109 lines
2.9 KiB
C
109 lines
2.9 KiB
C
/*
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checksum rom in psram, based on
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chksum64 V1.2, a program to calculate the ROM checksum of Nintendo64 ROMs.
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Copyright (C) 1997 Andreas Sterbenz (stan@sbox.tu-graz.ac.at)
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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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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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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 Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#include <libdragon.h>
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#include "sys.h"
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#include "chksum64.h"
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#define BUFSIZE 0x8000
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#define SDRAM_START 0xb0000000
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#define CHECKSUM_START 0x1000
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#define CHECKSUM_LENGTH 0x100000L
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#define CHECKSUM_HEADERPOS 0x10
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#define CHECKSUM_END (CHECKSUM_START + CHECKSUM_LENGTH)
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#define CHECKSUM_STARTVALUE 0xf8ca4ddc
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#define ROL(i, b) (((i)<<(b)) | ((i)>>(32-(b))))
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#define BYTES2LONG(b) ( (((b)[0] & 0xffL) << 24) | \
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(((b)[1] & 0xffL) << 16) | \
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(((b)[2] & 0xffL) << 8) | \
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(((b)[3] & 0xffL)) )
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#define LONG2BYTES(l, b) (b)[0] = ((l)>>24)&0xff; \
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(b)[1] = ((l)>>16)&0xff; \
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(b)[2] = ((l)>> 8)&0xff; \
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(b)[3] = ((l) )&0xff;
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static unsigned char __attribute__((aligned(16))) buffer1[BUFSIZE];
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void checksum_sdram(void)
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{
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unsigned int sum1, sum2, offs;
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{
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unsigned int i;
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unsigned int c1, k1, k2;
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unsigned int t1, t2, t3, t4;
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unsigned int t5, t6;
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unsigned int n;
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unsigned int clen = CHECKSUM_LENGTH;
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t1 = CHECKSUM_STARTVALUE;
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t2 = CHECKSUM_STARTVALUE;
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t3 = CHECKSUM_STARTVALUE;
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t4 = CHECKSUM_STARTVALUE;
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t5 = CHECKSUM_STARTVALUE;
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t6 = CHECKSUM_STARTVALUE;
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offs = CHECKSUM_START;
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for( ;; ) {
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n = (BUFSIZE < clen) ? BUFSIZE : clen;
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dma_read_s(buffer1, SDRAM_START+offs, n);
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data_cache_hit_writeback_invalidate(buffer1,n);
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offs += n;
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for( i=0; i<n; i+=4 ) {
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c1 = BYTES2LONG(&buffer1[i]);
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k1 = t6 + c1;
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if( k1 < t6 ) t4++;
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t6 = k1;
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t3 ^= c1;
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k2 = c1 & 0x1f;
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k1 = ROL(c1, k2);
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t5 += k1;
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if( c1 < t2 ) {
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t2 ^= k1;
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} else {
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t2 ^= t6 ^ c1;
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}
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t1 += c1 ^ t5;
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}
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clen -= n;
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if (!clen) break;
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}
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sum1 = t6 ^ t4 ^ t3;
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sum2 = t5 ^ t2 ^ t1;
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}
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LONG2BYTES(sum1, &buffer1[0]);
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LONG2BYTES(sum2, &buffer1[4]);
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dma_write_s(buffer1, SDRAM_START+CHECKSUM_HEADERPOS, 8);
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return;
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}
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