88 lines
2.3 KiB
C++
88 lines
2.3 KiB
C++
#include "EasyTransfer.h"
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//Captures address and size of struct
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void EasyTransfer::begin(uint8_t * ptr, uint8_t length, Stream *theStream){
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address = ptr;
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size = length;
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_stream = theStream;
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//dynamic creation of rx parsing buffer in RAM
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rx_buffer = (uint8_t*) malloc(size+1);
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}
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//Sends out struct in binary, with header, length info and checksum
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void EasyTransfer::sendData(){
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uint8_t CS = size;
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_stream->write(0x06);
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_stream->write(0x85);
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_stream->write(size);
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for(int i = 0; i<size; i++){
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CS^=*(address+i);
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_stream->write(*(address+i));
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}
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_stream->write(CS);
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}
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boolean EasyTransfer::receiveData(){
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//start off by looking for the header bytes. If they were already found in a previous call, skip it.
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if(rx_len == 0){
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//this size check may be redundant due to the size check below, but for now I'll leave it the way it is.
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if(_stream->available() >= 3){
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//this will block until a 0x06 is found or buffer size becomes less then 3.
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while(_stream->read() != 0x06) {
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//This will trash any preamble junk in the serial buffer
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//but we need to make sure there is enough in the buffer to process while we trash the rest
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//if the buffer becomes too empty, we will escape and try again on the next call
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if(_stream->available() < 3)
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return false;
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}
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if (_stream->read() == 0x85){
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rx_len = _stream->read();
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//make sure the binary structs on both Arduinos are the same size.
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if(rx_len != size){
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rx_len = 0;
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return false;
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}
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}
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}
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}
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//we get here if we already found the header bytes, the struct size matched what we know, and now we are byte aligned.
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if(rx_len != 0){
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while(_stream->available() && rx_array_inx <= rx_len){
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rx_buffer[rx_array_inx++] = _stream->read();
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}
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if(rx_len == (rx_array_inx-1)){
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//seem to have got whole message
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//last uint8_t is CS
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calc_CS = rx_len;
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for (int i = 0; i<rx_len; i++){
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calc_CS^=rx_buffer[i];
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}
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if(calc_CS == rx_buffer[rx_array_inx-1]){//CS good
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memcpy(address,rx_buffer,size);
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rx_len = 0;
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rx_array_inx = 0;
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return true;
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}
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else{
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//failed checksum, need to clear this out anyway
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rx_len = 0;
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rx_array_inx = 0;
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return false;
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}
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}
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}
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return false;
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}
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