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 #include "util.h"
  11
  12 #define FBDEV_PATH      "/dev/fb0"
  13 #define BPP             sizeof(fbval_t)
  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
  20 static int fb_len()
  21 {
  22         return vinfo.xres_virtual * vinfo.yres_virtual * BPP;
  23 }
  24
  25 #define NLEVELS 1 << 8
  26 void fb_cmap(void)
  27 {
  28         unsigned short red[NLEVELS], green[NLEVELS], blue[NLEVELS];
  29         struct fb_cmap cmap;
  30         int mr = 1 << vinfo.red.length;
  31         int mg = 1 << vinfo.green.length;
  32         int mb = 1 << vinfo.blue.length;
  33         int i;
  34         if (finfo.visual == FB_VISUAL_TRUECOLOR)
  35                 return;
  36
  37         for (i = 0; i < mr; i++)
  38                 red[i] = (65535 / (mr - 1)) * i;
  39         for (i = 0; i < mg; i++)
  40                 green[i] = (65535 / (mg - 1)) * i;
  41         for (i = 0; i < mb; i++)
  42                 blue[i] = (65535 / (mb - 1)) * i;
  43
  44         cmap.start = 0;
  45         cmap.len = MAX(mr, MAX(mg, mb));
  46         cmap.red = red;
  47         cmap.green = green;
  48         cmap.blue = blue;
  49         cmap.transp = 0;
  50
  51         ioctl(fd, FBIOPUTCMAP, &cmap);
  52 }
  53
  54 void fb_init(void)
  55 {
  56         fd = open(FBDEV_PATH, O_RDWR);
  57         if (fd == -1)
  58                 xerror("can't open " FBDEV_PATH);
  59         if (ioctl(fd, FBIOGET_VSCREENINFO, &vinfo) == -1)
  60                 xerror("ioctl failed");
  61         if (ioctl(fd, FBIOGET_FSCREENINFO, &finfo) == -1)
  62                 xerror("ioctl failed");
  63         fb = mmap(NULL, fb_len(), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
  64         if (fb == MAP_FAILED)
  65                 xerror("can't map the framebuffer");
  66         fb_cmap();
  67 }
  68
  69 void fb_put(int r, int c, fbval_t val)
  70 {
  71         long loc = (c + vinfo.xoffset) * BPP +
  72                 (r + vinfo.yoffset) * finfo.line_length;
  73         memcpy(fb + loc, &val, BPP);
  74 }
  75
  76 void fb_free()
  77 {
  78         munmap(fb, fb_len());
  79         close(fd);
  80 }
  81
  82 static fbval_t color_bits(struct fb_bitfield *bf, fbval_t v)
  83 {
  84         fbval_t moved = v >> (8 - bf->length);
  85         return moved << bf->offset;
  86 }
  87
  88 fbval_t fb_color(unsigned char r, unsigned char g, unsigned char b)
  89 {
  90         return color_bits(&vinfo.red, r) |
  91                 color_bits(&vinfo.green, g) |
  92                 color_bits(&vinfo.blue, b);
  93 }
  94
  95 int fb_rows(void)
  96 {
  97         return vinfo.yres_virtual;
  98 }
  99
 100 int fb_cols(void)
 101 {
 102         return vinfo.xres_virtual;
 103 }
 104
 105 void fb_box(int sr, int sc, int er, int ec, fbval_t val)
 106 {
 107         int r, c;
 108         for (r = sr; r < er; r++)
 109                 for (c = sc; c < ec; c++)
 110                         fb_put(r, c, val);
 111 }
 112
 113 static unsigned char *rowaddr(int r)
 114 {
 115         return fb + (r + vinfo.yoffset) * finfo.line_length;
 116 }
 117
 118 void fb_scroll(int sr, int nr, int n, fbval_t val)
 119 {
 120         memmove(rowaddr(sr + n), rowaddr(sr), nr * finfo.line_length);
 121         if (n > 0)
 122                 fb_box(sr, 0, sr + n, fb_cols(), val);
 123         else
 124                 fb_box(sr + nr + n, 0, sr + nr, fb_cols(), val);
 125 }