admin/intel8086
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

added add_eb_gb and add_ev_gv instructions, fixed some stuff ig

Browse Source
This commit is contained in:
pablusha
2025-06-08 22:28:03 +03:00
parent 930cd451a9
commit 500ffda8c2
4 changed files with 226 additions and 24 deletions
Download Patch File Download Diff File Expand all files Collapse all files

158
emulator.h
View File

@@ -41,7 +41,16 @@ 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);
void set_reg_byte(uint8_t code, uint8_t value);
uint16_t get_reg_word(uint8_t code);
void set_reg_word(uint8_t code, uint16_t value);
uint16_t get_displacement(uint8_t size);
uint32_t calc_effective_addr(ModRM modrm);
void update_flags_add(uint8_t b1, uint8_t b2, uint8_t res);
void update_flags_add16(uint16_t w1, uint16_t w2, uint16_t res);
uint32_t physical_addr(uint16_t seg, uint16_t offset) {
return ((uint32_t) seg << 4) + offset;
@@ -82,26 +91,8 @@ ModRM parse_modrm(uint8_t byte) {
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)
{
uint8_t get_reg_byte(uint8_t code) {
switch (code) {
case 0: return AX.low;
case 1: return CX.low;
case 2: return DX.low;
@@ -114,4 +105,129 @@ uint8_t set_reg_byte(uint8_t code) {
std::cerr << "invalid reg code for 8-bit reg";
return 0;
}
}
void set_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: CX.high = value; break;
case 6: DX.high = value; break;
case 7: BX.high = value; break;
default:
std::cerr << "invalid reg code for 8-bit reg";
}
}
uint16_t get_reg_word(uint8_t code) {
switch (code) {
case 0: return AX.value;
case 1: return CX.value;
case 2: return DX.value;
case 3: return BX.value;
case 4: return SP;
case 5: return BP;
case 6: return SI;
case 7: return DI;
default:
std::cerr << "invalid reg code for 8-bit reg";
return 0;
}
}
void set_reg_word(uint8_t code, uint16_t value) {
switch (code)
{
case 0: AX.value = value; break;
case 1: CX.value = value; break;
case 2: DX.value = value; break;
case 3: BX.value = value; break;
case 4: SP = value; break;
case 5: BP = value; break;
case 6: SI = value; break;
case 7: DI = value; break;
default:
std::cerr << "invalid reg code for 8-bit reg";
break;
}
}
uint16_t get_displacement(uint8_t size) {
uint16_t disp = 0;
uint32_t addr = physical_addr(CS, IP);
if (size == 1) { // 8-bit
disp = static_cast<int8_t>(ram[addr]);
IP++;
} else if (size == 2) {
disp = ram[addr] | (ram[addr + 1] << 8);
IP += 2;
}
return disp;
}
uint32_t calc_effective_addr(ModRM modrm) {
uint16_t base = 0;
uint16_t disp = 0;
bool has_disp = false;
switch (modrm.rm) {
case 0: base = BX.value + SI; break;
case 1: base = BX.value + DI; break;
case 2: base = BP + SI; break;
case 3: base = BP + DI; break;
case 4: base = SI; break;
case 5: base = DI; break;
case 6:
if (modrm.mod == 0) {
disp = get_displacement(2);
base = 0; // Для прямого адреса
} else base = BP;
break;
case 7: base = BX.value; break;
}
if (modrm.mod == 1) {
disp = get_displacement(1);
has_disp = true;
} else if (modrm.mod == 2) {
disp = get_displacement(2);
has_disp = true;
}
return base + (has_disp ? disp : 0);
}
void update_flags_add(uint8_t b1, uint8_t b2, uint8_t res) {
CF = (static_cast<uint16_t>(b1) + static_cast<uint16_t>(b2)) > 0xFF;
ZF = res == 0;
SF = (res & 0x80) != 0;
uint8_t count = 0;
for (int i = 0; i < 8; ++i)
count += (res >> i) & 1;
PF = (count % 2) == 0;
AF = ((b1 & 0xF) + (b2 & 0xF)) > 0xF;
OF = (~(b1 ^ b2) & (b2 ^ res) & 0x80) != 0;
}
void update_flags_add16(uint16_t w1, uint16_t w2, uint16_t res) {
CF = (static_cast<uint32_t>(w1) + static_cast<uint32_t>(w2)) > 0xFFFF;
ZF = (res == 0);
SF = (res & 0x8000) != 0;
uint8_t low_byte = res & 0xFF;
uint8_t count = 0;
for (int i = 0; i < 8; i++)
count += (low_byte >> i) & 1;
PF = (count % 2 == 0);
AF = ((w1 & 0xF) + (w2 & 0xF)) > 0xF;
OF = ((w1 ^ res) & (w2 ^ res) & 0x8000) != 0;
}