separate out
diff --git a/src/libmemdraw/unload.c b/src/libmemdraw/unload.c
new file mode 100644
index 0000000..8683575
--- /dev/null
+++ b/src/libmemdraw/unload.c
@@ -0,0 +1,25 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include <memdraw.h>
+
+int
+_unloadmemimage(Memimage *i, Rectangle r, uchar *data, int ndata)
+{
+ int y, l;
+ uchar *q;
+
+ if(!rectinrect(r, i->r))
+ return -1;
+ l = bytesperline(r, i->depth);
+ if(ndata < l*Dy(r))
+ return -1;
+ ndata = l*Dy(r);
+ q = byteaddr(i, r.min);
+ for(y=r.min.y; y<r.max.y; y++){
+ memmove(data, q, l);
+ q += i->width*sizeof(u32int);
+ data += l;
+ }
+ return ndata;
+}
