2010-10-28 08:19:37 +00:00
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/***************************************************************************
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* Copyright (C) 2010 by Spencer Oliver *
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* spen@spen-soft.co.uk *
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License for more details. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program; if not, write to the *
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* Free Software Foundation, Inc., *
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2013-06-02 19:32:36 +00:00
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. *
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2010-10-28 08:19:37 +00:00
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***************************************************************************/
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/*
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parameters:
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r0 - address in - crc out
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r1 - char count
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*/
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.text
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.syntax unified
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2012-05-01 08:46:07 +00:00
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.cpu cortex-m0
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2010-10-28 08:19:37 +00:00
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.thumb
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.thumb_func
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2012-05-01 08:46:07 +00:00
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2010-10-28 08:19:37 +00:00
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.align 2
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_start:
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2012-05-01 08:46:07 +00:00
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main:
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2010-10-28 08:19:37 +00:00
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mov r2, r0
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2012-05-01 08:46:07 +00:00
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movs r0, #0
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mvns r0, r0
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ldr r6, CRC32XOR
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2010-10-28 08:19:37 +00:00
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mov r3, r1
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2012-05-01 08:46:07 +00:00
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movs r4, #0
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2010-10-28 08:19:37 +00:00
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b ncomp
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nbyte:
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ldrb r1, [r2, r4]
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2012-05-01 08:46:07 +00:00
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lsls r1, r1, #24
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eors r0, r0, r1
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movs r5, #0
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2010-10-28 08:19:37 +00:00
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loop:
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cmp r0, #0
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2012-05-01 08:46:07 +00:00
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bge notset
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lsls r0, r0, #1
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eors r0, r0, r6
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b cont
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notset:
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lsls r0, r0, #1
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cont:
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adds r5, r5, #1
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2010-10-28 08:19:37 +00:00
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cmp r5, #8
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bne loop
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2012-05-01 08:46:07 +00:00
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adds r4, r4, #1
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2010-10-28 08:19:37 +00:00
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ncomp:
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cmp r4, r3
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bne nbyte
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bkpt #0
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2012-05-01 08:46:07 +00:00
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.align 2
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2010-10-28 08:19:37 +00:00
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CRC32XOR: .word 0x04c11db7
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.end
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