X-Git-Url: http://git.annexia.org/?a=blobdiff_plain;f=diskzip%2Fdiskzip_bitmap.ml;fp=diskzip%2Fdiskzip_bitmap.ml;h=982c46f7d6f48e8eab9f88faf5361a6cf538934e;hb=264faa6f381b1972327f830e3fca5ddd5881ff92;hp=0000000000000000000000000000000000000000;hpb=21643d806233bbc2462795bb5901d44f3cdf4ecf;p=virt-df.git

diff --git a/diskzip/diskzip_bitmap.ml b/diskzip/diskzip_bitmap.ml
new file mode 100644
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+++ b/diskzip/diskzip_bitmap.ml
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+(* 'diskzip' command for intelligently compressing disk images.
+   (C) Copyright 2007 Richard W.M. Jones, Red Hat Inc.
+   http://libvirt.org/
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *)
+
+open Int63.Operators
+
+type t = int63 * string array
+
+(* NB: Sys.max_string_length is by no means a 'round' number. *)
+let maxlen = Int63.of_int Sys.max_string_length
+
+let create size =
+  (* Get the size in bytes & round up. *)
+  let sizebytes = (size +^ ~^7) >^> 3 in
+
+  let n = Int63.to_int (sizebytes /^ maxlen) in
+  let overflow = Int63.to_int (sizebytes %^ maxlen) in
+  let zerochar = Char.chr 0 in
+  let array =
+    if overflow <> 0 then
+      Array.init (n+1)
+	(function
+	 | i when i = n -> String.make overflow zerochar
+	 | _ -> String.make Sys.max_string_length zerochar)
+    else
+      Array.init n (fun _ -> String.make Sys.max_string_length zerochar) in
+  size, array
+
+let mask7 = ~^7
+
+let set (size, t) offset =
+  if offset < Int63.zero || offset >= size then invalid_arg "bitmap";
+  let offset_bytes, offset_bits =
+    offset >^> 3,
+    Int63.to_int (offset &^ mask7) in
+  let offset_strs, offset_in_str =
+    Int63.to_int (offset_bytes /^ maxlen),
+    Int63.to_int (offset_bytes %^ maxlen) in
+  let c = Char.code t.(offset_strs).[offset_in_str] in
+  t.(offset_strs).[offset_in_str] <- Char.chr (c lor (1 lsl offset_bits))
+
+let clear (size, t) offset =
+  if offset < Int63.zero || offset >= size then invalid_arg "bitmap";
+  let offset_bytes, offset_bits =
+    offset >^> 3,
+    Int63.to_int (offset &^ mask7) in
+  let offset_strs, offset_in_str =
+    Int63.to_int (offset_bytes /^ maxlen),
+    Int63.to_int (offset_bytes %^ maxlen) in
+  let c = Char.code t.(offset_strs).[offset_in_str] in
+  t.(offset_strs).[offset_in_str] <-
+    Char.chr (c land (lnot (1 lsl offset_bits)))
+
+let get (size, t) offset =
+  if offset < Int63.zero || offset >= size then invalid_arg "bitmap";
+  let offset_bytes, offset_bits =
+    offset >^> 3,
+    Int63.to_int (offset &^ mask7) in
+  let offset_strs, offset_in_str =
+    Int63.to_int (offset_bytes /^ maxlen),
+    Int63.to_int (offset_bytes %^ maxlen) in
+  let c = Char.code t.(offset_strs).[offset_in_str] in
+  c land (1 lsl offset_bits) <> 0
+
+let set_bool t offset v =
+  (if v then set else clear) t offset
+
+let set_int t offset v =
+  (if v <> 0 then set else clear) t offset
+
+let iter_set f (size, t) =
+  let n = ref Int63.zero in
+  Array.iter (
+    fun str ->
+      let m = ref 0x80 in
+      for i = 0 to String.length str - 1 do
+	let c = Char.code str.[i] in
+	for j = 0 to 7 do
+	  let n' = !n in
+	  if n' < size then (
+	    let b = c land !m <> 0 in
+	    let b = f n' b in
+	    str.[i] <- Char.chr (if b then c lor !m else c land lnot !m)
+	  );
+	  n := Int63.succ n';
+	  m := !m lsr 1
+	done
+      done
+  ) t
+
+let iter f t =
+  let f i b = f i b; b in
+  iter_set f t