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