internal int read_buf(byte[] buf, int start, int size) {
int len=avail_in;
if(len>size) len=size;
if(len==0) return 0;
avail_in-=len;
if(dstate.noheader==0) {
adler=_adler.adler32(adler, next_in, next_in_index, len);
}
System.Array.Copy(next_in, next_in_index, buf, start, len);
next_in_index += len;
total_in += len;
return len;
}