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#ifndef COMMON_H_04DD2B2A
#define COMMON_H_04DD2B2A
#include <vector>
#include <string_view>
#include <fstream>
#include <stdexcept>
class BufferView {
public:
BufferView(const std::vector<char>& buffer) : data_(&buffer) {}
int ReadNextByte() {
int o2r = offset_;
offset_++;
return ReadByte(o2r);
}
int ReadByte(int addr) const {
return static_cast<unsigned char>((*data_)[addr]);
}
int ReadNextTwoBytes() {
int o2r = offset_;
offset_+=2;
return ReadTwoBytes(o2r);
}
int ReadTwoBytes(int addr) const {
return static_cast<unsigned char>((*data_)[addr]) | (static_cast<unsigned char>((*data_)[addr + 1]) << 8);
}
int ReadNextFourBytes() {
int o2r = offset_;
offset_+=4;
return ReadFourBytes(o2r);
}
unsigned long ReadFourBytes(int addr) const {
return static_cast<unsigned char>((*data_)[addr]) | (static_cast<unsigned char>((*data_)[addr + 1]) << 8) | (static_cast<unsigned char>((*data_)[addr + 2]) << 16) | (static_cast<unsigned char>((*data_)[addr + 3]) << 24);
}
void Seek(int offset) {
offset_ = offset;
}
void SeekAdd(int delta) {
offset_ += delta;
}
std::vector<char> Decompress(int addr) {
int start = addr;
Seek(addr);
if (ReadNextByte() != 0x10) {
throw std::domain_error("No LZ77 signature");
}
int length = ReadNextByte();
length += (ReadNextByte() << 8);
length += (ReadNextByte() << 16);
std::vector<char> result(length, 0);
int bPos = 0;
while (bPos < length) {
unsigned char ch = ReadNextByte();
for (int i=0;i<8;i++) {
switch ((ch >> (7-i)) & 1) {
case 0: {
if (bPos >= length) break;
result[bPos++] = ReadNextByte();
break;
}
case 1: {
int t = (ReadNextByte() << 8);
t += ReadNextByte();
int n = ((t >> 12) & 0xF) + 3; // num of bytes to copy
int o = (t & 0xFFF);
memcpy(result.data() + bPos, result.data() + bPos - o - 1, n);
bPos += n;
break;
}
default: break;
}
}
}
return result;
}
private:
const std::vector<char>* data_;
int offset_ = 0;
};
class Rom {
public:
explicit Rom(std::string_view filename) {
std::ifstream romfile(filename.data(), std::ios::binary);
if (!romfile.is_open()) {
throw std::invalid_argument("Could not find ROM file: " + std::string(filename));
}
romfile.seekg(0, romfile.end);
int length = romfile.tellg();
romfile.seekg(0, romfile.beg);
if (length != 0x2000000) {
throw std::invalid_argument("Incorrect ROM length");
}
data_ = std::vector<char>(length, 0);
romfile.read(data_.data(), length);
const char header[] = {'M','O','T','H','E','R','3',0,0,0,0,0,'A','3','U','J'};
std::string headerTest;
for (int i = 0xA0; i < 0xB0; i++) {
if (data_.at(i) != header[i-0xA0]) {
std::cout << i << std::endl;
throw std::invalid_argument("Invalid ROM header");
}
}
}
const std::vector<char>& data() const { return data_; }
BufferView buffer() const { return {data_}; }
private:
std::vector<char> data_;
};
#endif /* end of include guard: COMMON_H_04DD2B2A */
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