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
  12 #define BPP             sizeof(fbval_t)
  13 #define NLEVELS         (1 << 8)
  14
  15 static int fd;
  16 static unsigned char *fb;
  17 static struct fb_var_screeninfo vinfo;
  18 static struct fb_fix_screeninfo finfo;
  19 static int rl, rr, gl, gr, bl, br;
  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 = 0;
  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 = 0;
  63
  64         ioctl(fd, FBIOPUTCMAP, &cmap);
  65 }
  66
  67 static void xerror(char *msg)
  68 {
  69         perror(msg);
  70         exit(1);
  71 }
  72
  73 static void xdie(char *msg)
  74 {
  75         fprintf(stderr, "%s\n", msg);
  76         exit(1);
  77 }
  78
  79 static void init_colors(void)
  80 {
  81         nr = 1 << vinfo.red.length;
  82         ng = 1 << vinfo.green.length;
  83         nb = 1 << vinfo.blue.length;
  84         rr = 8 - vinfo.red.length;
  85         rl = vinfo.red.offset;
  86         gr = 8 - vinfo.green.length;
  87         gl = vinfo.green.offset;
  88         br = 8 - vinfo.blue.length;
  89         bl = vinfo.blue.offset;
  90 }
  91
  92 void fb_init(void)
  93 {
  94         fd = open(FBDEV_PATH, O_RDWR);
  95         if (fd == -1)
  96                 xerror("can't open " FBDEV_PATH);
  97         if (ioctl(fd, FBIOGET_VSCREENINFO, &vinfo) == -1)
  98                 xerror("ioctl failed");
  99         if (ioctl(fd, FBIOGET_FSCREENINFO, &finfo) == -1)
 100                 xerror("ioctl failed");
 101         if ((vinfo.bits_per_pixel + 7) >> 3 != BPP)
 102                 xdie("fbval_t does not match framebuffer depth");
 103         fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
 104         init_colors();
 105         fb = mmap(NULL, fb_len(), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 106         if (fb == MAP_FAILED)
 107                 xerror("can't map the framebuffer");
 108         fb_cmap_save(1);
 109         fb_cmap();
 110 }
 111
 112 void fb_set(int r, int c, fbval_t *mem, int len)
 113 {
 114         long loc = (c + vinfo.xoffset) * BPP +
 115                 (r + vinfo.yoffset) * finfo.line_length;
 116         memcpy(fb + loc, mem, len * BPP);
 117 }
 118
 119 void fb_free(void)
 120 {
 121         fb_cmap_save(0);
 122         munmap(fb, fb_len());
 123         close(fd);
 124 }
 125
 126 fbval_t fb_color(unsigned char r, unsigned char g, unsigned char b)
 127 {
 128         return ((r >> rr) << rl) | ((g >> gr) << gl) | ((b >> br) << bl);
 129 }
 130
 131 int fb_rows(void)
 132 {
 133         return vinfo.yres;
 134 }
 135
 136 int fb_cols(void)
 137 {
 138         return vinfo.xres;
 139 }