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 int
readPacket (BrailleDisplay *brl, Packet *packet) {
while (1) {
int size = sizeof(PacketHeader);
int hasPayload = 0;
if (brl->data->inputCount >= sizeof(PacketHeader)) {
if (brl->data->inputBuffer.packet.header.type & 0X80) {
hasPayload = 1;
size += brl->data->inputBuffer.packet.header.arg1 + 1;
}
}
if (size <= brl->data->inputCount) {
logInputPacket(brl->data->inputBuffer.bytes, size);
if (hasPayload) {
unsigned char checksum = 0;
int index;
for (index=0; index<size; index+=1)
checksum -= brl->data->inputBuffer.bytes[index];
if (checksum) logMessage(LOG_WARNING, "Input packet checksum error.");
}
memcpy(packet, &brl->data->inputBuffer, size);
memmove(&brl->data->inputBuffer.bytes[0], &brl->data->inputBuffer.bytes[size],
brl->data->inputCount -= size);
return size;
}
retry:
{
int count = gioReadData(brl->data->gioEndpoint,
&brl->data->inputBuffer.bytes[brl->data->inputCount],
size - brl->data->inputCount,
0);
if (count < 1) {
if (count == -1) {
logSystemError("read");
} else if ((count == 0) && (brl->data->inputCount > 0)) {
if (gioAwaitInput(brl->data->gioEndpoint, 1000)) goto retry;
if (errno != EAGAIN) count = -1;
logPartialPacket(brl->data->inputBuffer.bytes, brl->data->inputCount);
brl->data->inputCount = 0;
}
return count;
}
brl->data->acknowledgementsMissing = 0;
if (!brl->data->inputCount) {
static const unsigned char packets[] = {
PKT_ACK, PKT_NAK,
PKT_KEY, PKT_EXTKEY, PKT_BUTTON, PKT_WHEEL,
PKT_INFO
};
int first;
for (first=0; first<count; first+=1)
if (memchr(packets, brl->data->inputBuffer.bytes[first], sizeof(packets)))
break;
if (first) {
logDiscardedBytes(brl->data->inputBuffer.bytes, first);
memmove(&brl->data->inputBuffer.bytes[0], &brl->data->inputBuffer.bytes[first], count-=first);
}
}
brl->data->inputCount += count;
}
}
}