sys/src/libmemdraw/cread.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <draw.h>
   4 #include <memdraw.h>
   5
   6 Memimage*
   7 creadmemimage(int fd)
   8 {
   9         char hdr[5*12+1];
  10         Rectangle r;
  11         int m, nb, miny, maxy, new, ldepth, ncblock;
  12         uchar *buf;
  13         Memimage *i;
  14         ulong chan;
  15
  16         if(readn(fd, hdr, 5*12) != 5*12){
  17                 werrstr("readmemimage: short header (2)");
  18                 return nil;
  19         }
  20
  21         /*
  22          * distinguish new channel descriptor from old ldepth.
  23          * channel descriptors have letters as well as numbers,
  24          * while ldepths are a single digit formatted as %-11d.
  25          */
  26         new = 0;
  27         for(m=0; m<10; m++){
  28                 if(hdr[m] != ' '){
  29                         new = 1;
  30                         break;
  31                 }
  32         }
  33         if(hdr[11] != ' '){
  34                 werrstr("creadimage: bad format");
  35                 return nil;
  36         }
  37         if(new){
  38                 hdr[11] = '\0';
  39                 if((chan = strtochan(hdr)) == 0){
  40                         werrstr("creadimage: bad channel string %s", hdr);
  41                         return nil;
  42                 }
  43         }else{
  44                 ldepth = ((int)hdr[10])-'0';
  45                 if(ldepth<0 || ldepth>3){
  46                         werrstr("creadimage: bad ldepth %d", ldepth);
  47                         return nil;
  48                 }
  49                 chan = drawld2chan[ldepth];
  50         }
  51         r.min.x=atoi(hdr+1*12);
  52         r.min.y=atoi(hdr+2*12);
  53         r.max.x=atoi(hdr+3*12);
  54         r.max.y=atoi(hdr+4*12);
  55         if(r.min.x>r.max.x || r.min.y>r.max.y){
  56                 werrstr("creadimage: bad rectangle");
  57                 return nil;
  58         }
  59
  60         i = allocmemimage(r, chan);
  61         if(i == nil)
  62                 return nil;
  63         ncblock = _compblocksize(r, i->depth);
  64         buf = malloc(ncblock);
  65         if(buf == nil)
  66                 goto Errout;
  67         miny = r.min.y;
  68         while(miny != r.max.y){
  69                 if(readn(fd, hdr, 2*12) != 2*12){
  70                 Shortread:
  71                         werrstr("readmemimage: short read");
  72                 Errout:
  73                         freememimage(i);
  74                         free(buf);
  75                         return nil;
  76                 }
  77                 maxy = atoi(hdr+0*12);
  78                 nb = atoi(hdr+1*12);
  79                 if(maxy<=miny || r.max.y<maxy){
  80                         werrstr("readimage: bad maxy %d", maxy);
  81                         goto Errout;
  82                 }
  83                 if(nb<=0 || ncblock<nb){
  84                         werrstr("readimage: bad count %d", nb);
  85                         goto Errout;
  86                 }
  87                 if(readn(fd, buf, nb)!=nb)
  88                         goto Shortread;
  89                 if(!new)        /* old image: flip the data bits */
  90                         _twiddlecompressed(buf, nb);
  91                 cloadmemimage(i, Rect(r.min.x, miny, r.max.x, maxy), buf, nb);
  92                 miny = maxy;
  93         }
  94         free(buf);
  95         return i;
  96 }