+++ /dev/null
-(* Bitmatch library.
- * 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,
- * with the OCaml linking exception described in COPYING.LIB.
- *
- * 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.
- *)
-type bitstring = string * int * int
-
-(* Functions to create and load bitstrings. *)
-let empty_bitstring = "", 0, 0
-
-let make_bitstring len c =
- if len >= 0 then String.make ((len+7) lsr 3) c, 0, len
- else
- invalid_arg (
- sprintf "make_bitstring/create_bitstring: len %d < 0" len
- )
-
-let create_bitstring len = make_bitstring len '\000'
-
-let zeroes_bitstring = create_bitstring
-
-let ones_bitstring len = make_bitstring len '\xff'
-
-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
- let tmp = String.create tmpsize in
- let n = ref 0 in
- while n := input chan 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_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
- try
- let bs = bitstring_of_chan chan in
- close_in chan;
- bs
- with exn ->
- close_in chan;
- raise exn
-
-let bitstring_length (_, _, len) = len
-
-let subbitstring (data, off, len) off' len' =
- let off = off + off' in
- if len < off' + len' then invalid_arg "subbitstring";
- (data, off, len')
-
-let dropbits n (data, off, len) =
- let off = off + n in
- let len = len - n in
- if len < 0 then invalid_arg "dropbits";
- (data, off, len)
-
-let takebits n (data, off, len) =
- if len < n then invalid_arg "takebits";
- (data, off, n)
-
-(*----------------------------------------------------------------------*)
-(* 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.
- *
- * NB: internal functions, called from the generated macros, and
- * the parameters should have been checked for sanity already).
- *)
-
-(* Bitstrings. *)
-let extract_bitstring data off len flen =
- (data, off, flen), off+flen, len-flen
-
-let extract_remainder data off len =
- (data, off, len), off+len, 0
-
-(* Extract and convert to numeric. A single bit is returned as
- * a boolean. There are no endianness or signedness considerations.
- *)
-let extract_bit data off len _ = (* final param is always 1 *)
- let byteoff = off lsr 3 in
- let bitmask = 1 lsl (7 - (off land 7)) in
- 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
-
- (* 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 extract_int_ee_unsigned = function
- | BigEndian -> extract_int_be_unsigned
- | LittleEndian -> extract_int_le_unsigned
- | NativeEndian -> extract_int_ne_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 =
- (* 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 extract_int32_ee_unsigned = function
- | BigEndian -> extract_int32_be_unsigned
- | LittleEndian -> extract_int32_le_unsigned
- | NativeEndian -> extract_int32_ne_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
-
- 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
-
-let extract_int64_ee_unsigned = function
- | BigEndian -> extract_int64_be_unsigned
- | LittleEndian -> extract_int64_le_unsigned
- | NativeEndian -> extract_int64_ne_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;
- let last = Char.code str.[slenbytes] in (* last char *)
- let mask = 0xff lsl (8 - (slen land 7)) in
- t.last <- last land mask
- );
- 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_bit 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;
- let bitsleft = slen - (slenbytes lsl 3) in
- if bitsleft > 0 then (
- let c = Char.code str.[slenbytes] in
- for i = 0 to bitsleft - 1 do
- let bit = c land (0x80 lsr i) <> 0 in
- add_bit t bit
- done
- )
- );
- )
-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"
-
-let construct_int_ee_unsigned = function
- | BigEndian -> construct_int_be_unsigned
- | LittleEndian -> (*construct_int_le_unsigned*)
- (fun _ _ _ _ -> failwith "construct_int_le_unsigned")
- | NativeEndian -> construct_int_ne_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_le_unsigned buf v flen _ =
- Buffer.add_byte buf
- (Int32.to_int (Int32.logand v 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 (Int32.shift_right_logical v 16) 0xff_l)));
- Buffer.add_byte buf
- (Int32.to_int (Int32.shift_right_logical v 24))
-
-let construct_int32_ne_unsigned =
- if nativeendian = BigEndian
- then construct_int32_be_unsigned
- else construct_int32_le_unsigned
-
-let construct_int32_ee_unsigned = function
- | BigEndian -> construct_int32_be_unsigned
- | LittleEndian -> construct_int32_le_unsigned
- | NativeEndian -> construct_int32_ne_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"
-
-let construct_int64_ee_unsigned = function
- | BigEndian -> construct_int64_be_unsigned
- | LittleEndian -> (*construct_int64_le_unsigned*)
- (fun _ _ _ _ -> failwith "construct_int64_le_unsigned")
- | NativeEndian -> construct_int64_ne_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)
-
-(* Construct from a bitstring. *)
-let construct_bitstring buf (data, off, len) =
- (* Add individual bits until we get to the next byte boundary of
- * the underlying string.
- *)
- let blen = 7 - ((off + 7) land 7) in
- let blen = min blen len in
- let rec loop off len blen =
- if blen = 0 then (off, len)
- else (
- let b, off, len = extract_bit data off len 1 in
- Buffer.add_bit buf b;
- loop off len (blen-1)
- )
- in
- let off, len = loop off len blen in
- assert (len = 0 || (off land 7) = 0);
-
- (* Add the remaining 'len' bits. *)
- let data =
- let off = off lsr 3 in
- (* XXX dangerous allocation *)
- if off = 0 then data
- else String.sub data off (String.length data - off) in
-
- Buffer.add_bits buf data len
-
-(*----------------------------------------------------------------------*)
-(* 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 (
- let c, _, _ = extract_char_unsigned data off len len in
- str.[i] <- Char.chr (c lsl (8-len))
- )
- 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%!"