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 "config.h"
  10 #include "draw.h"
  11 #include "util.h"
  12
  13 #define BPP             sizeof(fbval_t)
  14 #define NLEVELS         (1 << 8)
  15
  16 static int fd;
  17 static unsigned char *fb;
  18 static struct fb_var_screeninfo vinfo;
  19 static struct fb_fix_screeninfo finfo;
  20 static int rl, rr, gl, gr, bl, br;
  21 static int nr, ng, nb;
  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 = 0;
  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 = 0;
  64
  65         ioctl(fd, FBIOPUTCMAP, &cmap);
  66 }
  67
  68 static void xerror(char *msg)
  69 {
  70         perror(msg);
  71         exit(1);
  72 }
  73
  74 static void xdie(char *msg)
  75 {
  76         fprintf(stderr, "%s\n", msg);
  77         exit(1);
  78 }
  79
  80 static void init_colors(void)
  81 {
  82         nr = 1 << vinfo.red.length;
  83         ng = 1 << vinfo.green.length;
  84         nb = 1 << vinfo.blue.length;
  85         rr = 8 - vinfo.red.length;
  86         rl = vinfo.red.offset;
  87         gr = 8 - vinfo.green.length;
  88         gl = vinfo.green.offset;
  89         br = 8 - vinfo.blue.length;
  90         bl = vinfo.blue.offset;
  91 }
  92
  93 void fb_init(void)
  94 {
  95         fd = open(FBDEV_PATH, O_RDWR);
  96         if (fd == -1)
  97                 xerror("can't open " FBDEV_PATH);
  98         if (ioctl(fd, FBIOGET_VSCREENINFO, &vinfo) == -1)
  99                 xerror("ioctl failed");
 100         if (ioctl(fd, FBIOGET_FSCREENINFO, &finfo) == -1)
 101                 xerror("ioctl failed");
 102         if ((vinfo.bits_per_pixel + 7) >> 3 != BPP)
 103                 xdie("fbval_t does not match framebuffer depth");
 104         fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
 105         init_colors();
 106         fb = mmap(NULL, fb_len(), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 107         if (fb == MAP_FAILED)
 108                 xerror("can't map the framebuffer");
 109         fb_cmap_save(1);
 110         fb_cmap();
 111 }
 112
 113 void fb_set(int r, int c, fbval_t *mem, int len)
 114 {
 115         long loc = (c + vinfo.xoffset) * BPP +
 116                 (r + vinfo.yoffset) * finfo.line_length;
 117         memcpy(fb + loc, mem, len * BPP);
 118 }
 119
 120 void fb_free(void)
 121 {
 122         fb_cmap_save(0);
 123         munmap(fb, fb_len());
 124         close(fd);
 125 }
 126
 127 fbval_t fb_color(unsigned char r, unsigned char g, unsigned char b)
 128 {
 129         return ((r >> rr) << rl) | ((g >> gr) << gl) | ((b >> br) << bl);
 130 }
 131
 132 int fb_rows(void)
 133 {
 134         return vinfo.yres;
 135 }
 136
 137 int fb_cols(void)
 138 {
 139         return vinfo.xres;
 140 }