clean up chip-8 into its own file

1 files changed, 212 insertions, 0 deletions

diff --git a/sources/chip8.c b/sources/chip8.c
new file mode 100644
index 0000000..f5a28a8
--- /dev/null
+++ b/sources/chip8.c
@@ -0,0 +1,212 @@
+#define C8_RESET_VECTOR     0x200
+#define C8_CYCLES_PER_FRAME 1000
+
+static const u8 fnt[] =
+{
+    0xF0, 0x90, 0x90, 0x90, 0xF0, /* 0 */
+    0x20, 0x60, 0x20, 0x20, 0x70, /* 1 */
+    0xF0, 0x10, 0xF0, 0x80, 0xF0, /* 2 */
+    0xF0, 0x10, 0xF0, 0x10, 0xF0, /* 3 */
+    0x90, 0x90, 0xF0, 0x10, 0x10, /* 4 */
+    0xF0, 0x80, 0xF0, 0x10, 0xF0, /* 5 */
+    0xF0, 0x80, 0xF0, 0x90, 0xF0, /* 6 */
+    0xF0, 0x10, 0x20, 0x40, 0x40, /* 7 */
+    0xF0, 0x90, 0xF0, 0x90, 0xF0, /* 8 */
+    0xF0, 0x90, 0xF0, 0x10, 0xF0, /* 9 */
+    0xF0, 0x90, 0xF0, 0x90, 0x90, /* A */
+    0xE0, 0x90, 0xE0, 0x90, 0xE0, /* B */
+    0xF0, 0x80, 0x80, 0x80, 0xF0, /* C */
+    0xE0, 0x90, 0x90, 0x90, 0xE0, /* D */
+    0xF0, 0x80, 0xF0, 0x80, 0xF0, /* E */
+    0xF0, 0x80, 0xF0, 0x80, 0x80  /* F */
+};
+
+
+typedef struct
+{
+    u16 pc;
+    u8  sp;
+
+    u16 i;
+    u16 keys;
+
+    u64 cycles;
+
+            /* timers: */
+    u8  dt; /* - delay */
+    u8  st; /* - sound */
+
+    bool running;
+
+    union
+    {
+        struct
+        {
+            u8  v[16];
+            u64 disp[32];
+            u8  font[sizeof(fnt)];
+            u16 stack[16];
+
+        } sys;
+        u8 ram[4*KB];
+    } mem;
+
+} chip8;
+
+#define V       mem.sys.v
+#define STACK   mem.sys.stack
+#define DISPLAY mem.sys.disp
+#define FONT    mem.sys.font
+#define RAM     mem.ram
+
+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;
+
+
+void c8_reset(chip8* c8)
+{
+    assert(c8);
+    assert(sizeof(c8->mem) > sizeof(fnt));
+    assert(sizeof(c8->mem) >= 4*KB);
+
+    memcpy(c8->FONT, fnt, sizeof(fnt));
+
+    c8->pc = C8_RESET_VECTOR;
+    c8->running = true;
+}
+
+void c8_dump_state(chip8* c8, bool stack)
+{
+    int i = 0;
+
+    for(i = 0; i < (int)sizeof(c8->V); i += 4)
+    {
+        printf("      V%x: %02X (%3d) ",  i+0, c8->V[i+0], c8->V[i+0]);
+        printf("V%x: %02X (%3d) ",  i+1, c8->V[i+1], c8->V[i+1]);
+        printf("V%x: %02X (%3d) ",  i+2, c8->V[i+2], c8->V[i+2]);
+        printf("V%x: %02X (%3d)\n", i+3, c8->V[i+3], c8->V[i+3]);
+    }
+
+    printf("      I:%04X SP: %02X DT: %02X ST: %02X CYCLES: %llu\n",
+            c8->i, c8->sp, c8->dt, c8->st, c8->cycles);
+
+    if(stack)
+    {
+        printf("stack:\n");
+        for(i = 0; i < (int)sizeof(c8->STACK); i += 2)
+        {
+            printf("      %-2d: %04X ",  i+0, c8->STACK[i+0]);
+            printf("%-2d: %04X\n", i+1, c8->STACK[i+1]);
+        }
+    }
+}
+
+
+
+#define c8_decode_generate(name)                    \
+void c8_##name(u8* code, u16 offset, void* usrdat)  \
+{                                                   \
+    u16 word, instr, nnn;                           \
+    u8  o, x, y, n, kk;                             \
+                                                    \
+    (void)usrdat;                                   \
+                                                    \
+    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);                       \
+                                                    \
+    (void)o;                                        \
+    (void)nnn;                                      \
+    (void)x;                                        \
+    (void)y;                                        \
+    (void)n;                                        \
+    (void)kk;                                       \
+                                                    \
+    X_C8_PRELUDE;                                   \
+                                                    \
+    if(o == 0 && nnn == 0x0E0)      X_C8_CLS;       \
+    else if(o == 0 && nnn == 0x0EE) X_C8_RET;       \
+    else if(o == 0)                 X_C8_SYS;       \
+    else if(o == 1)                 X_C8_JP;        \
+    else if(o == 2)                 X_C8_CALL;      \
+    else if(o == 0xA)               X_C8_LDI;       \
+    else if(o == 0xB)               X_C8_JPV;       \
+    else if(o == 3)                 X_C8_SEB;       \
+    else if(o == 4)                 X_C8_SNEB;      \
+    else if(o == 6)                 X_C8_LD;        \
+    else if(o == 7)                 X_C8_ADDB;      \
+    else if(o == 0xC)               X_C8_RND;       \
+    else if(o == 0xE && kk == 0x9E) X_C8_SKP;       \
+    else if(o == 0xE && kk == 0xA1) X_C8_SKNP;      \
+    else if(o == 0xF && kk == 0x07) X_C8_MVDT;      \
+    else if(o == 0xF && kk == 0x0A) X_C8_LDK;       \
+    else if(o == 0xF && kk == 0x15) X_C8_LDDT;      \
+    else if(o == 0xF && kk == 0x18) X_C8_LDST;      \
+    else if(o == 0xF && kk == 0x1E) X_C8_ADDI;      \
+    else if(o == 0xF && kk == 0x29) X_C8_HEX;       \
+    else if(o == 0xF && kk == 0x33) X_C8_BCD;       \
+    else if(o == 0xF && kk == 0x55) X_C8_SAVE;      \
+    else if(o == 0xF && kk == 0x65) X_C8_RESTORE;   \
+    else if(o == 5 && n == 0)       X_C8_SE;        \
+    else if(o == 8 && n == 0)       X_C8_MOVE;      \
+    else if(o == 8 && n == 1)       X_C8_OR;        \
+    else if(o == 8 && n == 2)       X_C8_AND;       \
+    else if(o == 8 && n == 3)       X_C8_XOR;       \
+    else if(o == 8 && n == 4)       X_C8_ADD;       \
+    else if(o == 8 && n == 5)       X_C8_SUB;       \
+    else if(o == 8 && n == 6)       X_C8_SHR;       \
+    else if(o == 8 && n == 7)       X_C8_SUBN;      \
+    else if(o == 8 && n == 0xE)     X_C8_SHL;       \
+    else if(o == 9 && n == 0)       X_C8_SNE;       \
+    else if(o == 0xD)               X_C8_DRW;       \
+    else                            X_C8_ILL;       \
+                                                    \
+    X_C8_EPILOGUE;                                  \
+}