| #pragma once |
| |
| #include <stdint.h> |
| #include <stdbool.h> |
| |
| #define REGISTERS R(A) R(X) R(Y) R(SP) |
| #define CPU_FB_ADDR 0x200 |
| #define CPU_FB_W 32 |
| #define CPU_FB_H 32 |
| |
| enum // Registers |
| { |
| A, X, Y, SP |
| }; |
| |
| enum // Flags |
| { |
| CARRY = 1 << 0, |
| ZERO = 1 << 1, |
| NO_INT = 1 << 2, |
| DECIMAL = 1 << 3, |
| BREAK = 1 << 4, |
| UNUSED = 1 << 5, |
| OVERFLW = 1 << 6, |
| NEGATIV = 1 << 7, |
| }; |
| |
| enum // Address Modes |
| { |
| AM_ACC, // Accumulator implied as operand |
| AM_IMP, // Implied operand |
| AM_IMM, // Immediate operand (8 bit) |
| AM_ABS, // Absolute operand (16 bit) |
| AM_ZP, // Zero-page operand |
| AM_REL, // Relative operand (signed 8 bit) |
| AM_IND, // Absolute indirect operand (16 bit address of 16 bit address) |
| AM_AX, // Absolute indexed with X |
| AM_AY, // Absolute indexed with Y |
| AM_ZPX, // Zero-page indexed with X |
| AM_ZPY, // Zero-page indexed with Y |
| AM_ZIX, // Zero-page indexed indirect (zp,x) |
| AM_ZIY, // Zero-page indirect indexed (zp),y |
| }; |
| |
| enum // Opcodes |
| { |
| LDA, |
| LDX, |
| LDY, |
| STA, |
| STX, |
| STY, |
| ADC, |
| SBC, |
| INC, |
| INX, |
| INY, |
| DEC, |
| DEX, |
| DEY, |
| ASL, |
| LSR, |
| ROL, |
| ROR, |
| AND, |
| ORA, |
| EOR, |
| CMP, |
| CPX, |
| CPY, |
| BIT, |
| BCC, |
| BCS, |
| BNE, |
| BEQ, |
| BPL, |
| BMI, |
| BVC, |
| BVS, |
| TAX, |
| TXA, |
| TAY, |
| TYA, |
| TSX, |
| TXS, |
| PHA, |
| PLA, |
| PHP, |
| PLP, |
| JMP, |
| JSR, |
| RTS, |
| RTI, |
| CLC, |
| SEC, |
| CLD, |
| SED, |
| CLI, |
| SEI, |
| CLV, |
| BRK, |
| NOP, |
| }; |
| |
| enum // Fetch flags |
| { |
| FETCH_NO_INDIRECTION = 1, // Do not follow indirection (used for disassembly) |
| }; |
| |
| // Status register |
| typedef struct __attribute__((packed)) |
| { |
| bool negative : 1; |
| bool overflow : 1; |
| bool unused : 1; |
| bool break_ : 1; |
| bool decimal : 1; |
| bool no_int : 1; |
| bool zero : 1; |
| bool carry : 1; |
| } status_t; |
| |
| // Emulator instance, create with new_cpu() |
| typedef struct |
| { |
| uint8_t regs[4]; // A, X, Y, SP registers |
| uint16_t pc; |
| status_t status; |
| uint8_t *mem; |
| bool running; |
| bool screen_dirty; |
| } cpu_t; |
| |
| // Argument type, includes both pointer and its value |
| typedef struct |
| { |
| uint16_t val; // Value at pointer (used by most instructions) |
| uint16_t ptr; // Pointer (used by jumps, etc) |
| } arg_t; |
| |
| cpu_t new_cpu(); |
| void step(cpu_t *cpu); |
| void free_cpu(cpu_t *cpu); |
| void die(const char *message); |
| void reset(cpu_t *cpu); |
| void disas(cpu_t *cpu); |
| void disas_num(cpu_t *cpu, uint16_t num); |
| // Buffer must be freed by user |
| char *disas_step(cpu_t *cpu); |
| void run(cpu_t *cpu); |