Grass Valley RSAT1 - Manual (Page 30)

Satellite Panel RSAT1 6. Annex
Operating Instructions - Rev. 3 / 7.2002 25
The lf character is optional.
unsigned char chksum, chk;
int i;
chksum = toascii(length) + type;
for ( i = 0; i < (length – 2 ); i++)
{
chksum += data[i];
}
chk = chksum & 0x3F;
The function char() simply adds a space (0x20) to the number.
The function toascii() converts the number into the ascii character. The datagram
length is therefore restricted to 9 bytes. The new text (t) command makes it neces-
sary to change the toascii() function. Allowed characters for the Length field are
now ’0’ .. ’9’ plus ’:’ .. ’~’ where a Lenght of ’:’ means 10 bytes and so on until ’~’
which means 78 bytes.
unsigned char toascii(size_t count)
{
unsigned char retval = ’0’;
if ( count <= (size_t) (’~’ – ’0’) )
{
retval += (unsigned char) count);
}
else
{
// error
}
return retval;
}