(* Bitmatch library.
- * $Id: bitmatch.ml,v 1.2 2008-04-01 08:56:43 rjones Exp $
+ * Copyright (C) 2008 Red Hat Inc., Richard W.M. Jones
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * $Id$
*)
open Printf
+include Bitmatch_types
+include Bitmatch_config
+
+(* Enable runtime debug messages. Must also have been enabled
+ * in pa_bitmatch.ml.
+ *)
+let debug = ref false
+
+(* Exceptions. *)
+exception Construct_failure of string * string * int * int
+
(* A bitstring is simply the data itself (as a string), and the
* bitoffset and the bitlength within the string. Note offset/length
* are counted in bits, not bytes.
let create_bitstring len = make_bitstring len '\000'
+let bitstring_of_string str = str, 0, String.length str lsl 3
+
let bitstring_of_chan chan =
let tmpsize = 16384 in
let buf = Buffer.create tmpsize in
done;
Buffer.contents buf, 0, Buffer.length buf lsl 3
+let bitstring_of_chan_max chan max =
+ let tmpsize = 16384 in
+ let buf = Buffer.create tmpsize in
+ let tmp = String.create tmpsize in
+ let len = ref 0 in
+ let rec loop () =
+ if !len < max then (
+ let r = min tmpsize (max - !len) in
+ let n = input chan tmp 0 r in
+ if n > 0 then (
+ Buffer.add_substring buf tmp 0 n;
+ len := !len + n;
+ loop ()
+ )
+ )
+ in
+ loop ();
+ Buffer.contents buf, 0, !len lsl 3
+
+let bitstring_of_file_descr fd =
+ let tmpsize = 16384 in
+ let buf = Buffer.create tmpsize in
+ let tmp = String.create tmpsize in
+ let n = ref 0 in
+ while n := Unix.read fd tmp 0 tmpsize; !n > 0 do
+ Buffer.add_substring buf tmp 0 !n;
+ done;
+ Buffer.contents buf, 0, Buffer.length buf lsl 3
+
+let bitstring_of_file_descr_max fd max =
+ let tmpsize = 16384 in
+ let buf = Buffer.create tmpsize in
+ let tmp = String.create tmpsize in
+ let len = ref 0 in
+ let rec loop () =
+ if !len < max then (
+ let r = min tmpsize (max - !len) in
+ let n = Unix.read fd tmp 0 r in
+ if n > 0 then (
+ Buffer.add_substring buf tmp 0 n;
+ len := !len + n;
+ loop ()
+ )
+ )
+ in
+ loop ();
+ Buffer.contents buf, 0, !len lsl 3
+
let bitstring_of_file fname =
let chan = open_in_bin fname in
- let bs = bitstring_of_chan chan in
- close_in chan;
- bs
+ try
+ let bs = bitstring_of_chan chan in
+ close_in chan;
+ bs
+ with exn ->
+ close_in chan;
+ raise exn
+
+let bitstring_length (_, _, len) = len
+
+(*----------------------------------------------------------------------*)
+(* Bitwise functions.
+ *
+ * We try to isolate all bitwise functions within these modules.
+ *)
+
+module I = struct
+ (* Bitwise operations on ints. Note that we assume int <= 31 bits. *)
+ let (<<) = (lsl)
+ let (>>) = (lsr)
+ external to_int : int -> int = "%identity"
+ let zero = 0
+ let one = 1
+ let minus_one = -1
+ let ff = 0xff
+
+ (* Create a mask so many bits wide. *)
+ let mask bits =
+ if bits < 30 then
+ pred (one << bits)
+ else if bits = 30 then
+ max_int
+ else if bits = 31 then
+ minus_one
+ else
+ invalid_arg "Bitmatch.I.mask"
+
+ (* Byte swap an int of a given size. *)
+ let byteswap v bits =
+ if bits <= 8 then v
+ else if bits <= 16 then (
+ let shift = bits-8 in
+ let v1 = v >> shift in
+ let v2 = (v land (mask shift)) << 8 in
+ v2 lor v1
+ ) else if bits <= 24 then (
+ let shift = bits - 16 in
+ let v1 = v >> (8+shift) in
+ let v2 = ((v >> shift) land ff) << 8 in
+ let v3 = (v land (mask shift)) << 16 in
+ v3 lor v2 lor v1
+ ) else (
+ let shift = bits - 24 in
+ let v1 = v >> (16+shift) in
+ let v2 = ((v >> (8+shift)) land ff) << 8 in
+ let v3 = ((v >> shift) land ff) << 16 in
+ let v4 = (v land (mask shift)) << 24 in
+ v4 lor v3 lor v2 lor v1
+ )
+
+ (* Check a value is in range 0 .. 2^bits-1. *)
+ let range_unsigned v bits =
+ let mask = lnot (mask bits) in
+ (v land mask) = zero
+
+ (* Call function g on the top bits, then f on each full byte
+ * (big endian - so start at top).
+ *)
+ let rec map_bytes_be g f v bits =
+ if bits >= 8 then (
+ map_bytes_be g f (v >> 8) (bits-8);
+ let lsb = v land ff in
+ f (to_int lsb)
+ ) else if bits > 0 then (
+ let lsb = v land (mask bits) in
+ g (to_int lsb) bits
+ )
+end
+
+module I32 = struct
+ (* Bitwise operations on int32s. Note we try to keep it as similar
+ * as possible to the I module above, to make it easier to track
+ * down bugs.
+ *)
+ let (<<) = Int32.shift_left
+ let (>>) = Int32.shift_right_logical
+ let (land) = Int32.logand
+ let (lor) = Int32.logor
+ let lnot = Int32.lognot
+ let pred = Int32.pred
+ let max_int = Int32.max_int
+ let to_int = Int32.to_int
+ let zero = Int32.zero
+ let one = Int32.one
+ let minus_one = Int32.minus_one
+ let ff = 0xff_l
+
+ (* Create a mask so many bits wide. *)
+ let mask bits =
+ if bits < 31 then
+ pred (one << bits)
+ else if bits = 31 then
+ max_int
+ else if bits = 32 then
+ minus_one
+ else
+ invalid_arg "Bitmatch.I32.mask"
+
+ (* Byte swap an int of a given size. *)
+ let byteswap v bits =
+ if bits <= 8 then v
+ else if bits <= 16 then (
+ let shift = bits-8 in
+ let v1 = v >> shift in
+ let v2 = (v land (mask shift)) << 8 in
+ v2 lor v1
+ ) else if bits <= 24 then (
+ let shift = bits - 16 in
+ let v1 = v >> (8+shift) in
+ let v2 = ((v >> shift) land ff) << 8 in
+ let v3 = (v land (mask shift)) << 16 in
+ v3 lor v2 lor v1
+ ) else (
+ let shift = bits - 24 in
+ let v1 = v >> (16+shift) in
+ let v2 = ((v >> (8+shift)) land ff) << 8 in
+ let v3 = ((v >> shift) land ff) << 16 in
+ let v4 = (v land (mask shift)) << 24 in
+ v4 lor v3 lor v2 lor v1
+ )
+
+ (* Check a value is in range 0 .. 2^bits-1. *)
+ let range_unsigned v bits =
+ let mask = lnot (mask bits) in
+ (v land mask) = zero
+
+ (* Call function g on the top bits, then f on each full byte
+ * (big endian - so start at top).
+ *)
+ let rec map_bytes_be g f v bits =
+ if bits >= 8 then (
+ map_bytes_be g f (v >> 8) (bits-8);
+ let lsb = v land ff in
+ f (to_int lsb)
+ ) else if bits > 0 then (
+ let lsb = v land (mask bits) in
+ g (to_int lsb) bits
+ )
+end
+
+module I64 = struct
+ (* Bitwise operations on int64s. Note we try to keep it as similar
+ * as possible to the I/I32 modules above, to make it easier to track
+ * down bugs.
+ *)
+ let (<<) = Int64.shift_left
+ let (>>) = Int64.shift_right_logical
+ let (land) = Int64.logand
+ let (lor) = Int64.logor
+ let lnot = Int64.lognot
+ let pred = Int64.pred
+ let max_int = Int64.max_int
+ let to_int = Int64.to_int
+ let zero = Int64.zero
+ let one = Int64.one
+ let minus_one = Int64.minus_one
+ let ff = 0xff_L
+
+ (* Create a mask so many bits wide. *)
+ let mask bits =
+ if bits < 63 then
+ pred (one << bits)
+ else if bits = 63 then
+ max_int
+ else if bits = 64 then
+ minus_one
+ else
+ invalid_arg "Bitmatch.I64.mask"
+
+ (* Byte swap an int of a given size. *)
+ (* let byteswap v bits = *)
+
+ (* Check a value is in range 0 .. 2^bits-1. *)
+ let range_unsigned v bits =
+ let mask = lnot (mask bits) in
+ (v land mask) = zero
+
+ (* Call function g on the top bits, then f on each full byte
+ * (big endian - so start at top).
+ *)
+ let rec map_bytes_be g f v bits =
+ if bits >= 8 then (
+ map_bytes_be g f (v >> 8) (bits-8);
+ let lsb = v land ff in
+ f (to_int lsb)
+ ) else if bits > 0 then (
+ let lsb = v land (mask bits) in
+ g (to_int lsb) bits
+ )
+end
(*----------------------------------------------------------------------*)
(* Extraction functions.
let b = Char.code data.[byteoff] land bitmask <> 0 in
b, off+1, len-1
+(* Returns 8 bit unsigned aligned bytes from the string.
+ * If the string ends then this returns 0's.
+ *)
+let _get_byte data byteoff strlen =
+ if strlen > byteoff then Char.code data.[byteoff] else 0
+let _get_byte32 data byteoff strlen =
+ if strlen > byteoff then Int32.of_int (Char.code data.[byteoff]) else 0l
+let _get_byte64 data byteoff strlen =
+ if strlen > byteoff then Int64.of_int (Char.code data.[byteoff]) else 0L
+
(* Extract [2..8] bits. Because the result fits into a single
* byte we don't have to worry about endianness, only signedness.
*)
let extract_char_unsigned data off len flen =
let byteoff = off lsr 3 in
- (* Extract the 16 bits at byteoff and byteoff+1 (note that the
- * second byte might not exist in the original string).
- *)
+ (* Optimize the common (byte-aligned) case. *)
+ if off land 7 = 0 then (
+ let byte = Char.code data.[byteoff] in
+ byte lsr (8 - flen), off+flen, len-flen
+ ) else (
+ (* Extract the 16 bits at byteoff and byteoff+1 (note that the
+ * second byte might not exist in the original string).
+ *)
+ let strlen = String.length data in
+
+ let word =
+ (_get_byte data byteoff strlen lsl 8) +
+ _get_byte data (byteoff+1) strlen in
+
+ (* Mask off the top bits. *)
+ let bitmask = (1 lsl (16 - (off land 7))) - 1 in
+ let word = word land bitmask in
+ (* Shift right to get rid of the bottom bits. *)
+ let shift = 16 - ((off land 7) + flen) in
+ let word = word lsr shift in
+
+ word, off+flen, len-flen
+ )
+
+(* Extract [9..31] bits. We have to consider endianness and signedness. *)
+let extract_int_be_unsigned data off len flen =
+ let byteoff = off lsr 3 in
+
+ let strlen = String.length data in
+
+ let word =
+ (* Optimize the common (byte-aligned) case. *)
+ if off land 7 = 0 then (
+ let word =
+ (_get_byte data byteoff strlen lsl 23) +
+ (_get_byte data (byteoff+1) strlen lsl 15) +
+ (_get_byte data (byteoff+2) strlen lsl 7) +
+ (_get_byte data (byteoff+3) strlen lsr 1) in
+ word lsr (31 - flen)
+ ) else if flen <= 24 then (
+ (* Extract the 31 bits at byteoff .. byteoff+3. *)
+ let word =
+ (_get_byte data byteoff strlen lsl 23) +
+ (_get_byte data (byteoff+1) strlen lsl 15) +
+ (_get_byte data (byteoff+2) strlen lsl 7) +
+ (_get_byte data (byteoff+3) strlen lsr 1) in
+ (* Mask off the top bits. *)
+ let bitmask = (1 lsl (31 - (off land 7))) - 1 in
+ let word = word land bitmask in
+ (* Shift right to get rid of the bottom bits. *)
+ let shift = 31 - ((off land 7) + flen) in
+ word lsr shift
+ ) else (
+ (* Extract the next 31 bits, slow method. *)
+ let word =
+ let c0, off, len = extract_char_unsigned data off len 8 in
+ let c1, off, len = extract_char_unsigned data off len 8 in
+ let c2, off, len = extract_char_unsigned data off len 8 in
+ let c3, off, len = extract_char_unsigned data off len 7 in
+ (c0 lsl 23) + (c1 lsl 15) + (c2 lsl 7) + c3 in
+ word lsr (31 - flen)
+ ) in
+ word, off+flen, len-flen
+
+let extract_int_le_unsigned data off len flen =
+ let v, off, len = extract_int_be_unsigned data off len flen in
+ let v = I.byteswap v flen in
+ v, off, len
+
+let extract_int_ne_unsigned =
+ if nativeendian = BigEndian
+ then extract_int_be_unsigned
+ else extract_int_le_unsigned
+
+let _make_int32_be c0 c1 c2 c3 =
+ Int32.logor
+ (Int32.logor
+ (Int32.logor
+ (Int32.shift_left c0 24)
+ (Int32.shift_left c1 16))
+ (Int32.shift_left c2 8))
+ c3
+
+let _make_int32_le c0 c1 c2 c3 =
+ Int32.logor
+ (Int32.logor
+ (Int32.logor
+ (Int32.shift_left c3 24)
+ (Int32.shift_left c2 16))
+ (Int32.shift_left c1 8))
+ c0
+
+(* Extract exactly 32 bits. We have to consider endianness and signedness. *)
+let extract_int32_be_unsigned data off len flen =
+ let byteoff = off lsr 3 in
+
+ let strlen = String.length data in
+
let word =
- (Char.code data.[byteoff] lsl 8) +
- (if String.length data > byteoff+1 then Char.code data.[byteoff+1]
- else 0) in
+ (* Optimize the common (byte-aligned) case. *)
+ if off land 7 = 0 then (
+ let word =
+ let c0 = _get_byte32 data byteoff strlen in
+ let c1 = _get_byte32 data (byteoff+1) strlen in
+ let c2 = _get_byte32 data (byteoff+2) strlen in
+ let c3 = _get_byte32 data (byteoff+3) strlen in
+ _make_int32_be c0 c1 c2 c3 in
+ Int32.shift_right_logical word (32 - flen)
+ ) else (
+ (* Extract the next 32 bits, slow method. *)
+ let word =
+ let c0, off, len = extract_char_unsigned data off len 8 in
+ let c1, off, len = extract_char_unsigned data off len 8 in
+ let c2, off, len = extract_char_unsigned data off len 8 in
+ let c3, _, _ = extract_char_unsigned data off len 8 in
+ let c0 = Int32.of_int c0 in
+ let c1 = Int32.of_int c1 in
+ let c2 = Int32.of_int c2 in
+ let c3 = Int32.of_int c3 in
+ _make_int32_be c0 c1 c2 c3 in
+ Int32.shift_right_logical word (32 - flen)
+ ) in
+ word, off+flen, len-flen
+
+let extract_int32_le_unsigned data off len flen =
+ let v, off, len = extract_int32_be_unsigned data off len flen in
+ let v = I32.byteswap v flen in
+ v, off, len
+
+let extract_int32_ne_unsigned =
+ if nativeendian = BigEndian
+ then extract_int32_be_unsigned
+ else extract_int32_le_unsigned
+
+let _make_int64_be c0 c1 c2 c3 c4 c5 c6 c7 =
+ Int64.logor
+ (Int64.logor
+ (Int64.logor
+ (Int64.logor
+ (Int64.logor
+ (Int64.logor
+ (Int64.logor
+ (Int64.shift_left c0 56)
+ (Int64.shift_left c1 48))
+ (Int64.shift_left c2 40))
+ (Int64.shift_left c3 32))
+ (Int64.shift_left c4 24))
+ (Int64.shift_left c5 16))
+ (Int64.shift_left c6 8))
+ c7
+
+let _make_int64_le c0 c1 c2 c3 c4 c5 c6 c7 =
+ _make_int64_be c7 c6 c5 c4 c3 c2 c1 c0
+
+(* Extract [1..64] bits. We have to consider endianness and signedness. *)
+let extract_int64_be_unsigned data off len flen =
+ let byteoff = off lsr 3 in
- (* Mask off the top bits. *)
- let bitmask = (1 lsl (16 - (off land 7))) - 1 in
- let word = word land bitmask in
- (* Shift right to get rid of the bottom bits. *)
- let shift = 16 - ((off land 7) + flen) in
- let word = word lsr shift in
+ let strlen = String.length data in
+ let word =
+ (* Optimize the common (byte-aligned) case. *)
+ if off land 7 = 0 then (
+ let word =
+ let c0 = _get_byte64 data byteoff strlen in
+ let c1 = _get_byte64 data (byteoff+1) strlen in
+ let c2 = _get_byte64 data (byteoff+2) strlen in
+ let c3 = _get_byte64 data (byteoff+3) strlen in
+ let c4 = _get_byte64 data (byteoff+4) strlen in
+ let c5 = _get_byte64 data (byteoff+5) strlen in
+ let c6 = _get_byte64 data (byteoff+6) strlen in
+ let c7 = _get_byte64 data (byteoff+7) strlen in
+ _make_int64_be c0 c1 c2 c3 c4 c5 c6 c7 in
+ Int64.shift_right_logical word (64 - flen)
+ ) else (
+ (* Extract the next 64 bits, slow method. *)
+ let word =
+ let c0, off, len = extract_char_unsigned data off len 8 in
+ let c1, off, len = extract_char_unsigned data off len 8 in
+ let c2, off, len = extract_char_unsigned data off len 8 in
+ let c3, off, len = extract_char_unsigned data off len 8 in
+ let c4, off, len = extract_char_unsigned data off len 8 in
+ let c5, off, len = extract_char_unsigned data off len 8 in
+ let c6, off, len = extract_char_unsigned data off len 8 in
+ let c7, _, _ = extract_char_unsigned data off len 8 in
+ let c0 = Int64.of_int c0 in
+ let c1 = Int64.of_int c1 in
+ let c2 = Int64.of_int c2 in
+ let c3 = Int64.of_int c3 in
+ let c4 = Int64.of_int c4 in
+ let c5 = Int64.of_int c5 in
+ let c6 = Int64.of_int c6 in
+ let c7 = Int64.of_int c7 in
+ _make_int64_be c0 c1 c2 c3 c4 c5 c6 c7 in
+ Int64.shift_right_logical word (64 - flen)
+ ) in
+ word, off+flen, len-flen
+
+let extract_int64_le_unsigned data off len flen =
+ let byteoff = off lsr 3 in
+
+ let strlen = String.length data in
+
+ let word =
+ (* Optimize the common (byte-aligned) case. *)
+ if off land 7 = 0 then (
+ let word =
+ let c0 = _get_byte64 data byteoff strlen in
+ let c1 = _get_byte64 data (byteoff+1) strlen in
+ let c2 = _get_byte64 data (byteoff+2) strlen in
+ let c3 = _get_byte64 data (byteoff+3) strlen in
+ let c4 = _get_byte64 data (byteoff+4) strlen in
+ let c5 = _get_byte64 data (byteoff+5) strlen in
+ let c6 = _get_byte64 data (byteoff+6) strlen in
+ let c7 = _get_byte64 data (byteoff+7) strlen in
+ _make_int64_le c0 c1 c2 c3 c4 c5 c6 c7 in
+ Int64.logand word (I64.mask flen)
+ ) else (
+ (* Extract the next 64 bits, slow method. *)
+ let word =
+ let c0, off, len = extract_char_unsigned data off len 8 in
+ let c1, off, len = extract_char_unsigned data off len 8 in
+ let c2, off, len = extract_char_unsigned data off len 8 in
+ let c3, off, len = extract_char_unsigned data off len 8 in
+ let c4, off, len = extract_char_unsigned data off len 8 in
+ let c5, off, len = extract_char_unsigned data off len 8 in
+ let c6, off, len = extract_char_unsigned data off len 8 in
+ let c7, _, _ = extract_char_unsigned data off len 8 in
+ let c0 = Int64.of_int c0 in
+ let c1 = Int64.of_int c1 in
+ let c2 = Int64.of_int c2 in
+ let c3 = Int64.of_int c3 in
+ let c4 = Int64.of_int c4 in
+ let c5 = Int64.of_int c5 in
+ let c6 = Int64.of_int c6 in
+ let c7 = Int64.of_int c7 in
+ _make_int64_le c0 c1 c2 c3 c4 c5 c6 c7 in
+ Int64.logand word (I64.mask flen)
+ ) in
word, off+flen, len-flen
+
+let extract_int64_ne_unsigned =
+ if nativeendian = BigEndian
+ then extract_int64_be_unsigned
+ else extract_int64_le_unsigned
+
+(*----------------------------------------------------------------------*)
+(* Constructor functions. *)
+
+module Buffer = struct
+ type t = {
+ buf : Buffer.t;
+ mutable len : int; (* Length in bits. *)
+ (* Last byte in the buffer (if len is not aligned). We store
+ * it outside the buffer because buffers aren't mutable.
+ *)
+ mutable last : int;
+ }
+
+ let create () =
+ (* XXX We have almost enough information in the generator to
+ * choose a good initial size.
+ *)
+ { buf = Buffer.create 128; len = 0; last = 0 }
+
+ let contents { buf = buf; len = len; last = last } =
+ let data =
+ if len land 7 = 0 then
+ Buffer.contents buf
+ else
+ Buffer.contents buf ^ (String.make 1 (Char.chr last)) in
+ data, 0, len
+
+ (* Add exactly 8 bits. *)
+ let add_byte ({ buf = buf; len = len; last = last } as t) byte =
+ if byte < 0 || byte > 255 then invalid_arg "Bitmatch.Buffer.add_byte";
+ let shift = len land 7 in
+ if shift = 0 then
+ (* Target buffer is byte-aligned. *)
+ Buffer.add_char buf (Char.chr byte)
+ else (
+ (* Target buffer is unaligned. 'last' is meaningful. *)
+ let first = byte lsr shift in
+ let second = (byte lsl (8 - shift)) land 0xff in
+ Buffer.add_char buf (Char.chr (last lor first));
+ t.last <- second
+ );
+ t.len <- t.len + 8
+
+ (* Add exactly 1 bit. *)
+ let add_bit ({ buf = buf; len = len; last = last } as t) bit =
+ let shift = 7 - (len land 7) in
+ if shift > 0 then
+ (* Somewhere in the middle of 'last'. *)
+ t.last <- last lor ((if bit then 1 else 0) lsl shift)
+ else (
+ (* Just a single spare bit in 'last'. *)
+ let last = last lor if bit then 1 else 0 in
+ Buffer.add_char buf (Char.chr last);
+ t.last <- 0
+ );
+ t.len <- len + 1
+
+ (* Add a small number of bits (definitely < 8). This uses a loop
+ * to call add_bit so it's slow.
+ *)
+ let _add_bits t c slen =
+ if slen < 1 || slen >= 8 then invalid_arg "Bitmatch.Buffer._add_bits";
+ for i = slen-1 downto 0 do
+ let bit = c land (1 lsl i) <> 0 in
+ add_bit t bit
+ done
+
+ let add_bits ({ buf = buf; len = len } as t) str slen =
+ if slen > 0 then (
+ if len land 7 = 0 then (
+ if slen land 7 = 0 then
+ (* Common case - everything is byte-aligned. *)
+ Buffer.add_substring buf str 0 (slen lsr 3)
+ else (
+ (* Target buffer is aligned. Copy whole bytes then leave the
+ * remaining bits in last.
+ *)
+ let slenbytes = slen lsr 3 in
+ if slenbytes > 0 then Buffer.add_substring buf str 0 slenbytes;
+ t.last <- Char.code str.[slenbytes] lsl (8 - (slen land 7))
+ );
+ t.len <- len + slen
+ ) else (
+ (* Target buffer is unaligned. Copy whole bytes using
+ * add_byte which knows how to deal with an unaligned
+ * target buffer, then call _add_bits for the remaining < 8 bits.
+ *
+ * XXX This is going to be dog-slow.
+ *)
+ let slenbytes = slen lsr 3 in
+ for i = 0 to slenbytes-1 do
+ let byte = Char.code str.[i] in
+ add_byte t byte
+ done;
+ _add_bits t (Char.code str.[slenbytes]) (slen - (slenbytes lsl 3))
+ );
+ )
+end
+
+(* Construct a single bit. *)
+let construct_bit buf b _ _ =
+ Buffer.add_bit buf b
+
+(* Construct a field, flen = [2..8]. *)
+let construct_char_unsigned buf v flen exn =
+ let max_val = 1 lsl flen in
+ if v < 0 || v >= max_val then raise exn;
+ if flen = 8 then
+ Buffer.add_byte buf v
+ else
+ Buffer._add_bits buf v flen
+
+(* Construct a field of up to 31 bits. *)
+let construct_int_be_unsigned buf v flen exn =
+ (* Check value is within range. *)
+ if not (I.range_unsigned v flen) then raise exn;
+ (* Add the bytes. *)
+ I.map_bytes_be (Buffer._add_bits buf) (Buffer.add_byte buf) v flen
+
+let construct_int_ne_unsigned =
+ if nativeendian = BigEndian
+ then construct_int_be_unsigned
+ else (*construct_int_le_unsigned*)
+ fun _ _ _ _ -> failwith "construct_int_le_unsigned"
+
+(* Construct a field of exactly 32 bits. *)
+let construct_int32_be_unsigned buf v flen _ =
+ Buffer.add_byte buf
+ (Int32.to_int (Int32.shift_right_logical v 24));
+ Buffer.add_byte buf
+ (Int32.to_int ((Int32.logand (Int32.shift_right_logical v 16) 0xff_l)));
+ Buffer.add_byte buf
+ (Int32.to_int ((Int32.logand (Int32.shift_right_logical v 8) 0xff_l)));
+ Buffer.add_byte buf
+ (Int32.to_int (Int32.logand v 0xff_l))
+
+let construct_int32_ne_unsigned =
+ if nativeendian = BigEndian
+ then construct_int32_be_unsigned
+ else (*construct_int32_le_unsigned*)
+ fun _ _ _ _ -> failwith "construct_int32_le_unsigned"
+
+(* Construct a field of up to 64 bits. *)
+let construct_int64_be_unsigned buf v flen exn =
+ (* Check value is within range. *)
+ if not (I64.range_unsigned v flen) then raise exn;
+ (* Add the bytes. *)
+ I64.map_bytes_be (Buffer._add_bits buf) (Buffer.add_byte buf) v flen
+
+let construct_int64_ne_unsigned =
+ if nativeendian = BigEndian
+ then construct_int64_be_unsigned
+ else (*construct_int64_le_unsigned*)
+ fun _ _ _ _ -> failwith "construct_int64_le_unsigned"
+
+(* Construct from a string of bytes, exact multiple of 8 bits
+ * in length of course.
+ *)
+let construct_string buf str =
+ let len = String.length str in
+ Buffer.add_bits buf str (len lsl 3)
+
+(*----------------------------------------------------------------------*)
+(* Extract a string from a bitstring. *)
+
+let string_of_bitstring (data, off, len) =
+ if off land 7 = 0 && len land 7 = 0 then
+ (* Easy case: everything is byte-aligned. *)
+ String.sub data (off lsr 3) (len lsr 3)
+ else (
+ (* Bit-twiddling case. *)
+ let strlen = (len + 7) lsr 3 in
+ let str = String.make strlen '\000' in
+ let rec loop data off len i =
+ if len >= 8 then (
+ let c, off, len = extract_char_unsigned data off len 8 in
+ str.[i] <- Char.chr c;
+ loop data off len (i+1)
+ ) else if len > 0 then (
+ (* XXX Is this correct? It should write into the high bits
+ * of the last byte.
+ *)
+ let c, off, len = extract_char_unsigned data off len len in
+ str.[i] <- Char.chr c
+ )
+ in
+ loop data off len 0;
+ str
+ )
+
+(* To channel. *)
+
+let bitstring_to_chan ((data, off, len) as bits) chan =
+ (* Fail if the bitstring length isn't a multiple of 8. *)
+ if len land 7 <> 0 then invalid_arg "bitstring_to_chan";
+
+ if off land 7 = 0 then
+ (* Easy case: string is byte-aligned. *)
+ output chan data (off lsr 3) (len lsr 3)
+ else (
+ (* Bit-twiddling case: reuse string_of_bitstring *)
+ let str = string_of_bitstring bits in
+ output_string chan str
+ )
+
+let bitstring_to_file bits filename =
+ let chan = open_out_bin filename in
+ try
+ bitstring_to_chan bits chan;
+ close_out chan
+ with exn ->
+ close_out chan;
+ raise exn
+
+(*----------------------------------------------------------------------*)
+(* Display functions. *)
+
+let isprint c =
+ let c = Char.code c in
+ c >= 32 && c < 127
+
+let hexdump_bitstring chan (data, off, len) =
+ let count = ref 0 in
+ let off = ref off in
+ let len = ref len in
+ let linelen = ref 0 in
+ let linechars = String.make 16 ' ' in
+
+ fprintf chan "00000000 ";
+
+ while !len > 0 do
+ let bits = min !len 8 in
+ let byte, off', len' = extract_char_unsigned data !off !len bits in
+ off := off'; len := len';
+
+ let byte = byte lsl (8-bits) in
+ fprintf chan "%02x " byte;
+
+ incr count;
+ linechars.[!linelen] <-
+ (let c = Char.chr byte in
+ if isprint c then c else '.');
+ incr linelen;
+ if !linelen = 8 then fprintf chan " ";
+ if !linelen = 16 then (
+ fprintf chan " |%s|\n%08x " linechars !count;
+ linelen := 0;
+ for i = 0 to 15 do linechars.[i] <- ' ' done
+ )
+ done;
+
+ if !linelen > 0 then (
+ let skip = (16 - !linelen) * 3 + if !linelen < 8 then 1 else 0 in
+ for i = 0 to skip-1 do fprintf chan " " done;
+ fprintf chan " |%s|\n%!" linechars
+ ) else
+ fprintf chan "\n%!"
git.annexia.org / ocaml-bitstring.git / blobdiff