static size_t
readPacket (BrailleDisplay *brl, InputPacket *packet) {
const size_t length = 10;
size_t offset = 0;
while (1) {
unsigned char byte;
{
int started = offset > 0;
if (!gioReadByte(brl->gioEndpoint, &byte, started)) {
if (started) logPartialPacket(packet->bytes, offset);
return 0;
}
}
if (!offset) {
if (byte != 0XFA) {
logIgnoredByte(byte);
continue;
}
}
packet->bytes[offset++] = byte;
if (offset == length) {
if (byte == 0XFB) {
{
int checksum = -packet->data.checksum;
{
size_t i;
for (i=0; i<offset; i+=1) checksum += packet->bytes[i];
}
if ((checksum & 0XFF) != packet->data.checksum) {
logInputProblem("Incorrect Input Checksum", packet->bytes, offset);
}
}
logInputPacket(packet->bytes, offset);
return length;
}
{
const unsigned char *start = memchr(packet->bytes+1, packet->bytes[0], offset-1);
const unsigned char *end = packet->bytes + offset;
if (!start) start = end;
logDiscardedBytes(packet->bytes, start-packet->bytes);
memmove(packet->bytes, start, (offset = end - start));
}
}
}
}
static BraillePacketVerifierResult
verifyPacket (
BrailleDisplay *brl,
const unsigned char *bytes, size_t size,
size_t *length, void *data
) {
unsigned char byte = bytes[size-1];
switch (size) {
case 1: {
switch (byte) {
case 0XFA:
*length = 10;
break;
default:
return BRL_PVR_INVALID;
}
break;
}
default:
break;
}
if (size == *length) {
switch (bytes[0]) {
case 0XFA: {
if (byte != 0XFB) return BRL_PVR_INVALID;
const InputPacket *packet = (const void *)bytes;
int checksum = -packet->fields.checksum;
for (size_t i=0; i<size; i+=1) checksum += packet->bytes[i];
if ((checksum & 0XFF) != packet->fields.checksum) {
logInputProblem("incorrect input checksum", packet->bytes, size);
return BRL_PVR_INVALID;
}
break;
}
default:
break;
}
}
return BRL_PVR_INCLUDE;
}
void
logDiscardedBytes (const unsigned char *bytes, size_t count) {
logInputProblem("Discarded Bytes", bytes, count);
}
void
logCorruptPacket (const void *packet, size_t size) {
logInputProblem("Corrupt Packet", packet, size);
}
void
logUnexpectedPacket (const void *packet, size_t size) {
logInputProblem("Unexpected Packet", packet, size);
}
void
logShortPacket (const void *packet, size_t size) {
logInputProblem("Short Packet", packet, size);
}
void
logTruncatedPacket (const void *packet, size_t size) {
logInputProblem("Truncated Packet", packet, size);
}
void
logPartialPacket (const void *packet, size_t size) {
logInputProblem("Partial Packet", packet, size);
}
void
logUnknownPacket (unsigned char byte) {
logInputProblem("Unknown Packet", &byte, 1);
}
void
logDiscardedByte (unsigned char byte) {
logInputProblem("Discarded Byte", &byte, 1);
}
void
logIgnoredByte (unsigned char byte) {
logInputProblem("Ignored Byte", &byte, 1);
}
