mirror of
https://github.com/tuz358/cpu-emulator.git
synced 2025-12-18 21:14:35 +03:00
131 lines
3.1 KiB
C++
131 lines
3.1 KiB
C++
#include "include/instructions.h"
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void Instructions::init(uint32_t eip, uint32_t esp, Memory memory){
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// initialize general purpose registers
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memset(this->registers, 0, sizeof(this->registers));
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this->registers[4] = esp;
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// initialize eflags register
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this->eflags = 0;
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// initialize instruction pointer
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this->eip = eip;
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this->memory = memory;
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this->init_instructions();
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this->init_modrm();
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}
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void Instructions::init_instructions(){
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memset(this->instructions, 0, sizeof(this->instructions));
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this->instructions[0x31] = &Instructions::xor_rm32_r32;
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this->instructions[0x90] = &Instructions::nop;
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this->instructions[0xb9] = &Instructions::mov_ecx_imm32;
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this->instructions[0xbb] = &Instructions::mov_ebx_imm32;
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this->instructions[0xeb] = &Instructions::jmp_imm8;
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this->instructions[0xf4] = &Instructions::hlt;
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}
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void Instructions::init_modrm(){
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this->modrm = 0;
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this->mod = 0;
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this->R = 0;
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this->M = 0;
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}
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void Instructions::calc_modrm(){
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this->mod = (this->modrm & 0xc0) >> 6;
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this->R = (this->modrm & 0x38) >> 3;
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this->M = this->modrm & 0x07;
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}
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void Instructions::execute_opcode(uint8_t opcode){
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(this->*instructions[opcode])();
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}
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void Instructions::xor_rm32_r32(){
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printf("xor_rm32_r32 called.\n");
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uint32_t addr, dst, imm32;
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uint8_t imm8;
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this->modrm = memory.read_uint8(this->eip);
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this->calc_modrm();
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switch (this->mod) {
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case 0:
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// xor [M], R
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// addr : M
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this->eip++;
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addr = this->registers[this->M];
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// dst : data of [M]
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dst = memory.read_uint32(addr);
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memory.write_uint32(addr, dst ^ this->registers[this->R]);
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break;
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case 1:
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// xor [M+imm8], R
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this->eip++;
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imm8 = memory.read_uint8(this->eip);
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// addr : M
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addr = this->registers[this->M];
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// dst : data of [M+imm8]
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dst = memory.read_uint32(addr + imm8);
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memory.write_uint32(addr + imm8, dst ^ this->registers[this->R]);
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break;
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case 2:
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// xor [M+imm32], R
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this->eip++;
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imm32 = memory.read_uint32(this->eip);
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imm32 = swap_endian32(imm32);
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// addr : M
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addr = this->registers[this->M];
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// dst : data of [M+imm32]
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dst = memory.read_uint32(addr + imm32);
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memory.write_uint32(addr, dst ^ this->registers[this->R]);
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this->eip += 4;
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break;
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default:
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// case mod == 3
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// xor M, R
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this->eip++;
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this->registers[this->M] ^= this->registers[this->R];
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break;
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}
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}
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void Instructions::nop(){
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printf("nop called.\n");
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}
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void Instructions::mov_ecx_imm32(){
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printf("mov_ecx_imm32 called.\n");
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this->eip++;
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uint32_t imm32 = memory.read_uint32(this->eip);
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this->registers[1] = imm32;
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this->eip += 3;
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}
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void Instructions::mov_ebx_imm32(){
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printf("mov_ebx_imm32 called.\n");
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this->eip++;
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uint32_t imm32 = memory.read_uint32(this->eip);
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this->registers[3] = imm32;
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this->eip += 3;
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}
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void jmp_imm8() {
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printf("jmp_imm8 called.\n");
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this->eip++;
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uint8_t imm8 = memory.read_uint8(this->eip);
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this->eip += imm8;
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}
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void Instructions::hlt(){
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printf("hlt called.\n");
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this->eip = 0x00;
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}
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