draw.c

   1 #include <fcntl.h>
   2 #include <linux/fb.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <string.h>
   6 #include <sys/ioctl.h>
   7 #include <sys/mman.h>
   8 #include <unistd.h>
   9 #include "draw.h"
  10
  11 #define MIN(a, b)       ((a) < (b) ? (a) : (b))
  12 #define MAX(a, b)       ((a) > (b) ? (a) : (b))
  13 #define NLEVELS         (1 << 8)
  14
  15 static struct fb_var_screeninfo vinfo;  /* linux-specific FB structure */
  16 static struct fb_fix_screeninfo finfo;  /* linux-specific FB structure */
  17 static char fbdev[1024];                /* FB device */
  18 static int fd;                          /* FB device file descriptor */
  19 static void *fb;                        /* mmap()ed FB memory */
  20 static int bpp;                         /* bytes per pixel */
  21 static int nr, ng, nb;                  /* color levels */
  22 static int rl, rr, gl, gr, bl, br;      /* shifts per color */
  23 static int xres, yres, xoff, yoff;      /* drawing region */
  24
  25 static int fb_len(void)
  26 {
  27         return finfo.line_length * vinfo.yres_virtual;
  28 }
  29
  30 static void fb_cmap_save(int save)
  31 {
  32         static unsigned short red[NLEVELS], green[NLEVELS], blue[NLEVELS];
  33         struct fb_cmap cmap;
  34         if (finfo.visual == FB_VISUAL_TRUECOLOR)
  35                 return;
  36         cmap.start = 0;
  37         cmap.len = MAX(nr, MAX(ng, nb));
  38         cmap.red = red;
  39         cmap.green = green;
  40         cmap.blue = blue;
  41         cmap.transp = NULL;
  42         ioctl(fd, save ? FBIOGETCMAP : FBIOPUTCMAP, &cmap);
  43 }
  44
  45 void fb_cmap(void)
  46 {
  47         unsigned short red[NLEVELS], green[NLEVELS], blue[NLEVELS];
  48         struct fb_cmap cmap;
  49         int i;
  50         if (finfo.visual == FB_VISUAL_TRUECOLOR)
  51                 return;
  52
  53         for (i = 0; i < nr; i++)
  54                 red[i] = (65535 / (nr - 1)) * i;
  55         for (i = 0; i < ng; i++)
  56                 green[i] = (65535 / (ng - 1)) * i;
  57         for (i = 0; i < nb; i++)
  58                 blue[i] = (65535 / (nb - 1)) * i;
  59
  60         cmap.start = 0;
  61         cmap.len = MAX(nr, MAX(ng, nb));
  62         cmap.red = red;
  63         cmap.green = green;
  64         cmap.blue = blue;
  65         cmap.transp = NULL;
  66
  67         ioctl(fd, FBIOPUTCMAP, &cmap);
  68 }
  69
  70 unsigned fb_mode(void)
  71 {
  72         return ((rl < gl) << 22) | ((rl < bl) << 21) | ((gl < bl) << 20) |
  73                 (bpp << 16) | (vinfo.red.length << 8) |
  74                 (vinfo.green.length << 4) | (vinfo.blue.length);
  75 }
  76
  77 static void init_colors(void)
  78 {
  79         nr = 1 << vinfo.red.length;
  80         ng = 1 << vinfo.blue.length;
  81         nb = 1 << vinfo.green.length;
  82         rr = 8 - vinfo.red.length;
  83         rl = vinfo.red.offset;
  84         gr = 8 - vinfo.green.length;
  85         gl = vinfo.green.offset;
  86         br = 8 - vinfo.blue.length;
  87         bl = vinfo.blue.offset;
  88 }
  89
  90 int fb_init(char *dev)
  91 {
  92         char *path = dev ? dev : FBDEV;
  93         char *geom = dev ? strchr(dev, ':') : NULL;
  94         if (geom) {
  95                 *geom = '\0';
  96                 sscanf(geom + 1, "%dx%d%d%d", &xres, &yres, &xoff, &yoff);
  97         }
  98         snprintf(fbdev, sizeof(fbdev), "%s", path);
  99         fd = open(path, O_RDWR);
 100         if (fd < 0)
 101                 goto failed;
 102         if (ioctl(fd, FBIOGET_VSCREENINFO, &vinfo) < 0)
 103                 goto failed;
 104         if (ioctl(fd, FBIOGET_FSCREENINFO, &finfo) < 0)
 105                 goto failed;
 106         fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
 107         bpp = (vinfo.bits_per_pixel + 7) >> 3;
 108         fb = mmap(NULL, fb_len(), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 109         if (fb == MAP_FAILED)
 110                 goto failed;
 111         init_colors();
 112         fb_cmap_save(1);
 113         fb_cmap();
 114         return 0;
 115 failed:
 116         perror("fb_init()");
 117         close(fd);
 118         return 1;
 119 }
 120
 121 void fb_free(void)
 122 {
 123         fb_cmap_save(0);
 124         munmap(fb, fb_len());
 125         close(fd);
 126 }
 127
 128 int fb_rows(void)
 129 {
 130         return yres ? yres : vinfo.yres;
 131 }
 132
 133 int fb_cols(void)
 134 {
 135         return xres ? xres : vinfo.xres;
 136 }
 137
 138 void *fb_mem(int r)
 139 {
 140         return fb + (r + vinfo.yoffset + yoff) * finfo.line_length + (vinfo.xoffset + xoff) * bpp;
 141 }
 142
 143 unsigned fb_val(int r, int g, int b)
 144 {
 145         return ((r >> rr) << rl) | ((g >> gr) << gl) | ((b >> br) << bl);
 146 }
 147
 148 char *fb_dev(void)
 149 {
 150         return fbdev;
 151 }