pbm2lpbm.cpp

/*
 *  pbm2lpbm.cpp
 */

#include <cstring>
#include <iostream>

// convert a .pbm raw file to our custom .lpbm format

int main(int argc, char* argv[]) {
    unsigned char c;
    const int LEN = 256;
    char s[LEN];
    std::cin.getline(s, LEN);
    if (std::strncmp(s, "P4", 2)) {
        std::cerr << "input file is not .pbm (P4)" << std::endl;
        return -1;
    }
    std::cin.getline(s, LEN);
    while (s[0] == '#' || s[0] == ' ')
        std::cin.getline(s, LEN);
    unsigned int w = 0, h = 0;
    if (std::sscanf(s, "%d %d", &w, &h) != 2) {
        std::cerr << "height and width not found" << std::endl;
        return -1;
    }
    if (w != 160 || h != 43) {
        std::cerr << "incorrect width / height, mandated: 160x43, found: " << w << "x" << h
                  << std::endl;
        return -1;
    }
    std::cin >> std::noskipws;
    int i = 0, row = -1;
    unsigned char buf[160 * 48];
    std::memset(buf, 0, 160 * 43);
    while (std::cin >> c) {
        if (i % 20 == 0)
            row++;
        if (row == 8)
            row = 0;
        buf[7 + (i % 20) * 8 + i / 160 * 160] |= ((c >> 0) & 0x01) << row;
        buf[6 + (i % 20) * 8 + i / 160 * 160] |= ((c >> 1) & 0x01) << row;
        buf[5 + (i % 20) * 8 + i / 160 * 160] |= ((c >> 2) & 0x01) << row;
        buf[4 + (i % 20) * 8 + i / 160 * 160] |= ((c >> 3) & 0x01) << row;
        buf[3 + (i % 20) * 8 + i / 160 * 160] |= ((c >> 4) & 0x01) << row;
        buf[2 + (i % 20) * 8 + i / 160 * 160] |= ((c >> 5) & 0x01) << row;
        buf[1 + (i % 20) * 8 + i / 160 * 160] |= ((c >> 6) & 0x01) << row;
        buf[0 + (i % 20) * 8 + i / 160 * 160] |= ((c >> 7) & 0x01) << row;
        i++;
    }
    if (i != 160 * 43 / 8) {
        std::cerr << "wrong number of bytes, expected " << 160 * 43 / 8 << ", got " << i
                  << std::endl;
    }
    for (int i = 0; i < 160 * 48 / 8; i++) {
        std::cout << std::hex << (char)buf[i];
    }
}