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