refresh.c revision e16cb84e2324f05334d18dcf5956f20f44262b62 
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
19int64_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
27int 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