/*
* Returns number of bytes to be dropped, 0 if packet is okay.
*/
static int
vsxxxaa_check_packet (struct vsxxxaa *mouse, int packet_len)
{
int i;
/* First byte must be a header byte */
if (!IS_HDR_BYTE (mouse->buf[0])) {
DBG ("vsck: len=%d, 1st=0x%02x\n", packet_len, mouse->buf[0]);
return 1;
}
/* Check all following bytes */
if (packet_len > 1) {
for (i = 1; i < packet_len; i++) {
if (IS_HDR_BYTE (mouse->buf[i])) {
printk (KERN_ERR "Need to drop %d bytes "
"of a broken packet.\n",
i - 1);
DBG (KERN_INFO "check: len=%d, b[%d]=0x%02x\n",
packet_len, i, mouse->buf[i]);
return i - 1;
}
}
}
return 0;
}
static void vsxxxaa_parse_buffer(struct vsxxxaa *mouse)
{
unsigned char *buf = mouse->buf;
int stray_bytes;
/*
* Parse buffer to death...
*/
do {
/*
* Out of sync? Throw away what we don't understand. Each
* packet starts with a byte whose bit 7 is set. Unhandled
* packets (ie. which we don't know about or simply b0rk3d
* data...) will get shifted out of the buffer after some
* activity on the mouse.
*/
while (mouse->count > 0 && !IS_HDR_BYTE(buf[0])) {
printk(KERN_ERR "%s on %s: Dropping a byte to regain "
"sync with mouse data stream...\n",
mouse->name, mouse->phys);
vsxxxaa_drop_bytes(mouse, 1);
}
/*
* Check for packets we know about.
*/
if (vsxxxaa_smells_like_packet(mouse, VSXXXAA_PACKET_REL, 3)) {
/* Check for broken packet */
stray_bytes = vsxxxaa_check_packet(mouse, 3);
if (!stray_bytes)
vsxxxaa_handle_REL_packet(mouse);
} else if (vsxxxaa_smells_like_packet(mouse,
VSXXXAA_PACKET_ABS, 5)) {
/* Check for broken packet */
stray_bytes = vsxxxaa_check_packet(mouse, 5);
if (!stray_bytes)
vsxxxaa_handle_ABS_packet(mouse);
} else if (vsxxxaa_smells_like_packet(mouse,
VSXXXAA_PACKET_POR, 4)) {
/* Check for broken packet */
stray_bytes = vsxxxaa_check_packet(mouse, 4);
if (!stray_bytes)
vsxxxaa_handle_POR_packet(mouse);
} else {
break; /* No REL, ABS or POR packet found */
}
if (stray_bytes > 0) {
printk(KERN_ERR "Dropping %d bytes now...\n",
stray_bytes);
vsxxxaa_drop_bytes(mouse, stray_bytes);
}
} while (1);
}
