if (n > 0) {
int l = 0;
while (l < n) {
int n1 = MIN(CHUNK_SIZE,n-l);
write_int(f,n1);
write_buf(f,map_ptr(buf,offset+l,n1),n1);
if (n > 0) {
int l = 0;
while (l < n) {
int n1 = MIN(CHUNK_SIZE,n-l);
write_int(f,n1);
write_buf(f,map_ptr(buf,offset+l,n1),n1);