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
|
/*
* FORKMAN: a platformer game with IPC
*
* This executable will fork. One process is responsible for writing to the
* screen and getting user input, the other is responsible for game logic.
*
*/
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#define GAME_WIDTH 480
#define GAME_HEIGHT 360
#define SHARED_PAGES 10
#define PAGE_SIZE 4096
typedef struct {
uint32_t *mapped_memory;
int width;
int height;
int bpp;
int scale;
size_t size;
} framebuffer;
typedef struct {
volatile size_t frame;
volatile size_t dummy_counter;
volatile int lock;
volatile uint8_t mem[PAGE_SIZE * (SHARED_PAGES - 1)];
} sharedmem;
static int display_server_entry(sharedmem *);
static int client_entry(sharedmem *);
int main(void)
{
uint8_t *current_break = sbrk(0);
if (!current_break) {
fprintf(stderr, "sbrk failure\n");
return 1;
}
printf("ABOUT TO FORK\n");
int child = fork();
if (child < 0) {
fprintf(stderr, "fork failed!\n");
return 1;
}
if (child) {
printf("FORK GOOD, CHILD IS %d\n", child);
sharedmem *shared = allocshared(SHARED_PAGES, child);
if (!shared) {
fprintf(stderr, "memory share failure\n");
return 1;
}
return display_server_entry(shared);
} else {
printf("FORK GOOD, WE ARE CHILD\n");
sharedmem *shared;
while (!(shared = popsharedmem()))
sleep(1);
return client_entry(shared);
}
}
static void set_pixel(framebuffer *fb, size_t x, size_t y,
int state) // state is 0 or 1
{
fb->mapped_memory[x + y * fb->width] = state * (0x00010101);
}
static int display_server_entry(sharedmem *shared)
{
framebuffer fb;
if (drm((void **)&fb.mapped_memory, &fb.width, &fb.height, &fb.bpp)) {
fprintf(stderr, "Unable to map framebuffer, display server failing\n");
return 1;
}
fb.size = (fb.width * fb.height * fb.bpp) / 8;
size_t last_frame = 1;
while (1) {
if (shared->frame == last_frame) {
continue;
}
printf("server writing frame %zu\n", last_frame);
last_frame += 1;
shared->frame = last_frame;
}
return 0;
}
static int client_entry(sharedmem *shared)
{
size_t last_frame = shared->frame;
do {
if (last_frame == shared->frame)
continue;
printf("client writing frame %zu\n", last_frame);
last_frame += 1;
shared->frame = last_frame;
} while (1);
return 0;
}
|
