/* Returns 0 if everything is right, -1 if an error occured while sending */
static ssize_t brl_writePacket(BrailleDisplay *brl, const void *packet, size_t size)
{
const unsigned char *p = packet;
int lgtho = 1;
unsigned char obuf[MAXPACKETSIZE];
const unsigned char *x;
unsigned char *y = obuf;
unsigned char chksum=0;
int i,res;
*y++ = 02;
for (x=p; (x-p) < size; x++) {
chksum ^= *x;
if ((*x) <= 5) {
*y = 01;
y++; lgtho++;
*y = ( *x ) | 0x40;
} else *y = *x;
y++; lgtho++;
}
if (chksum<=5) {
*y = 1; y++; lgtho++;
chksum |= 0x40;
}
*y = chksum; y++; lgtho++;
*y = 3; y++; lgtho++;
for (i=1; i<=5; i++) {
if (serialWriteData(serialDevice,obuf,lgtho) != lgtho) continue; /* write failed, retry */
serialAwaitOutput(serialDevice);
serialAwaitInput(serialDevice, 1000);
res = serialReadData(serialDevice,&chksum,1,0,0);
if ((res==1) && (chksum == 0x04)) return 0;
}
return (-1);
}
static int
serialWriteAttributes (SerialDevice *serial, const SerialAttributes *attributes) {
if (!serialCompareAttributes(attributes, &serial->currentAttributes)) {
if (!serialAwaitOutput(serial)) return 0;
if (!serialPutAttributes(serial, attributes)) return 0;
serialCopyAttributes(&serial->currentAttributes, attributes);
}
return 1;
}