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 FBDEV_PATH      "/dev/fb0"
  12 #define MAXWIDTH        (1 << 12)
  13 #define BPP             sizeof(fbval_t)
  14 #define NLEVELS         (1 << 8)
  15 #define ARRAY_SIZE(a)   (sizeof(a) / sizeof((a)[0]))
  16
  17 static void xerror(char *msg)
  18 {
  19         perror(msg);
  20         exit(1);
  21 }
  22
  23 static int fd;
  24 static unsigned char *fb;
  25 static struct fb_var_screeninfo vinfo;
  26 static struct fb_fix_screeninfo finfo;
  27
  28 static int fb_len()
  29 {
  30         return vinfo.xres_virtual * vinfo.yres_virtual * BPP;
  31 }
  32
  33 static void fb_cmap_save(int save)
  34 {
  35         static unsigned short red[NLEVELS], green[NLEVELS], blue[NLEVELS];
  36         struct fb_cmap cmap;
  37         int mr = 1 << vinfo.red.length;
  38         int mg = 1 << vinfo.green.length;
  39         int mb = 1 << vinfo.blue.length;
  40         if (finfo.visual == FB_VISUAL_TRUECOLOR)
  41                 return;
  42         cmap.start = 0;
  43         cmap.len = MAX(mr, MAX(mg, mb));
  44         cmap.red = red;
  45         cmap.green = green;
  46         cmap.blue = blue;
  47         cmap.transp = 0;
  48         if (save)
  49                 ioctl(fd, FBIOGETCMAP, &cmap);
  50         else
  51                 ioctl(fd, FBIOPUTCMAP, &cmap);
  52 }
  53
  54 void fb_cmap(void)
  55 {
  56         unsigned short red[NLEVELS], green[NLEVELS], blue[NLEVELS];
  57         struct fb_cmap cmap;
  58         int mr = 1 << vinfo.red.length;
  59         int mg = 1 << vinfo.green.length;
  60         int mb = 1 << vinfo.blue.length;
  61         int i;
  62         if (finfo.visual == FB_VISUAL_TRUECOLOR)
  63                 return;
  64
  65         for (i = 0; i < mr; i++)
  66                 red[i] = (65535 / (mr - 1)) * i;
  67         for (i = 0; i < mg; i++)
  68                 green[i] = (65535 / (mg - 1)) * i;
  69         for (i = 0; i < mb; i++)
  70                 blue[i] = (65535 / (mb - 1)) * i;
  71
  72         cmap.start = 0;
  73         cmap.len = MAX(mr, MAX(mg, mb));
  74         cmap.red = red;
  75         cmap.green = green;
  76         cmap.blue = blue;
  77         cmap.transp = 0;
  78
  79         ioctl(fd, FBIOPUTCMAP, &cmap);
  80 }
  81
  82 static void xdie(char *msg)
  83 {
  84         fprintf(stderr, "%s\n", msg);
  85         exit(1);
  86 }
  87
  88 void fb_init(void)
  89 {
  90         fd = open(FBDEV_PATH, O_RDWR);
  91         if (fd == -1)
  92                 xerror("can't open " FBDEV_PATH);
  93         if (ioctl(fd, FBIOGET_VSCREENINFO, &vinfo) == -1)
  94                 xerror("ioctl failed");
  95         if (ioctl(fd, FBIOGET_FSCREENINFO, &finfo) == -1)
  96                 xerror("ioctl failed");
  97         if ((vinfo.bits_per_pixel + 7) >> 3 != BPP)
  98                 xdie("fbval_t does not match framebuffer depth");
  99         fb = mmap(NULL, fb_len(), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 100         if (fb == MAP_FAILED)
 101                 xerror("can't map the framebuffer");
 102         fb_cmap_save(1);
 103         fb_cmap();
 104 }
 105
 106 void fb_set(int r, int c, fbval_t *mem, int len)
 107 {
 108         long loc = (c + vinfo.xoffset) * BPP +
 109                 (r + vinfo.yoffset) * finfo.line_length;
 110         memcpy(fb + loc, mem, len * BPP);
 111 }
 112
 113 void fb_free()
 114 {
 115         fb_cmap_save(0);
 116         munmap(fb, fb_len());
 117         close(fd);
 118 }
 119
 120 static fbval_t color_bits(struct fb_bitfield *bf, fbval_t v)
 121 {
 122         fbval_t moved = v >> (8 - bf->length);
 123         return moved << bf->offset;
 124 }
 125
 126 fbval_t fb_color(unsigned char r, unsigned char g, unsigned char b)
 127 {
 128         return color_bits(&vinfo.red, r) |
 129                 color_bits(&vinfo.green, g) |
 130                 color_bits(&vinfo.blue, b);
 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[MAXWIDTH];
 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, ARRAY_SIZE(cache));
 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 }