old-bannertool/source/3ds/lz11.cpp

#include "lz11.h"

#include <stdio.h>
#include <string.h>

#include <sstream>

#define MIN(a,b) (((a)<(b))?(a):(b))

// Ported from: https://github.com/svn2github/3DS-Explorer/blob/master/3DSExplorer/DSDecmp/Formats/Nitro/LZ11.cs

int lz11_get_occurence_length(u8* newPtr, int newLength, u8* oldPtr, int oldLength, int* disp) {
    if(disp != NULL) {
        *disp = 0;
    }

    if(newLength == 0) {
        return 0;
    }

    int maxLength = 0;
    for(int i = 0; i < oldLength - 1; i++) {
        u8* currentOldStart = oldPtr + i;
        int currentLength = 0;
        for(int j = 0; j < newLength; j++) {
            if(*(currentOldStart + j) != *(newPtr + j)) {
                break;
            }

            currentLength++;
        }

        if(currentLength > maxLength) {
            maxLength = currentLength;
            if(disp != NULL) {
                *disp = oldLength - i;
            }

            if(maxLength == newLength) {
                break;
            }
        }
    }

    return maxLength;
}

u8* lz11_compress(u8* input, u32 inputSize, u32* size) {
    if (inputSize > 0xFFFFFF) {
        printf("ERROR: LZ11 input is too large.\n");
        return NULL;
    }

    std::stringstream ss;

    u8 header[4] = { 0x11, (u8) (inputSize & 0xFF), (u8) ((inputSize >> 8) & 0xFF), (u8) ((inputSize >> 16) & 0xFF) };
    ss.write((char*) header, 4);

    int compressedLength = 4;
    u8 outbuffer[8 * 4 + 1];
    outbuffer[0] = 0;
    int bufferlength = 1;
    int bufferedBlocks = 0;
    int readBytes = 0;
    while(readBytes < inputSize) {
        if(bufferedBlocks == 8) {
            ss.write((char*) outbuffer, bufferlength);
            compressedLength += bufferlength;
            outbuffer[0] = 0;
            bufferlength = 1;
            bufferedBlocks = 0;
        }

        int disp = 0;
        int oldLength = MIN(readBytes, 0x1000);
        int length = lz11_get_occurence_length(input + readBytes, MIN(inputSize - readBytes, 0x10110), input + readBytes - oldLength, oldLength, &disp);
        if(length < 3) {
            outbuffer[bufferlength++] = *(input + (readBytes++));
        } else {
            readBytes += length;
            outbuffer[0] |= (u8)(1 << (7 - bufferedBlocks));
            if(length > 0x110) {
                outbuffer[bufferlength] = 0x10;
                outbuffer[bufferlength] |= (u8)(((length - 0x111) >> 12) & 0x0F);
                bufferlength++;
                outbuffer[bufferlength] = (u8)(((length - 0x111) >> 4) & 0xFF);
                bufferlength++;
                outbuffer[bufferlength] = (u8)(((length - 0x111) << 4) & 0xF0);
            } else if(length > 0x10) {
                outbuffer[bufferlength] = 0x00;
                outbuffer[bufferlength] |= (u8)(((length - 0x111) >> 4) & 0x0F);
                bufferlength++;
                outbuffer[bufferlength] = (u8)(((length - 0x111) << 4) & 0xF0);
            } else {
                outbuffer[bufferlength] = (u8)(((length - 1) << 4) & 0xF0);
            }

            outbuffer[bufferlength] |= (u8)(((disp - 1) >> 8) & 0x0F);
            bufferlength++;
            outbuffer[bufferlength] = (u8)((disp - 1) & 0xFF);
            bufferlength++;
        }

        bufferedBlocks++;
    }

    if(bufferedBlocks > 0) {
        ss.write((char*) outbuffer, bufferlength);
        compressedLength += bufferlength;
    }

    if(compressedLength % 4 != 0) {
        int padLength = 4 - (compressedLength % 4);
        u8 pad[padLength];
        memset(pad, 0, (size_t) padLength);

        ss.write((char*) pad, padLength);
        compressedLength += padLength;
    }

    u8* buf = (u8*) malloc((size_t) compressedLength);
    ss.read((char*) buf, compressedLength);

    *size = (u32) compressedLength;
    return buf;
}