1 #include <stdio.h>
2 #include <stdlib.h>
3 #include <string.h>
4 #include <stdint.h>
5 #include <sys/types.h>
6
7 #include <unistd.h>
8 #include <fcntl.h>
9 #include <math.h>
10 #include <time.h>
11 #include <errno.h>
12
13 #include <sys/resource.h>
14 #include <sys/syscall.h>
15 #include <sys/mman.h>
16
17 #include <linux/fb.h>
18
systemTime()19 int64_t systemTime()
20 {
21 struct timespec t;
22 t.tv_sec = t.tv_nsec = 0;
23 clock_gettime(CLOCK_MONOTONIC, &t);
24 return (int64_t)(t.tv_sec)*1000000000LL + t.tv_nsec;
25 }
26
main(int argc,char ** argv)27 int main(int argc, char** argv)
28 {
29 char const * const device_template[] = {
30 "/dev/graphics/fb%u",
31 "/dev/fb%u",
32 0 };
33 int fd = -1;
34 int i=0;
35 int j=0;
36 char name[64];
37 while ((fd==-1) && device_template[i]) {
38 snprintf(name, 64, device_template[i], 0);
39 fd = open(name, O_RDWR, 0);
40 i++;
41 }
42 if (fd < 0)
43 return -errno;
44
45 struct fb_fix_screeninfo finfo;
46 if (ioctl(fd, FBIOGET_FSCREENINFO, &finfo) == -1)
47 return -errno;
48
49 struct fb_var_screeninfo info;
50 if (ioctl(fd, FBIOGET_VSCREENINFO, &info) == -1)
51 return -errno;
52
53 info.reserved[0] = 0;
54 info.reserved[1] = 0;
55 info.reserved[2] = 0;
56 info.xoffset = 0;
57 info.yoffset = 0;
58 info.bits_per_pixel = 16;
59 info.activate = FB_ACTIVATE_NOW;
60
61 if (ioctl(fd, FBIOPUT_VSCREENINFO, &info) == -1) {
62 printf("FBIOPUT_VSCREENINFO failed (%d x %d)\n",
63 info.xres_virtual, info.yres_virtual);
64 return 0;
65 }
66
67 if (ioctl(fd, FBIOGET_VSCREENINFO, &info) == -1)
68 return -errno;
69
70 int refreshRate = 1000000000000000LLU /
71 (
72 (uint64_t)( info.upper_margin + info.lower_margin + info.yres )
73 * ( info.left_margin + info.right_margin + info.xres )
74 * info.pixclock
75 );
76
77 float xdpi = (info.xres * 25.4f) / info.width;
78 float ydpi = (info.yres * 25.4f) / info.height;
79 float fps = refreshRate / 1000.0f;
80
81 printf( "using (fd=%d)\n"
82 "id = %s\n"
83 "xres = %d px\n"
84 "yres = %d px\n"
85 "xres_virtual = %d px\n"
86 "yres_virtual = %d px\n"
87 "bpp = %d\n"
88 "r = %2u:%u\n"
89 "g = %2u:%u\n"
90 "b = %2u:%u\n",
91 fd,
92 finfo.id,
93 info.xres,
94 info.yres,
95 info.xres_virtual,
96 info.yres_virtual,
97 info.bits_per_pixel,
98 info.red.offset, info.red.length,
99 info.green.offset, info.green.length,
100 info.blue.offset, info.blue.length
101 );
102
103 printf( "width = %d mm (%f dpi)\n"
104 "height = %d mm (%f dpi)\n"
105 "refresh rate = %.2f Hz\n",
106 info.width, xdpi,
107 info.height, ydpi,
108 fps
109 );
110
111 printf("upper_margin=%d, lower_margin=%d, left_margin=%d, right_margin=%d, pixclock=%d, finfo.smem_len=%d\n",
112 info.upper_margin, info.lower_margin, info.left_margin, info.right_margin, info.pixclock, finfo.smem_len);
113
114 if (ioctl(fd, FBIOGET_FSCREENINFO, &finfo) == -1)
115 return -errno;
116
117 if (finfo.smem_len <= 0)
118 return -errno;
119
120 /*
121 * Open and map the display.
122 */
123
124 uint16_t* buffer = (uint16_t*) mmap(
125 0, finfo.smem_len,
126 PROT_READ | PROT_WRITE,
127 MAP_SHARED,
128 fd, 0);
129
130 if (buffer == MAP_FAILED)
131 return -errno;
132
133 // at least for now, always clear the fb
134 memset(buffer, 0, finfo.smem_len);
135 memset(buffer, 0xff, 320*(info.yres_virtual/2)*2);
136
137 int l,t,w,h;
138 l=0;
139 t=0;
140 w=320;
141 h=480;
142 info.reserved[0] = 0x54445055; // "UPDT";
143 info.reserved[1] = (uint16_t)l | ((uint32_t)t << 16);
144 info.reserved[2] = (uint16_t)(l+w) | ((uint32_t)(t+h) << 16);
145
146 int err;
147 int c = 0;
148 int64_t time = systemTime();
149 while (1) {
150
151 info.activate = FB_ACTIVATE_VBL;
152 info.yoffset = 0;
153 ioctl(fd, FBIOPUT_VSCREENINFO, &info);
154
155 info.activate = FB_ACTIVATE_VBL;
156 info.yoffset = info.yres_virtual/2;
157 err = ioctl(fd, FBIOPUT_VSCREENINFO, &info);
158
159 c+=2;
160 if (c==60*2) {
161 int64_t now = systemTime();
162 time = now - time;
163 printf("refresh rate = %f Hz\n", (c*1000000000.0 / (double)time));
164 c = 0;
165 time = now;
166 }
167 }
168 return 0;
169 }
170