это ужас

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2025-06-07 18:45:05 +03:00
commit 930cd451a9
4 changed files with 157 additions and 0 deletions

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emulator.h Normal file
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#include <iostream>
#include <cstdint>
#include <fstream>
#define MEMORY_SIZE 1048576
union reg16 {
struct {
uint8_t low;
uint8_t high;
};
uint16_t value;
};
struct ModRM {
uint8_t mod; // addressing mode
uint8_t reg; // source
uint8_t rm; // dest
};
reg16 AX, BX, CX, DX; // general regs
uint16_t SI, DI; // source index, dest index
uint16_t BP, SP; // base ptr, stack ptr
uint16_t IP; // instruction ptr
uint16_t CS, DS, ES, SS; // code segmets reg, data segment reg, extra segment reg, stack segment reg
bool CF; // carry
bool PF; // parity
bool AF; // auxiliary carry
bool ZF; // zero
bool SF; // sign
bool TF; // trap
bool IF; // interrupt
bool DF; // direction
bool OF; // overflow
uint8_t ram[MEMORY_SIZE];
uint32_t physical_addr(uint16_t seg, uint16_t offset);
bool load_binary(char* filename, size_t addr);
ModRM parse_modrm(uint8_t byte);
uint8_t get_reg_byte(uint8_t code);
uint8_t set_reg_byte(uint8_t code, uint8_t value);
uint32_t physical_addr(uint16_t seg, uint16_t offset) {
return ((uint32_t) seg << 4) + offset;
}
bool load_binary(char* filename, size_t addr) {
std::ifstream file(filename, std::ios::binary);
if (!file) {
std::cerr << "failed to open file " << filename << "\n";
return false;
}
file.seekg(0, std::ios::end);
size_t file_size = file.tellg();
file.seekg(0, std::ios::beg);
if (file_size > MEMORY_SIZE - addr) {
std::cerr << "file is too big";
return false;
}
file.read(reinterpret_cast<char*>(ram + addr), file_size);
if (!file) {
std::cerr << "failed to read entire file";
return false;
}
std::cout << "file " << filename << " loaded to ram\n";
return true;
}
ModRM parse_modrm(uint8_t byte) {
ModRM modrm;
modrm.mod = (byte >> 6) & 0x3;
modrm.reg = (byte >> 3) & 0x7;
modrm.rm = byte & 0x7;
return modrm;
}
uint8_t get_reg_byte(uint8_t code, uint8_t value) {
switch (code)
{
case 0: AX.low = value; break;
case 1: CX.low = value; break;
case 2: DX.low = value; break;
case 3: BX.low = value; break;
case 4: AX.high = value; break;
case 5: AX.high = value; break;
case 6: AX.high = value; break;
case 7: AX.high = value; break;
default:
std::cerr << "invalid reg code for 8-bit reg";
return 0;
}
}
uint8_t set_reg_byte(uint8_t code) {
switch (code)
{
case 0: return AX.low;
case 1: return CX.low;
case 2: return DX.low;
case 3: return BX.low;
case 4: return AX.high;
case 5: return CX.high;
case 6: return DX.high;
case 7: return BX.high;
default:
std::cerr << "invalid reg code for 8-bit reg";
return 0;
}
}