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bitstring.ml
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bitstring.ml
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(* Bitstring 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 Bitstring_types
include Bitstring_config
(* Enable runtime debug messages. Must also have been enabled
* in pa_bitstring.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
type t = bitstring
(* 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 off' < 0 || len' < 0 || off' > len - 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 || n < 0 then invalid_arg "dropbits";
(data, off, len)
let takebits n (data, off, len) =
if len < n || n < 0 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. *)
external (<<<) : int -> int -> int = "%lslint"
external (>>>) : int -> int -> int = "%lsrint"
external to_int : int -> int = "%identity"
let zero = 0
let one = 1
let minus_one = -1
let ff = 0xff
(* Create a mask 0-31 bits wide. *)
let mask bits =
if bits < 30 ||
(bits < 32 && Sys.word_size = 64) then
(one <<< bits) - 1
else if bits = 30 then
max_int
else if bits = 31 then
minus_one
else
invalid_arg "Bitstring.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
let range_signed v bits =
if
v >= zero
then
range_unsigned v bits
else
if
bits = 31 && Sys.word_size = 32
then
v >= min_int
else
pred (minus_one <<< pred bits) < v
(* 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
)
(* Call function g on the top bits, then f on each full byte
* (little endian - so start at root).
*)
let rec map_bytes_le g f v bits =
if bits >= 8 then (
let lsb = v land ff in
f (to_int lsb);
map_bytes_le g f (v >>> 8) (bits-8)
) 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 "Bitstring.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
)
(* Call function g on the top bits, then f on each full byte
* (little endian - so start at root).
*)
let rec map_bytes_le g f v bits =
if bits >= 8 then (
let lsb = v land ff in
f (to_int lsb);
map_bytes_le g f (v >>> 8) (bits-8)
) 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 "Bitstring.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
)
(* Call function g on the top bits, then f on each full byte
* (little endian - so start at root).
*)
let rec map_bytes_le g f v bits =
if bits >= 8 then (
let lsb = v land ff in
f (to_int lsb);
map_bytes_le g f (v >>> 8) (bits-8)
) 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).
*)
(* 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
(* Extend signed [2..31] bits int to 31 bits int or 63 bits int for 64
bits platform*)
let extend_sign len v =
let b = pred Sys.word_size - len in
(v lsl b) asr b
let extract_and_extend_sign f data off len flen =
let w = f data off len flen in
extend_sign len w
(* 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*)
)
let extract_char_signed =
extract_and_extend_sign extract_char_unsigned
(* 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 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c1 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c2 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c3 = 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_be_signed =
extract_and_extend_sign extract_int_be_unsigned
let extract_int_le_unsigned data off len flen =
let v = extract_int_be_unsigned data off len flen in
let v = I.byteswap v flen in
v
let extract_int_le_signed =
extract_and_extend_sign extract_int_le_unsigned
let extract_int_ne_unsigned =
if nativeendian = BigEndian
then extract_int_be_unsigned
else extract_int_le_unsigned
let extract_int_ne_signed =
extract_and_extend_sign extract_int_ne_unsigned
let extract_int_ee_unsigned = function
| BigEndian -> extract_int_be_unsigned
| LittleEndian -> extract_int_le_unsigned
| NativeEndian -> extract_int_ne_unsigned
let extract_int_ee_signed e =
extract_and_extend_sign (extract_int_ee_unsigned e)
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 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c1 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c2 = extract_char_unsigned data off len 8
and off = off + 8 and len = 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 = extract_int32_be_unsigned data off len flen in
let v = I32.byteswap v flen in
v
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 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c1 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c2 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c3 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c4 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c5 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c6 = extract_char_unsigned data off len 8
and off = off + 8 and len = 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 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c1 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c2 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c3 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c4 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c5 = extract_char_unsigned data off len 8
and off = off + 8 and len = len - 8 in
let c6 = extract_char_unsigned data off len 8
and off = off + 8 and len = 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
external extract_fastpath_int16_be_unsigned : string -> int -> int = "ocaml_bitstring_extract_fastpath_int16_be_unsigned" "noalloc"
external extract_fastpath_int16_le_unsigned : string -> int -> int = "ocaml_bitstring_extract_fastpath_int16_le_unsigned" "noalloc"
external extract_fastpath_int16_ne_unsigned : string -> int -> int = "ocaml_bitstring_extract_fastpath_int16_ne_unsigned" "noalloc"
external extract_fastpath_int16_be_signed : string -> int -> int = "ocaml_bitstring_extract_fastpath_int16_be_signed" "noalloc"
external extract_fastpath_int16_le_signed : string -> int -> int = "ocaml_bitstring_extract_fastpath_int16_le_signed" "noalloc"
external extract_fastpath_int16_ne_signed : string -> int -> int = "ocaml_bitstring_extract_fastpath_int16_ne_signed" "noalloc"
(*
external extract_fastpath_int24_be_unsigned : string -> int -> int = "ocaml_bitstring_extract_fastpath_int24_be_unsigned" "noalloc"
external extract_fastpath_int24_le_unsigned : string -> int -> int = "ocaml_bitstring_extract_fastpath_int24_le_unsigned" "noalloc"
external extract_fastpath_int24_ne_unsigned : string -> int -> int = "ocaml_bitstring_extract_fastpath_int24_ne_unsigned" "noalloc"
external extract_fastpath_int24_be_signed : string -> int -> int = "ocaml_bitstring_extract_fastpath_int24_be_signed" "noalloc"
external extract_fastpath_int24_le_signed : string -> int -> int = "ocaml_bitstring_extract_fastpath_int24_le_signed" "noalloc"
external extract_fastpath_int24_ne_signed : string -> int -> int = "ocaml_bitstring_extract_fastpath_int24_ne_signed" "noalloc"
*)
external extract_fastpath_int32_be_unsigned : string -> int -> int32 = "ocaml_bitstring_extract_fastpath_int32_be_unsigned"
external extract_fastpath_int32_le_unsigned : string -> int -> int32 = "ocaml_bitstring_extract_fastpath_int32_le_unsigned"
external extract_fastpath_int32_ne_unsigned : string -> int -> int32 = "ocaml_bitstring_extract_fastpath_int32_ne_unsigned"
external extract_fastpath_int32_be_signed : string -> int -> int32 = "ocaml_bitstring_extract_fastpath_int32_be_signed"
external extract_fastpath_int32_le_signed : string -> int -> int32 = "ocaml_bitstring_extract_fastpath_int32_le_signed"
external extract_fastpath_int32_ne_signed : string -> int -> int32 = "ocaml_bitstring_extract_fastpath_int32_ne_signed"
(*
external extract_fastpath_int40_be_unsigned : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int40_be_unsigned"
external extract_fastpath_int40_le_unsigned : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int40_le_unsigned"
external extract_fastpath_int40_ne_unsigned : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int40_ne_unsigned"
external extract_fastpath_int40_be_signed : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int40_be_signed"
external extract_fastpath_int40_le_signed : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int40_le_signed"
external extract_fastpath_int40_ne_signed : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int40_ne_signed"
external extract_fastpath_int48_be_unsigned : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int48_be_unsigned"
external extract_fastpath_int48_le_unsigned : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int48_le_unsigned"
external extract_fastpath_int48_ne_unsigned : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int48_ne_unsigned"
external extract_fastpath_int48_be_signed : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int48_be_signed"
external extract_fastpath_int48_le_signed : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int48_le_signed"
external extract_fastpath_int48_ne_signed : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int48_ne_signed"
external extract_fastpath_int56_be_unsigned : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int56_be_unsigned"
external extract_fastpath_int56_le_unsigned : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int56_le_unsigned"
external extract_fastpath_int56_ne_unsigned : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int56_ne_unsigned"
external extract_fastpath_int56_be_signed : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int56_be_signed"
external extract_fastpath_int56_le_signed : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int56_le_signed"
external extract_fastpath_int56_ne_signed : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int56_ne_signed"
*)
external extract_fastpath_int64_be_unsigned : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int64_be_unsigned"
external extract_fastpath_int64_le_unsigned : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int64_le_unsigned"
external extract_fastpath_int64_ne_unsigned : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int64_ne_unsigned"
external extract_fastpath_int64_be_signed : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int64_be_signed"
external extract_fastpath_int64_le_signed : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int64_le_signed"
external extract_fastpath_int64_ne_signed : string -> int -> int64 = "ocaml_bitstring_extract_fastpath_int64_ne_signed"
(*----------------------------------------------------------------------*)
(* 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 "Bitstring.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 "Bitstring.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 lastidx = min slenbytes (String.length str - 1) in
let last = Char.code str.[lastidx] 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
let construct_char_signed buf v flen exn =
let max_val = 1 lsl flen
and min_val = - (1 lsl pred flen) in
if v < min_val || v >= max_val then
raise exn;
if flen = 8 then
Buffer.add_byte buf (if v >= 0 then v else 256 + v)
else
Buffer._add_bits buf v flen
(* Construct a field of up to 31 bits. *)
let construct_int check_func map_func buf v flen exn =
if not (check_func v flen) then raise exn;
map_func (Buffer._add_bits buf) (Buffer.add_byte buf) v flen
let construct_int_be_unsigned =
construct_int I.range_unsigned I.map_bytes_be
let construct_int_be_signed =
construct_int I.range_signed I.map_bytes_be
let construct_int_le_unsigned =
construct_int I.range_unsigned I.map_bytes_le
let construct_int_le_signed =
construct_int I.range_signed I.map_bytes_le
let construct_int_ne_unsigned =
if nativeendian = BigEndian
then construct_int_be_unsigned
else construct_int_le_unsigned
let construct_int_ne_signed =
if nativeendian = BigEndian
then construct_int_be_signed
else construct_int_le_signed
let construct_int_ee_unsigned = function
| BigEndian -> construct_int_be_unsigned
| LittleEndian -> construct_int_le_unsigned
| NativeEndian -> construct_int_ne_unsigned
let construct_int_ee_signed = function
| BigEndian -> construct_int_be_signed
| LittleEndian -> construct_int_le_signed
| NativeEndian -> construct_int_ne_signed
(* 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)));