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