:
ldrb r1, [r2, r4]
lsls r1, r1, #24
eors r0, r0, r1
movs r5, #0
loop:
cmp r0, #0
bge notset
lsls r0, r0, #1
eors r0, r0, r6
b cont
notset:
lsls r0, r0, #1
cont:
adds r5, r5, #1
cmp r5, #8
bne loop
adds r4, r4, #1
ncomp:
cmp r4, r3
bne nbyte
bkpt #0
.align 2
CRC32XOR: .word 0x04c11db7
.end
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