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