73 lines
2.3 KiB
ArmAsm
73 lines
2.3 KiB
ArmAsm
/***************************************************************************
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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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* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
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***************************************************************************/
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.global main
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.text
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.set noreorder
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/* params:
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* $a0 address in
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* $a1 byte count
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* vars
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* $a0 crc
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* $a1 crc data byte
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* temps:
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* t3 v0 a3 a2 t0 v1
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*/
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.ent main
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main:
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addiu $t4, $a0, 0 /* address in */
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addiu $t2, $a1, 0 /* count */
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addiu $a0, $zero, 0xffffffff /* a0 crc - result */
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beq $zero, $zero, ncomp
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addiu $t3, $zero, 0 /* clear bytes read */
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nbyte:
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lb $a1, ($t4) /* load byte from source address */
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addi $t4, $t4, 1 /* inc byte count */
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crc:
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sll $a1, $a1, 24
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lui $v0, 0x04c1
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xor $a0, $a0, $a1
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ori $a3, $v0, 0x1db7
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addu $a2, $zero, $zero /* clear bit count */
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loop:
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sll $t0, $a0, 1
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addiu $a2, $a2, 1 /* inc bit count */
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slti $a0, $a0, 0
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xor $t1, $t0, $a3
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movn $t0, $t1, $a0
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slti $v1, $a2, 8 /* 8bits processed */
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bne $v1, $zero, loop
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addu $a0, $t0, $zero
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ncomp:
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bne $t2, $t3, nbyte /* all bytes processed */
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addiu $t3, $t3, 1
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wait:
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sdbbp
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.end main
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