separate out
diff --git a/src/libmemdraw/openmemsubfont.c b/src/libmemdraw/openmemsubfont.c
new file mode 100644
index 0000000..c8d926e
--- /dev/null
+++ b/src/libmemdraw/openmemsubfont.c
@@ -0,0 +1,53 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include <memdraw.h>
+
+Memsubfont*
+openmemsubfont(char *name)
+{
+ Memsubfont *sf;
+ Memimage *i;
+ Fontchar *fc;
+ int fd, n;
+ char hdr[3*12+4+1];
+ uchar *p;
+
+ fd = open(name, OREAD);
+ if(fd < 0)
+ return nil;
+ p = nil;
+ i = readmemimage(fd);
+ if(i == nil)
+ goto Err;
+ if(read(fd, hdr, 3*12) != 3*12){
+ werrstr("openmemsubfont: header read error: %r");
+ goto Err;
+ }
+ n = atoi(hdr);
+ p = malloc(6*(n+1));
+ if(p == nil)
+ goto Err;
+ if(read(fd, p, 6*(n+1)) != 6*(n+1)){
+ werrstr("openmemsubfont: fontchar read error: %r");
+ goto Err;
+ }
+ fc = malloc(sizeof(Fontchar)*(n+1));
+ if(fc == nil)
+ goto Err;
+ _unpackinfo(fc, p, n);
+ sf = allocmemsubfont(name, n, atoi(hdr+12), atoi(hdr+24), fc, i);
+ if(sf == nil){
+ free(fc);
+ goto Err;
+ }
+ free(p);
+ return sf;
+Err:
+ close(fd);
+ if (i != nil)
+ freememimage(i);
+ if (p != nil)
+ free(p);
+ return nil;
+}
