ft8_lib/ft8/text.cpp

#include "text.h"

#include <string.h>

namespace ft8 {
    
const char * trim_front(const char *str) {
    // Skip leading whitespace
    while (*str == ' ') {
        str++;
    }    
    return str;
}

void trim_back(char *str) {
    // Skip trailing whitespace by replacing it with '\0' characters
    int idx = strlen(str) - 1;
    while (idx >= 0 && str[idx] == ' ') {
        str[idx--] = '\0';
    }
}

// 1) trims a string from the back by changing whitespaces to '\0'
// 2) trims a string from the front by skipping whitespaces
char * trim(char *str) {
    str = (char *)trim_front(str);
    trim_back(str);
    // return a pointer to the first non-whitespace character
    return str; 
}

char to_upper(char c) {
    return (c >= 'a' && c <= 'z') ? (c - 'a' + 'A') : c;
}

bool is_digit(char c) {
    return (c >= '0') && (c <= '9');
}

bool is_letter(char c) {
    return ((c >= 'A') && (c <= 'Z')) || ((c >= 'a') && (c <= 'z'));
}

bool is_space(char c) {
    return (c == ' ');
}

bool in_range(char c, char min, char max) {
    return (c >= min) && (c <= max);
}

bool starts_with(const char *string, const char *prefix) {
    return 0 == memcmp(string, prefix, strlen(prefix));
}

bool equals(const char *string1, const char *string2) {
    return 0 == strcmp(string1, string2);
}


int char_index(const char *string, char c) {
    for (int i = 0; *string; ++i, ++string) {
        if (c == *string) {
            return i;
        }
    }
    return -1;  // Not found
}


// Text message formatting: 
//   - replaces lowercase letters with uppercase
//   - merges consecutive spaces into single space
void fmtmsg(char *msg_out, const char *msg_in) {
    char c;
    char last_out = 0;
    while ( (c = *msg_in) ) {
        if (c != ' ' || last_out != ' ') {
            last_out = to_upper(c);
            *msg_out = last_out;
            ++msg_out;
        }
        ++msg_in;
    }
    *msg_out = 0; // Add zero termination
}


// Parse a 2 digit integer from string
int dd_to_int(const char *str, int length) {
    int result = 0;
    bool negative;
    int i;
    if (str[0] == '-') {
        negative = true;
        i = 1;                          // Consume the - sign
    }
    else {
        negative = false;
        i = (str[0] == '+') ? 1 : 0;    // Consume a + sign if found
    }
    
    while (i < length) {
        if (str[i] == 0) break;
        if (!is_digit(str[i])) break;
        result *= 10;
        result += (str[i] - '0');
        ++i;
    }

    return negative ? -result : result;
}


// Convert a 2 digit integer to string
void int_to_dd(char *str, int value, int width, bool full_sign) {
    if (value < 0) {
        *str = '-';
        ++str;
        value = -value;
    }
    else if (full_sign) {
        *str = '+';
        ++str;
    }

    int divisor = 1;
    for (int i = 0; i < width - 1; ++i) {
        divisor *= 10;
    }

    while (divisor >= 1) {
        int digit = value / divisor;

        *str = '0' + digit;
        ++str;

        value -= digit * divisor;
        divisor /= 10;
    }
    *str = 0;   // Add zero terminator
}

// convert integer index to ASCII character according to one of 6 tables:
// table 0: " 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ+-./?"
// table 1: " 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
// table 2: "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
// table 3: "0123456789"
// table 4: " ABCDEFGHIJKLMNOPQRSTUVWXYZ"
// table 5: " 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ/"
char charn(int c, int table_idx) {
    if (table_idx != 2 && table_idx != 3) {
        if (c == 0) return ' ';
        c -= 1;
    }
    if (table_idx != 4) {
        if (c < 10) return '0' + c;
        c -= 10;
    }
    if (table_idx != 3) {
        if (c < 26) return 'A' + c;
        c -= 26;
    }
    
    if (table_idx == 0) {
        if (c < 5) return "+-./?" [c];
    }
    else if (table_idx == 5) {
        if (c == 0) return '/';
    }

    return '_'; // unknown character, should never get here
}

// Convert character to its index (charn in reverse) according to a table
int nchar(char c, int table_idx) {
    int n = 0;
    if (table_idx != 2 && table_idx != 3) {
        if (c == ' ') return n + 0;
        n += 1;
    }
    if (table_idx != 4) {
        if (c >= '0' && c <= '9') return n + (c - '0');
        n += 10;
    }
    if (table_idx != 3) {
        if (c >= 'A' && c <= 'Z') return n + (c - 'A');
        n += 26;
    }
    
    if (table_idx == 0) {
        if (c == '+') return n + 0;
        if (c == '-') return n + 1;
        if (c == '.') return n + 2;
        if (c == '/') return n + 3;
        if (c == '?') return n + 4;
    }
    else if (table_idx == 5) {
        if (c == '/') return n + 0;
    }
    
    // Character not found
    return -1; 
}

} // namespace