-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathchip8.c
276 lines (226 loc) · 11.1 KB
/
chip8.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
#include "chip8.h"
#include "cpu.h"
#include "memory.h"
#include "display.h"
#include "sprite.h"
#include "utils.h"
#include "libs/KBQueue.h"
#include <stdlib.h>
#include <stdint.h>
#include <SDL2/SDL.h>
struct CHIP8_s {
CPU cpu;
Memory memory;
Display display;
KBQueue kbQueue;
};
static int _execute(CHIP8 chip8) {
uint8_t i;
Sprite sprite;
uint16_t opcode;
SDL_Event event;
int shouldExit = 0;
while (!shouldExit) {
opcode = memReadWord(chip8->memory, chip8->cpu.regs.PC);
switch (NIBBLE1(opcode)) {
case 0x0:
switch (LOWEST12BIT(opcode)) {
case 0x0E0: //CLS: display clear
dispClear(chip8->display);
break;
case 0x0EE: //RET: return from a subroutine
chip8->cpu.regs.SP--;
chip8->cpu.regs.PC = chip8->cpu.stack[chip8->cpu.regs.SP];
break;
}
break;
case 0x1: //JP: 1nnn jump @ address
chip8->cpu.regs.PC = LOWEST12BIT(opcode) - 2;
break;
case 0x2: //CALL 2nnn: call subroutine @ address
chip8->cpu.stack[chip8->cpu.regs.SP] = chip8->cpu.regs.PC;
chip8->cpu.regs.SP++;
chip8->cpu.regs.PC = LOWEST12BIT(opcode) - 2;
break;
case 0x3: //3xkk - SE Vx, byte: skip next instruction if Vx==kk
if (chip8->cpu.regs.VX[NIBBLE2(opcode)] == LOWBYTE(opcode))
chip8->cpu.regs.PC += 2;
break;
case 0x4: //4xkk - SNE Vx, byte: skip next instruction if Vx!=kk
if (chip8->cpu.regs.VX[NIBBLE2(opcode)] != LOWBYTE(opcode))
chip8->cpu.regs.PC += 2;
break;
case 0x5: //5xy0 - SE Vx, Vy: skip next instruction if Vx==Vy
if (chip8->cpu.regs.VX[NIBBLE2(opcode)] == chip8->cpu.regs.VX[NIBBLE3(opcode)])
chip8->cpu.regs.PC += 2;
break;
case 0x6: //6xkk - LD Vx, byte: set Vx = kk
chip8->cpu.regs.VX[NIBBLE2(opcode)] = LOWBYTE(opcode);
break;
case 0x7: //7xkk - ADD Vx, byte: set Vx=Vx+kk
chip8->cpu.regs.VX[NIBBLE2(opcode)] += LOWBYTE(opcode);
break;
case 0x8:
switch (NIBBLE4(opcode)) {
case 0: //8xy0 - LD Vx, Vy: set Vx=Vy
chip8->cpu.regs.VX[NIBBLE2(opcode)] = chip8->cpu.regs.VX[NIBBLE3(opcode)];
break;
case 1: //8xy1 - OR Vx, Vy: set Vx = Vx | Vy
chip8->cpu.regs.VX[NIBBLE2(opcode)] |= chip8->cpu.regs.VX[NIBBLE3(opcode)];
break;
case 2: //8xy2 - AND Vx, Vy: set Vx = Vx & Vy
chip8->cpu.regs.VX[NIBBLE2(opcode)] &= chip8->cpu.regs.VX[NIBBLE3(opcode)];
break;
case 3: //8xy3 - XOR Vx, Vy: set Vx = Vx ^ Vy
chip8->cpu.regs.VX[NIBBLE2(opcode)] ^= chip8->cpu.regs.VX[NIBBLE3(opcode)];
break;
case 4: //8xy4 - ADD Vx, Vy: set Vx = Vx + Vy, set VF = carry
chip8->cpu.regs.VX[0xF] =
((uint16_t) chip8->cpu.regs.VX[NIBBLE2(opcode)] +
(uint16_t) chip8->cpu.regs.VX[NIBBLE3(opcode)]) > 255;
chip8->cpu.regs.VX[NIBBLE2(opcode)] += chip8->cpu.regs.VX[NIBBLE3(opcode)];
break;
case 5: //8xy5 - SUB Vx, Vy: set Vx = Vx-Vy, set VF = NOT borrow
chip8->cpu.regs.VX[0xF] =
chip8->cpu.regs.VX[NIBBLE2(opcode)] > chip8->cpu.regs.VX[NIBBLE3(opcode)];
chip8->cpu.regs.VX[NIBBLE2(opcode)] -= chip8->cpu.regs.VX[NIBBLE3(opcode)];
break;
case 6: //8xy6 - SHR Vx {, Vy}: Set Vx = Vx SHR 1
chip8->cpu.regs.VX[0xF] = chip8->cpu.regs.VX[NIBBLE2(opcode)] & 0x1u;
chip8->cpu.regs.VX[NIBBLE2(opcode)] >>= 1u;
break;
case 7: //8xy7 - SUBN Vx, Vy: Set Vx = Vy - Vx, set VF = NOT borrow.
chip8->cpu.regs.VX[0xF] =
chip8->cpu.regs.VX[NIBBLE3(opcode)] > chip8->cpu.regs.VX[NIBBLE2(opcode)];
chip8->cpu.regs.VX[NIBBLE2(opcode)] -= chip8->cpu.regs.VX[NIBBLE3(opcode)];
break;
case 0xE: //8xyE - SHL Vx {, Vy}: Set Vx = Vx SHL 1.
chip8->cpu.regs.VX[0xF] = chip8->cpu.regs.VX[NIBBLE2(opcode)] & 0x1u;
chip8->cpu.regs.VX[NIBBLE2(opcode)] <<= 1u;
break;
}
break;
case 0x9: //9xy0 - SNE Vx, Vy: Skip next instruction if Vx != Vy
if (chip8->cpu.regs.VX[NIBBLE2(opcode)] != chip8->cpu.regs.VX[NIBBLE3(opcode)])
chip8->cpu.regs.PC += 2;
break;
case 0xA: //Annn - LD I, addr: Set I = nnn
chip8->cpu.regs.I = LOWEST12BIT(opcode);
break;
case 0xB: //Bnnn - JP V0, addr: Jump to location nnn + V0
chip8->cpu.regs.PC = LOWEST12BIT(opcode) + chip8->cpu.regs.VX[0] - 2;
break;
case 0xC: //Cxkk - RND Vx, byte: Set Vx = random byte AND kk
chip8->cpu.regs.VX[NIBBLE2(opcode)] = randomUInt8() & LOWBYTE(opcode);
break;
case 0xD:
//Dxyn - DRW Vx, Vy, nibble
//Display n-byte sprite starting at memory location I at (Vx, Vy), set VF = collision.
sprite = spriteReadFromMemory(chip8->memory.data + chip8->cpu.regs.I, NIBBLE4(opcode));
chip8->cpu.regs.VX[0xF] =
dispDispSprite(chip8->display, sprite, chip8->cpu.regs.VX[NIBBLE2(opcode)],
chip8->cpu.regs.VX[NIBBLE3(opcode)]);
break;
case 0xE:
switch (LOWBYTE(opcode)) {
case 0x9E:
//Ex9E - SKP Vx
//Skip next instruction if key with the value of Vx is pressed.
if (chip8->cpu.regs.VX[NIBBLE2(opcode)] == kbQueueDequeue(chip8->kbQueue))
chip8->cpu.regs.PC += 2;
break;
case 0xA1:
//ExA1 - SKNP Vx
//Skip next instruction if key with the value of Vx is not pressed.
if (chip8->cpu.regs.VX[NIBBLE2(opcode)] != kbQueueDequeue(chip8->kbQueue))
chip8->cpu.regs.PC += 2;
break;
}
break;
case 0xF:
switch (LOWBYTE(opcode)) {
case 0x07: //Fx07 - LD Vx, DT: Set Vx = delay timer value.
chip8->cpu.regs.VX[NIBBLE2(opcode)] = chip8->cpu.regs.DT;
break;
case 0x0A:
//Fx0A - LD Vx, K
//Wait for a key press, store the value of the key in Vx.
if ((i = kbQueueDequeue(chip8->kbQueue)) == 255u)
chip8->cpu.regs.PC -= 2;
else
chip8->cpu.regs.VX[NIBBLE2(opcode)] = i;
break;
case 0x15: //Fx15 - LD DT, Vx: Set delay timer = Vx.
chip8->cpu.regs.DT = chip8->cpu.regs.VX[NIBBLE2(opcode)];
SDL_DetachThread(SDL_CreateThread(DTthread, "DTthread", &chip8->cpu));
break;
case 0x18: //Fx18 - LD ST, Vx: Set sound timer = Vx.
chip8->cpu.regs.ST = chip8->cpu.regs.VX[NIBBLE2(opcode)];
SDL_DetachThread(SDL_CreateThread(STthread, "STthread", &chip8->cpu));
break;
case 0x1E: //Fx1E - ADD I, Vx: Set I = I + Vx.
chip8->cpu.regs.I += chip8->cpu.regs.VX[NIBBLE2(opcode)];
break;
case 0x29: //Fx29 - LD F, Vx: Set I = location of sprite for digit Vx.
chip8->cpu.regs.I =
(chip8->cpu.regs.VX[NIBBLE2(opcode)] * SPRITE_CHAR_HEIGHT) + FIRST_CHAR_SPRITE_OFFSET;
break;
case 0x33:
//Fx33 - LD B, Vx
//Store BCD representation of Vx in memory locations I, I+1, and I+2.
chip8->memory.data[chip8->cpu.regs.I + 2] = chip8->cpu.regs.VX[NIBBLE2(opcode)] % 10;
chip8->memory.data[chip8->cpu.regs.I + 1] = chip8->cpu.regs.VX[NIBBLE2(opcode)] / 10 % 10;
chip8->memory.data[chip8->cpu.regs.I + 0] = chip8->cpu.regs.VX[NIBBLE2(opcode)] / 100 % 10;
break;
case 0x55:
//Fx55 - LD [I], Vx
//Store registers V0 through Vx in memory starting at location I.
for (i = 0; i <= NIBBLE2(opcode); i++)
chip8->memory.data[chip8->cpu.regs.I + i] = chip8->cpu.regs.VX[i];
break;
case 0x65:
//Fx65 - LD Vx, [I]
//Read registers V0 through Vx from memory starting at location I.
for (i = 0; i <= NIBBLE2(opcode); i++)
chip8->cpu.regs.VX[i] = chip8->memory.data[chip8->cpu.regs.I + i];
break;
}
break;
}
chip8->cpu.regs.PC += 2;
SDL_Delay(1000 / 60);
while (SDL_PollEvent(&event)) {
if (event.type == SDL_QUIT) {
shouldExit = 1;
break;
} else if (event.type == SDL_KEYDOWN) {
if ((event.key.keysym.sym >= SDLK_0 && event.key.keysym.sym <= SDLK_9) ||
(event.key.keysym.sym >= SDLK_a && event.key.keysym.sym <= SDLK_f)) {
kbQueueEnqueue(chip8->kbQueue, KCODE2INT(event.key.keysym.sym));
}
}
}
}
}
CHIP8 chip8Init(const char *romFile) {
CHIP8 chip8 = malloc(sizeof(struct CHIP8_s));
SDL_Init(SDL_INIT_VIDEO); //TODO: Something better...
chip8->cpu = cpuInit(ROM_LOAD_OFFSET);
chip8->memory = memInit();
chip8->display = dispInit();
chip8->kbQueue = kbQueueInit();
spriteGenCharInMemory(chip8->memory.data);
if (memCopyROMFromFile(chip8->memory, romFile)) {
showMessageBox("Error", "Error reading rom file", MB_ERROR);
} else {
_execute(chip8);
}
return chip8;
}
void chip8Free(CHIP8 chip8) {
dispFree(chip8->display);
kbQueueFree(chip8->kbQueue);
memFree(chip8->memory);
SDL_Quit();
free(chip8);
}