convert 32 bit long int or string to string or int.

str-int.c

/* @TODO A simple optimization is to concatenate all sub strings into one big string.
 * this will save some memory and probably make accessing more efficient.
 */

/* char value to binary string look-up table, generated by Python */
static const char* _convTab[256] = {
    "00000000","00000001","00000010","00000011","00000100","00000101","00000110","00000111",
    "00001000","00001001","00001010","00001011","00001100","00001101","00001110","00001111",
    "00010000","00010001","00010010","00010011","00010100","00010101","00010110","00010111",
    "00011000","00011001","00011010","00011011","00011100","00011101","00011110","00011111",
    "00100000","00100001","00100010","00100011","00100100","00100101","00100110","00100111",
    "00101000","00101001","00101010","00101011","00101100","00101101","00101110","00101111",
    "00110000","00110001","00110010","00110011","00110100","00110101","00110110","00110111",
    "00111000","00111001","00111010","00111011","00111100","00111101","00111110","00111111",
    "01000000","01000001","01000010","01000011","01000100","01000101","01000110","01000111",
    "01001000","01001001","01001010","01001011","01001100","01001101","01001110","01001111",
    "01010000","01010001","01010010","01010011","01010100","01010101","01010110","01010111",
    "01011000","01011001","01011010","01011011","01011100","01011101","01011110","01011111",
    "01100000","01100001","01100010","01100011","01100100","01100101","01100110","01100111",
    "01101000","01101001","01101010","01101011","01101100","01101101","01101110","01101111",
    "01110000","01110001","01110010","01110011","01110100","01110101","01110110","01110111",
    "01111000","01111001","01111010","01111011","01111100","01111101","01111110","01111111",
    "10000000","10000001","10000010","10000011","10000100","10000101","10000110","10000111",
    "10001000","10001001","10001010","10001011","10001100","10001101","10001110","10001111",
    "10010000","10010001","10010010","10010011","10010100","10010101","10010110","10010111",
    "10011000","10011001","10011010","10011011","10011100","10011101","10011110","10011111",
    "10100000","10100001","10100010","10100011","10100100","10100101","10100110","10100111",
    "10101000","10101001","10101010","10101011","10101100","10101101","10101110","10101111",
    "10110000","10110001","10110010","10110011","10110100","10110101","10110110","10110111",
    "10111000","10111001","10111010","10111011","10111100","10111101","10111110","10111111",
    "11000000","11000001","11000010","11000011","11000100","11000101","11000110","11000111",
    "11001000","11001001","11001010","11001011","11001100","11001101","11001110","11001111",
    "11010000","11010001","11010010","11010011","11010100","11010101","11010110","11010111",
    "11011000","11011001","11011010","11011011","11011100","11011101","11011110","11011111",
    "11100000","11100001","11100010","11100011","11100100","11100101","11100110","11100111",
    "11101000","11101001","11101010","11101011","11101100","11101101","11101110","11101111",
    "11110000","11110001","11110010","11110011","11110100","11110101","11110110","11110111",
    "11111000","11111001","11111010","11111011","11111100","11111101","11111110","11111111",
};

static inline void
int_to_str(int i, char *str) {
    /* convert int to an binary form string @TODO consider the endianess */
    const char *a = _convTab[ (i >> 24) & 0xFF ];
    const char *b = _convTab[ (i >> 16) & 0xFF ];
    const char *c = _convTab[ (i >> 8 ) & 0xFF ];
    const char *d = _convTab[ (i >> 0 ) & 0xFF ];
    
    while ( *str++ = *a++ ) ; str--;
    while ( *str++ = *b++ ) ; str--;
    while ( *str++ = *c++ ) ; str--;
    while ( *str++ = *d++ ) ;
}


static inline int
str_to_int(const char *str) {
    /* convert 32 byte long str to an integer */
    int i, s = 0;
    for (i = 0; i < 32; ++i)
        s += (str[i] - '0') << (31 - i);
    return s;
}