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#include "usart.h"
static struct _usart_device *_usart = (struct _usart_device *) ADDR_DEV_USART;
void usart_set_baudrate(uint16_t baudrate)
{
// enable latch access
_usart->LCR.divisor_latch_access = 1;
_usart->buffer = 0x00FF & baudrate; // LSBs
memcpy(&_usart->IER, &(baudrate >>8), 1);
// _usart->IER = 0x00FF & (baudrate >> 8); // MSBs
_usart->LCR.divisor_latch_access = 0;
}
void usart_set_parity(int mode)
{
if (mode == USART_PARITY_EVEN) {
_usart->LCR.even_parity = 1;
}
else if (mode == USART_PARITY_ODD) {
_usart->LCR.even_parity = 0;
}
_usart->LCR.parity = (mode == USART_PARITY_NONE) ? 0 : 1;
}
void usart_set_stop_bits(int count)
{
_usart->LCR.stop_bits = (count == USART_STOP_BITS_1) ? 0 : 1;
}
void usart_word_length(int length)
{
_usart->LCR.word_length = length;
}
void usart_set_autoflow(int mode)
{
_usart->MCR.autoflow = (mode == USART_AUTOFLOW_OFF) ? 0 : 1;
_usart->MCR.data_terminal_ready = (mode == USART_AUTOFLOW_ALL);
}
inline void usart_init(uint16_t baudrate, int parity, int stop_bits)
{
usart_set_baudrate(baudrate);
usart_set_parity(parity);
usart_set_stop_bits(stop_bits);
usart_set_autoflow(USART_AUTOFLOW_OFF);
}
void usart_transmit(uint8_t data)
{
_usart->buffer = data;
while (_usart->LSR.transmitter_holder_empty == 0); // wait
}
uint8_t usart_receive()
{
return _usart->buffer;
}
int usart_write(uint8_t *data, size_t size)
{
uint8_t *dp = data;
while (size--) {
_usart->buffer = *(dp++);
while (_usart->LSR.transmitter_empty);
}
// TODO: do something that actually counts for sent bytes
return size;
}
int usart_read(uint8_t *buffer, size_t count)
{
uint8_t *bp = buffer;
size_t read_count = 0;
while (count--) {
*(bp++) = _usart->buffer;
// check for errors
if (_usart->LSR.framing_error || _usart->LSR.parity_error) {
bp--; // delete last byte (?)
} else {
read_count++;
}
}
return read_count;
}
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