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 BPP             sizeof(fbval_t)
  12 #define NLEVELS         (1 << 8)
  13
  14 static int fd;
  15 static unsigned char *fb;
  16 static struct fb_var_screeninfo vinfo;
  17 static struct fb_fix_screeninfo finfo;
  18 static int rl, rr, gl, gr, bl, br;
  19 static int nr, ng, nb;
  20
  21 static int fb_len(void)
  22 {
  23         return finfo.line_length * vinfo.yres_virtual;
  24 }
  25
  26 static void fb_cmap_save(int save)
  27 {
  28         static unsigned short red[NLEVELS], green[NLEVELS], blue[NLEVELS];
  29         struct fb_cmap cmap;
  30         if (finfo.visual == FB_VISUAL_TRUECOLOR)
  31                 return;
  32         cmap.start = 0;
  33         cmap.len = MAX(nr, MAX(ng, nb));
  34         cmap.red = red;
  35         cmap.green = green;
  36         cmap.blue = blue;
  37         cmap.transp = 0;
  38         ioctl(fd, save ? FBIOGETCMAP : FBIOPUTCMAP, &cmap);
  39 }
  40
  41 void fb_cmap(void)
  42 {
  43         unsigned short red[NLEVELS], green[NLEVELS], blue[NLEVELS];
  44         struct fb_cmap cmap;
  45         int i;
  46         if (finfo.visual == FB_VISUAL_TRUECOLOR)
  47                 return;
  48
  49         for (i = 0; i < nr; i++)
  50                 red[i] = (65535 / (nr - 1)) * i;
  51         for (i = 0; i < ng; i++)
  52                 green[i] = (65535 / (ng - 1)) * i;
  53         for (i = 0; i < nb; i++)
  54                 blue[i] = (65535 / (nb - 1)) * i;
  55
  56         cmap.start = 0;
  57         cmap.len = MAX(nr, MAX(ng, nb));
  58         cmap.red = red;
  59         cmap.green = green;
  60         cmap.blue = blue;
  61         cmap.transp = 0;
  62
  63         ioctl(fd, FBIOPUTCMAP, &cmap);
  64 }
  65
  66 static void xerror(char *msg)
  67 {
  68         perror(msg);
  69         exit(1);
  70 }
  71
  72 static void xdie(char *msg)
  73 {
  74         fprintf(stderr, "%s\n", msg);
  75         exit(1);
  76 }
  77
  78 static void init_colors(void)
  79 {
  80         nr = 1 << vinfo.red.length;
  81         ng = 1 << vinfo.green.length;
  82         nb = 1 << vinfo.blue.length;
  83         rr = 8 - vinfo.red.length;
  84         rl = vinfo.red.offset;
  85         gr = 8 - vinfo.green.length;
  86         gl = vinfo.green.offset;
  87         br = 8 - vinfo.blue.length;
  88         bl = vinfo.blue.offset;
  89 }
  90
  91 void fb_init(void)
  92 {
  93         fd = open(FBDEV_PATH, O_RDWR);
  94         if (fd == -1)
  95                 xerror("can't open " FBDEV_PATH);
  96         if (ioctl(fd, FBIOGET_VSCREENINFO, &vinfo) == -1)
  97                 xerror("ioctl failed");
  98         if (ioctl(fd, FBIOGET_FSCREENINFO, &finfo) == -1)
  99                 xerror("ioctl failed");
 100         if ((vinfo.bits_per_pixel + 7) >> 3 != BPP)
 101                 xdie("fbval_t does not match framebuffer depth");
 102         fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
 103         init_colors();
 104         fb = mmap(NULL, fb_len(), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 105         if (fb == MAP_FAILED)
 106                 xerror("can't map the framebuffer");
 107         fb_cmap_save(1);
 108         fb_cmap();
 109 }
 110
 111 void fb_set(int r, int c, fbval_t *mem, int len)
 112 {
 113         long loc = (c + vinfo.xoffset) * BPP +
 114                 (r + vinfo.yoffset) * finfo.line_length;
 115         memcpy(fb + loc, mem, len * BPP);
 116 }
 117
 118 void fb_free(void)
 119 {
 120         fb_cmap_save(0);
 121         munmap(fb, fb_len());
 122         close(fd);
 123 }
 124
 125 fbval_t fb_color(unsigned char r, unsigned char g, unsigned char b)
 126 {
 127         return ((r >> rr) << rl) | ((g >> gr) << gl) | ((b >> br) << bl);
 128 }
 129
 130 int fb_rows(void)
 131 {
 132         return vinfo.yres;
 133 }
 134
 135 int fb_cols(void)
 136 {
 137         return vinfo.xres;
 138 }