ref: 39fb26df70b6d8878953ff18046cdc12817a2e42
dir: /sys/src/libmemdraw/cread.c/
#include <u.h> #include <libc.h> #include <draw.h> #include <memdraw.h> Memimage* creadmemimage(int fd) { char hdr[5*12+1]; Rectangle r; int m, nb, miny, maxy, new, ldepth, ncblock; uchar *buf; Memimage *i; ulong chan; if(readn(fd, hdr, 5*12) != 5*12){ werrstr("readmemimage: short header (2)"); return nil; } /* * distinguish new channel descriptor from old ldepth. * channel descriptors have letters as well as numbers, * while ldepths are a single digit formatted as %-11d. */ new = 0; for(m=0; m<10; m++){ if(hdr[m] != ' '){ new = 1; break; } } if(hdr[11] != ' '){ werrstr("creadimage: bad format"); return nil; } if(new){ hdr[11] = '\0'; if((chan = strtochan(hdr)) == 0){ werrstr("creadimage: bad channel string %s", hdr); return nil; } }else{ ldepth = ((int)hdr[10])-'0'; if(ldepth<0 || ldepth>3){ werrstr("creadimage: bad ldepth %d", ldepth); return nil; } chan = drawld2chan[ldepth]; } r.min.x=atoi(hdr+1*12); r.min.y=atoi(hdr+2*12); r.max.x=atoi(hdr+3*12); r.max.y=atoi(hdr+4*12); if(r.min.x>r.max.x || r.min.y>r.max.y){ werrstr("creadimage: bad rectangle"); return nil; } i = allocmemimage(r, chan); if(i == nil) return nil; ncblock = _compblocksize(r, i->depth); buf = malloc(ncblock); if(buf == nil) goto Errout; miny = r.min.y; while(miny != r.max.y){ if(readn(fd, hdr, 2*12) != 2*12){ Shortread: werrstr("readmemimage: short read"); Errout: freememimage(i); free(buf); return nil; } maxy = atoi(hdr+0*12); nb = atoi(hdr+1*12); if(maxy<=miny || r.max.y<maxy){ werrstr("readimage: bad maxy %d", maxy); goto Errout; } if(nb<=0 || ncblock<nb){ werrstr("readimage: bad count %d", nb); goto Errout; } if(readn(fd, buf, nb)!=nb) goto Shortread; if(!new) /* old image: flip the data bits */ _twiddlecompressed(buf, nb); cloadmemimage(i, Rect(r.min.x, miny, r.max.x, maxy), buf, nb); miny = maxy; } free(buf); return i; }