pkmncompress.c

#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>

uint8_t *compressed;
int xrows;
int xwidth;
int curbit;
int curbyte;

void writebit(bit)
{
    if(++curbit == 8)
    {
        curbyte++;
        curbit = 0;
    }
    compressed[curbyte] |= bit << 7 - curbit;
}

void method_1(uint8_t *RAM)
{
    int i;
    int j;
    int nibble_1;
    int nibble_2;
    int code_1;
    int code_2;
    int table;
    static int method_1[2][0x10] = {{0x0, 0x1, 0x3, 0x2, 0x6, 0x7, 0x5, 0x4, 0xC, 0xD, 0xF, 0xE, 0xA, 0xB, 0x9, 0x8}, {0x8, 0x9, 0xB, 0xA, 0xE, 0xF, 0xD, 0xC, 0x4, 0x5, 0x7, 0x6, 0x2, 0x3, 0x1, 0x0}};

    for(i = 0; i < xrows * xwidth * 8; i++)
    {
        j = i / xrows;
        j += i % xrows * xwidth * 8;
        if(!(i % xrows))
        {
            nibble_2 = 0;
        }
        nibble_1 = (RAM[j] >> 4) & 0x0F;
        table = 0;
        if(nibble_2 & 1)
        {
            table = 1;
        }
        code_1 = method_1[table][nibble_1];
        nibble_2 = RAM[j] & 0x0F;
        table = 0;
        if(nibble_1 & 1)
        {
            table = 1;
        }
        code_2 = method_1[table][nibble_2];
        RAM[j] = (code_1 << 4) | code_2;
    }
}

void RLE(int nums)
{
    int search;
    int i;
    int j;
    int bitcount;
    int number;
    static int RLE[0x10] = {0x0001, 0x0003, 0x0007, 0x000F, 0x001F, 0x003F, 0x007F, 0x00FF, 0x01FF, 0x03FF, 0x07FF, 0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF};

    bitcount = -1;
    search = ++nums;
    while(search > 0)
    {
        for(i = 0; i < 0xF; i++)
        {
            if(RLE[i] == search)
            {
                bitcount = i;
                break;
            }
        }
        if(bitcount != -1)
        {
            break;
        }
        search--;
    }
    number = nums - RLE[bitcount];
    for(j = 0; j < bitcount; j++)
    {
        writebit(1);
    }
    writebit(0);
    for(j = bitcount; j >= 0; j--)
    {
        writebit((number >> j) & 1);
    }
}

void data_packet(uint8_t *bitgroups, int bgi)
{
    int i;
    for(i = 0; i < bgi; i++)
    {
        writebit((bitgroups[i] >> 1) & 1);
        writebit(bitgroups[i] & 1);
    }
    writebit(0);
    writebit(0);
}

int interpret_compress(uint8_t *RAM_1, uint8_t *RAM_2, int interpretation, int switchram)
{
    uint8_t *_1_RAM;
    uint8_t *_2_RAM;
    int i;
    int ram;
    int type;
    int nums;
    uint8_t *bitgroups;
    int byte;
    int bit;
    int bitgroup;
    int bgi = 0;

    _1_RAM = (uint8_t*) calloc(0x188, 1);
    _2_RAM = (uint8_t*) calloc(0x188, 1);
    if(switchram)
    {
        memcpy(_1_RAM, RAM_2, 0x188);
        memcpy(_2_RAM, RAM_1, 0x188);
    }
    else
    {
        memcpy(_1_RAM, RAM_1, 0x188);
        memcpy(_2_RAM, RAM_2, 0x188);
    }

    switch(interpretation)
    {
        case 1:
            method_1(_1_RAM);
            method_1(_2_RAM);
        break;
        case 2:
        case 3:
            for(i = 0; i < xrows * xwidth * 8; i++)
            {
                _2_RAM[i] ^= _1_RAM[i];
            }
            method_1(_1_RAM);
        break;
    }
    if(interpretation == 3)
    {
        method_1(_2_RAM);
    }

    curbit = 7;
    curbyte = 0;
    compressed = (uint8_t*) calloc(0x310, 1);
    compressed[0] = (xrows << 4) | xwidth;
    writebit(switchram);

    for(ram = 0; ram < 2; ram++)
    {
        type = 0;
        nums = 0;
        bitgroups = (uint8_t*) calloc(0x1000, 1);
        for(i = 0; i < xrows * xwidth * 32; i++)
        {
            byte = i / (xwidth * 32);
            byte = byte * xwidth * 8 + i % (xwidth * 8);
            bit = i / (xwidth * 8);
            bit = (bit * 2) % 8;
            if(ram)
            {
                bitgroup = (_2_RAM[byte] >> 6 - bit) & 3;
            }
            else
            {
                bitgroup = (_1_RAM[byte] >> 6 - bit) & 3;
            }
            if(!bitgroup)
            {
                if(!type)
                {
                    writebit(0);
                }
                else if(type == 1)
                {
                    nums++;
                }
                else
                {
                    data_packet(bitgroups, bgi);
                }
                type = 1;
                free(bitgroups);
                bitgroups = (uint8_t*) calloc(0x1000, 1);
                bgi = 0;
            }
            else
            {
                if(!type)
                {
                    writebit(1);
                }
                else if(type == 1)
                {
                    RLE(nums);
                }
                type = -1;
                bitgroups[bgi++] = bitgroup;
                nums = 0;
            }
        }
        if(type == 1)
        {
            RLE(nums);
        }
        else
        {
            data_packet(bitgroups, bgi);
        }
        if(!ram)
        {
            if(interpretation < 2)
            {
                writebit(0);
            }
            else
            {
                writebit(1);
                writebit(interpretation - 2);
            }
        }
    }
    free(bitgroups);
    free(_1_RAM);
    free(_2_RAM);
    return curbyte + 1;
}

int compress(uint8_t *data, int width, int height)
{
    uint8_t *RAM_1;
    uint8_t *RAM_2;
    int i;
    int newsize;
    int size = -1;
    uint8_t *current = NULL;

    xrows = height;
    xwidth = width;

    RAM_1 = (uint8_t*) calloc(0x188, 1);
    RAM_2 = (uint8_t*) calloc(0x188, 1);

    for(i = 0; i < xrows * xwidth * 8; i++)
    {
        RAM_1[i] = data[(i << 1)];
        RAM_2[i] = data[(i << 1) | 1];
    }

    for(i = 0; i < 6; i++)
    {
        newsize = interpret_compress(RAM_1, RAM_2, i / 2 + 1, i % 2);
        if(size == -1 || newsize < size)
        {
            if(current != NULL)
            {
                free(current);
            }
            current = (uint8_t*) calloc(0x310, 1);
            memcpy(current, compressed, newsize);
            free(compressed);
            size = newsize;
        }
    }
    memcpy(compressed, current, size);
    free(current);

    free(RAM_1);
    free(RAM_2);

    return size;
}

int main(int argc, char *argv[])
{
    FILE *f;
    int fz;
    int size;
    int i;
    uint8_t *contents;

    if(argc < 3)
    {
        fputs("Usage: pkmncompress infile.2bpp outfile.bin\n", stderr);
        return EXIT_FAILURE;
    }

    f = fopen(argv[1], "rb");

    if(!f)
    {
        perror("Opening file failed");
        return EXIT_FAILURE;
    }

    fseek(f, 0, SEEK_END);
    fz = ftell(f);
    if(fz > 0x310)
    {
        fputs("Error: file too large.\n", stderr);
        return EXIT_FAILURE;
    }

    contents = (uint8_t*) calloc(0x310, 1);
    fseek(f, 0, SEEK_SET);
    fread(contents, 1, fz, f);
    fclose(f);

    size = compress(contents, 7, 7);

    free(contents);

    f = fopen(argv[2], "wb");
    fwrite(compressed, 1, size, f);

    free(compressed);

    printf("Success! File size: %i bytes\n", size);

    return EXIT_SUCCESS;
}