I'm working on interfacing some older positioning equipment with an arduino, but having done the majority of my work with higher level language I'm having trouble adjusting to the limitations of AVR-GCC.
I basically have two questions: Is this a good way to parse out the strings? What can I do to optimize this code for an embedded platform?
// this is in the global scope of my program. normally accepted as bad code,
// but it seems to make sense in the context of an embedded platform.
// "global" cache
int data[10];
void getPosition(){
// position message is always less than 25 bytes with null termination characters
byte bufferIndex = 0;
char buffer[25];
// read the position command from the serial port
// should look like:
// D20BIX+00733Y+00080S99\r\n
//
// and we need the X+00000 and Y+00000 parts
//
if (Serial.available() > 0){
while (Serial.available() > 0 && bufferIndex < 25){
buffer[bufferIndex] = Serial.read();
if (buffer[bufferIndex++] == '\n'){
buffer[bufferIndex] = '\0';
break;
}
}
Serial.flush();
// check to see if we have good orientation on the buffer by
// checking for lines starting with model identifier 'D'
String input = String(buffer);
if (buffer[0] == 'D' && bufferIndex <=24){
int x_result = data[1];
int y_result = data[4];
String check;
char token_buffer[8] = {'0', '0', '0', '0', '0', '0', '0', '0' };
// scan for x, target token is X+00000
String x_token = input.substring(5, 11);
check = x_token.substring(2, 6);
check.toCharArray(token_buffer, 8);
x_result = atoi(token_buffer);
if (x_token[1] == '-'){
x_result *= -1;
}
// scan for y, target token is Y+00000
String y_token = input.substring(12, 18);
check = y_token.substring(2, 6);
check.toCharArray(token_buffer, 8);
y_result = atoi(token_buffer);
if (y_token[1] == '-'){
y_result *= -1;
}
// finalize results
data[1] = x_result;
data[4] = y_result;
}
}
}
