draw.c

   1 #include <fcntl.h>
   2 #include <linux/fb.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <sys/ioctl.h>
   6 #include <sys/mman.h>
   7 #include <unistd.h>
   8 #include <string.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 int fd;
  16 static void *fb;
  17 static struct fb_var_screeninfo vinfo;
  18 static struct fb_fix_screeninfo finfo;
  19 static int bpp;
  20 static int nr, ng, nb;
  21
  22 static int fb_len(void)
  23 {
  24         return finfo.line_length * vinfo.yres_virtual;
  25 }
  26
  27 static void fb_cmap_save(int save)
  28 {
  29         static unsigned short red[NLEVELS], green[NLEVELS], blue[NLEVELS];
  30         struct fb_cmap cmap;
  31         if (finfo.visual == FB_VISUAL_TRUECOLOR)
  32                 return;
  33         cmap.start = 0;
  34         cmap.len = MAX(nr, MAX(ng, nb));
  35         cmap.red = red;
  36         cmap.green = green;
  37         cmap.blue = blue;
  38         cmap.transp = NULL;
  39         ioctl(fd, save ? FBIOGETCMAP : FBIOPUTCMAP, &cmap);
  40 }
  41
  42 void fb_cmap(void)
  43 {
  44         unsigned short red[NLEVELS], green[NLEVELS], blue[NLEVELS];
  45         struct fb_cmap cmap;
  46         int i;
  47         if (finfo.visual == FB_VISUAL_TRUECOLOR)
  48                 return;
  49
  50         for (i = 0; i < nr; i++)
  51                 red[i] = (65535 / (nr - 1)) * i;
  52         for (i = 0; i < ng; i++)
  53                 green[i] = (65535 / (ng - 1)) * i;
  54         for (i = 0; i < nb; i++)
  55                 blue[i] = (65535 / (nb - 1)) * i;
  56
  57         cmap.start = 0;
  58         cmap.len = MAX(nr, MAX(ng, nb));
  59         cmap.red = red;
  60         cmap.green = green;
  61         cmap.blue = blue;
  62         cmap.transp = NULL;
  63
  64         ioctl(fd, FBIOPUTCMAP, &cmap);
  65 }
  66
  67 unsigned fb_mode(void)
  68 {
  69         return (bpp << 16) | (vinfo.red.length << 8) |
  70                 (vinfo.green.length << 4) | (vinfo.blue.length);
  71 }
  72
  73 int fb_init(void)
  74 {
  75         fd = open(FBDEV_PATH, O_RDWR);
  76         if (fd == -1)
  77                 goto failed;
  78         if (ioctl(fd, FBIOGET_VSCREENINFO, &vinfo) == -1)
  79                 goto failed;
  80         if (ioctl(fd, FBIOGET_FSCREENINFO, &finfo) == -1)
  81                 goto failed;
  82         fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
  83         bpp = (vinfo.bits_per_pixel + 7) >> 3;
  84         nr = 1 << vinfo.red.length;
  85         ng = 1 << vinfo.blue.length;
  86         nb = 1 << vinfo.green.length;
  87         fb = mmap(NULL, fb_len(), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
  88         if (fb == MAP_FAILED)
  89                 goto failed;
  90         fb_cmap_save(1);
  91         fb_cmap();
  92         return 0;
  93 failed:
  94         perror("fb_init()");
  95         close(fd);
  96         return 1;
  97 }
  98
  99 void fb_free(void)
 100 {
 101         fb_cmap_save(0);
 102         munmap(fb, fb_len());
 103         close(fd);
 104 }
 105
 106 int fb_rows(void)
 107 {
 108         return vinfo.yres;
 109 }
 110
 111 int fb_cols(void)
 112 {
 113         return vinfo.xres;
 114 }
 115
 116 void *fb_mem(int r)
 117 {
 118         return fb + (r + vinfo.yoffset) * finfo.line_length;
 119 }
 120
 121 void fb_set(int r, int c, void *mem, int len)
 122 {
 123         memcpy(fb_mem(r) + (c + vinfo.xoffset) * bpp, mem, len * bpp);
 124 }
 125
 126 unsigned fb_val(int r, int g, int b)
 127 {
 128         switch (fb_mode() & 0x0fff) {
 129         default:
 130                 fprintf(stderr, "fb_val: unknown fb_mode()\n");
 131         case 0x0888:
 132                 return (r << 16) | (g << 8) | b;
 133         case 0x0565:
 134                 return ((r >> 3) << 11) | ((g >> 2) << 5) | (b >> 3);
 135         case 0x0233:
 136                 return ((r >> 6) << 6) | ((g >> 5) << 3) | (b >> 5);
 137         }
 138 }