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