diff options
Diffstat (limited to 'contrib/loaders/checksum/armv7m_crc.s')
| -rw-r--r-- | contrib/loaders/checksum/armv7m_crc.s | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/contrib/loaders/checksum/armv7m_crc.s b/contrib/loaders/checksum/armv7m_crc.s new file mode 100644 index 00000000..e50db0a7 --- /dev/null +++ b/contrib/loaders/checksum/armv7m_crc.s @@ -0,0 +1,66 @@ +/*************************************************************************** + * 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-m3 + .thumb + .thumb_func + + .align 2 + +_start: +main: + mov r2, r0 + mov r0, #0xffffffff /* crc */ + mov r3, r1 + mov r4, #0 + b ncomp +nbyte: + ldrb r1, [r2, r4] + + ldr r7, CRC32XOR + eor r0, r0, r1, asl #24 + mov r5, #0 +loop: + cmp r0, #0 + mov r6, r0, asl #1 + add r5, r5, #1 + mov r0, r6 + it lt + eorlt r0, r6, r7 + cmp r5, #8 + bne loop + + add r4, r4, #1 +ncomp: + cmp r4, r3 + bne nbyte + bkpt #0 + +CRC32XOR: .word 0x04c11db7 + + .end |