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.
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 {{:#reference}Jump straight to the reference section for
23 documentation on types and functions}.
27 Bitmatch adds Erlang-style bitstrings and matching over bitstrings
28 as a syntax extension and library for OCaml. You can use
29 this module to both parse and generate binary formats, for
30 example, communications protocols, disk formats and binary files.
32 {{:http://code.google.com/p/bitmatch/}OCaml bitmatch website}
36 A function which can parse IPv4 packets:
43 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
44 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
45 | 4 | IHL |Type of Service| Total Length |
46 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
47 | Identification |Flags| Fragment Offset |
48 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
49 | Time to Live | Protocol | Header Checksum |
50 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
52 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
53 | Destination Address |
54 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
56 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
58 | { 4 : 4; hdrlen : 4; tos : 8; length : 16;
59 identification : 16; flags : 3; fragoffset : 13;
60 ttl : 8; protocol : 8; checksum : 16;
63 options : (hdrlen-5)*32 : bitstring;
64 payload : -1 : bitstring } ->
67 printf " header length: %d * 32 bit words\n" hdrlen;
68 printf " type of service: %d\n" tos;
69 printf " packet length: %d bytes\n" length;
70 printf " identification: %d\n" identification;
71 printf " flags: %d\n" flags;
72 printf " fragment offset: %d\n" fragoffset;
73 printf " ttl: %d\n" ttl;
74 printf " protocol: %d\n" protocol;
75 printf " checksum: %d\n" checksum;
76 printf " source: %lx dest: %lx\n" source dest;
77 printf " header options + padding:\n";
78 Bitmatch.hexdump_bitstring stdout options;
79 printf " packet payload:\n";
80 Bitmatch.hexdump_bitstring stdout payload
83 eprintf "unknown IP version %d\n" version;
87 eprintf "data is smaller than one nibble:\n";
88 Bitmatch.hexdump_bitstring stderr pkt;
92 A program which can parse
93 {{:http://lxr.linux.no/linux/include/linux/ext3_fs.h}Linux EXT3 filesystem superblocks}:
96 let bits = Bitmatch.bitstring_of_file "tests/ext3_sb"
100 | { s_inodes_count : 32 : littleendian; (* Inodes count *)
101 s_blocks_count : 32 : littleendian; (* Blocks count *)
102 s_r_blocks_count : 32 : littleendian; (* Reserved blocks count *)
103 s_free_blocks_count : 32 : littleendian; (* Free blocks count *)
104 s_free_inodes_count : 32 : littleendian; (* Free inodes count *)
105 s_first_data_block : 32 : littleendian; (* First Data Block *)
106 s_log_block_size : 32 : littleendian; (* Block size *)
107 s_log_frag_size : 32 : littleendian; (* Fragment size *)
108 s_blocks_per_group : 32 : littleendian; (* # Blocks per group *)
109 s_frags_per_group : 32 : littleendian; (* # Fragments per group *)
110 s_inodes_per_group : 32 : littleendian; (* # Inodes per group *)
111 s_mtime : 32 : littleendian; (* Mount time *)
112 s_wtime : 32 : littleendian; (* Write time *)
113 s_mnt_count : 16 : littleendian; (* Mount count *)
114 s_max_mnt_count : 16 : littleendian; (* Maximal mount count *)
115 0xef53 : 16 : littleendian } -> (* Magic signature *)
117 printf "ext3 superblock:\n";
118 printf " s_inodes_count = %ld\n" s_inodes_count;
119 printf " s_blocks_count = %ld\n" s_blocks_count;
120 printf " s_free_inodes_count = %ld\n" s_free_inodes_count;
121 printf " s_free_blocks_count = %ld\n" s_free_blocks_count
124 eprintf "not an ext3 superblock!\n%!";
128 Constructing packets for a simple binary message
133 +---------------+---------------+--------------------------+
134 | type | subtype | parameter |
135 +---------------+---------------+--------------------------+
136 <-- 16 bits --> <-- 16 bits --> <------- 32 bits -------->
138 All fields are in network byte order.
141 let make_message typ subtype param =
149 {2 Loading, creating bitstrings}
151 The basic data type is the {!bitstring}, a string of bits of
152 arbitrary length. Bitstrings can be any length in bits and
153 operations do not need to be byte-aligned (although they will
154 generally be more efficient if they are byte-aligned).
156 Internally a bitstring is stored as a normal OCaml [string]
157 together with an offset and length, where the offset and length are
158 measured in bits. Thus one can efficiently form substrings of
159 bitstrings, overlay a bitstring on existing data, and load and save
160 bitstrings from files or other external sources.
162 To load a bitstring from a file use {!bitstring_of_file} or
163 {!bitstring_of_chan}.
165 There are also functions to create bitstrings from arbitrary data.
166 See the {{:#reference}reference} below.
168 {2 Matching bitstrings with patterns}
170 Use the [bitmatch] operator (part of the syntax extension) to break
171 apart a bitstring into its fields. [bitmatch] works a lot like the
172 OCaml [match] operator.
174 The general form of [bitmatch] is:
176 [bitmatch] {i bitstring-expression} [with]
178 [| {] {i pattern} [} ->] {i code}
180 [| {] {i pattern} [} ->] {i code}
184 As with normal match, the statement attempts to match the
185 bitstring against each pattern in turn. If none of the patterns
186 match then the standard library [Match_failure] exception is
189 Patterns look a bit different from normal match patterns. They
190 consist of a list of bitfields separated by [;] where each bitfield
191 contains a bind variable, the width (in bits) of the field, and
192 other information. Some example patterns:
197 | { version : 8; name : 8; param : 8 } -> ...
199 (* Bitstring of at least 3 bytes. First byte is the version
200 number, second byte is a field called name, third byte is
201 a field called parameter. *)
204 printf "flag is %b\n" flag
206 (* A single flag bit (mapped into an OCaml boolean). *)
208 | { len : 4; data : 1+len } ->
209 printf "len = %d, data = 0x%Lx\n" len data
211 (* A 4-bit length, followed by 1-16 bits of data, where the
212 length of the data is computed from len. *)
214 | { ipv6_source : 128 : bitstring;
215 ipv6_dest : 128 : bitstring } -> ...
217 (* IPv6 source and destination addresses. Each is 128 bits
218 and is mapped into a bitstring type which will be a substring
219 of the main bitstring expression. *)
222 You can also add conditional when-clauses:
226 when version = 4 || version = 6 -> ...
228 (* Only match and run the code when version is 4 or 6. If
229 it isn't we will drop through to the next case. *)
232 Note that the pattern is only compared against the first part of
233 the bitstring (there may be more data in the bitstring following
234 the pattern, which is not matched). In terms of regular
235 expressions you might say that the pattern matches [^pattern], not
236 [^pattern$]. To ensure that the bitstring contains only the
237 pattern, add a length -1 bitstring to the end and test that its
238 length is zero in the when-clause:
242 rest : -1 : bitstring }
243 when Bitmatch.bitstring_length rest = 0 -> ...
245 (* Only matches exactly 4 bits. *)
248 Normally the first part of each field is a binding variable,
249 but you can also match a constant, as in:
252 | { (4|6) : 4 } -> ...
254 (* Only matches if the first 4 bits contain either
255 the integer 4 or the integer 6. *)
258 One may also match on strings:
261 | { "MAGIC" : 5*8 : string } -> ...
263 (* Only matches if the string "MAGIC" appears at the start
267 {3:patternfieldreference Pattern field reference}
269 The exact format of each pattern field is:
271 [pattern : length [: qualifier [,qualifier ...]]]
273 [pattern] is the pattern, binding variable name, or constant to
274 match. [length] is the length in bits which may be either a
275 constant or an expression. The length expression is just an OCaml
276 expression and can use any values defined in the program, and refer
277 back to earlier fields (but not to later fields).
279 Integers can only have lengths in the range \[1..64\] bits. See the
280 {{:#integertypes}integer types} section below for how these are
281 mapped to the OCaml int/int32/int64 types. This is checked
282 at compile time if the length expression is constant, otherwise it is
283 checked at runtime and you will get a runtime exception eg. in
284 the case of a computed length expression.
286 A bitstring field of length -1 matches all the rest of the
287 bitstring (thus this is only useful as the last field in a
290 A bitstring field of length 0 matches an empty bitstring
291 (occasionally useful when matching optional subfields).
293 Qualifiers are a list of identifiers/expressions which control the type,
294 signedness and endianness of the field. Permissible qualifiers are:
296 - [int]: field has an integer type
297 - [string]: field is a string type
298 - [bitstring]: field is a bitstring type
299 - [signed]: field is signed
300 - [unsigned]: field is unsigned
301 - [bigendian]: field is big endian - a.k.a network byte order
302 - [littleendian]: field is little endian - a.k.a Intel byte order
303 - [nativeendian]: field is same endianness as the machine
304 - [endian (expr)]: [expr] should be an expression which evaluates to
305 a {!endian} type, ie. [LittleEndian], [BigEndian] or [NativeEndian].
306 The expression is an arbitrary OCaml expression and can use the
307 value of earlier fields in the bitmatch.
308 - [offset (expr)]: see {{:#computedoffsets}computed offsets} below.
310 The default settings are [int], [unsigned], [bigendian], no offset.
312 Note that many of these qualifiers cannot be used together,
313 eg. bitstrings do not have endianness. The syntax extension should
314 give you a compile-time error if you use incompatible qualifiers.
316 {3 Other cases in bitmatch}
318 As well as a list of fields, it is possible to name the
319 bitstring and/or have a default match case:
324 (* Default match case. *)
326 | { _ } as pkt -> ...
328 (* Default match case, with 'pkt' bound to the whole bitstring. *)
331 {2 Constructing bitstrings}
333 Bitstrings may be constructed using the [BITSTRING] operator (as an
334 expression). The [BITSTRING] operator takes a list of fields,
335 similar to the list of fields for matching:
346 (* Constructs a 16-bit bitstring with the first four bits containing
347 the integer 1, and the following 12 bits containing the integer 10,
348 arranged in network byte order. *)
350 Bitmatch.hexdump_bitstring stdout bits ;;
358 The format of each field is the same as for pattern fields (see
359 {{:#patternfieldreference}Pattern field reference section}), and
360 things like computed length fields, fixed value fields, insertion
361 of bitstrings within bitstrings, etc. are all supported.
363 {3 Construction exception}
365 The [BITSTRING] operator may throw a {!Construct_failure}
366 exception at runtime.
368 Runtime errors include:
370 - int field length not in the range \[1..64\]
371 - a bitstring with a length declared which doesn't have the
372 same length at runtime
373 - trying to insert an out of range value into an int field
374 (eg. an unsigned int field which is 2 bits wide can only
375 take values in the range \[0..3\]).
377 {2:integertypes Integer types}
379 Integer types are mapped to OCaml types [bool], [int], [int32] or
380 [int64] using a system which tries to ensure that (a) the types are
381 reasonably predictable and (b) the most efficient type is
384 The rules are slightly different depending on whether the bit
385 length expression in the field is a compile-time constant or a
388 Detection of compile-time constants is quite simplistic so only
389 simple integer literals and simple expressions (eg. [5*8]) are
390 recognized as constants.
392 In any case the bit size of an integer is limited to the range
393 \[1..64\]. This is detected as a compile-time error if that is
394 possible, otherwise a runtime check is added which can throw an
395 [Invalid_argument] exception.
400 Bit size ---- OCaml type ----
401 Constant Computed expression
409 A possible future extension may allow people with 64 bit computers
410 to specify a more optimal [int] type for bit sizes in the range
411 [32..63]. If this was implemented then such code {i could not even
412 be compiled} on 32 bit platforms, so it would limit portability.
414 Another future extension may be to allow computed
415 expressions to assert min/max range for the bit size,
416 allowing a more efficient data type than int64 to be
417 used. (Of course under such circumstances there would
418 still need to be a runtime check to enforce the
421 {2:computedoffsets Computed offsets}
423 You can add an [offset(..)] qualifier to bitmatch patterns in order
424 to move the current offset within the bitstring forwards.
431 field2 : 8 : offset(160) } -> ...
434 matches [field1] at the start of the bitstring and [field2]
435 at 160 bits into the bitstring. The middle 152 bits go
436 unmatched (ie. can be anything).
438 The generated code is efficient. If field lengths and offsets
439 are known to be constant at compile time, then almost all
440 runtime checks are avoided. Non-constant field lengths and/or
441 non-constant offsets can result in more runtime checks being added.
443 Note that moving the offset backwards, and moving the offset in
444 [BITSTRING] constructors, are both not supported at present.
446 {2 Named patterns and persistent patterns}
448 Please see {!Bitmatch_persistent} for documentation on this subject.
452 Using the compiler directly you can do:
455 ocamlc -I +bitmatch \
456 -pp "camlp4o bitmatch.cma bitmatch_persistent.cma \
457 `ocamlc -where`/bitmatch/pa_bitmatch.cmo" \
458 bitmatch.cma test.ml -o test
461 Simpler method using findlib:
465 -package bitmatch.syntax -syntax bitmatch.syntax \
466 -linkpkg test.ml -o test
469 {2 Security and type safety}
471 {3 Security on input}
473 The main concerns for input are buffer overflows and denial
476 It is believed that this library is robust against attempted buffer
477 overflows. In addition to OCaml's normal bounds checks, we check
478 that field lengths are >= 0, and many additional checks.
480 Denial of service attacks are more problematic. We only work
481 forwards through the bitstring, thus computation will eventually
482 terminate. As for computed lengths, code such as this is thought
488 buffer : Int64.to_int len : bitstring } ->
491 The [len] field can be set arbitrarily large by an attacker, but
492 when pattern-matching against the [buffer] field this merely causes
493 a test such as [if len <= remaining_size] to fail. Even if the
494 length is chosen so that [buffer] bitstring is allocated, the
495 allocation of sub-bitstrings is efficient and doesn't involve an
496 arbitary-sized allocation or any copying.
498 However the above does not necessarily apply to strings used in
499 matching, since they may cause the library to use the
500 {!Bitmatch.string_of_bitstring} function, which allocates a string.
501 So you should take care if you use the [string] type particularly
502 with a computed length that is derived from external input.
504 The main protection against attackers should be to ensure that the
505 main program will only read input bitstrings up to a certain
506 length, which is outside the scope of this library.
508 {3 Security on output}
510 As with the input side, computed lengths are believed to be
514 let len = read_untrusted_source () in
515 let buffer = allocate_bitstring () in
517 buffer : len : bitstring
521 This code merely causes a check that buffer's length is the same as
522 [len]. However the program function [allocate_bitstring] must
523 refuse to allocate an oversized buffer (but that is outside the
524 scope of this library).
526 {3 Order of evaluation}
528 In [bitmatch] statements, fields are evaluated left to right.
530 Note that the when-clause is evaluated {i last}, so if you are
531 relying on the when-clause to filter cases then your code may do a
532 lot of extra and unncessary pattern-matching work on fields which
533 may never be needed just to evaluate the when-clause. You can
534 usually rearrange the code to do only the first part of the match,
535 followed by the when-clause, followed by a second inner bitmatch.
539 The current implementation is believed to be fully type-safe,
540 and makes compile and run-time checks where appropriate. If
541 you find a case where a check is missing please submit a
542 bug report or a patch.
546 These are thought to be the current limits:
548 Integers: \[1..64\] bits.
550 Bitstrings (32 bit platforms): maximum length is limited
551 by the string size, ie. 16 MBytes.
553 Bitstrings (64 bit platforms): maximum length is thought to be
554 limited by the string size, ie. effectively unlimited.
556 Bitstrings must be loaded into memory before we can match against
557 them. Thus available memory may be considered a limit for some
560 {2:reference Reference}
564 type endian = BigEndian | LittleEndian | NativeEndian
566 val string_of_endian : endian -> string
569 type bitstring = string * int * int
570 (** [bitstring] is the basic type used to store bitstrings.
572 The type contains the underlying data (a string),
573 the current bit offset within the string and the
574 current bit length of the string (counting from the
575 bit offset). Note that the offset and length are
576 in {b bits}, not bytes.
578 Normally you don't need to use the bitstring type
579 directly, since there are functions and syntax
580 extensions which hide the details.
582 See also {!bitstring_of_string}, {!bitstring_of_file},
583 {!hexdump_bitstring}, {!bitstring_length}.
586 (** {3 Exceptions} *)
588 exception Construct_failure of string * string * int * int
589 (** [Construct_failure (message, file, line, char)] may be
590 raised by the [BITSTRING] constructor.
592 Common reasons are that values are out of range of
593 the fields that contain them, or that computed lengths
594 are impossible (eg. negative length bitfields).
596 [message] is the error message.
598 [file], [line] and [char] point to the original source
599 location of the [BITSTRING] constructor that failed.
602 (** {3 Bitstrings} *)
604 val empty_bitstring : bitstring
605 (** [empty_bitstring] is the empty, zero-length bitstring. *)
607 val create_bitstring : int -> bitstring
608 (** [create_bitstring n] creates an [n] bit bitstring
609 containing all zeroes. *)
611 val make_bitstring : int -> char -> bitstring
612 (** [make_bitstring n c] creates an [n] bit bitstring
613 containing the repeated 8 bit pattern in [c].
615 For example, [make_bitstring 16 '\x5a'] will create
616 the bitstring [0x5a5a] or in binary [0101 1010 0101 1010].
618 Note that the length is in bits, not bytes. The length does NOT
619 need to be a multiple of 8. *)
621 val zeroes_bitstring : int -> bitstring
622 (** [zeroes_bitstring] creates an [n] bit bitstring of all 0's.
624 Actually this is the same as {!create_bitstring}. *)
626 val ones_bitstring : int -> bitstring
627 (** [ones_bitstring] creates an [n] bit bitstring of all 1's. *)
629 val bitstring_of_string : string -> bitstring
630 (** [bitstring_of_string str] creates a bitstring
631 of length [String.length str * 8] (bits) containing the
634 Note that the bitstring uses [str] as the underlying
635 string (see the representation of {!bitstring}) so you
636 should not change [str] after calling this. *)
638 val bitstring_of_file : string -> bitstring
639 (** [bitstring_of_file filename] loads the named file
642 val bitstring_of_chan : in_channel -> bitstring
643 (** [bitstring_of_chan chan] loads the contents of
644 the input channel [chan] as a bitstring.
646 The length of the final bitstring is determined
647 by the remaining input in [chan], but will always
648 be a multiple of 8 bits.
650 See also {!bitstring_of_chan_max}. *)
652 val bitstring_of_chan_max : in_channel -> int -> bitstring
653 (** [bitstring_of_chan_max chan max] works like
654 {!bitstring_of_chan} but will only read up to
655 [max] bytes from the channel (or fewer if the end of input
656 occurs before that). *)
658 val bitstring_of_file_descr : Unix.file_descr -> bitstring
659 (** [bitstring_of_file_descr fd] loads the contents of
660 the file descriptor [fd] as a bitstring.
662 See also {!bitstring_of_chan}, {!bitstring_of_file_descr_max}. *)
664 val bitstring_of_file_descr_max : Unix.file_descr -> int -> bitstring
665 (** [bitstring_of_file_descr_max fd max] works like
666 {!bitstring_of_file_descr} but will only read up to
667 [max] bytes from the channel (or fewer if the end of input
668 occurs before that). *)
670 val bitstring_length : bitstring -> int
671 (** [bitstring_length bitstring] returns the length of
672 the bitstring in bits. *)
674 val string_of_bitstring : bitstring -> string
675 (** [string_of_bitstring bitstring] converts a bitstring to a string
676 (eg. to allow comparison).
678 This function is inefficient. In the best case when the bitstring
679 is nicely byte-aligned we do a [String.sub] operation. If the
680 bitstring isn't aligned then this involves a lot of bit twiddling
681 and is particularly inefficient.
683 If the bitstring is not a multiple of 8 bits wide then the
684 final byte of the string contains the high bits set to the
685 remaining bits and the low bits set to 0. *)
687 val bitstring_to_file : bitstring -> string -> unit
688 (** [bitstring_to_file bits filename] writes the bitstring [bits]
689 to the file [filename]. It overwrites the output file.
691 Some restrictions apply, see {!bitstring_to_chan}. *)
693 val bitstring_to_chan : bitstring -> out_channel -> unit
694 (** [bitstring_to_file bits filename] writes the bitstring [bits]
695 to the channel [chan].
697 Channels are made up of bytes, bitstrings can be any bit length
698 including fractions of bytes. So this function only works
699 if the length of the bitstring is an exact multiple of 8 bits
700 (otherwise it raises [Invalid_argument "bitstring_to_chan"]).
702 Furthermore the function is efficient only in the case where
703 the bitstring is stored fully aligned, otherwise it has to
704 do inefficient bit twiddling like {!string_of_bitstring}.
706 In the common case where the bitstring was generated by the
707 [BITSTRING] operator and is an exact multiple of 8 bits wide,
708 then this function will always work efficiently.
711 (** {3 Printing bitstrings} *)
713 val hexdump_bitstring : out_channel -> bitstring -> unit
714 (** [hexdump_bitstring chan bitstring] prints the bitstring
715 to the output channel in a format similar to the
716 Unix command [hexdump -C]. *)
718 (** {3 Bitstring buffer} *)
722 val create : unit -> t
723 val contents : t -> bitstring
724 val add_bits : t -> string -> int -> unit
725 val add_bit : t -> bool -> unit
726 val add_byte : t -> int -> unit
728 (** Buffers are mainly used by the [BITSTRING] constructor, but
729 may also be useful for end users. They work much like the
730 standard library [Buffer] module. *)
732 (** {3 Miscellaneous} *)
735 (** The package name, always ["ocaml-bitmatch"] *)
738 (** The package version as a string. *)
741 (** Set this variable to true to enable extended debugging.
742 This only works if debugging was also enabled in the
743 [pa_bitmatch.ml] file at compile time, otherwise it
748 (* Private functions, called from generated code. Do not use
749 * these directly - they are not safe.
752 val extract_bitstring : string -> int -> int -> int -> bitstring * int * int
754 val extract_remainder : string -> int -> int -> bitstring * int * int
756 val extract_bit : string -> int -> int -> int -> bool * int * int
758 val extract_char_unsigned : string -> int -> int -> int -> int * int * int
760 val extract_int_be_unsigned : string -> int -> int -> int -> int * int * int
762 val extract_int_le_unsigned : string -> int -> int -> int -> int * int * int
764 val extract_int_ne_unsigned : string -> int -> int -> int -> int * int * int
766 val extract_int_ee_unsigned : endian -> string -> int -> int -> int -> int * int * int
768 val extract_int32_be_unsigned : string -> int -> int -> int -> int32 * int * int
770 val extract_int32_le_unsigned : string -> int -> int -> int -> int32 * int * int
772 val extract_int32_ne_unsigned : string -> int -> int -> int -> int32 * int * int
774 val extract_int32_ee_unsigned : endian -> string -> int -> int -> int -> int32 * int * int
776 val extract_int64_be_unsigned : string -> int -> int -> int -> int64 * int * int
778 val extract_int64_le_unsigned : string -> int -> int -> int -> int64 * int * int
780 val extract_int64_ne_unsigned : string -> int -> int -> int -> int64 * int * int
782 val extract_int64_ee_unsigned : endian -> string -> int -> int -> int -> int64 * int * int
784 val construct_bit : Buffer.t -> bool -> int -> exn -> unit
786 val construct_char_unsigned : Buffer.t -> int -> int -> exn -> unit
788 val construct_int_be_unsigned : Buffer.t -> int -> int -> exn -> unit
790 val construct_int_ne_unsigned : Buffer.t -> int -> int -> exn -> unit
792 val construct_int_ee_unsigned : endian -> Buffer.t -> int -> int -> exn -> unit
794 val construct_int32_be_unsigned : Buffer.t -> int32 -> int -> exn -> unit
796 val construct_int32_ne_unsigned : Buffer.t -> int32 -> int -> exn -> unit
798 val construct_int32_ee_unsigned : endian -> Buffer.t -> int32 -> int -> exn -> unit
800 val construct_int64_be_unsigned : Buffer.t -> int64 -> int -> exn -> unit
802 val construct_int64_ne_unsigned : Buffer.t -> int64 -> int -> exn -> unit
804 val construct_int64_ee_unsigned : endian -> Buffer.t -> int64 -> int -> exn -> unit
806 val construct_string : Buffer.t -> string -> unit
808 val construct_bitstring : Buffer.t -> bitstring -> unit