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 MAXWIDTH        (1 << 12)
  14 #define BPP             sizeof(fbval_t)
  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
  21 static int fb_len()
  22 {
  23         return vinfo.xres_virtual * vinfo.yres_virtual * BPP;
  24 }
  25
  26 #define NLEVELS 1 << 8
  27 void fb_cmap(void)
  28 {
  29         unsigned short red[NLEVELS], green[NLEVELS], blue[NLEVELS];
  30         struct fb_cmap cmap;
  31         int mr = 1 << vinfo.red.length;
  32         int mg = 1 << vinfo.green.length;
  33         int mb = 1 << vinfo.blue.length;
  34         int i;
  35         if (finfo.visual == FB_VISUAL_TRUECOLOR)
  36                 return;
  37
  38         for (i = 0; i < mr; i++)
  39                 red[i] = (65535 / (mr - 1)) * i;
  40         for (i = 0; i < mg; i++)
  41                 green[i] = (65535 / (mg - 1)) * i;
  42         for (i = 0; i < mb; i++)
  43                 blue[i] = (65535 / (mb - 1)) * i;
  44
  45         cmap.start = 0;
  46         cmap.len = MAX(mr, MAX(mg, mb));
  47         cmap.red = red;
  48         cmap.green = green;
  49         cmap.blue = blue;
  50         cmap.transp = 0;
  51
  52         ioctl(fd, FBIOPUTCMAP, &cmap);
  53 }
  54
  55 void fb_init(void)
  56 {
  57         fd = open(FBDEV_PATH, O_RDWR);
  58         if (fd == -1)
  59                 xerror("can't open " FBDEV_PATH);
  60         if (ioctl(fd, FBIOGET_VSCREENINFO, &vinfo) == -1)
  61                 xerror("ioctl failed");
  62         if (ioctl(fd, FBIOGET_FSCREENINFO, &finfo) == -1)
  63                 xerror("ioctl failed");
  64         fb = mmap(NULL, fb_len(), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
  65         if (fb == MAP_FAILED)
  66                 xerror("can't map the framebuffer");
  67         fb_cmap();
  68 }
  69
  70 void fb_set(int r, int c, fbval_t *mem, int len)
  71 {
  72         long loc = (c + vinfo.xoffset) * BPP +
  73                 (r + vinfo.yoffset) * finfo.line_length;
  74         memcpy(fb + loc, mem, len * BPP);
  75 }
  76
  77 void fb_free()
  78 {
  79         munmap(fb, fb_len());
  80         close(fd);
  81 }
  82
  83 static fbval_t color_bits(struct fb_bitfield *bf, fbval_t v)
  84 {
  85         fbval_t moved = v >> (8 - bf->length);
  86         return moved << bf->offset;
  87 }
  88
  89 fbval_t fb_color(unsigned char r, unsigned char g, unsigned char b)
  90 {
  91         return color_bits(&vinfo.red, r) |
  92                 color_bits(&vinfo.green, g) |
  93                 color_bits(&vinfo.blue, b);
  94 }
  95
  96 int fb_rows(void)
  97 {
  98         return vinfo.yres;
  99 }
 100
 101 int fb_cols(void)
 102 {
 103         return vinfo.xres;
 104 }
 105
 106 static unsigned char *rowaddr(int r)
 107 {
 108         return fb + (r + vinfo.yoffset) * finfo.line_length;
 109 }
 110
 111 static unsigned long cache[MAXWIDTH];
 112 void fb_box(int sr, int sc, int er, int ec, fbval_t val)
 113 {
 114         int i;
 115         int pc = sizeof(cache[0]) / sizeof(val);
 116         int cn = MIN((ec - sc) / pc + 1, ARRAY_SIZE(cache));
 117         unsigned long nv = val;
 118         for (i = 1; i < pc; i++)
 119                 nv = (nv << (sizeof(val) * 8)) | val;
 120         for (i = 0; i < cn; i++)
 121                 cache[i] = nv;
 122         for (i = sr; i < er; i++)
 123                 memcpy(rowaddr(i) + sc * BPP, cache, (ec - sc) * BPP);
 124 }
 125
 126 void fb_scroll(int sr, int nr, int n, fbval_t val)
 127 {
 128         memmove(rowaddr(sr + n), rowaddr(sr), nr * finfo.line_length);
 129         if (n > 0)
 130                 fb_box(sr, 0, sr + n, fb_cols(), val);
 131         else
 132                 fb_box(sr + nr + n, 0, sr + nr, fb_cols(), val);
 133 }