rem: for (i=0; i<4; i++) { byte = data[i]; rbyte = avr_txrx ( fd, byte ); if (i == 2) { if (rbyte == data[1]) avrok = 1; } }  if (!avrok)
add: if (res[2] != cmd[1])
context: int avr_program_enable ( int fd ){  unsigned char data[4] = {0xac, 0x53, 0x00, 0x00};  unsigned char byte, rbyte;  int avrok;  int i;  avrok = 0;  for (i=0; i<4; i++) {    byte = data[i];    rbyte = avr_txrx ( fd, byte );    if (i == 2) {      if (rbyte == data[1])        avrok = 1;    }  }  if (!avrok)    return -1;  return 0;}