-
Notifications
You must be signed in to change notification settings - Fork 0
/
chip8.c
533 lines (436 loc) · 17.7 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
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <time.h>
#include "structs.h"
#include "raylib.h"
#include "debug.h"
bool set_config(config_t *config,int argc,char **argv){
config->window_h=32;
config->window_w=64;
config->scale_factor=20;
config->emulation_speed=800; // 800 Instructions speed
for(int i=1;i<argc;i++) (void)argv[i];
return true;
}
// Input handler
void handle_input(chip8_t *chip8){
switch(GetKeyPressed()){
case KEY_SPACE:
if(chip8->state==RUNNING){
chip8->state=PAUSED;
TraceLog(LOG_INFO,"CHIP8 Paused!");
}else chip8->state=RUNNING;
break;
case KEY_ESCAPE:
chip8->state=QUIT;
break;
}
// ON
if(IsKeyDown(KEY_ONE)) chip8->keys[0x1]=true;
if(IsKeyDown(KEY_TWO)) chip8->keys[0x2]=true;
if(IsKeyDown(KEY_THREE)) chip8->keys[0x3]=true;
if(IsKeyDown(KEY_FOUR)) chip8->keys[0xC]=true;
if(IsKeyDown(KEY_Q)) chip8->keys[0x4]=true;
if(IsKeyDown(KEY_W)) chip8->keys[0x5]=true;
if(IsKeyDown(KEY_E)) chip8->keys[0x6]=true;
if(IsKeyDown(KEY_R)) chip8->keys[0xD]=true;
if(IsKeyDown(KEY_A)) chip8->keys[0x7]=true;
if(IsKeyDown(KEY_S)) chip8->keys[0x8]=true;
if(IsKeyDown(KEY_D)) chip8->keys[0x9]=true;
if(IsKeyDown(KEY_F)) chip8->keys[0xE]=true;
if(IsKeyDown(KEY_Z)) chip8->keys[0xA]=true;
if(IsKeyDown(KEY_X)) chip8->keys[0x0]=true;
if(IsKeyDown(KEY_C)) chip8->keys[0xB]=true;
if(IsKeyDown(KEY_V)) chip8->keys[0xF]=true;
// OFF
if(IsKeyUp(KEY_ONE)) chip8->keys[0x1]=false;
if(IsKeyUp(KEY_TWO)) chip8->keys[0x2]=false;
if(IsKeyUp(KEY_THREE)) chip8->keys[0x3]=false;
if(IsKeyUp(KEY_FOUR)) chip8->keys[0xC]=false;
if(IsKeyUp(KEY_Q)) chip8->keys[0x4]=false;
if(IsKeyUp(KEY_W)) chip8->keys[0x5]=false;
if(IsKeyUp(KEY_E)) chip8->keys[0x6]=false;
if(IsKeyUp(KEY_R)) chip8->keys[0xD]=false;
if(IsKeyUp(KEY_A)) chip8->keys[0x7]=false;
if(IsKeyUp(KEY_S)) chip8->keys[0x8]=false;
if(IsKeyUp(KEY_D)) chip8->keys[0x9]=false;
if(IsKeyUp(KEY_F)) chip8->keys[0xE]=false;
if(IsKeyUp(KEY_Z)) chip8->keys[0xA]=false;
if(IsKeyUp(KEY_X)) chip8->keys[0x0]=false;
if(IsKeyUp(KEY_C)) chip8->keys[0xB]=false;
if(IsKeyUp(KEY_V)) chip8->keys[0xF]=false;
// if KEY_THREE: chip8->keys[0x3]=true;break;
// if KEY_FOUR: chip8->keys[0xC]=true;break;
// case KEY_Q: chip8->keys[0x4]=true;break;
// case KEY_W: chip8->keys[0x5]=true;break;
// case KEY_E: chip8->keys[0x6]=true;TraceLog(LOG_INFO,"ON!");break;
// case KEY_R: chip8->keys[0xD]=true;break;
// case KEY_A: chip8->keys[0x7]=true;break;
// case KEY_S: chip8->keys[0x8]=true;break;
// case KEY_D: chip8->keys[0x9]=true;break;
// case KEY_F: chip8->keys[0xE]=true;break;
// case KEY_Z: chip8->keys[0xA]=true;break;
// case KEY_X: chip8->keys[0x0]=true;break;
// case KEY_C: chip8->keys[0xB]=true;break;
// case KEY_V: chip8->keys[0xF]=true;break;
// if(IsKeyDown(key_id)){
// switch(key_id){
// case KEY_SPACE:
// if(chip8->state==RUNNING){
// chip8->state=PAUSED;
// TraceLog(LOG_INFO,"CHIP8 Paused!");
// }else chip8->state=RUNNING;
// break;
// case KEY_ESCAPE: chip8->state=QUIT;break;
// case KEY_ONE: chip8->keys[0x1]=true;break;
// case KEY_TWO: chip8->keys[0x2]=true;break;
// case KEY_THREE: chip8->keys[0x3]=true;break;
// case KEY_FOUR: chip8->keys[0xC]=true;break;
// case KEY_Q: chip8->keys[0x4]=true;break;
// case KEY_W: chip8->keys[0x5]=true;break;
// case KEY_E: chip8->keys[0x6]=true;TraceLog(LOG_INFO,"ON!");break;
// case KEY_R: chip8->keys[0xD]=true;break;
// case KEY_A: chip8->keys[0x7]=true;break;
// case KEY_S: chip8->keys[0x8]=true;break;
// case KEY_D: chip8->keys[0x9]=true;break;
// case KEY_F: chip8->keys[0xE]=true;break;
// case KEY_Z: chip8->keys[0xA]=true;break;
// case KEY_X: chip8->keys[0x0]=true;break;
// case KEY_C: chip8->keys[0xB]=true;break;
// case KEY_V: chip8->keys[0xF]=true;break;
// default: break;
//}
// }
// if(IsKeyUp(key_id)){
// switch(key_id){
// case KEY_ONE: chip8->keys[0x1]=false;break;
// case KEY_TWO: chip8->keys[0x2]=false;break;
// case KEY_THREE: chip8->keys[0x3]=false;break;
// case KEY_FOUR: chip8->keys[0xC]=false;break;
// case KEY_Q: chip8->keys[0x4]=false;break;
// case KEY_W: chip8->keys[0x5]=false;break;
// case KEY_E: chip8->keys[0x6]=false;TraceLog(LOG_INFO,"ON!");break;
// case KEY_R: chip8->keys[0xD]=false;break;
// case KEY_A: chip8->keys[0x7]=false;break;
// case KEY_S: chip8->keys[0x8]=false;break;
// case KEY_D: chip8->keys[0x9]=false;break;
// case KEY_F: chip8->keys[0xE]=false;break;
// case KEY_Z: chip8->keys[0xA]=false;break;
// case KEY_X: chip8->keys[0x0]=false;break;
// case KEY_C: chip8->keys[0xB]=false;break;
// case KEY_V: chip8->keys[0xF]=false;break;
// default: break;
// }
// }
}
void emulate_instruction(chip8_t *chip8, config_t config){
chip8->instruction.opcode = chip8->ram[chip8->pc]<<8|chip8->ram[chip8->pc+1];
chip8->pc+=2;
chip8->instruction.NNN = chip8->instruction.opcode & 0x0FFF;
chip8->instruction.NN = chip8->instruction.opcode & 0x0FF;
chip8->instruction.N = chip8->instruction.opcode & 0x0F;
chip8->instruction.X = (chip8->instruction.opcode>>8) & 0x0F;
chip8->instruction.Y = (chip8->instruction.opcode>>4) & 0x0F;
#ifdef DEBUG
print_debug_for_instruction(chip8);
#endif
// Finding opcode category
uint8_t category=chip8->instruction.opcode>>12&0xF;
switch(category){
case 0x0:
// 00E0: Clear Screen
if(chip8->instruction.NN==0xE0){
memset(&chip8->display[0],false,sizeof chip8->display);
// 00EE: Return from subroutine
}else if(chip8->instruction.NN==0x0EE){
chip8->pc = *--chip8->stack_ptr;
}
break;
case 0x1:
// 1nnn: Jump to location nnn
chip8->pc=chip8->instruction.NNN;
break;
case 0x2:
// 2nnn: Call subroutine at nnn
*chip8->stack_ptr++ = chip8->pc;
chip8->pc = chip8->instruction.NNN;
break;
case 0x3:
// 3xkk: Skip next inst if vx==kk
if(chip8->V[chip8->instruction.X] == chip8->instruction.NN) chip8->pc+=2;
break;
case 0x4:
// 4xkk: Skip next inst if vx!=kk
if(chip8->V[chip8->instruction.X] != chip8->instruction.NN) chip8->pc+=2;
break;
case 0x5:
// 5xy0: Skip next inst if vx==vy
if(chip8->V[chip8->instruction.X] == chip8->V[chip8->instruction.Y]) chip8->pc+=2;
break;
case 0x6:
// 6xkk: Set vx==kk
chip8->V[chip8->instruction.X] = chip8->instruction.NNN;
break;
case 0x7:
// 7xkk: Set vx=vx+kk
chip8->V[chip8->instruction.X]=chip8->V[chip8->instruction.X]+chip8->instruction.NN;
break;
case 0x8:
switch(chip8->instruction.N){
case 0x0:
// 8xy0: Set vx=vy
chip8->V[chip8->instruction.X]=chip8->V[chip8->instruction.Y];
break;
case 0x1:
// 8xy1: Set vx=vx|vy
chip8->V[chip8->instruction.X]=chip8->V[chip8->instruction.X]|chip8->V[chip8->instruction.Y];
break;
case 0x2:
// 8xy2: Set vx=vx&vy
chip8->V[chip8->instruction.X]=chip8->V[chip8->instruction.X]&chip8->V[chip8->instruction.Y];
break;
case 0x3:
// 8xy3: Set vx=vx^vy
chip8->V[chip8->instruction.X]=chip8->V[chip8->instruction.X]^chip8->V[chip8->instruction.Y];
break;
case 0x4:
// 8xy4: Set vx=vx+vy, if result more than 8 bit vf=1
uint16_t result = chip8->V[chip8->instruction.X]+chip8->V[chip8->instruction.Y];
if(result>255) chip8->V[0xF]=1;
chip8->V[chip8->instruction.X]+=chip8->V[chip8->instruction.Y];
break;
case 0x5:
// 8xy5: Set vx=vx-vy, set vf= NOT borrow
// if(chip8->V[chip8->instruction.X]<chip8->V[chip8->instruction.Y]) chip8->V[0xF]=1;
// chip8->V[chip8->instruction.X]-=chip8->V[chip8->instruction.Y];
chip8->V[0xF]=chip8->V[chip8->instruction.X]>=chip8->V[chip8->instruction.Y];
chip8->V[chip8->instruction.X]-=chip8->V[chip8->instruction.Y];
break;
case 0x6:
// 8xy6: If least sig of vx=1, vf=1 and divide vx by 2
chip8->V[0xF]=chip8->V[chip8->instruction.X]&1;
chip8->V[chip8->instruction.X]>>=1;
break;
case 0x7:
// 8xy7: If vy>vx set vf=1 and vx is sub from vy (vx=vy-vx)
chip8->V[0xF]=chip8->V[chip8->instruction.Y]>=chip8->V[chip8->instruction.X];
chip8->V[chip8->instruction.X]=chip8->V[chip8->instruction.Y]-chip8->V[chip8->instruction.X];
break;
case 0xE:
// 8xye: Skip inst if vx!=vy
chip8->V[0xF]=(chip8->V[chip8->instruction.X]&0x80)>>7;
chip8->V[chip8->instruction.X]<<=1;
break;
}
break;
case 0x9:
// 9xy0: Skip next inst if vx!=vy
if(chip8->V[chip8->instruction.X]!=chip8->V[chip8->instruction.Y]) chip8->pc+=2;
break;
case 0xA:
// annn: Set index_reg to nnn
chip8->index_reg = chip8->instruction.NNN;
break;
case 0xB:
// bnnn: Jump to location nnn+v[0]
chip8->pc=chip8->V[0]+chip8->instruction.NNN;
break;
case 0xC:
// cnnn: Set vx=rand()%256 & NN
chip8->V[chip8->instruction.X] = (rand()%256) & chip8->instruction.NN;
break;
case 0xD:
// dxyn: Draw n byte sprite at mem location I at vx,vy and set vf=collision
// Wrap and find X and Y coords
uint8_t X_coor=chip8->V[chip8->instruction.X]%config.window_w;
uint8_t Y_coor=chip8->V[chip8->instruction.Y]%config.window_h;
uint8_t mover = X_coor;
chip8->V[0xF]=0;
// Loop over height of sprite
for(uint8_t i=0;i<chip8->instruction.N;i++){
// Fetch sprite data
uint8_t sprite=chip8->ram[chip8->index_reg+i];
X_coor=mover; // Restting X_coor for new row to draw
for(int8_t j=7;j>=0;j--){
bool *pixel = &chip8->display[Y_coor*config.window_w+X_coor];
bool sprite_bit=sprite&(1<<j);
if(sprite_bit&&(*pixel)) chip8->V[0xF]=1;
*pixel^=sprite_bit;
// Stops drawing sprite if row hits right edge of screen
if(++X_coor>=config.window_w)break;
}
// Stop entire sprite drawing if hits bottom edge
if(++Y_coor>=config.window_h) break;
}
break;
case 0xE:
switch(chip8->instruction.NN){
case 0x9E:
if(chip8->keys[chip8->V[chip8->instruction.X]]) chip8->pc+=2;
break;
case 0xA1:
if(!chip8->keys[chip8->V[chip8->instruction.X]]) chip8->pc+=2;
break;
}
break;
case 0xF:
switch(chip8->instruction.NN){
case 0x07:
chip8->V[chip8->instruction.X]=chip8->deplay_timer;
break;
case 0x0A:
bool is_key_pressed=false;
for(uint8_t i=0;i<sizeof chip8->keys;i++){
if(chip8->display[i]){
chip8->V[chip8->instruction.X]=i;
is_key_pressed=true;
break;
}
}
// Stay with current opcode
if(!is_key_pressed) chip8->pc-=2;
break;
case 0x15:
chip8->deplay_timer=chip8->V[chip8->instruction.X];
break;
case 0x18:
chip8->sound_timer=chip8->V[chip8->instruction.X];
break;
case 0x1E:
chip8->index_reg+=chip8->V[chip8->instruction.X];
break;
case 0x29:
// fx29: I=sprite_addr[vx]
// catch
chip8->index_reg=chip8->V[chip8->instruction.X]*5;
break;
case 0x33:
// fx33: Store BCD of VX
// I -> 100s digit, I+1 -> 10s digit, I+2 -> 1s digit
uint8_t bcd_repr=chip8->V[chip8->instruction.X];
chip8->ram[chip8->index_reg+2]=bcd_repr%10;
bcd_repr/=10;
chip8->ram[chip8->index_reg+1]=bcd_repr%10;
bcd_repr/=10;
chip8->ram[chip8->index_reg]=bcd_repr;
break;
case 0x55:
for(uint8_t i=0;i<=chip8->instruction.X;i++){
chip8->ram[chip8->index_reg+i]=chip8->V[i];
}
break;
case 0x65:
for(uint8_t i=0;i<=chip8->instruction.X;i++){
chip8->V[i]=chip8->ram[chip8->index_reg+i];
}
break;
}
default:
break;
}
}
bool init_chip8(chip8_t *chip8,char *rom_name){
chip8->state=RUNNING;
uint32_t entry = 0x200;
uint8_t font[] = {
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
};
memcpy(&chip8->ram[0],font,sizeof font);
FILE *rom = fopen(rom_name,"rb");
if(!rom){
TraceLog(LOG_ERROR,"ROM %s doesnt exist \n",rom_name);
return false;
}
fseek(rom,0,SEEK_END);
size_t rom_size = ftell(rom);
size_t max_size = sizeof chip8->ram - entry;
rewind(rom);
if(rom_size > max_size){
TraceLog(LOG_ERROR,"Rom file out of size!\n");
return false;
}
if(fread(&chip8->ram[entry],rom_size,1,rom)!=1){
TraceLog(LOG_ERROR,"Unable to read Rom file %s\n",rom_name);
return false;
}
fclose(rom);
chip8->pc = entry;
chip8->rom_name = rom_name;
chip8->stack_ptr = &chip8->stack[0];
return true;
}
void updateTimers(chip8_t *chip8){
if(chip8->deplay_timer>0) chip8->deplay_timer--;
// Do sound timer
}
void updateScreen(chip8_t *chip8,config_t config){
// Setting rectangle dimensions
int rect_x,rect_y;
for(uint32_t i=0;i<sizeof chip8->display;i++){
rect_x=(i%config.window_w)*config.scale_factor;
rect_y=(i/config.window_w)*config.scale_factor;
// If pixel ON draw white color
if(chip8->display[i]) {
// Rect + outline
DrawRectangle(rect_x,rect_y,config.scale_factor,config.scale_factor,WHITE);
DrawRectangleLines(rect_x,rect_y,config.scale_factor,config.scale_factor,BLACK);
}
// If pixel OFF draw black color
else DrawRectangle(rect_x,rect_y,config.scale_factor,config.scale_factor,BLACK);
}
}
// Main Function
int main(int argc,char **argv){
// Will use later
(void)argc;
(void)argv;
// Invalid inputs for args
if(argc<2){
TraceLog(LOG_ERROR,"Usage: ./chip8 <ROM_NAME>");
exit(EXIT_FAILURE);
}
// Logging info
SetTraceLogLevel(LOG_ALL);
// Setting up configs
config_t config;
chip8_t *chip8 = malloc(sizeof(chip8_t));
uint32_t FPS=60;
SetTargetFPS(FPS);
// Main configs
if(!set_config(&config,argc,argv)) exit(EXIT_FAILURE);
if(!init_chip8(chip8,argv[1])) exit(EXIT_FAILURE);
InitWindow(config.window_w*config.scale_factor,config.window_h*config.scale_factor,"CHIP8 Emulator");
// Seeding the random num gen
srand(time(NULL));
while(chip8->state!=QUIT){
handle_input(chip8);
if(chip8->state!=PAUSED) {
for(uint32_t i=0;i<config.emulation_speed/FPS;i++) emulate_instruction(chip8,config);
emulate_instruction(chip8,config);
}
BeginDrawing();
ClearBackground(BLACK);
updateScreen(chip8,config);
updateTimers(chip8);
EndDrawing();
}
CloseWindow();
return 0;
}