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[LZ77 decompressor] Move to own source file

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wheremyfoodat 2023-03-21 19:49:01 +02:00
parent 5d6bf24a9d
commit a573036f6b
3 changed files with 86 additions and 78 deletions
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2
CMakeLists.txt
View file

@ -68,7 +68,7 @@ set(PICA_SOURCE_FILES src/core/PICA/gpu.cpp src/core/PICA/regs.cpp src/core/PICA
)
set(RENDERER_GL_SOURCE_FILES src/core/renderer_gl/renderer_gl.cpp src/core/renderer_gl/textures.cpp src/core/renderer_gl/etc1.cpp)
set(LOADER_SOURCE_FILES src/core/loader/elf.cpp src/core/loader/ncsd.cpp src/core/loader/ncch.cpp)
set(LOADER_SOURCE_FILES src/core/loader/elf.cpp src/core/loader/ncsd.cpp src/core/loader/ncch.cpp src/core/loader/lz77.cpp)
set(FS_SOURCE_FILES src/core/fs/archive_self_ncch.cpp src/core/fs/archive_save_data.cpp src/core/fs/archive_sdmc.cpp
src/core/fs/archive_ext_save_data.cpp src/core/fs/archive_ncch.cpp
)

82
include/loader/lz77.hpp
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@ -1,89 +1,17 @@
#pragma once
#include <algorithm>
#include <cstring>
#include <vector>
#include "helpers.hpp"
// For parsing the LZ77 format used for compressing the .code file in the ExeFS
namespace CartLZ77 {
// The difference in size between the compressed and decompressed file is stored
// As a footer in the compressed file. To get the decompressed size, we extract the diff
// And add it to the compressed size
static u32 decompressedSize(const u8* buffer, u32 compressedSize) {
u32 sizeDiff;
std::memcpy(&sizeDiff, buffer + compressedSize - 4, sizeof(u32));
return sizeDiff + compressedSize;
}
// Retrieves the uncompressed size of the compressed LZ77 data stored in buffer with a specific compressed size
u32 decompressedSize(const u8* buffer, u32 compressedSize);
template <typename T>
static u32 decompressedSize(const std::vector<T>& buffer) {
return decompressedSize((u8*)buffer.data(), u32(buffer.size() * sizeof(T)));
}
static bool decompress(std::vector<u8>& output, const std::vector<u8>& input) {
u32 sizeCompressed = input.size() * sizeof(u8);
u32 sizeDecompressed = decompressedSize(input);
output.resize(sizeDecompressed);
const u8* compressed = (u8*)input.data();
const u8* footer = compressed + sizeCompressed - 8;
u32 bufferTopAndBottom;
std::memcpy(&bufferTopAndBottom, footer, sizeof(u32));
u32 out = sizeDecompressed; // TODO: Is this meant to be u32 or s32?
u32 index = sizeCompressed - ((bufferTopAndBottom >> 24) & 0xff);
u32 stopIndex = sizeCompressed - (bufferTopAndBottom & 0xffffff);
// Set all of the decompressed buffer to 0 and copy the compressed buffer to the start of it
std::fill(output.begin(), output.end(), 0);
std::copy(input.begin(), input.end(), output.begin());
while (index > stopIndex) {
u8 control = compressed[--index];
for (uint i = 0; i < 8; i++) {
if (index <= stopIndex)
break;
if (index <= 0)
break;
if (out <= 0)
break;
if (control & 0x80) {
// Check if compression is out of bounds
if (index < 2)
return false;
index -= 2;
u32 segmentOffset = compressed[index] | (compressed[index + 1] << 8);
u32 segment_size = ((segmentOffset >> 12) & 15) + 3;
segmentOffset &= 0x0FFF;
segmentOffset += 2;
// Check if compression is out of bounds
if (out < segment_size)
return false;
for (uint j = 0; j < segment_size; j++) {
// Check if compression is out of bounds
if (out + segmentOffset >= sizeDecompressed)
return false;
u8 data = output[out + segmentOffset];
output[--out] = data;
}
}
else {
// Check if compression is out of bounds
if (out < 1)
return false;
output[--out] = compressed[--index];
}
control <<= 1;
}
}
return true;
}
}
// Decompresses an LZ77-compressed buffer stored in input to output
bool decompress(std::vector<u8>& output, const std::vector<u8>& input);
} // End namespace CartLZ77

80
src/core/loader/lz77.cpp Normal file
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@ -0,0 +1,80 @@
#pragma once
#include <algorithm>
#include <cstring>
#include "loader/lz77.hpp"
// The difference in size between the compressed and decompressed file is stored
// As a footer in the compressed file. To get the decompressed size, we extract the diff
// And add it to the compressed size
u32 CartLZ77::decompressedSize(const u8* buffer, u32 compressedSize) {
u32 sizeDiff;
std::memcpy(&sizeDiff, buffer + compressedSize - 4, sizeof(u32));
return sizeDiff + compressedSize;
}
bool CartLZ77::decompress(std::vector<u8>& output, const std::vector<u8>& input) {
u32 sizeCompressed = input.size() * sizeof(u8);
u32 sizeDecompressed = decompressedSize(input);
output.resize(sizeDecompressed);
const u8* compressed = (u8*)input.data();
const u8* footer = compressed + sizeCompressed - 8;
u32 bufferTopAndBottom;
std::memcpy(&bufferTopAndBottom, footer, sizeof(u32));
u32 out = sizeDecompressed; // TODO: Is this meant to be u32 or s32?
u32 index = sizeCompressed - ((bufferTopAndBottom >> 24) & 0xff);
u32 stopIndex = sizeCompressed - (bufferTopAndBottom & 0xffffff);
// Set all of the decompressed buffer to 0 and copy the compressed buffer to the start of it
std::fill(output.begin(), output.end(), 0);
std::copy(input.begin(), input.end(), output.begin());
while (index > stopIndex) {
u8 control = compressed[--index];
for (uint i = 0; i < 8; i++) {
if (index <= stopIndex)
break;
if (index <= 0)
break;
if (out <= 0)
break;
if (control & 0x80) {
// Check if compression is out of bounds
if (index < 2)
return false;
index -= 2;
u32 segmentOffset = compressed[index] | (compressed[index + 1] << 8);
u32 segment_size = ((segmentOffset >> 12) & 15) + 3;
segmentOffset &= 0x0FFF;
segmentOffset += 2;
// Check if compression is out of bounds
if (out < segment_size)
return false;
for (uint j = 0; j < segment_size; j++) {
// Check if compression is out of bounds
if (out + segmentOffset >= sizeDecompressed)
return false;
u8 data = output[out + segmentOffset];
output[--out] = data;
}
}
else {
// Check if compression is out of bounds
if (out < 1)
return false;
output[--out] = compressed[--index];
}
control <<= 1;
}
}
return true;
}