Mattis Lind wrote:
>
> > > I have two actual messages from equipment employing IBM BSC:
> > > 32016CD90240404070032688
> > > and
> > > 32016CD90240C84050030D28
>�> >
>
How about this code:
#include <stdio.h>
int crc16(unsigned char *ptr, int count)
{
unsigned int crc;
char i;
crc = 0x0000;
while (--count >= 0)
{
crc = crc ^ (unsigned int) *ptr++;
i = 8;
do
{
if (crc & 0x0001)
crc = (crc >> 1) ^ 0xA001; /* 0x8005 bit reversed */
else
crc = (crc >> 1);
} while(--i);
}
return (crc);
}
void main()
{
/* 32 01 6C D9 02 40 40 40 70 03 26 88 */
unsigned char data1[] = {0x6c, 0xd9, 0x02, 0x40, 0x40, 0x40, 0x50, 0x03};
/* 32 01 6C D9 02 40 C8 40 50 03 0D 28 */
unsigned char data2[] = {0x6c, 0xd9, 0x02, 0x40, 0xc8, 0x40, 0x50, 0x03};
printf("crc sent: 8826 computed: %4.4x\n", crc16(data1, sizeof(data1)));
printf("crc sent: 280d computed: %4.4x\n", crc16(data2, sizeof(data2)));
return;
}
Please note that I had to cheat to get this to work. It worked initially
for the second case but it only worked for the first case when I tweaked
70 to 50, ie I substituted the corresponding value from the second case.
Regards,
Peter Coghlan.
