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deobfuscated.cc
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deobfuscated.cc
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#include <SDL2/SDL.h>
#include <cstdint>
#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>
#define OPCREL(_) opcrel = (opcode - _) / 8
#define OP4_NX8(_,X) case _: case _ + 8*X: case _ + 16*X: case _ + 24*X:
#define OP4_NX16_REL(_) OP4_NX8(_, 2) opcrel = (opcode - _) / 16;
#define OP5_FLAG(_, always) \
OP4_NX8(_, 1) \
case always: \
OPCREL(_), carry = opcode == always || !(F & F_mask[opcrel]) ^ opcrel & 1;
#define OP8_REL(_) \
case _ ... _ + 7: \
tmp8 = reg8_access(0, 0, opcrel = opcode);
#define OP8_NX8_REL(_) \
OP4_NX8(_, 1) OP4_NX8(_ + 32, 1) tmp8 = reg8_access(0, 0, OPCREL(_));
#define OP64_REL(_) \
case _ ... _ + 55: OP8_REL(_ + 56) OPCREL(_);
#define OP9_IMM_PTR(_) \
OP8_REL(_) case _ + 70 : operand = opcode & 64 ? mem8(PC++) : tmp8;
uint8_t opcode, opcrel, tmp8, operand, carry, neg, *rom0, *rom1, io[512],
video_ram[8192], work_ram[16384], *extram, *extrambank,
reg8[] = {19, 0, 216, 0, 77, 1, 176, 1}, &F = reg8[6], &A = reg8[7],
*reg8_group[] = {reg8 + 1, reg8, reg8 + 3, reg8 + 2,
reg8 + 5, reg8 + 4, &F, &A},
&IF = io[271], &LCDC = io[320], &LY = io[324], IME, halt;
uint8_t const *key_state;
uint16_t PC = 256, *reg16 = (uint16_t *)reg8, &HL = reg16[2], SP = 65534,
&DIV = (uint16_t &)io[259], ppu_dot = 32,
*reg16_group1[] = {reg16, reg16 + 1, &HL, &SP},
*reg16_group2[] = {reg16, reg16 + 1, &HL, &HL}, prev_cycles, cycles;
int tmp, tmp2, F_mask[] = {128, 128, 16, 16}, frame_buffer[23040],
palette[] = {-1, -23197, -65536, -1 << 24,
-1, -8092417, -12961132, -1 << 24};
void tick() { cycles += 4; }
uint8_t mem8(uint16_t addr = HL, uint8_t val = 0, int write = 0) {
tick();
switch (addr >> 13) {
case 1:
if (write)
rom1 = rom0 + ((val ? val & 63 : 1) << 14);
case 0:
return rom0[addr];
case 2:
if (write && val <= 3)
extrambank = extram + (val << 13);
case 3:
return rom1[addr & 16383];
case 4:
addr &= 8191;
if (write)
video_ram[addr] = val;
return video_ram[addr];
case 5:
addr &= 8191;
if (write)
extrambank[addr] = val;
return extrambank[addr];
case 7:
if (addr >= 65024) {
if (write) {
if (addr == 65350)
for (int y = 160; --y >= 0;)
io[y] = mem8(val << 8 | y);
io[addr & 511] = val;
}
if (addr == 65280) {
if (~io[256] & 16)
return ~(16 + key_state[SDL_SCANCODE_DOWN] * 8 +
key_state[SDL_SCANCODE_UP] * 4 +
key_state[SDL_SCANCODE_LEFT] * 2 +
key_state[SDL_SCANCODE_RIGHT]);
if (~io[256] & 32)
return ~(32 + key_state[SDL_SCANCODE_RETURN] * 8 +
key_state[SDL_SCANCODE_TAB] * 4 +
key_state[SDL_SCANCODE_Z] * 2 +
key_state[SDL_SCANCODE_X]);
return 255;
}
return io[addr & 511];
}
case 6:
addr &= 16383;
if (write)
work_ram[addr] = val;
return work_ram[addr];
}
}
void set_flags(uint8_t mask, int Z, int N, int H, int C) {
F = F & mask | !Z << 7 | N << 6 | H << 5 | C << 4;
}
uint16_t read16(uint16_t &addr = PC) {
tmp8 = mem8(addr++);
return mem8(addr++) << 8 | tmp8;
}
void push(uint16_t val) {
mem8(--SP, val >> 8, 1);
mem8(--SP, val, 1);
tick();
}
uint8_t reg8_access(uint8_t val, int write = 1, uint8_t o = opcrel) {
return (o &= 7) == 6 ? mem8(HL, val, write)
: write ? *reg8_group[o] = val
: *reg8_group[o];
}
uint8_t get_color(int tile, int y_offset, int x_offset) {
uint8_t *tile_data = &video_ram[tile * 16 + y_offset * 2];
return (tile_data[1] >> x_offset) % 2 * 2 + (*tile_data >> x_offset) % 2;
}
int main() {
rom1 = (rom0 = (uint8_t *)mmap(0, 1 << 20, PROT_READ, MAP_SHARED,
open("rom.gb", O_RDONLY), 0)) +
32768;
tmp = open("rom.sav", O_CREAT|O_RDWR, 0666);
ftruncate(tmp, 32768);
extrambank = extram =
(uint8_t *)mmap(0, 32768, PROT_READ | PROT_WRITE, MAP_SHARED, tmp, 0);
LCDC = 145;
DIV = 44032;
SDL_Init(SDL_INIT_VIDEO);
SDL_Renderer *renderer = SDL_CreateRenderer(
SDL_CreateWindow("pokegb", 0, 0, 800, 720, SDL_WINDOW_SHOWN), -1,
SDL_RENDERER_PRESENTVSYNC);
SDL_Texture *texture = SDL_CreateTexture(
renderer, SDL_PIXELFORMAT_RGBA32, SDL_TEXTUREACCESS_STREAMING, 160, 144);
key_state = SDL_GetKeyboardState(0);
while (1) {
prev_cycles = cycles;
if (IME & IF & io[511]) {
IF = halt = IME = 0;
cycles += 8;
push(PC);
PC = 64;
} else if (halt)
tick();
else
switch (opcode = mem8(PC++)) {
OP4_NX16_REL(1) // LD r16, u16
*reg16_group1[opcrel] = read16();
case 0: // NOP
break;
OP4_NX16_REL(10) // LD A, (r16)
OP4_NX16_REL(2) // LD (r16), A
tmp = opcode & 8;
reg8_access(mem8(*reg16_group2[opcrel], A, !tmp), tmp, 7);
HL += opcrel < 2 ? 0 : 5 - 2 * opcrel;
break;
OP4_NX16_REL(11) // DEC r16
OP4_NX16_REL(3) // INC r16
*reg16_group1[opcrel] += opcode & 8 ? -1 : 1;
tick();
break;
OP8_NX8_REL(5) // DEC r8 / DEC (HL)
OP8_NX8_REL(4) // INC r8 / INC (HL)
neg = opcode & 1;
reg8_access(tmp8 += 1 - neg * 2);
set_flags(16, tmp8, neg, !(tmp8 + neg & 15), 0);
break;
OP8_NX8_REL(6) // LD r8, u8 / LD (HL), u8
reg8_access(mem8(PC++));
break;
OP4_NX16_REL(9) // ADD HL, r16
tmp = *reg16_group1[opcrel];
set_flags(128, 1, 0, HL % 4096 + tmp % 4096 > 4095, HL + tmp > 65535);
HL += tmp;
tick();
break;
OP4_NX8(7,1)
neg = 1;
goto ROTATE;
OP5_FLAG(32, 24) // JR i8 / JR <condition>, i8
tmp8 = mem8(PC++);
if (carry)
PC += (int8_t)tmp8, tick();
break;
case 39: // DAA
carry = tmp8 = 0;
if (F & 32 || ~F & 64 && A % 16 > 9)
tmp8 = 6;
if (F & 16 || ~F & 64 && A > 153)
tmp8 |= 96, carry = 1;
set_flags(65, A += F & 64 ? -tmp8 : tmp8, 0, 0, carry);
break;
case 47: // CPL
A = ~A;
set_flags(144, 1, 1, 1, 0);
break;
case 55: case 63: // SCF / CCF
set_flags(128, 1, 0, 0, opcode & 8 ? !(F & 16) : 1);
break;
OP64_REL(64) // LD r8, r8 / LD r8, (HL) / LD (HL), r8 / HALT
opcode == 118 ? halt = 1 : reg8_access(tmp8);
break;
OP9_IMM_PTR(128) // ADD A, r8 / ADD A, (HL) / ADD A, u8
neg = carry = 0;
goto ALU;
OP9_IMM_PTR(136) // ADC A, r8 / ADC A, (HL) / ADC A, u8
neg = 0;
carry = F / 16 % 2;
goto ALU;
OP9_IMM_PTR(184) // CP A, r8 / CP A, (HL) / CP A, u8
goto SUB;
OP9_IMM_PTR(144) // SUB A, r8 / SUB A, (HL) / SUB A, u8
SUB:
carry = 1;
goto SUBTRACT;
OP9_IMM_PTR(152) // SBC A, r8 / SBC A, (HL) / SBC A, u8
carry = !(F / 16 % 2);
SUBTRACT:
neg = 1;
operand = ~operand;
ALU:
set_flags(0, tmp8 = A + operand + carry, neg,
(A % 16 + operand % 16 + carry > 15) ^ neg,
(A + operand + carry > 255) ^ neg);
if (~(opcode / 8) & 7)
A = tmp8;
break;
OP9_IMM_PTR(160) // AND A, r8 / AND A, (HL) / AND A, u8
set_flags(0, A &= operand, 0, 1, 0);
break;
OP9_IMM_PTR(168) // XOR A, r8 / XOR A, (HL) / XOR A, u8
set_flags(0, A ^= operand, 0, 0, 0);
break;
OP9_IMM_PTR(176) // OR A, r8 / OR A, (HL) / OR A, u8
set_flags(0, A |= operand, 0, 0, 0);
break;
case 217: // RETI
carry = IME = 1;
goto RET;
OP5_FLAG(192, 201) // RET / RET <condition>
RET:
tick();
if (carry)
PC = read16(SP);
break;
OP4_NX16_REL(193) // POP r16
reg16[opcrel] = read16(SP);
break;
OP5_FLAG(194, 195) // JP u16 / JP <condition>, u16
goto CALL;
OP5_FLAG(196, 205) // CALL u16 / CALL <condition>, u16
CALL:
tmp = read16();
if (carry)
opcode & 4 ? push(PC) : tick(), PC = tmp;
break;
OP4_NX16_REL(197) // PUSH r16
push(reg16[opcrel]);
break;
case 203:
neg = 0;
opcode = mem8(PC++);
ROTATE:
switch (opcode) {
OP8_REL(0) // RLC r8 / RLC (HL)
OP8_REL(16) // RL r8 / RL (HL)
OP8_REL(32) // SLA r8 / SLA (HL)
carry = tmp8 >> 7;
tmp8 += tmp8 + (opcode & 16 ? F / 16 % 2 : opcode & 32 ? 0 : carry);
goto CARRY_ZERO_FLAGS_U;
OP8_REL(48) // SWAP r8 / SWAP (HL)
carry = 0;
tmp8 = tmp8 * 16 + tmp8 / 16;
goto CARRY_ZERO_FLAGS_U;
OP8_REL(8) // RRC r8 / RRC (HL)
OP8_REL(24) // RR r8 / RR (HL)
OP8_REL(40) // SRA r8 / SRA (HL)
OP8_REL(56) // SRL r8 / SRL (HL)
carry = tmp8 & 1;
tmp8 = (opcode & 48) == 32
? (int8_t)tmp8 >> 1
: tmp8 / 2 + (opcode & 32 ? 0
: opcode & 16 ? (F * 8 & 128)
: carry * 128);
CARRY_ZERO_FLAGS_U:
reg8_access(tmp8);
set_flags(0, neg || tmp8, 0, 0, carry);
break;
OP64_REL(64) // BIT bit, r8 / BIT bit, (HL)
set_flags(16, tmp8 & 1 << opcrel, 0, 1, 0);
break;
OP64_REL(128) // RES bit, r8 / RES bit, (HL)
reg8_access(tmp8 & ~(1 << opcrel),1,opcode);
break;
OP64_REL(192) // SET bit, r8 / SET bit, (HL)
reg8_access(tmp8 | 1 << opcrel,1,opcode);
}
break;
case 224: case 226: case 234:
case 240: case 242: case 250:
// LD A, (FF00 + u8) / LD A, (FF00 + C) / LD A, (u16)
// LD (FF00 + u8), A / LD (FF00 + C), A / LD (u16), A
tmp = opcode & 16;
reg8_access(mem8(opcode & 8
? read16()
: 65280 + (opcode & 2 ? *reg8 : mem8(PC++)),
A, !tmp),
tmp, 7);
break;
case 233: // JP HL
PC = HL;
break;
case 243: case 251: // DI / EI
IME = opcode != 243;
break;
case 248: // LD HL, SP + i8
HL = SP + (int8_t)(tmp8 = mem8(PC++));
set_flags(0, 1, 0, SP % 16 + tmp8 % 16 > 15, (uint8_t)SP + tmp8 > 255);
tick();
break;
case 249: // LD SP, HL
SP = HL;
tick();
}
for (DIV += cycles - prev_cycles; prev_cycles++ != cycles;)
if (LCDC & 128) {
if (++ppu_dot == 456) {
if (LY < 144)
for (tmp = 160; --tmp >= 0;) {
uint8_t is_window =
LCDC & 32 && LY >= io[330] && tmp >= io[331] - 7,
x_offset = is_window ? tmp - io[331] + 7 : tmp + io[323],
y_offset = is_window ? LY - io[330] : LY + io[322];
uint16_t
palette_index = 0,
tile = video_ram[(LCDC & (is_window ? 64 : 8) ? 7 : 6) << 10 |
y_offset / 8 * 32 + x_offset / 8],
color = get_color(LCDC & 16 ? tile : 256 + (int8_t)tile,
y_offset & 7, 7 - x_offset & 7);
if (LCDC & 2)
for (uint8_t *sprite = io; sprite < io + 160; sprite += 4) {
uint8_t sprite_x = tmp - sprite[1] + 8,
sprite_y = LY - *sprite + 16,
sprite_color = get_color(
sprite[2], sprite_y ^ (sprite[3] & 64 ? 7 : 0),
sprite_x ^ (sprite[3] & 32 ? 0 : 7));
if (sprite_x < 8 && sprite_y < 8 &&
!(sprite[3] & 128 && color) && sprite_color) {
color = sprite_color;
palette_index = 1 + !!(sprite[3] & 16);
break;
}
}
frame_buffer[LY * 160 + tmp] =
palette[(io[327 + palette_index] >> 2 * color) % 4 +
palette_index * 4 &
7];
}
if (LY == 143) {
IF |= 1;
SDL_UpdateTexture(texture, 0, frame_buffer, 640);
SDL_RenderCopy(renderer, texture, 0, 0);
SDL_RenderPresent(renderer);
SDL_Event event;
while (SDL_PollEvent(&event))
if (event.type == SDL_QUIT)
return 0;
}
LY = (LY + 1) % 154;
ppu_dot = 0;
}
} else
LY = ppu_dot = 0;
}
}