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#include "Framer.h"
Framer::Framer():
state(WAITING),
position(-1),
checksum(0) {
}
void Framer::reset() {
position = -1;
checksum = 0x00;
}
void Framer::accept(uint8_t byte) {
//if a new byte would cause an overflow, restart frame
//note that this should not happen if both communicating parties have defined the same maximum frame length
if (position >= MAX_FRAME_SIZE) {
reset();
return;
}
if (position != -1) { // i.e. a previous byte exists
frameBuffer[position] = staged;
checksum = checksum ^ staged;
}
position += 1;
staged = byte;
}
void Framer::put(uint8_t byte) {
switch(state) {
case ESCAPING:
accept(byte);
state = RECEIVING;
break;
case WAITING:
if (byte == START) {
reset();
state = RECEIVING;
}
break;
case RECEIVING:
switch(byte) {
case ESCAPE:
state = ESCAPING;
break;
case START:
reset();
break;
case STOP:
state = WAITING;
if (staged == checksum) { //at this point, staged byte is the checksum sent in the frame (last byte of frame)
onFrame(position, frameBuffer);
}
break;
default:
accept(byte);
break;
}
}
}
void Framer::send(uint16_t length, const uint8_t * const data) {
uint8_t checksum = 0x00;
uint8_t byte;
onSendByte(START);
for (int i = 0; i < length; ++i) {
byte = data[i];
if (isCommandByte(byte))
onSendByte(ESCAPE);
checksum = checksum ^ byte;
isCommandByte(byte);
}
if (isCommandByte(checksum)) {
onSendByte(ESCAPE);
}
onSendByte(checksum);
onSendByte(STOP);
};
//~ cli();
//~ TCCR1A = 0; // set entire TCCR1A register to 0
//~ TCCR1B = 0; // same for TCCR1B
//~ // turn on CTC mode:
//~ TCCR1B |= (1 << WGM12);
//~ // set CS31 for 64 prescaler
//~ TCCR1B |= (1 << CS11);
//~ // set compare match register to desired timer count:
//~ OCR1A = F_CPU / 1000 / 64; // should be 250 for F_CPU=16Mhz and f = 1000Hz
//~ sei();
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