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typedef enum
{
C8_ILL,
/* Onnn = 0,1,2,A,B */
/* 00E0 - CLS */ C8_CLS,
/* 00EE - RET */ C8_RET,
/* 0nnn - SYS addr */ C8_SYS,
/* 1nnn - JP addr */ C8_JP,
/* 2nnn - CALL addr */ C8_CALL,
/* Annn - LD I, addr */ C8_LDI,
/* Bnnn - JP V0, addr */ C8_JPV,
/* Oxkk = 3,4,6,7,C,E,F */
/* 3xkk - SE Vx, byte */ C8_SEB,
/* 4xkk - SNE Vx, byte */ C8_SNEB,
/* 6xkk - LD Vx, byte */ C8_LD,
/* 7xkk - ADD Vx, byte */ C8_ADDB,
/* Cxkk - RND Vx, byte */ C8_RND,
/* Ex9E - SKP Vx */ C8_SKP,
/* ExA1 - SKNP Vx */ C8_SKNP,
/* Fx07 - LD Vx, DT */ C8_MVDT,
/* Fx0A - LD Vx, K */ C8_LDK,
/* Fx15 - LD DT, Vx */ C8_LDDT,
/* Fx18 - LD ST, Vx */ C8_LDST,
/* Fx1E - ADD I, Vx */ C8_ADDI,
/* Fx29 - LD F, Vx */ C8_HEX,
/* Fx33 - LD B, Vx */ C8_BCD,
/* Fx55 - LD [I], Vx */ C8_SAVE,
/* Fx65 - LD Vx, [I] */ C8_RESTORE,
/* Oxyn = 5,8,9,D */
/* 5xy0 - SE Vx, Vy */ C8_SE,
/* 8xy0 - LD Vx, Vy */ C8_MOVE,
/* 8xy1 - OR Vx, Vy */ C8_OR,
/* 8xy2 - AND Vx, Vy */ C8_AND,
/* 8xy3 - XOR Vx, Vy */ C8_XOR,
/* 8xy4 - ADD Vx, Vy */ C8_ADD,
/* 8xy5 - SUB Vx, Vy */ C8_SUB,
/* 8xy6 - SHR Vx {, Vy} */ C8_SHR,
/* 8xy7 - SUBN Vx, Vy */ C8_SUBN,
/* 8xyE - SHL Vx {, Vy} */ C8_SHL,
/* 9xy0 - SNE Vx, Vy */ C8_SNE,
/* Dxyn - DRW Vx, Vy, nibble */ C8_DRW,
C8_OP_CNT
} chip8_op;
typedef void (*instr_func)(chip8* c8, chip8_op op, u16 nnn, u8 x, u8 y, u8 n, u8 kk);
const char* chip8_disasm_fmts[C8_OP_CNT] =
{
"ILL unknown",
"CLS",
"RET",
"SYS %03X",
"JP %03X",
"CALL %03X",
"LD I, %03X",
"JP V0, %03X",
"SE V%-2x, %-2d",
"SNE V%-2x, %-2d",
"LD V%-2x, %-2d",
"ADD V%-2x, %-2d",
"RND V%-2x, %-2d",
"SKP V%-2x",
"SKNP V%-2x",
"LD V%-2x, DT",
"LD V%-2x, K",
"LD DT, V%-2x",
"LD ST, V%-2x",
"ADD I, V%-2x",
"LD F, V%-2x",
"LD B, V%-2x",
"LD [I], V%-2x",
"LD V%-2x, [I]",
"SE V%-2x, V%-2x",
"LD V%-2x, V%-2x",
"OR V%-2x, V%-2x",
"AND V%-2x, V%-2x",
"XOR V%-2x, V%-2x",
"ADD V%-2x, V%-2x",
"SUB V%-2x, V%-2x",
"SHR V%-2x, V%-2x",
"SUBN V%-2x, V%-2x",
"SHL V%-2x, V%-2x",
"SNE V%-2x, V%-2x",
"DRW V%-2x, V%-2x, %-1d"
};
void c8_decode(u8* code, u16 offset, instr_func func, chip8* c8);
void c8_disasm(chip8* c8, chip8_op op, u16 nnn, u8 x, u8 y, u8 n, u8 kk);
void c8_do(chip8* c8, chip8_op op, u16 nnn, u8 x, u8 y, u8 n, u8 kk);
void c8_decode(u8* code, u16 offset, instr_func func, chip8* c8)
{
chip8_op op = C8_ILL;
u16 word, instr, nnn;
u8 o, x, y, n, kk;
word = *(u16*)(code + offset);
instr = be16toh(word);
o = (instr & 0xF000) >> 12;
nnn = (instr & 0x0FFF);
x = (instr & 0x0F00) >> 8;
y = (instr & 0x00F0) >> 4;
n = (instr & 0x000F);
kk = (instr & 0x00FF);
if(o == 0 && nnn == 0x0E0) op = C8_CLS;
else if(o == 0 && nnn == 0x0EE) op = C8_RET;
else if(o == 0) op = C8_SYS;
else if(o == 1) op = C8_JP;
else if(o == 2) op = C8_CALL;
else if(o == 0xA) op = C8_LDI;
else if(o == 0xB) op = C8_JPV;
else if(o == 3) op = C8_SEB;
else if(o == 4) op = C8_SNEB;
else if(o == 6) op = C8_LD;
else if(o == 7) op = C8_ADDB;
else if(o == 0xC) op = C8_RND;
else if(o == 0xE && kk == 0x9E) op = C8_SKP;
else if(o == 0xE && kk == 0xA1) op = C8_SKNP;
else if(o == 0xF && kk == 0x07) op = C8_MVDT;
else if(o == 0xF && kk == 0x0A) op = C8_LDK;
else if(o == 0xF && kk == 0x15) op = C8_LDDT;
else if(o == 0xF && kk == 0x18) op = C8_LDST;
else if(o == 0xF && kk == 0x1E) op = C8_ADDI;
else if(o == 0xF && kk == 0x29) op = C8_HEX;
else if(o == 0xF && kk == 0x33) op = C8_BCD;
else if(o == 0xF && kk == 0x55) op = C8_SAVE;
else if(o == 0xF && kk == 0x65) op = C8_RESTORE;
else if(o == 5 && n == 0) op = C8_SE;
else if(o == 8 && n == 0) op = C8_MOVE;
else if(o == 8 && n == 1) op = C8_OR;
else if(o == 8 && n == 2) op = C8_AND;
else if(o == 8 && n == 3) op = C8_XOR;
else if(o == 8 && n == 4) op = C8_ADD;
else if(o == 8 && n == 5) op = C8_SUB;
else if(o == 8 && n == 6) op = C8_SHR;
else if(o == 8 && n == 7) op = C8_SUBN;
else if(o == 8 && n == 0xE) op = C8_SHL;
else if(o == 9 && n == 0) op = C8_SNE;
else if(o == 0xD) op = C8_DRW;
func(c8, op, nnn, x, y, n, kk);
}
void c8_disasm(chip8* c8, chip8_op op, u16 nnn, u8 x, u8 y, u8 kk, u8 n);
void c8_do(chip8* c8, chip8_op op, u16 nnn, u8 x, u8 y, u8 kk, u8 n);
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