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             2
  14
  15 static int fd;
  16 static 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 void fb_init(void)
  26 {
  27         fd = open(FBDEV_PATH, O_RDWR);
  28         if (fd == -1)
  29                 xerror("can't open " FBDEV_PATH);
  30         if (ioctl(fd, FBIOGET_VSCREENINFO, &vinfo) == -1)
  31                 xerror("ioctl failed");
  32         if (ioctl(fd, FBIOGET_FSCREENINFO, &finfo) == -1)
  33                 xerror("ioctl failed");
  34         fb = mmap(NULL, fb_len(), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
  35         if (fb == MAP_FAILED)
  36                 xerror("can't map the framebuffer");
  37 }
  38
  39 void fb_put(int r, int c, u16_t val)
  40 {
  41         long loc = (c + vinfo.xoffset) * BPP +
  42                 (r + vinfo.yoffset) * finfo.line_length;
  43         memcpy(fb + loc, &val, BPP);
  44 }
  45
  46 void fb_free()
  47 {
  48         munmap(fb, fb_len());
  49         close(fd);
  50 }
  51
  52 static u16_t color_bits(struct fb_bitfield *bf, unsigned char v)
  53 {
  54         unsigned char moved = v >> (8 - bf->length);
  55         return moved << bf->offset;
  56 }
  57
  58 u16_t fb_color(u8_t r, u8_t g, u8_t b)
  59 {
  60         return color_bits(&vinfo.red, r) |
  61                 color_bits(&vinfo.green, g) |
  62                 color_bits(&vinfo.blue, b);
  63 }
  64
  65 int fb_rows(void)
  66 {
  67         return vinfo.yres_virtual;
  68 }
  69
  70 int fb_cols(void)
  71 {
  72         return vinfo.xres_virtual;
  73 }
  74
  75 void fb_box(int sr, int sc, int er, int ec, u16_t val)
  76 {
  77         int r, c;
  78         for (r = sr; r < er; r++)
  79                 for (c = sc; c < ec; c++)
  80                         fb_put(r, c, val);
  81 }
  82
  83 static char *rowaddr(int r)
  84 {
  85         return fb + (r + vinfo.yoffset) * finfo.line_length;
  86 }
  87
  88 void fb_scroll(int n, u16_t val)
  89 {
  90         int s = 0, e = fb_rows();
  91         int r;
  92         if (n > 0)
  93                 e -= n;
  94         else
  95                 s = -n;
  96         for (r = s; r < e; r++)
  97                 memcpy(rowaddr(r + n), rowaddr(r), finfo.line_length);
  98         if (n > 0)
  99                 fb_box(0, 0, n, fb_cols(), val);
 100         else
 101                 fb_box(fb_rows() + n, 0, fb_rows(), fb_cols(), val);
 102 }