//
//
// hello.array.44.c
//
// Charlieplex LED array hello-world
//
// Neil Gershenfeld
// 11/13/10
//
// (c) Massachusetts Institute of Technology 2010
// Permission granted for experimental and personal use;
// license for commercial sale available from MIT.
//

#include <avr/io.h>
#include <util/delay.h>
#include <avr/pgmspace.h>

#define output(directions,pin) (directions |= pin) // set port direction for output
#define set(port,pin) (port |= pin) // set port pin
#define clear(port,pin) (port &= (~pin)) // clear port pin
#define pin_test(pins,pin) (pins & pin) // test for port pin
#define bit_test(byte,bit) (byte & (1 << bit)) // test for bit set
#define bit_delay_time 100 // bit delay for 115200 with overhead
#define bit_delay() _delay_us(bit_delay_time) // RS232 bit delay
#define half_bit_delay() _delay_us(bit_delay_time/2) // RS232 half bit delay
#define char_delay() _delay_ms(10) // char delay

#define serial_port PORTB
#define serial_direction DDRB
#define serial_pins PINB
#define serial_pin_in (1 << PB2)  //FTDI Tx pin, send character to attiny44
#define serial_pin_out (1 << PB1) //FTDI Rx pin, attiny44 send out some character to FTDI

#define max_buffer 25

void get_char(volatile unsigned char *pins, unsigned char pin, char *rxbyte) {
    //
    // read character into rxbyte on pins pin
    //    assumes line driver (inverts bits)
    //
    *rxbyte = 0;
    while (pin_test(*pins,pin))
        //
        // wait for start bit
        //
        ;
    //
    // delay to middle of first data bit
    //
    half_bit_delay();
    bit_delay();
    //
    // unrolled loop to read data bits
    //
    if pin_test(*pins,pin)
        *rxbyte |= (1 << 0);
    else
        *rxbyte |= (0 << 0);
    bit_delay();
    if pin_test(*pins,pin)
        *rxbyte |= (1 << 1);
    else
        *rxbyte |= (0 << 1);
    bit_delay();
    if pin_test(*pins,pin)
        *rxbyte |= (1 << 2);
    else
        *rxbyte |= (0 << 2);
    bit_delay();
    if pin_test(*pins,pin)
        *rxbyte |= (1 << 3);
    else
        *rxbyte |= (0 << 3);
    bit_delay();
    if pin_test(*pins,pin)
        *rxbyte |= (1 << 4);
    else
        *rxbyte |= (0 << 4);
    bit_delay();
    if pin_test(*pins,pin)
        *rxbyte |= (1 << 5);
    else
        *rxbyte |= (0 << 5);
    bit_delay();
    if pin_test(*pins,pin)
        *rxbyte |= (1 << 6);
    else
        *rxbyte |= (0 << 6);
    bit_delay();
    if pin_test(*pins,pin)
        *rxbyte |= (1 << 7);
    else
        *rxbyte |= (0 << 7);
    //
    // wait for stop bit
    //
    bit_delay();
    half_bit_delay();
}

void put_char(volatile unsigned char *port, unsigned char pin, char txchar) {
    //
    // send character in txchar on port pin
    //    assumes line driver (inverts bits)
    //
    // start bit
    //
    clear(*port,pin);
    bit_delay();
    //
    // unrolled loop to write data bits
    //
    if bit_test(txchar,0)
        set(*port,pin);
    else
        clear(*port,pin);
    bit_delay();
    if bit_test(txchar,1)
        set(*port,pin);
    else
        clear(*port,pin);
    bit_delay();
    if bit_test(txchar,2)
        set(*port,pin);
    else
        clear(*port,pin);
    bit_delay();
    if bit_test(txchar,3)
        set(*port,pin);
    else
        clear(*port,pin);
    bit_delay();
    if bit_test(txchar,4)
        set(*port,pin);
    else
        clear(*port,pin);
    bit_delay();
    if bit_test(txchar,5)
        set(*port,pin);
    else
        clear(*port,pin);
    bit_delay();
    if bit_test(txchar,6)
        set(*port,pin);
    else
        clear(*port,pin);
    bit_delay();
    if bit_test(txchar,7)
        set(*port,pin);
    else
        clear(*port,pin);
    bit_delay();
    //
    // stop bit
    //
    set(*port,pin);
    bit_delay();
    //
    // char delay
    //
    bit_delay();
}

void put_flash_string(volatile unsigned char *port, unsigned char pin, PGM_P str) {
    //
    // print a null-terminated string from flash
    //
    static char chr;
    static int index;
    index = 0;
    do {
        chr = pgm_read_byte(&(str[index]));
        put_char(port, pin, chr);
        ++index;
    } while (chr != 0);
}

void put_ram_string(volatile unsigned char *port, unsigned char pin, char *str) {
    //
    // print a null-terminated string from SRAM
    //
    static int index;
    index = 0;
    do {
        put_char(port, pin, str[index]);
        ++index;
    } while (str[index] != 0);
}

int main(void) {
    //
    // mains
    //
    static char chr;
    static char buffer[max_buffer] = {0};
    static int index;
    //
    // set clock divider to /1
    //
    CLKPR = (1 << CLKPCE);
    CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
    //
    // initialize output pins
    //
    set(serial_port, serial_pin_out);
    output(serial_direction, serial_pin_out);
    //
    // main loop
    //
    index = 0;
    while (1) {
        //get_char(&serial_pins, serial_pin_in, &chr);
		put_char(&serial_port, serial_pin_out, 97);
		char_delay();
    }
}