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Corrected CRC16 calculation.

This commit is contained in:
masscat 2007-05-23 11:44:10 +00:00
parent 1bba9c9573
commit 29f5eac6e8
1 changed files with 20 additions and 8 deletions
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28
desmume/src/bios.c
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@ -22,6 +22,7 @@
#include "cp15.h"
#include <math.h>
#include "MMU.h"
#include "SPU.h"
#include "debug.h"
extern BOOL execute;
@ -878,7 +879,7 @@ u32 Diff8bitUnFilterWram(armcpu_t* cpu)
source += 4;
if(((source & 0xe000000) == 0) ||
((source + ((header >> 8) & 0x1fffff) & 0xe000000) == 0))
(( (source + ((header >> 8) & 0x1fffff)) & 0xe000000) == 0))
return 0;
len = header >> 8;
@ -963,18 +964,29 @@ u32 getVolumeTab(armcpu_t* cpu)
u32 getCRC16(armcpu_t* cpu)
{
int i,j;
u32 crc;
unsigned int i,j;
u16 start = cpu->R[0];
u16 datap = cpu->R[1];
u32 crc = cpu->R[0];
u32 datap = cpu->R[1];
u32 size = cpu->R[2];
static u16 val[] = { 0xC0C1,0xC181,0xC301,0xC601,0xCC01,0xD801,0xF001,0xA001 };
for(i=datap; i<(datap+size); i++)
for(i = 0; i < size; i++)
{
crc=crc ^ MMU_readHWord(cpu->proc_ID,datap+i);
for(j=0; j<7; j++) crc=crc >> 1; if(crc) crc=crc ^ (val[j] << (7-j));
crc = crc ^ MMU_readByte( cpu->proc_ID, datap + i);
for(j = 0; j < 8; j++) {
int do_bit = 0;
if ( crc & 0x1)
do_bit = 1;
crc = crc >> 1;
if ( do_bit) {
crc = crc ^ (val[j] << (7-j));
}
}
}
cpu->R[0] = crc;
return 1;