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 MIN(a, b)       ((a) < (b) ? (a) : (b))
  12 #define MAX(a, b)       ((a) > (b) ? (a) : (b))
  13 #define FBDEV_PATH      "/dev/fb0"
  14 #define MAXFBWIDTH      (1 << 12)
  15 #define BPP             sizeof(fbval_t)
  16 #define NLEVELS         (1 << 8)
  17
  18 static int fd;
  19 static unsigned char *fb;
  20 static struct fb_var_screeninfo vinfo;
  21 static struct fb_fix_screeninfo finfo;
  22 static int rl, rr, gl, gr, bl, br;
  23 static int nr, ng, nb;
  24
  25 static int fb_len()
  26 {
  27         return vinfo.xres_virtual * vinfo.yres_virtual * BPP;
  28 }
  29
  30 static void fb_cmap_save(int save)
  31 {
  32         static unsigned short red[NLEVELS], green[NLEVELS], blue[NLEVELS];
  33         struct fb_cmap cmap;
  34         if (finfo.visual == FB_VISUAL_TRUECOLOR)
  35                 return;
  36         cmap.start = 0;
  37         cmap.len = MAX(nr, MAX(ng, nb));
  38         cmap.red = red;
  39         cmap.green = green;
  40         cmap.blue = blue;
  41         cmap.transp = 0;
  42         ioctl(fd, save ? FBIOGETCMAP : FBIOPUTCMAP, &cmap);
  43 }
  44
  45 void fb_cmap(void)
  46 {
  47         unsigned short red[NLEVELS], green[NLEVELS], blue[NLEVELS];
  48         struct fb_cmap cmap;
  49         int i;
  50         if (finfo.visual == FB_VISUAL_TRUECOLOR)
  51                 return;
  52
  53         for (i = 0; i < nr; i++)
  54                 red[i] = (65535 / (nr - 1)) * i;
  55         for (i = 0; i < ng; i++)
  56                 green[i] = (65535 / (ng - 1)) * i;
  57         for (i = 0; i < nb; i++)
  58                 blue[i] = (65535 / (nb - 1)) * i;
  59
  60         cmap.start = 0;
  61         cmap.len = MAX(nr, MAX(ng, nb));
  62         cmap.red = red;
  63         cmap.green = green;
  64         cmap.blue = blue;
  65         cmap.transp = 0;
  66
  67         ioctl(fd, FBIOPUTCMAP, &cmap);
  68 }
  69
  70 static void xerror(char *msg)
  71 {
  72         perror(msg);
  73         exit(1);
  74 }
  75
  76 static void xdie(char *msg)
  77 {
  78         fprintf(stderr, "%s\n", msg);
  79         exit(1);
  80 }
  81
  82 static void init_colors(void)
  83 {
  84         nr = 1 << vinfo.red.length;
  85         ng = 1 << vinfo.green.length;
  86         nb = 1 << vinfo.blue.length;
  87         rr = 8 - vinfo.red.length;
  88         rl = vinfo.red.offset;
  89         gr = 8 - vinfo.green.length;
  90         gl = vinfo.green.offset;
  91         br = 8 - vinfo.blue.length;
  92         bl = vinfo.blue.offset;
  93 }
  94
  95 void fb_init(void)
  96 {
  97         fd = open(FBDEV_PATH, O_RDWR);
  98         if (fd == -1)
  99                 xerror("can't open " FBDEV_PATH);
 100         if (ioctl(fd, FBIOGET_VSCREENINFO, &vinfo) == -1)
 101                 xerror("ioctl failed");
 102         if (ioctl(fd, FBIOGET_FSCREENINFO, &finfo) == -1)
 103                 xerror("ioctl failed");
 104         if ((vinfo.bits_per_pixel + 7) >> 3 != BPP)
 105                 xdie("fbval_t does not match framebuffer depth");
 106         init_colors();
 107         fb = mmap(NULL, fb_len(), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 108         if (fb == MAP_FAILED)
 109                 xerror("can't map the framebuffer");
 110         fb_cmap_save(1);
 111         fb_cmap();
 112 }
 113
 114 void fb_set(int r, int c, fbval_t *mem, int len)
 115 {
 116         long loc = (c + vinfo.xoffset) * BPP +
 117                 (r + vinfo.yoffset) * finfo.line_length;
 118         memcpy(fb + loc, mem, len * BPP);
 119 }
 120
 121 void fb_free()
 122 {
 123         fb_cmap_save(0);
 124         munmap(fb, fb_len());
 125         close(fd);
 126 }
 127
 128 fbval_t fb_color(unsigned char r, unsigned char g, unsigned char b)
 129 {
 130         return ((r >> rr) << rl) | ((g >> gr) << gl) | ((b >> br) << bl);
 131 }
 132
 133 int fb_rows(void)
 134 {
 135         return vinfo.yres;
 136 }
 137
 138 int fb_cols(void)
 139 {
 140         return vinfo.xres;
 141 }
 142
 143 static unsigned char *rowaddr(int r)
 144 {
 145         return fb + (r + vinfo.yoffset) * finfo.line_length;
 146 }
 147
 148 static unsigned long cache[MAXFBWIDTH];
 149 void fb_box(int sr, int sc, int er, int ec, fbval_t val)
 150 {
 151         int i;
 152         int pc = sizeof(cache[0]) / sizeof(val);
 153         int cn = MIN((ec - sc) / pc + 1, MAXFBWIDTH);
 154         unsigned long nv = val;
 155         for (i = 1; i < pc; i++)
 156                 nv = (nv << (sizeof(val) * 8)) | val;
 157         for (i = 0; i < cn; i++)
 158                 cache[i] = nv;
 159         for (i = sr; i < er; i++)
 160                 memcpy(rowaddr(i) + sc * BPP, cache, (ec - sc) * BPP);
 161 }