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 FBDEV_PATH      "/dev/fb0"
  12 #define MAXFBWIDTH      (1 << 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()
  24 {
  25         return vinfo.xres_virtual * vinfo.yres_virtual * BPP;
  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         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()
 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 }
 140
 141 static unsigned char *rowaddr(int r)
 142 {
 143         return fb + (r + vinfo.yoffset) * finfo.line_length;
 144 }
 145
 146 static unsigned long cache[MAXFBWIDTH];
 147 void fb_box(int sr, int sc, int er, int ec, fbval_t val)
 148 {
 149         int i;
 150         int pc = sizeof(cache[0]) / sizeof(val);
 151         int cn = MIN((ec - sc) / pc + 1, MAXFBWIDTH);
 152         unsigned long nv = val;
 153         for (i = 1; i < pc; i++)
 154                 nv = (nv << (sizeof(val) * 8)) | val;
 155         for (i = 0; i < cn; i++)
 156                 cache[i] = nv;
 157         for (i = sr; i < er; i++)
 158                 memcpy(rowaddr(i) + sc * BPP, cache, (ec - sc) * BPP);
 159 }