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#ifndef __USART_H__
#define __USART_H__
#include "addresses.h"
#include <stdint.h>
#include <string.h>
// baudrate clock divisors
// values from TL16C550C datasheet (table 9 for 1.8432 MHz crystal)
#define USART_BAUDRATE_50 2304
#define USART_BAUDRATE_75 1536
#define USART_BAUDRATE_110 1047
#define USART_BAUDRATE_134_5 857
#define USART_BAUDRATE_150 768
#define USART_BAUDRATE_300 384
#define USART_BAUDRATE_600 192
#define USART_BAUDRATE_1200 96
#define USART_BAUDRATE_1800 64
#define USART_BAUDRATE_2000 58
#define USART_BAUDRATE_2400 48
#define USART_BAUDRATE_3600 32
#define USART_BAUDRATE_4800 24
#define USART_BAUDRATE_7200 16
#define USART_BAUDRATE_9600 12
#define USART_BAUDRATE_19200 6
#define USART_BAUDRATE_38400 3
#define USART_BAUDRATE_56000 3
// parity
#define USART_PARITY_NONE 0
#define USART_PARITY_EVEN 1
#define USART_PARITY_ODD 2
// stop bits
#define USART_STOP_BITS_1 10
#define USART_STOP_BITS_15 15
#define USART_STOP_BITS_2 20
// word lenght
#define USART_WORD_LENGTH_5 0
#define USART_WORD_LENGTH_6 1
#define USART_WORD_LENGTH_7 2
#define USART_WORD_LENGTH_8 3
// autoflow
#define USART_AUTOFLOW_ALL 3
#define USART_AUTOFLOW_CTS 2
#define USART_AUTOFLOW_OFF 0
typedef unsigned int uint;
typedef volatile uint8_t register_t;
/* stuctures for usart registers */
struct IER
{
volatile uint received_data_interrupt :1;
volatile uint transmitter_empty_interrupt :1;
volatile uint receiver_line_status_interrupt :1;
volatile uint modem_status_interrupt :1;
volatile uint reserved :4;
};
struct IIR
{
volatile uint interrupt_pending :1;
volatile uint interrupt_id :3;
volatile uint reserved :2;
volatile uint fifos :2;
};
struct FCR
{
volatile uint fifo_enable :1;
volatile uint receiver_fifo_rst :1;
volatile uint trasmitter_fifo_rst :1;
volatile uint dma_mode_select :1;
volatile uint reserved :1;
volatile uint receiver_trigger :2;
};
struct LCR
{
volatile uint word_length :2;
volatile uint stop_bits :1;
volatile uint parity :1;
volatile uint even_parity :1;
volatile uint stick_parity :1;
volatile uint break_control :1;
volatile uint divisor_latch_access :1;
};
struct MCR
{
volatile uint data_terminal_ready :1;
volatile uint request_to_send :1;
volatile uint out1;
volatile uint out2;
volatile uint loop;
volatile uint autoflow :1;
volatile uint reserved :2;
};
struct LSR
{
volatile uint data_ready :1;
volatile uint overrun_error :1;
volatile uint parity_error :1;
volatile uint framing_error :1;
volatile uint break_interrupt :1;
volatile uint transmitter_holder_empty :1;
volatile uint transmitter_empty :1;
volatile uint fifo_recv_error :1;
};
struct MSR
{
volatile uint delta_cts :1;
volatile uint delta_data_set_ready :1;
volatile uint trailing_edge_ring_indicator :1;
volatile uint delta_data_carrier_detect :1;
volatile uint clear_to_send :1;
volatile uint data_set_ready :1;
volatile uint ring_indicator :1;
volatile uint data_carrier_detect :1;
};
/* this structure is only for internal usage */
struct _usart_device
{
register_t buffer; // also used as LSB for divisor latch
struct IER IER;
struct IIR IIR;
struct FCR FCR;
struct LCR LCR;
struct MCR MCR;
struct LSR LSR;
struct MSR MSR;
register_t scratch;
};
// setup functions (wrappers)
void usart_set_baudrate(uint16_t baudrate);
void usart_set_parity(int mode);
void usart_set_stop_bits(int count);
void usart_set_word_length(int length);
void usart_set_autoflow(int mode);
inline void usart_init(uint16_t baudrate, int parity, int stop_bits);
void usart_transmit(uint8_t data);
uint8_t usart_receive();
int usart_write(uint8_t *data, size_t size);
int usart_read(uint8_t *buffer, size_t count);
#endif // __USART__H__
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