1 (** Bitmatch library. *)
2 (* Copyright (C) 2008 Red Hat Inc., Richard W.M. Jones
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version,
8 * with the OCaml linking exception described in COPYING.LIB.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 {{:#reference}Jump straight to the reference section for
24 documentation on types and functions}.
28 Bitmatch adds Erlang-style bitstrings and matching over bitstrings
29 as a syntax extension and library for OCaml. You can use
30 this module to both parse and generate binary formats, for
31 example, communications protocols, disk formats and binary files.
33 {{:http://code.google.com/p/bitmatch/}OCaml bitmatch website}
37 A function which can parse IPv4 packets:
44 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
45 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
46 | 4 | IHL |Type of Service| Total Length |
47 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
48 | Identification |Flags| Fragment Offset |
49 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
50 | Time to Live | Protocol | Header Checksum |
51 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
53 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
54 | Destination Address |
55 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
57 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
59 | { 4 : 4; hdrlen : 4; tos : 8; length : 16;
60 identification : 16; flags : 3; fragoffset : 13;
61 ttl : 8; protocol : 8; checksum : 16;
64 options : (hdrlen-5)*32 : bitstring;
65 payload : -1 : bitstring } ->
68 printf " header length: %d * 32 bit words\n" hdrlen;
69 printf " type of service: %d\n" tos;
70 printf " packet length: %d bytes\n" length;
71 printf " identification: %d\n" identification;
72 printf " flags: %d\n" flags;
73 printf " fragment offset: %d\n" fragoffset;
74 printf " ttl: %d\n" ttl;
75 printf " protocol: %d\n" protocol;
76 printf " checksum: %d\n" checksum;
77 printf " source: %lx dest: %lx\n" source dest;
78 printf " header options + padding:\n";
79 Bitmatch.hexdump_bitstring stdout options;
80 printf " packet payload:\n";
81 Bitmatch.hexdump_bitstring stdout payload
84 eprintf "unknown IP version %d\n" version;
88 eprintf "data is smaller than one nibble:\n";
89 Bitmatch.hexdump_bitstring stderr pkt;
93 A program which can parse
94 {{:http://lxr.linux.no/linux/include/linux/ext3_fs.h}Linux EXT3 filesystem superblocks}:
97 let bits = Bitmatch.bitstring_of_file "tests/ext3_sb"
101 | { s_inodes_count : 32 : littleendian; (* Inodes count *)
102 s_blocks_count : 32 : littleendian; (* Blocks count *)
103 s_r_blocks_count : 32 : littleendian; (* Reserved blocks count *)
104 s_free_blocks_count : 32 : littleendian; (* Free blocks count *)
105 s_free_inodes_count : 32 : littleendian; (* Free inodes count *)
106 s_first_data_block : 32 : littleendian; (* First Data Block *)
107 s_log_block_size : 32 : littleendian; (* Block size *)
108 s_log_frag_size : 32 : littleendian; (* Fragment size *)
109 s_blocks_per_group : 32 : littleendian; (* # Blocks per group *)
110 s_frags_per_group : 32 : littleendian; (* # Fragments per group *)
111 s_inodes_per_group : 32 : littleendian; (* # Inodes per group *)
112 s_mtime : 32 : littleendian; (* Mount time *)
113 s_wtime : 32 : littleendian; (* Write time *)
114 s_mnt_count : 16 : littleendian; (* Mount count *)
115 s_max_mnt_count : 16 : littleendian; (* Maximal mount count *)
116 0xef53 : 16 : littleendian } -> (* Magic signature *)
118 printf "ext3 superblock:\n";
119 printf " s_inodes_count = %ld\n" s_inodes_count;
120 printf " s_blocks_count = %ld\n" s_blocks_count;
121 printf " s_free_inodes_count = %ld\n" s_free_inodes_count;
122 printf " s_free_blocks_count = %ld\n" s_free_blocks_count
125 eprintf "not an ext3 superblock!\n%!";
129 Constructing packets for a simple binary message
134 +---------------+---------------+--------------------------+
135 | type | subtype | parameter |
136 +---------------+---------------+--------------------------+
137 <-- 16 bits --> <-- 16 bits --> <------- 32 bits -------->
139 All fields are in network byte order.
142 let make_message typ subtype param =
150 {2 Loading, creating bitstrings}
152 The basic data type is the {!bitstring}, a string of bits of
153 arbitrary length. Bitstrings can be any length in bits and
154 operations do not need to be byte-aligned (although they will
155 generally be more efficient if they are byte-aligned).
157 Internally a bitstring is stored as a normal OCaml [string]
158 together with an offset and length, where the offset and length are
159 measured in bits. Thus one can efficiently form substrings of
160 bitstrings, overlay a bitstring on existing data, and load and save
161 bitstrings from files or other external sources.
163 To load a bitstring from a file use {!bitstring_of_file} or
164 {!bitstring_of_chan}.
166 There are also functions to create bitstrings from arbitrary data.
167 See the {{:#reference}reference} below.
169 {2 Matching bitstrings with patterns}
171 Use the [bitmatch] operator (part of the syntax extension) to break
172 apart a bitstring into its fields. [bitmatch] works a lot like the
173 OCaml [match] operator.
175 The general form of [bitmatch] is:
177 [bitmatch] {i bitstring-expression} [with]
179 [| {] {i pattern} [} ->] {i code}
181 [| {] {i pattern} [} ->] {i code}
185 As with normal match, the statement attempts to match the
186 bitstring against each pattern in turn. If none of the patterns
187 match then the standard library [Match_failure] exception is
190 Patterns look a bit different from normal match patterns. They
191 consist of a list of bitfields separated by [;] where each bitfield
192 contains a bind variable, the width (in bits) of the field, and
193 other information. Some example patterns:
198 | { version : 8; name : 8; param : 8 } -> ...
200 (* Bitstring of at least 3 bytes. First byte is the version
201 number, second byte is a field called name, third byte is
202 a field called parameter. *)
205 printf "flag is %b\n" flag
207 (* A single flag bit (mapped into an OCaml boolean). *)
209 | { len : 4; data : 1+len } ->
210 printf "len = %d, data = 0x%Lx\n" len data
212 (* A 4-bit length, followed by 1-16 bits of data, where the
213 length of the data is computed from len. *)
215 | { ipv6_source : 128 : bitstring;
216 ipv6_dest : 128 : bitstring } -> ...
218 (* IPv6 source and destination addresses. Each is 128 bits
219 and is mapped into a bitstring type which will be a substring
220 of the main bitstring expression. *)
223 You can also add conditional when-clauses:
227 when version = 4 || version = 6 -> ...
229 (* Only match and run the code when version is 4 or 6. If
230 it isn't we will drop through to the next case. *)
233 Note that the pattern is only compared against the first part of
234 the bitstring (there may be more data in the bitstring following
235 the pattern, which is not matched). In terms of regular
236 expressions you might say that the pattern matches [^pattern], not
237 [^pattern$]. To ensure that the bitstring contains only the
238 pattern, add a length -1 bitstring to the end and test that its
239 length is zero in the when-clause:
243 rest : -1 : bitstring }
244 when Bitmatch.bitstring_length rest = 0 -> ...
246 (* Only matches exactly 4 bits. *)
249 Normally the first part of each field is a binding variable,
250 but you can also match a constant, as in:
253 | { (4|6) : 4 } -> ...
255 (* Only matches if the first 4 bits contain either
256 the integer 4 or the integer 6. *)
259 One may also match on strings:
262 | { "MAGIC" : 5*8 : string } -> ...
264 (* Only matches if the string "MAGIC" appears at the start
268 {3:patternfieldreference Pattern field reference}
270 The exact format of each pattern field is:
272 [pattern : length [: qualifier [,qualifier ...]]]
274 [pattern] is the pattern, binding variable name, or constant to
275 match. [length] is the length in bits which may be either a
276 constant or an expression. The length expression is just an OCaml
277 expression and can use any values defined in the program, and refer
278 back to earlier fields (but not to later fields).
280 Integers can only have lengths in the range \[1..64\] bits. See the
281 {{:#integertypes}integer types} section below for how these are
282 mapped to the OCaml int/int32/int64 types. This is checked
283 at compile time if the length expression is constant, otherwise it is
284 checked at runtime and you will get a runtime exception eg. in
285 the case of a computed length expression.
287 A bitstring field of length -1 matches all the rest of the
288 bitstring (thus this is only useful as the last field in a
291 A bitstring field of length 0 matches an empty bitstring
292 (occasionally useful when matching optional subfields).
294 Qualifiers are a list of identifiers/expressions which control the type,
295 signedness and endianness of the field. Permissible qualifiers are:
297 - [int]: field has an integer type
298 - [string]: field is a string type
299 - [bitstring]: field is a bitstring type
300 - [signed]: field is signed
301 - [unsigned]: field is unsigned
302 - [bigendian]: field is big endian - a.k.a network byte order
303 - [littleendian]: field is little endian - a.k.a Intel byte order
304 - [nativeendian]: field is same endianness as the machine
305 - [endian (expr)]: [expr] should be an expression which evaluates to
306 a {!endian} type, ie. [LittleEndian], [BigEndian] or [NativeEndian].
307 The expression is an arbitrary OCaml expression and can use the
308 value of earlier fields in the bitmatch.
309 - [offset (expr)]: see {{:#computedoffsets}computed offsets} below.
311 The default settings are [int], [unsigned], [bigendian], no offset.
313 Note that many of these qualifiers cannot be used together,
314 eg. bitstrings do not have endianness. The syntax extension should
315 give you a compile-time error if you use incompatible qualifiers.
317 {3 Other cases in bitmatch}
319 As well as a list of fields, it is possible to name the
320 bitstring and/or have a default match case:
325 (* Default match case. *)
327 | { _ } as pkt -> ...
329 (* Default match case, with 'pkt' bound to the whole bitstring. *)
332 {2 Constructing bitstrings}
334 Bitstrings may be constructed using the [BITSTRING] operator (as an
335 expression). The [BITSTRING] operator takes a list of fields,
336 similar to the list of fields for matching:
347 (* Constructs a 16-bit bitstring with the first four bits containing
348 the integer 1, and the following 12 bits containing the integer 10,
349 arranged in network byte order. *)
351 Bitmatch.hexdump_bitstring stdout bits ;;
359 The format of each field is the same as for pattern fields (see
360 {{:#patternfieldreference}Pattern field reference section}), and
361 things like computed length fields, fixed value fields, insertion
362 of bitstrings within bitstrings, etc. are all supported.
364 {3 Construction exception}
366 The [BITSTRING] operator may throw a {!Construct_failure}
367 exception at runtime.
369 Runtime errors include:
371 - int field length not in the range \[1..64\]
372 - a bitstring with a length declared which doesn't have the
373 same length at runtime
374 - trying to insert an out of range value into an int field
375 (eg. an unsigned int field which is 2 bits wide can only
376 take values in the range \[0..3\]).
378 {2:integertypes Integer types}
380 Integer types are mapped to OCaml types [bool], [int], [int32] or
381 [int64] using a system which tries to ensure that (a) the types are
382 reasonably predictable and (b) the most efficient type is
385 The rules are slightly different depending on whether the bit
386 length expression in the field is a compile-time constant or a
389 Detection of compile-time constants is quite simplistic so only
390 simple integer literals and simple expressions (eg. [5*8]) are
391 recognized as constants.
393 In any case the bit size of an integer is limited to the range
394 \[1..64\]. This is detected as a compile-time error if that is
395 possible, otherwise a runtime check is added which can throw an
396 [Invalid_argument] exception.
401 Bit size ---- OCaml type ----
402 Constant Computed expression
410 A possible future extension may allow people with 64 bit computers
411 to specify a more optimal [int] type for bit sizes in the range
412 [32..63]. If this was implemented then such code {i could not even
413 be compiled} on 32 bit platforms, so it would limit portability.
415 Another future extension may be to allow computed
416 expressions to assert min/max range for the bit size,
417 allowing a more efficient data type than int64 to be
418 used. (Of course under such circumstances there would
419 still need to be a runtime check to enforce the
422 {2:computedoffsets Computed offsets}
424 You can add an [offset(..)] qualifier to bitmatch patterns in order
425 to move the current offset within the bitstring forwards.
432 field2 : 8 : offset(160) } -> ...
435 matches [field1] at the start of the bitstring and [field2]
436 at 160 bits into the bitstring. The middle 152 bits go
437 unmatched (ie. can be anything).
439 The generated code is efficient. If field lengths and offsets
440 are known to be constant at compile time, then almost all
441 runtime checks are avoided. Non-constant field lengths and/or
442 non-constant offsets can result in more runtime checks being added.
444 Note that moving the offset backwards, and moving the offset in
445 [BITSTRING] constructors, are both not supported at present.
447 {2 Named patterns and persistent patterns}
449 Please see {!Bitmatch_persistent} for documentation on this subject.
453 Using the compiler directly you can do:
456 ocamlc -I +bitmatch \
457 -pp "camlp4of bitmatch.cma bitmatch_persistent.cma \
458 `ocamlc -where`/bitmatch/pa_bitmatch.cmo" \
459 unix.cma bitmatch.cma test.ml -o test
462 Simpler method using findlib:
466 -package bitmatch,bitmatch.syntax -syntax bitmatch.syntax \
467 -linkpkg test.ml -o test
470 {2 Security and type safety}
472 {3 Security on input}
474 The main concerns for input are buffer overflows and denial
477 It is believed that this library is robust against attempted buffer
478 overflows. In addition to OCaml's normal bounds checks, we check
479 that field lengths are >= 0, and many additional checks.
481 Denial of service attacks are more problematic. We only work
482 forwards through the bitstring, thus computation will eventually
483 terminate. As for computed lengths, code such as this is thought
489 buffer : Int64.to_int len : bitstring } ->
492 The [len] field can be set arbitrarily large by an attacker, but
493 when pattern-matching against the [buffer] field this merely causes
494 a test such as [if len <= remaining_size] to fail. Even if the
495 length is chosen so that [buffer] bitstring is allocated, the
496 allocation of sub-bitstrings is efficient and doesn't involve an
497 arbitary-sized allocation or any copying.
499 However the above does not necessarily apply to strings used in
500 matching, since they may cause the library to use the
501 {!Bitmatch.string_of_bitstring} function, which allocates a string.
502 So you should take care if you use the [string] type particularly
503 with a computed length that is derived from external input.
505 The main protection against attackers should be to ensure that the
506 main program will only read input bitstrings up to a certain
507 length, which is outside the scope of this library.
509 {3 Security on output}
511 As with the input side, computed lengths are believed to be
515 let len = read_untrusted_source () in
516 let buffer = allocate_bitstring () in
518 buffer : len : bitstring
522 This code merely causes a check that buffer's length is the same as
523 [len]. However the program function [allocate_bitstring] must
524 refuse to allocate an oversized buffer (but that is outside the
525 scope of this library).
527 {3 Order of evaluation}
529 In [bitmatch] statements, fields are evaluated left to right.
531 Note that the when-clause is evaluated {i last}, so if you are
532 relying on the when-clause to filter cases then your code may do a
533 lot of extra and unncessary pattern-matching work on fields which
534 may never be needed just to evaluate the when-clause. You can
535 usually rearrange the code to do only the first part of the match,
536 followed by the when-clause, followed by a second inner bitmatch.
540 The current implementation is believed to be fully type-safe,
541 and makes compile and run-time checks where appropriate. If
542 you find a case where a check is missing please submit a
543 bug report or a patch.
547 These are thought to be the current limits:
549 Integers: \[1..64\] bits.
551 Bitstrings (32 bit platforms): maximum length is limited
552 by the string size, ie. 16 MBytes.
554 Bitstrings (64 bit platforms): maximum length is thought to be
555 limited by the string size, ie. effectively unlimited.
557 Bitstrings must be loaded into memory before we can match against
558 them. Thus available memory may be considered a limit for some
561 {2:reference Reference}
565 type endian = BigEndian | LittleEndian | NativeEndian
567 val string_of_endian : endian -> string
570 type bitstring = string * int * int
571 (** [bitstring] is the basic type used to store bitstrings.
573 The type contains the underlying data (a string),
574 the current bit offset within the string and the
575 current bit length of the string (counting from the
576 bit offset). Note that the offset and length are
577 in {b bits}, not bytes.
579 Normally you don't need to use the bitstring type
580 directly, since there are functions and syntax
581 extensions which hide the details.
583 See also {!bitstring_of_string}, {!bitstring_of_file},
584 {!hexdump_bitstring}, {!bitstring_length}.
587 (** {3 Exceptions} *)
589 exception Construct_failure of string * string * int * int
590 (** [Construct_failure (message, file, line, char)] may be
591 raised by the [BITSTRING] constructor.
593 Common reasons are that values are out of range of
594 the fields that contain them, or that computed lengths
595 are impossible (eg. negative length bitfields).
597 [message] is the error message.
599 [file], [line] and [char] point to the original source
600 location of the [BITSTRING] constructor that failed.
603 (** {3 Bitstring manipulation} *)
605 val bitstring_length : bitstring -> int
606 (** [bitstring_length bitstring] returns the length of
607 the bitstring in bits.
609 Note this just returns the third field in the {!bitstring} tuple. *)
611 val subbitstring : bitstring -> int -> int -> bitstring
612 (** [subbitstring bits off len] returns a sub-bitstring
613 of the bitstring, starting at offset [off] bits and
614 with length [len] bits.
616 If the original bitstring is not long enough to do this
617 then the function raises [Invalid_argument "subbitstring"].
619 Note that this function just changes the offset and length
620 fields of the {!bitstring} tuple, so is very efficient. *)
622 val dropbits : int -> bitstring -> bitstring
623 (** Drop the first n bits of the bitstring and return a new
624 bitstring which is shorter by n bits.
626 If the length of the original bitstring is less than n bits,
627 this raises [Invalid_argument "dropbits"].
629 Note that this function just changes the offset and length
630 fields of the {!bitstring} tuple, so is very efficient. *)
632 val takebits : int -> bitstring -> bitstring
633 (** Take the first n bits of the bitstring and return a new
634 bitstring which is exactly n bits long.
636 If the length of the original bitstring is less than n bits,
637 this raises [Invalid_argument "takebits"].
639 Note that this function just changes the offset and length
640 fields of the {!bitstring} tuple, so is very efficient. *)
642 (** {3 Constructing bitstrings} *)
644 val empty_bitstring : bitstring
645 (** [empty_bitstring] is the empty, zero-length bitstring. *)
647 val create_bitstring : int -> bitstring
648 (** [create_bitstring n] creates an [n] bit bitstring
649 containing all zeroes. *)
651 val make_bitstring : int -> char -> bitstring
652 (** [make_bitstring n c] creates an [n] bit bitstring
653 containing the repeated 8 bit pattern in [c].
655 For example, [make_bitstring 16 '\x5a'] will create
656 the bitstring [0x5a5a] or in binary [0101 1010 0101 1010].
658 Note that the length is in bits, not bytes. The length does NOT
659 need to be a multiple of 8. *)
661 val zeroes_bitstring : int -> bitstring
662 (** [zeroes_bitstring] creates an [n] bit bitstring of all 0's.
664 Actually this is the same as {!create_bitstring}. *)
666 val ones_bitstring : int -> bitstring
667 (** [ones_bitstring] creates an [n] bit bitstring of all 1's. *)
669 val bitstring_of_string : string -> bitstring
670 (** [bitstring_of_string str] creates a bitstring
671 of length [String.length str * 8] (bits) containing the
674 Note that the bitstring uses [str] as the underlying
675 string (see the representation of {!bitstring}) so you
676 should not change [str] after calling this. *)
678 val bitstring_of_file : string -> bitstring
679 (** [bitstring_of_file filename] loads the named file
682 val bitstring_of_chan : in_channel -> bitstring
683 (** [bitstring_of_chan chan] loads the contents of
684 the input channel [chan] as a bitstring.
686 The length of the final bitstring is determined
687 by the remaining input in [chan], but will always
688 be a multiple of 8 bits.
690 See also {!bitstring_of_chan_max}. *)
692 val bitstring_of_chan_max : in_channel -> int -> bitstring
693 (** [bitstring_of_chan_max chan max] works like
694 {!bitstring_of_chan} but will only read up to
695 [max] bytes from the channel (or fewer if the end of input
696 occurs before that). *)
698 val bitstring_of_file_descr : Unix.file_descr -> bitstring
699 (** [bitstring_of_file_descr fd] loads the contents of
700 the file descriptor [fd] as a bitstring.
702 See also {!bitstring_of_chan}, {!bitstring_of_file_descr_max}. *)
704 val bitstring_of_file_descr_max : Unix.file_descr -> int -> bitstring
705 (** [bitstring_of_file_descr_max fd max] works like
706 {!bitstring_of_file_descr} but will only read up to
707 [max] bytes from the channel (or fewer if the end of input
708 occurs before that). *)
710 (** {3 Converting bitstrings} *)
712 val string_of_bitstring : bitstring -> string
713 (** [string_of_bitstring bitstring] converts a bitstring to a string
714 (eg. to allow comparison).
716 This function is inefficient. In the best case when the bitstring
717 is nicely byte-aligned we do a [String.sub] operation. If the
718 bitstring isn't aligned then this involves a lot of bit twiddling
719 and is particularly inefficient.
721 If the bitstring is not a multiple of 8 bits wide then the
722 final byte of the string contains the high bits set to the
723 remaining bits and the low bits set to 0. *)
725 val bitstring_to_file : bitstring -> string -> unit
726 (** [bitstring_to_file bits filename] writes the bitstring [bits]
727 to the file [filename]. It overwrites the output file.
729 Some restrictions apply, see {!bitstring_to_chan}. *)
731 val bitstring_to_chan : bitstring -> out_channel -> unit
732 (** [bitstring_to_file bits filename] writes the bitstring [bits]
733 to the channel [chan].
735 Channels are made up of bytes, bitstrings can be any bit length
736 including fractions of bytes. So this function only works
737 if the length of the bitstring is an exact multiple of 8 bits
738 (otherwise it raises [Invalid_argument "bitstring_to_chan"]).
740 Furthermore the function is efficient only in the case where
741 the bitstring is stored fully aligned, otherwise it has to
742 do inefficient bit twiddling like {!string_of_bitstring}.
744 In the common case where the bitstring was generated by the
745 [BITSTRING] operator and is an exact multiple of 8 bits wide,
746 then this function will always work efficiently.
749 (** {3 Printing bitstrings} *)
751 val hexdump_bitstring : out_channel -> bitstring -> unit
752 (** [hexdump_bitstring chan bitstring] prints the bitstring
753 to the output channel in a format similar to the
754 Unix command [hexdump -C]. *)
756 (** {3 Bitstring buffer} *)
760 val create : unit -> t
761 val contents : t -> bitstring
762 val add_bits : t -> string -> int -> unit
763 val add_bit : t -> bool -> unit
764 val add_byte : t -> int -> unit
766 (** Buffers are mainly used by the [BITSTRING] constructor, but
767 may also be useful for end users. They work much like the
768 standard library [Buffer] module. *)
770 (** {3 Miscellaneous} *)
773 (** The package name, always ["ocaml-bitmatch"] *)
776 (** The package version as a string. *)
779 (** Set this variable to true to enable extended debugging.
780 This only works if debugging was also enabled in the
781 [pa_bitmatch.ml] file at compile time, otherwise it
786 (* Private functions, called from generated code. Do not use
787 * these directly - they are not safe.
790 val extract_bitstring : string -> int -> int -> int -> bitstring * int * int
792 val extract_remainder : string -> int -> int -> bitstring * int * int
794 val extract_bit : string -> int -> int -> int -> bool * int * int
796 val extract_char_unsigned : string -> int -> int -> int -> int * int * int
798 val extract_int_be_unsigned : string -> int -> int -> int -> int * int * int
800 val extract_int_le_unsigned : string -> int -> int -> int -> int * int * int
802 val extract_int_ne_unsigned : string -> int -> int -> int -> int * int * int
804 val extract_int_ee_unsigned : endian -> string -> int -> int -> int -> int * int * int
806 val extract_int32_be_unsigned : string -> int -> int -> int -> int32 * int * int
808 val extract_int32_le_unsigned : string -> int -> int -> int -> int32 * int * int
810 val extract_int32_ne_unsigned : string -> int -> int -> int -> int32 * int * int
812 val extract_int32_ee_unsigned : endian -> string -> int -> int -> int -> int32 * int * int
814 val extract_int64_be_unsigned : string -> int -> int -> int -> int64 * int * int
816 val extract_int64_le_unsigned : string -> int -> int -> int -> int64 * int * int
818 val extract_int64_ne_unsigned : string -> int -> int -> int -> int64 * int * int
820 val extract_int64_ee_unsigned : endian -> string -> int -> int -> int -> int64 * int * int
822 val construct_bit : Buffer.t -> bool -> int -> exn -> unit
824 val construct_char_unsigned : Buffer.t -> int -> int -> exn -> unit
826 val construct_int_be_unsigned : Buffer.t -> int -> int -> exn -> unit
828 val construct_int_ne_unsigned : Buffer.t -> int -> int -> exn -> unit
830 val construct_int_ee_unsigned : endian -> Buffer.t -> int -> int -> exn -> unit
832 val construct_int32_be_unsigned : Buffer.t -> int32 -> int -> exn -> unit
834 val construct_int32_ne_unsigned : Buffer.t -> int32 -> int -> exn -> unit
836 val construct_int32_ee_unsigned : endian -> Buffer.t -> int32 -> int -> exn -> unit
838 val construct_int64_be_unsigned : Buffer.t -> int64 -> int -> exn -> unit
840 val construct_int64_ne_unsigned : Buffer.t -> int64 -> int -> exn -> unit
842 val construct_int64_ee_unsigned : endian -> Buffer.t -> int64 -> int -> exn -> unit
844 val construct_string : Buffer.t -> string -> unit
846 val construct_bitstring : Buffer.t -> bitstring -> unit