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 uint64_t denominator = (uint64_t)( info.upper_margin + info.lower_margin + info.yres )
71 * ( info.left_margin + info.right_margin + info.xres )
72 * info.pixclock;
73 int refreshRate = denominator ? (1000000000000000LLU / denominator) : 0;
74
75 float xdpi = (info.xres * 25.4f) / info.width;
76 float ydpi = (info.yres * 25.4f) / info.height;
77 float fps = refreshRate / 1000.0f;
78
79 printf( "using (fd=%d)\n"
80 "id = %s\n"
81 "xres = %d px\n"
82 "yres = %d px\n"
83 "xres_virtual = %d px\n"
84 "yres_virtual = %d px\n"
85 "bpp = %d\n"
86 "r = %2u:%u\n"
87 "g = %2u:%u\n"
88 "b = %2u:%u\n",
89 fd,
90 finfo.id,
91 info.xres,
92 info.yres,
93 info.xres_virtual,
94 info.yres_virtual,
95 info.bits_per_pixel,
96 info.red.offset, info.red.length,
97 info.green.offset, info.green.length,
98 info.blue.offset, info.blue.length
99 );
100
101 printf( "width = %d mm (%f dpi)\n"
102 "height = %d mm (%f dpi)\n"
103 "refresh rate = %.2f Hz\n",
104 info.width, xdpi,
105 info.height, ydpi,
106 fps
107 );
108
109 printf("upper_margin=%d, lower_margin=%d, left_margin=%d, right_margin=%d, pixclock=%d, finfo.smem_len=%d\n",
110 info.upper_margin, info.lower_margin, info.left_margin, info.right_margin, info.pixclock, finfo.smem_len);
111
112 if (ioctl(fd, FBIOGET_FSCREENINFO, &finfo) == -1)
113 return -errno;
114
115 if (finfo.smem_len <= 0)
116 return -errno;
117
118 /*
119 * Open and map the display.
120 */
121
122 uint16_t* buffer = (uint16_t*) mmap(
123 0, finfo.smem_len,
124 PROT_READ | PROT_WRITE,
125 MAP_SHARED,
126 fd, 0);
127
128 if (buffer == MAP_FAILED)
129 return -errno;
130
131 // at least for now, always clear the fb
132 memset(buffer, 0, finfo.smem_len);
133 memset(buffer, 0xff, 320*(info.yres_virtual/2)*2);
134
135 int l,t,w,h;
136 l=0;
137 t=0;
138 w=320;
139 h=480;
140 info.reserved[0] = 0x54445055; // "UPDT";
141 info.reserved[1] = (uint16_t)l | ((uint32_t)t << 16);
142 info.reserved[2] = (uint16_t)(l+w) | ((uint32_t)(t+h) << 16);
143
144 int err;
145 int c = 0;
146 int64_t time = systemTime();
147 while (1) {
148
149 info.activate = FB_ACTIVATE_VBL;
150 info.yoffset = 0;
151 ioctl(fd, FBIOPUT_VSCREENINFO, &info);
152
153 info.activate = FB_ACTIVATE_VBL;
154 info.yoffset = info.yres_virtual/2;
155 err = ioctl(fd, FBIOPUT_VSCREENINFO, &info);
156
157 c+=2;
158 if (c==60*2) {
159 int64_t now = systemTime();
160 time = now - time;
161 printf("refresh rate = %f Hz\n", (c*1000000000.0 / (double)time));
162 c = 0;
163 time = now;
164 }
165 }
166 return 0;
167 }
168