avr/morse/morse.c

#include <util/delay.h>
#include <string.h>
#include "morse.h"

/* TODO: all of this is a candidate for living in an EEPROM */
typedef struct morse_codepoint {
    size_t length;
    uint8_t values[5];
} morse_codepoint_t;

const struct morse_codepoint MORSE[] = {
    /* 0 */ { .length = 5, .values = { DASH, DASH, DASH, DASH, DASH } },
    /* 1 */ { .length = 5, .values = { DOT,  DASH, DASH, DASH, DASH } },
    /* 2 */ { .length = 5, .values = { DOT,  DOT,  DASH, DASH, DASH } },
    /* 3 */ { .length = 5, .values = { DOT,  DOT,  DOT,  DASH, DASH } },
    /* 4 */ { .length = 5, .values = { DOT,  DOT,  DOT,  DOT,  DASH } },
    /* 5 */ { .length = 5, .values = { DOT,  DOT,  DOT,  DOT,  DOT } },
    /* 6 */ { .length = 5, .values = { DASH, DOT,  DOT,  DOT,  DOT } },
    /* 7 */ { .length = 5, .values = { DASH, DASH, DOT,  DOT,  DOT } },
    /* 8 */ { .length = 5, .values = { DASH, DASH, DASH, DOT,  DOT } },
    /* 9 */ { .length = 5, .values = { DASH, DASH, DASH, DASH, DOT } },
    /* a */ { .length = 2, .values = { DOT,  DASH } },
    /* b */ { .length = 4, .values = { DASH, DOT,  DOT,  DOT } },
    /* c */ { .length = 4, .values = { DASH, DOT,  DASH, DOT } },
    /* d */ { .length = 3, .values = { DASH, DOT,  DOT } },
    /* e */ { .length = 1, .values = { DOT } },
    /* f */ { .length = 4, .values = { DOT,  DOT,  DASH, DOT } },
    /* g */ { .length = 3, .values = { DASH, DASH, DOT } },
    /* h */ { .length = 4, .values = { DOT,  DOT,  DOT,  DOT } },
    /* i */ { .length = 2, .values = { DOT,  DOT } },
    /* j */ { .length = 4, .values = { DOT,  DASH, DASH, DASH } },
    /* k */ { .length = 3, .values = { DASH, DOT,  DASH } },
    /* l */ { .length = 4, .values = { DOT,  DASH, DOT,  DOT } },
    /* m */ { .length = 2, .values = { DASH, DASH } },
    /* n */ { .length = 2, .values = { DASH, DOT } },
    /* o */ { .length = 3, .values = { DASH, DASH, DASH } },
    /* p */ { .length = 4, .values = { DOT,  DASH, DASH, DOT } },
    /* q */ { .length = 4, .values = { DASH, DASH, DOT,  DASH } },
    /* r */ { .length = 3, .values = { DOT,  DASH, DOT } },
    /* s */ { .length = 3, .values = { DOT,  DOT,  DOT } },
    /* t */ { .length = 1, .values = { DASH } },
    /* u */ { .length = 3, .values = { DOT,  DOT,  DASH } },
    /* v */ { .length = 4, .values = { DOT,  DOT,  DOT,  DASH } },
    /* w */ { .length = 3, .values = { DOT,  DASH, DASH } },
    /* x */ { .length = 4, .values = { DASH, DOT,  DOT,  DASH } },
    /* y */ { .length = 4, .values = { DASH, DOT,  DASH, DASH } },
    /* z */ { .length = 4, .values = { DASH, DASH, DOT,  DOT } },
};

const struct morse_codepoint * morse_lookup(char val) {
    size_t idx = -1;
    if (val >= '0' && val <= '9') {
        idx = val - '0';
    } else if (val >= 'a' && val <= 'z') {
        idx = (val - 'a') + 10;
    } else if (val >= 'A' && val <= 'Z') {
        idx = (val - 'A') + 10;
    }
    if (idx < 0) return NULL;
    return &MORSE[idx];
}

void send_codepoint(gpio_t *gpio, const struct morse_codepoint *codepoint) {
    const uint8_t one = 1 << gpio->addr;
    for (size_t i = 0; i < codepoint->length; i++) {
        *gpio->port = *(gpio->port) | one;
        if (codepoint->values[i] == DOT) {
            _delay_ms(DOT * SCALE);
        } else {
            _delay_ms(DASH * SCALE);
        }
        *gpio->port = *(gpio->port) & ~one;
        _delay_ms(DIVIDER * SCALE);
    }
    _delay_ms(INTERCHAR * SCALE);
}

void send_morse(gpio_t *gpio, char *message) {
    for (size_t i = 0; i < strlen(message); i++) {
        if (message[i] == ' ') {
            _delay_ms(INTERWORD * SCALE);
        }
        const struct morse_codepoint *codepoint = morse_lookup(message[i]);
        if (codepoint != NULL) {
            send_codepoint(gpio, codepoint);
        }
    }
}