Here's the code for the 8o1 variant.
//
// The receive routine called by the interrupt handler
//
void SoftwareSerial::recv()
{
#if GCC_VERSION < 40302
// Work-around for avr-gcc 4.3.0 OSX version bug
// Preserve the registers that the compiler misses
// (courtesy of Arduino forum user *etracer*)
asm volatile(
"push r18 \n\t"
"push r19 \n\t"
"push r20 \n\t"
"push r21 \n\t"
"push r22 \n\t"
"push r23 \n\t"
"push r26 \n\t"
"push r27 \n\t"
::);
#endif
uint8_t d = 0;
// If RX line is high, then we don't see any start bit
// so interrupt is probably not for us
if (_inverse_logic ? rx_pin_read() : !rx_pin_read())
{
// Wait approximately 1/2 of a bit width to "center" the sample
tunedDelay(_rx_delay_centering);
DebugPulse(_DEBUG_PIN2, 1);
// Read each of the 8 bits
for (uint8_t i=0x1; i; i <<= 1)
{
tunedDelay(_rx_delay_intrabit);
DebugPulse(_DEBUG_PIN2, 1);
uint8_t noti = ~i;
if (rx_pin_read())
d |= i;
else // else clause added to ensure function timing is ~balanced
d &= noti;
}
// skip the parity bit
tunedDelay(_rx_delay_stopbit);
DebugPulse(_DEBUG_PIN2, 1);
// skip the 2 stop bits
tunedDelay(_rx_delay_stopbit);
DebugPulse(_DEBUG_PIN2, 1);
if (_inverse_logic)
d = ~d;
// if buffer full, set the overflow flag and return
if ((_receive_buffer_tail + 1) % _SS_MAX_RX_BUFF != _receive_buffer_head)
{
// save new data in buffer: tail points to where byte goes
_receive_buffer[_receive_buffer_tail] = d; // save new byte
_receive_buffer_tail = (_receive_buffer_tail + 1) % _SS_MAX_RX_BUFF;
}
else
{
#if _DEBUG // for scope: pulse pin as overflow indictator
DebugPulse(_DEBUG_PIN1, 1);
#endif
_buffer_overflow = true;
}
}
#if GCC_VERSION < 40302
// Work-around for avr-gcc 4.3.0 OSX version bug
// Restore the registers that the compiler misses
asm volatile(
"pop r27 \n\t"
"pop r26 \n\t"
"pop r23 \n\t"
"pop r22 \n\t"
"pop r21 \n\t"
"pop r20 \n\t"
"pop r19 \n\t"
"pop r18 \n\t"
::);
#endif
}
and the write part:
size_t SoftwareSerial::write(uint8_t b)
{
if (_tx_delay == 0) {
setWriteError();
return 0;
}
uint8_t oldSREG = SREG;
cli(); // turn off interrupts for a clean txmit
// Write the start bit
tx_pin_write(_inverse_logic ? HIGH : LOW);
tunedDelay(_tx_delay + XMIT_START_ADJUSTMENT);
uint8_t p = 0;
uint8_t t;
for (t = 0x80; t; t >>= 1)
if (b & t) p++;
// Write each of the 8 bits
if (_inverse_logic)
{
for (byte mask = 0x01; mask; mask <<= 1)
{
if (b & mask) // choose bit
tx_pin_write(LOW); // send 1
else
tx_pin_write(HIGH); // send 0
tunedDelay(_tx_delay);
}
// parity
if (p & 0x01)
tx_pin_write(LOW); // send 1
else
tx_pin_write(HIGH); // send 0
tunedDelay(_tx_delay);
tx_pin_write(LOW); // restore pin to natural state
}
else
{
for (byte mask = 0x01; mask; mask <<= 1)
{
if (b & mask) // choose bit
tx_pin_write(HIGH); // send 1
else
tx_pin_write(LOW); // send 0
tunedDelay(_tx_delay);
}
// parity
if (p & 0x01)
tx_pin_write(HIGH); // send 1
else
tx_pin_write(LOW); // send 0
tunedDelay(_tx_delay);
tx_pin_write(HIGH); // restore pin to natural state
}
SREG = oldSREG; // turn interrupts back on
tunedDelay(_tx_delay);
return 1;
}
The compiler errors you get indicate that you're working with MacOS X as the compilation machine. Correct?
I got the compilation error away on my machine by changing the following code too:
inline void SoftwareSerial8o1::tunedDelay(volatile uint16_t delay) {
volatile uint8_t tmp=0;
asm volatile("sbiw %0, 0x01 \n\t"
"ldi %1, 0xFF \n\t"
"cpi %A0, 0xFF \n\t"
"cpc %B0, %1 \n\t"
"brne .-10 \n\t"
: "+r" (delay), "+a" (tmp)
: "0" (delay)
);
}
Note the inserted volatile statements to keep the compiler from optimizing the variables away.