-
Notifications
You must be signed in to change notification settings - Fork 24
/
example10.c
321 lines (239 loc) · 12.9 KB
/
example10.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
//this example shows non-looped vertical scroll, with 2x2 metatiles and attributes
//it is close enough to one that would be needed in an actual game
//horizontal mirroring (gives 32x60 nametable layout) is used to hide the changing row
//this example uses about 20% of CPU time
#include "neslib.h"
static unsigned char update_list[3+32+3+8+1];//3 bytes address and length for 32 tiles, 3 bytes address and length for 8 attributes, end marker
//palette data
const unsigned char palette[16]={ 0x0f,0x16,0x26,0x36,0x0f,0x18,0x28,0x38,0x0f,0x19,0x29,0x39,0x0f,0x1c,0x2c,0x3c };
//metatile palettes
#define BGPAL0 0x00 //bin 00000000
#define BGPAL1 0x55 //bin 01010101
#define BGPAL2 0xaa //bin 10101010
#define BGPAL3 0xff //bin 11111111
//metatile definitions, one metatile by another, 4 bytes per metatile
const unsigned char metatiles[]={
0x00,0x00,0x00,0x00,
0x80,0x81,0x90,0x91,
0x82,0x83,0x92,0x93,
0x84,0x85,0x94,0x95,
0x86,0x87,0x96,0x97
};
//metatile attributes, define which palette should be used for a metatile
const unsigned char metaattrs[]={
BGPAL0,
BGPAL0,
BGPAL1,
BGPAL2,
BGPAL3
};
//level data, it is upside down to make it easier to access
const unsigned char level_data[]={
0x03,0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x03,0x04,
0x01,0x02,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x02,
0x00,0x00,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x00,0x00,
0x00,0x00,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x00,0x00,
0x00,0x00,0x03,0x03,0x03,0x03,0x03,0x03,0x03,0x03,0x03,0x03,0x03,0x03,0x00,0x00,
0x00,0x00,0x04,0x04,0x04,0x04,0x04,0x04,0x04,0x04,0x04,0x04,0x04,0x04,0x00,0x00,
0x03,0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x03,0x04,
0x01,0x02,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x02,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x00,0x02,0x02,0x02,0x02,0x02,0x02,0x00,0x01,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x00,0x02,0x00,0x00,0x00,0x00,0x02,0x00,0x01,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x00,0x02,0x00,0x03,0x03,0x00,0x02,0x00,0x01,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x00,0x02,0x00,0x03,0x03,0x00,0x02,0x00,0x01,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x00,0x02,0x00,0x04,0x04,0x00,0x02,0x00,0x01,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x00,0x02,0x00,0x04,0x04,0x00,0x02,0x00,0x01,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x00,0x02,0x00,0x00,0x00,0x00,0x02,0x00,0x01,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x00,0x02,0x02,0x02,0x02,0x02,0x02,0x00,0x01,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x03,0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x03,0x04,
0x01,0x02,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x02,
0x00,0x00,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x00,0x00,
0x00,0x00,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x00,0x00,
0x00,0x00,0x03,0x03,0x03,0x03,0x03,0x03,0x03,0x03,0x03,0x03,0x03,0x03,0x00,0x00,
0x00,0x00,0x04,0x04,0x04,0x04,0x04,0x04,0x04,0x04,0x04,0x04,0x04,0x04,0x00,0x00,
0x03,0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x03,0x04,
0x01,0x02,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x02,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x01,0x00,0x01,0x02,0x02,0x02,0x03,0x03,0x03,0x04,0x04,0x00,0x00,0x00,0x00,0x00,
0x01,0x01,0x01,0x02,0x00,0x02,0x03,0x00,0x00,0x04,0x00,0x04,0x00,0x00,0x00,0x00,
0x01,0x00,0x01,0x02,0x00,0x02,0x03,0x00,0x00,0x04,0x00,0x04,0x00,0x00,0x00,0x00,
0x01,0x00,0x01,0x02,0x02,0x00,0x03,0x00,0x00,0x04,0x00,0x04,0x00,0x00,0x00,0x00,
0x01,0x00,0x01,0x02,0x00,0x02,0x03,0x00,0x00,0x04,0x00,0x04,0x00,0x00,0x00,0x00,
0x01,0x01,0x01,0x02,0x02,0x02,0x03,0x03,0x03,0x04,0x04,0x00,0x00,0x00,0x00,0x00,
0x00,0x01,0x00,0x01,0x02,0x02,0x02,0x03,0x03,0x03,0x04,0x04,0x00,0x00,0x00,0x00,
0x00,0x01,0x01,0x01,0x02,0x00,0x02,0x03,0x00,0x00,0x04,0x00,0x04,0x00,0x00,0x00,
0x00,0x01,0x00,0x01,0x02,0x00,0x02,0x03,0x00,0x00,0x04,0x00,0x04,0x00,0x00,0x00,
0x00,0x01,0x00,0x01,0x02,0x02,0x00,0x03,0x00,0x00,0x04,0x00,0x04,0x00,0x00,0x00,
0x00,0x01,0x00,0x01,0x02,0x00,0x02,0x03,0x00,0x00,0x04,0x00,0x04,0x00,0x00,0x00,
0x00,0x01,0x01,0x01,0x02,0x02,0x02,0x03,0x03,0x03,0x04,0x04,0x00,0x00,0x00,0x00,
0x00,0x00,0x01,0x00,0x01,0x02,0x02,0x02,0x03,0x03,0x03,0x04,0x04,0x00,0x00,0x00,
0x00,0x00,0x01,0x01,0x01,0x02,0x00,0x02,0x03,0x00,0x00,0x04,0x00,0x04,0x00,0x00,
0x00,0x00,0x01,0x00,0x01,0x02,0x00,0x02,0x03,0x00,0x00,0x04,0x00,0x04,0x00,0x00,
0x00,0x00,0x01,0x00,0x01,0x02,0x02,0x00,0x03,0x00,0x00,0x04,0x00,0x04,0x00,0x00,
0x00,0x00,0x01,0x00,0x01,0x02,0x00,0x02,0x03,0x00,0x00,0x04,0x00,0x04,0x00,0x00,
0x00,0x00,0x01,0x01,0x01,0x02,0x02,0x02,0x03,0x03,0x03,0x04,0x04,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x00,0x01,0x02,0x02,0x02,0x03,0x03,0x03,0x04,0x04,0x00,0x00,
0x00,0x00,0x00,0x01,0x01,0x01,0x02,0x00,0x02,0x03,0x00,0x00,0x04,0x00,0x04,0x00,
0x00,0x00,0x00,0x01,0x00,0x01,0x02,0x00,0x02,0x03,0x00,0x00,0x04,0x00,0x04,0x00,
0x00,0x00,0x00,0x01,0x00,0x01,0x02,0x02,0x00,0x03,0x00,0x00,0x04,0x00,0x04,0x00,
0x00,0x00,0x00,0x01,0x00,0x01,0x02,0x00,0x02,0x03,0x00,0x00,0x04,0x00,0x04,0x00,
0x00,0x00,0x00,0x01,0x01,0x01,0x02,0x02,0x02,0x03,0x03,0x03,0x04,0x04,0x00,0x00,
0x00,0x00,0x00,0x00,0x01,0x00,0x01,0x02,0x02,0x02,0x03,0x03,0x03,0x04,0x04,0x00,
0x00,0x00,0x00,0x00,0x01,0x01,0x01,0x02,0x00,0x02,0x03,0x00,0x00,0x04,0x00,0x04,
0x00,0x00,0x00,0x00,0x01,0x00,0x01,0x02,0x00,0x02,0x03,0x00,0x00,0x04,0x00,0x04,
0x00,0x00,0x00,0x00,0x01,0x00,0x01,0x02,0x02,0x00,0x03,0x00,0x00,0x04,0x00,0x04,
0x00,0x00,0x00,0x00,0x01,0x00,0x01,0x02,0x00,0x02,0x03,0x00,0x00,0x04,0x00,0x04,
0x00,0x00,0x00,0x00,0x01,0x01,0x01,0x02,0x02,0x02,0x03,0x03,0x03,0x04,0x04,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x03,0x00,0x03,0x00,0x03,0x00,0x03,0x00,0x03,0x00,0x03,0x00,0x00,
0x00,0x00,0x03,0x00,0x03,0x04,0x03,0x00,0x03,0x00,0x03,0x04,0x03,0x00,0x00,0x00,
0x00,0x00,0x00,0x02,0x04,0x02,0x04,0x02,0x00,0x02,0x04,0x02,0x04,0x02,0x00,0x00,
0x00,0x00,0x02,0x04,0x02,0x00,0x02,0x04,0x02,0x04,0x02,0x00,0x02,0x04,0x00,0x00,
0x00,0x00,0x04,0x01,0x00,0x01,0x00,0x01,0x04,0x01,0x00,0x01,0x00,0x01,0x00,0x00,
0x00,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x00,0x00,
0x03,0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x03,0x04,
0x01,0x02,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x02,
0x00,0x00,0x00,0x01,0x00,0x00,0x02,0x02,0x02,0x00,0x03,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x00,0x00,0x02,0x00,0x02,0x00,0x03,0x03,0x03,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x00,0x00,0x02,0x00,0x02,0x00,0x03,0x00,0x03,0x00,0x00,0x00,
0x00,0x00,0x00,0x01,0x00,0x00,0x02,0x00,0x02,0x00,0x03,0x00,0x03,0x00,0x00,0x00,
0x00,0x00,0x01,0x01,0x01,0x00,0x02,0x02,0x02,0x00,0x03,0x03,0x03,0x00,0x00,0x00,
0x03,0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x03,0x04,
0x01,0x02,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x02
};
//calculate height of the level in pixels
#define LEVEL_HEIGHT (sizeof(level_data)/16*16)
//this function prepares data for a row update
//also used to fill the screen before scrolling starts
void prepare_row_update(unsigned char name_row,unsigned int level_row)
{
static unsigned char i,tile,attr,tile_off,updn_off,upda_off,mask1,mask2,mask3,mask4;
static unsigned int name_adr,attr_adr;
static const unsigned char *src;
if(name_row<30)//calculate tile and attribute row addresses in a nametable
{
name_adr=NAMETABLE_A+(name_row<<5);
attr_adr=NAMETABLE_A+960+((name_row>>2)<<3);
}
else
{
name_row-=30;
name_adr=NAMETABLE_C+(name_row<<5);
attr_adr=NAMETABLE_C+960+((name_row>>2)<<3);
}
update_list[0]=MSB(name_adr)|NT_UPD_HORZ;//set nametable update address
update_list[1]=LSB(name_adr);
update_list[35]=MSB(attr_adr)|NT_UPD_HORZ;//set attribute table update address
update_list[36]=LSB(attr_adr);
updn_off=3;//offset in the update list for nametable data
upda_off=3+32+3;//offset for attribute data
src=&level_data[level_row<<4];//get offset in the level data
if(!(name_row&1)) tile_off=0; else tile_off=2;//metatile data offset, 2 for odd row numbers
if(!(name_row&2))//select appropriate masks for attribute bytes
{
mask1=0xfc;
mask2=0x03;
mask3=0xf3;
mask4=0x0c;
}
else
{
mask1=0xcf;
mask2=0x30;
mask3=0x3f;
mask4=0xc0;
}
for(i=0;i<8;++i)//as two neighborn attributes are grouped into a byte, the loop handles two metatiles in one iteration
{
tile=*src++;//get first metatile code
attr=(update_list[upda_off]&mask1)|(metaattrs[tile]&mask2);//get metatile attribute, remember it
tile=(tile<<2)+tile_off;//get metatile offset
update_list[updn_off+0]=metatiles[tile+0];//put top or bottom half of the first metatile into the update buffer
update_list[updn_off+1]=metatiles[tile+1];
tile=*src++;//get second metatile code
update_list[upda_off++]=(attr&mask3)|(metaattrs[tile]&mask4);//get attribute, add the other attribute, put into update buffer
tile=(tile<<2)+tile_off;//get metatile offset
update_list[updn_off+2]=metatiles[tile+0];//put top or bottom half of the second metatile into the update buffer
update_list[updn_off+3]=metatiles[tile+1];
updn_off+=4;
}
}
//fill the whole screen with actual level graphics
//it uses the prepare_row function, but copies the data into VRAM using
//flush_vram_update instead of the update system (would take 30 frames otherwise)
void preload_screen(unsigned int level_y)
{
static unsigned char i;
for(i=0;i<30;++i)
{
prepare_row_update(29-i,level_y>>4);//prepare a row, bottom to top
flush_vram_update(update_list);
level_y+=8;
}
}
//get metatile code for given x,y level position in pixels, relative to current offset in the level
//funciton like this could be used for collision detection purposes
unsigned char get_metatile(int level_y,unsigned int x,unsigned int y)
{
level_y=level_y-240+(240-y);//the level is stored upside down, flip the axis
if(level_y<0) level_y+=LEVEL_HEIGHT;//loop the level to avoid reading outside the level data
return level_data[((level_y>>4)<<4)|(x>>4)];//level_y/16 is pixels to row, then *16 is row to offset, then x/16 is pixels to column
}
//main function, program starts here
void main(void)
{
static unsigned char pad,tile,name_row,sprite_x,sprite_y;
static unsigned int level_y;
static int scroll_y;
pal_bg(palette);//set background palette from an array
pal_col(17,0x30);//white color for sprite
update_list[0]=0x20|NT_UPD_HORZ;//horizontal update sequence, dummy address
update_list[1]=0x00;
update_list[2]=32;//length of nametable update sequence
update_list[35]=0x20|NT_UPD_HORZ;
update_list[36]=0x00;
update_list[37]=8;//length of attribute update sequence
update_list[46]=NT_UPD_EOF;
preload_screen(0);//fill the whole screen with beginning of the level
level_y=8*30;//30 lines were already preloaded, advance the level offset
scroll_y=0;//screen scroll value, it loops in range of 0..479 (240*2-1)
sprite_x=128;
sprite_y=120;
ppu_on_all();//enable rendering
delay(60);//delay to show the preloaded part of the level
while(1)
{
ppu_wait_nmi();
set_vram_update(NULL);//disable update just in case, not really needed in this example
if(!(level_y&7))//put new row every 8 pixels
{
name_row=(scroll_y>>3)+59;//update row just above the visible part of the screen
if(name_row>=60) name_row-=60;//keep the row number within the limits
prepare_row_update(name_row,level_y>>4);
set_vram_update(update_list);//the update is handled at next NMI
}
scroll(0,scroll_y);//scroll value will be applied on the next nmi as well
++level_y;
if(level_y>=LEVEL_HEIGHT) level_y=0;//loop the level
--scroll_y;
if(scroll_y<0) scroll_y=240*2-1;//keep Y within the total height of two nametables
//this part demonstrates how BG collision detection could be done
tile=get_metatile(level_y,sprite_x,sprite_y);//get metatile number from the level
if(!tile) tile=0x1f; else tile+=0x20;//? for tile 0, ABCD for tiles 1,2,3,4
oam_spr(sprite_x-4,sprite_y-4,tile,0,0);//display sprite
pad=pad_poll(0);//move the sprite around
if(pad&PAD_LEFT) if(sprite_x>4) sprite_x-=2;
if(pad&PAD_RIGHT) if(sprite_x<252) sprite_x+=2;
if(pad&PAD_UP) if(sprite_y>4) sprite_y-=2;
if(pad&PAD_DOWN) if(sprite_y<236) sprite_y+=2;
}
}