mirror of
https://github.com/UzixLS/famicom-dumper.git
synced 2025-07-19 07:21:16 +03:00
143 lines
2.8 KiB
C
143 lines
2.8 KiB
C
#include "defines.h"
|
|
#include <inttypes.h>
|
|
#include <util/delay.h>
|
|
#include "comm.h"
|
|
#include "usart.h"
|
|
|
|
static uint8_t comm_send_crc;
|
|
static unsigned int comm_send_length;
|
|
static unsigned int comm_send_pos;
|
|
|
|
static int comm_recv_pos;
|
|
static uint8_t comm_recv_crc;
|
|
static uint8_t comm_recv_error;
|
|
|
|
volatile uint8_t comm_recv_command;
|
|
volatile unsigned int comm_recv_length;
|
|
volatile uint8_t recv_buffer[RECV_BUFFER];
|
|
volatile uint8_t comm_recv_done;
|
|
|
|
static void comm_calc_send_crc(uint8_t inbyte)
|
|
{
|
|
uint8_t j;
|
|
for (j=0;j<8;j++)
|
|
{
|
|
uint8_t mix = (comm_send_crc ^ inbyte) & 0x01;
|
|
comm_send_crc >>= 1;
|
|
if (mix)
|
|
comm_send_crc ^= 0x8C;
|
|
inbyte >>= 1;
|
|
}
|
|
}
|
|
|
|
static void comm_calc_recv_crc(uint8_t inbyte)
|
|
{
|
|
uint8_t j;
|
|
for (j=0;j<8;j++)
|
|
{
|
|
uint8_t mix = (comm_recv_crc ^ inbyte) & 0x01;
|
|
comm_recv_crc >>= 1;
|
|
if (mix)
|
|
comm_recv_crc ^= 0x8C;
|
|
inbyte >>= 1;
|
|
}
|
|
}
|
|
|
|
static void comm_send_and_calc(uint8_t data)
|
|
{
|
|
comm_calc_send_crc(data);
|
|
USART_TransmitByte(data);
|
|
#ifdef SEND_DELAY
|
|
_delay_us(SEND_DELAY);
|
|
#endif
|
|
}
|
|
|
|
void comm_start(uint8_t command, unsigned int length)
|
|
{
|
|
comm_send_crc = 0;
|
|
comm_send_and_calc('F');
|
|
comm_send_and_calc(command);
|
|
comm_send_and_calc(length & 0xff);
|
|
comm_send_and_calc((length >> 8) & 0xff);
|
|
comm_send_length = length;
|
|
comm_send_pos = 0;
|
|
|
|
if (!comm_send_length)
|
|
USART_TransmitByte(comm_send_crc);
|
|
}
|
|
|
|
void comm_send_byte(uint8_t data)
|
|
{
|
|
comm_send_and_calc(data);
|
|
comm_send_pos++;
|
|
|
|
if (comm_send_pos == comm_send_length)
|
|
USART_TransmitByte(comm_send_crc);
|
|
}
|
|
|
|
void comm_proceed(uint8_t data)
|
|
{
|
|
if (comm_recv_error && data != 'F') return;
|
|
comm_recv_error = 0;
|
|
if (!comm_recv_pos)
|
|
{
|
|
comm_recv_crc = 0;
|
|
comm_recv_done = 0;
|
|
}
|
|
comm_calc_recv_crc(data);
|
|
unsigned int l = comm_recv_pos-4;
|
|
switch (comm_recv_pos)
|
|
{
|
|
case 0:
|
|
if (data != 'F')
|
|
{
|
|
comm_recv_error = 1;
|
|
comm_start(COMMAND_ERROR_INVALID, 0);
|
|
}
|
|
break;
|
|
case 1:
|
|
comm_recv_command = data;
|
|
break;
|
|
case 2:
|
|
comm_recv_length = data;
|
|
break;
|
|
case 3:
|
|
comm_recv_length |= (uint16_t)data << 8;
|
|
break;
|
|
default:
|
|
if (l >= RECV_BUFFER)
|
|
{
|
|
comm_recv_pos = 0;
|
|
comm_recv_error = 1;
|
|
comm_start(COMMAND_ERROR_OVERFLOW, 0);
|
|
return;
|
|
}
|
|
else if (l < comm_recv_length)
|
|
{
|
|
recv_buffer[l] = data;
|
|
} else if (l == comm_recv_length)
|
|
{
|
|
if (!comm_recv_crc)
|
|
{
|
|
comm_recv_done = 1;
|
|
}
|
|
else
|
|
{
|
|
comm_recv_error = 1;
|
|
comm_start(COMMAND_ERROR_CRC, 0);
|
|
}
|
|
comm_recv_pos = 0;
|
|
return;
|
|
}
|
|
break;
|
|
}
|
|
comm_recv_pos++;
|
|
}
|
|
|
|
void comm_init()
|
|
{
|
|
comm_recv_pos = 0;
|
|
comm_recv_done = 0;
|
|
comm_recv_error = 0;
|
|
}
|