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    /*
     * generate_q - Generates the permutations q0 and q1 for twofish.
     * Copyright (C) 1999 Ruud de Rooij <ruud@debian.org>
     *
     * This program is free software; you can redistribute it and/or modify
     * it under the terms of the GNU General Public License as published by
     * the Free Software Foundation; either version 2 of the License, or
     * (at your option) any later version.
     *
     * This program is distributed in the hope that it will be useful,
     * but WITHOUT ANY WARRANTY; without even the implied warranty of
     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     * GNU General Public License for more details.
     *
     * You should have received a copy of the GNU General Public License
     * along with this program; if not, write to the Free Software
     * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
     */
    
    #include <stdio.h>
    
    typedef unsigned char byte;
    
    #define ror4(x) (((x) >> 1) | (((x) & 1) << 3))
    
    static byte q0(byte x)
    {
    
        static byte t0[16] = { 0x8, 0x1, 0x7, 0xD, 0x6, 0xF, 0x3, 0x2,
                               0x0, 0xB, 0x5, 0x9, 0xE, 0xC, 0xA, 0x4 };
        static byte t1[16] = { 0xE, 0xC, 0xB, 0x8, 0x1, 0x2, 0x3, 0x5,
                               0xF, 0x4, 0xA, 0x6, 0x7, 0x0, 0x9, 0xD };
        static byte t2[16] = { 0xB, 0xA, 0x5, 0xE, 0x6, 0xD, 0x9, 0x0,
                               0xC, 0x8, 0xF, 0x3, 0x2, 0x4, 0x7, 0x1 };
        static byte t3[16] = { 0xD, 0x7, 0xF, 0x4, 0x1, 0x2, 0x6, 0xE,
                               0x9, 0xB, 0x3, 0x0, 0x8, 0x5, 0xC, 0xA };
    
        byte a0 = x / 16;
        byte b0 = x % 16;
    
        byte a1 = a0 ^ b0;
        byte b1 = a0 ^ ror4(b0) ^ ((8*a0) % 16);
    
        byte a2 = t0[a1];
        byte b2 = t1[b1];
    
        byte a3 = a2 ^ b2;
        byte b3 = a2 ^ ror4(b2) ^ ((8*a2) % 16);
    
        byte a4 = t2[a3];
        byte b4 = t3[b3];
    
        byte y = 16*b4 + a4;
    
        return y;
    }
    
    static byte q1(byte x)
    {
        static byte t0[16] = { 0x2, 0x8, 0xB, 0xD, 0xF, 0x7, 0x6, 0xE,
                               0x3, 0x1, 0x9, 0x4, 0x0, 0xA, 0xC, 0x5 };
        static byte t1[16] = { 0x1, 0xE, 0x2, 0xB, 0x4, 0xC, 0x3, 0x7,
                               0x6, 0xD, 0xA, 0x5, 0xF, 0x9, 0x0, 0x8 };
        static byte t2[16] = { 0x4, 0xC, 0x7, 0x5, 0x1, 0x6, 0x9, 0xA,
                               0x0, 0xE, 0xD, 0x8, 0x2, 0xB, 0x3, 0xF };
        static byte t3[16] = { 0xB, 0x9, 0x5, 0x1, 0xC, 0x3, 0xD, 0xE,
                               0x6, 0x4, 0x7, 0xF, 0x2, 0x0, 0x8, 0xA };
    
        byte a0 = x / 16;
        byte b0 = x % 16;
    
        byte a1 = a0 ^ b0;
        byte b1 = a0 ^ ror4(b0) ^ ((8*a0) % 16);
    
        byte a2 = t0[a1];
        byte b2 = t1[b1];
    
        byte a3 = a2 ^ b2;
        byte b3 = a2 ^ ror4(b2) ^ ((8*a2) % 16);
    
        byte a4 = t2[a3];
        byte b4 = t3[b3];
    
        byte y = 16*b4 + a4;
    
        return y;
    }
    
    int
    main(void)
    {
        int i, j;
    
        printf("static byte q0[] = { ");
        for (i = 0; i < 32; i++) {
            for (j = 0; j < 8; j++)
                printf("0x%02X, ", q0(i*8+j));
            if (i == 31)
                printf("};\n\n");
            else
                printf("\n                     ");
        }
    
        printf("static byte q1[] = { ");
        for (i = 0; i < 32; i++) {
            for (j = 0; j < 8; j++)
                printf("0x%02X, ", q1(i*8+j));
            if (i == 31)
                printf("};\n");
            else
                printf("\n                     ");
        }
    
        return 0;
    }