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
23 include Bitmatch_types
24 include Bitmatch_config
26 (* Enable runtime debug messages. Must also have been enabled
32 exception Construct_failure of string * string * int * int
34 (* A bitstring is simply the data itself (as a string), and the
35 * bitoffset and the bitlength within the string. Note offset/length
36 * are counted in bits, not bytes.
38 type bitstring = string * int * int
40 (* Functions to create and load bitstrings. *)
41 let empty_bitstring = "", 0, 0
43 let make_bitstring len c =
44 if len >= 0 then String.make ((len+7) lsr 3) c, 0, len
47 sprintf "make_bitstring/create_bitstring: len %d < 0" len
50 let create_bitstring len = make_bitstring len '\000'
52 let zeroes_bitstring = create_bitstring
54 let ones_bitstring len = make_bitstring len '\xff'
56 let bitstring_of_string str = str, 0, String.length str lsl 3
58 let bitstring_of_chan chan =
59 let tmpsize = 16384 in
60 let buf = Buffer.create tmpsize in
61 let tmp = String.create tmpsize in
63 while n := input chan tmp 0 tmpsize; !n > 0 do
64 Buffer.add_substring buf tmp 0 !n;
66 Buffer.contents buf, 0, Buffer.length buf lsl 3
68 let bitstring_of_chan_max chan max =
69 let tmpsize = 16384 in
70 let buf = Buffer.create tmpsize in
71 let tmp = String.create tmpsize in
75 let r = min tmpsize (max - !len) in
76 let n = input chan tmp 0 r in
78 Buffer.add_substring buf tmp 0 n;
85 Buffer.contents buf, 0, !len lsl 3
87 let bitstring_of_file_descr fd =
88 let tmpsize = 16384 in
89 let buf = Buffer.create tmpsize in
90 let tmp = String.create tmpsize in
92 while n := Unix.read fd tmp 0 tmpsize; !n > 0 do
93 Buffer.add_substring buf tmp 0 !n;
95 Buffer.contents buf, 0, Buffer.length buf lsl 3
97 let bitstring_of_file_descr_max fd max =
98 let tmpsize = 16384 in
99 let buf = Buffer.create tmpsize in
100 let tmp = String.create tmpsize in
104 let r = min tmpsize (max - !len) in
105 let n = Unix.read fd tmp 0 r in
107 Buffer.add_substring buf tmp 0 n;
114 Buffer.contents buf, 0, !len lsl 3
116 let bitstring_of_file fname =
117 let chan = open_in_bin fname in
119 let bs = bitstring_of_chan chan in
126 let bitstring_length (_, _, len) = len
128 (*----------------------------------------------------------------------*)
129 (* Bitwise functions.
131 * We try to isolate all bitwise functions within these modules.
135 (* Bitwise operations on ints. Note that we assume int <= 31 bits. *)
138 external to_int : int -> int = "%identity"
144 (* Create a mask so many bits wide. *)
148 else if bits = 30 then
150 else if bits = 31 then
153 invalid_arg "Bitmatch.I.mask"
155 (* Byte swap an int of a given size. *)
156 let byteswap v bits =
158 else if bits <= 16 then (
159 let shift = bits-8 in
160 let v1 = v >> shift in
161 let v2 = (v land (mask shift)) << 8 in
163 ) else if bits <= 24 then (
164 let shift = bits - 16 in
165 let v1 = v >> (8+shift) in
166 let v2 = ((v >> shift) land ff) << 8 in
167 let v3 = (v land (mask shift)) << 16 in
170 let shift = bits - 24 in
171 let v1 = v >> (16+shift) in
172 let v2 = ((v >> (8+shift)) land ff) << 8 in
173 let v3 = ((v >> shift) land ff) << 16 in
174 let v4 = (v land (mask shift)) << 24 in
175 v4 lor v3 lor v2 lor v1
178 (* Check a value is in range 0 .. 2^bits-1. *)
179 let range_unsigned v bits =
180 let mask = lnot (mask bits) in
183 (* Call function g on the top bits, then f on each full byte
184 * (big endian - so start at top).
186 let rec map_bytes_be g f v bits =
188 map_bytes_be g f (v >> 8) (bits-8);
189 let lsb = v land ff in
191 ) else if bits > 0 then (
192 let lsb = v land (mask bits) in
198 (* Bitwise operations on int32s. Note we try to keep it as similar
199 * as possible to the I module above, to make it easier to track
202 let (<<) = Int32.shift_left
203 let (>>) = Int32.shift_right_logical
204 let (land) = Int32.logand
205 let (lor) = Int32.logor
206 let lnot = Int32.lognot
207 let pred = Int32.pred
208 let max_int = Int32.max_int
209 let to_int = Int32.to_int
210 let zero = Int32.zero
212 let minus_one = Int32.minus_one
215 (* Create a mask so many bits wide. *)
219 else if bits = 31 then
221 else if bits = 32 then
224 invalid_arg "Bitmatch.I32.mask"
226 (* Byte swap an int of a given size. *)
227 let byteswap v bits =
229 else if bits <= 16 then (
230 let shift = bits-8 in
231 let v1 = v >> shift in
232 let v2 = (v land (mask shift)) << 8 in
234 ) else if bits <= 24 then (
235 let shift = bits - 16 in
236 let v1 = v >> (8+shift) in
237 let v2 = ((v >> shift) land ff) << 8 in
238 let v3 = (v land (mask shift)) << 16 in
241 let shift = bits - 24 in
242 let v1 = v >> (16+shift) in
243 let v2 = ((v >> (8+shift)) land ff) << 8 in
244 let v3 = ((v >> shift) land ff) << 16 in
245 let v4 = (v land (mask shift)) << 24 in
246 v4 lor v3 lor v2 lor v1
249 (* Check a value is in range 0 .. 2^bits-1. *)
250 let range_unsigned v bits =
251 let mask = lnot (mask bits) in
254 (* Call function g on the top bits, then f on each full byte
255 * (big endian - so start at top).
257 let rec map_bytes_be g f v bits =
259 map_bytes_be g f (v >> 8) (bits-8);
260 let lsb = v land ff in
262 ) else if bits > 0 then (
263 let lsb = v land (mask bits) in
269 (* Bitwise operations on int64s. Note we try to keep it as similar
270 * as possible to the I/I32 modules above, to make it easier to track
273 let (<<) = Int64.shift_left
274 let (>>) = Int64.shift_right_logical
275 let (land) = Int64.logand
276 let (lor) = Int64.logor
277 let lnot = Int64.lognot
278 let pred = Int64.pred
279 let max_int = Int64.max_int
280 let to_int = Int64.to_int
281 let zero = Int64.zero
283 let minus_one = Int64.minus_one
286 (* Create a mask so many bits wide. *)
290 else if bits = 63 then
292 else if bits = 64 then
295 invalid_arg "Bitmatch.I64.mask"
297 (* Byte swap an int of a given size. *)
298 (* let byteswap v bits = *)
300 (* Check a value is in range 0 .. 2^bits-1. *)
301 let range_unsigned v bits =
302 let mask = lnot (mask bits) in
305 (* Call function g on the top bits, then f on each full byte
306 * (big endian - so start at top).
308 let rec map_bytes_be g f v bits =
310 map_bytes_be g f (v >> 8) (bits-8);
311 let lsb = v land ff in
313 ) else if bits > 0 then (
314 let lsb = v land (mask bits) in
319 (*----------------------------------------------------------------------*)
320 (* Extraction functions.
322 * NB: internal functions, called from the generated macros, and
323 * the parameters should have been checked for sanity already).
327 let extract_bitstring data off len flen =
328 (data, off, flen), off+flen, len-flen
330 let extract_remainder data off len =
331 (data, off, len), off+len, 0
333 (* Extract and convert to numeric. A single bit is returned as
334 * a boolean. There are no endianness or signedness considerations.
336 let extract_bit data off len _ = (* final param is always 1 *)
337 let byteoff = off lsr 3 in
338 let bitmask = 1 lsl (7 - (off land 7)) in
339 let b = Char.code data.[byteoff] land bitmask <> 0 in
342 (* Returns 8 bit unsigned aligned bytes from the string.
343 * If the string ends then this returns 0's.
345 let _get_byte data byteoff strlen =
346 if strlen > byteoff then Char.code data.[byteoff] else 0
347 let _get_byte32 data byteoff strlen =
348 if strlen > byteoff then Int32.of_int (Char.code data.[byteoff]) else 0l
349 let _get_byte64 data byteoff strlen =
350 if strlen > byteoff then Int64.of_int (Char.code data.[byteoff]) else 0L
352 (* Extract [2..8] bits. Because the result fits into a single
353 * byte we don't have to worry about endianness, only signedness.
355 let extract_char_unsigned data off len flen =
356 let byteoff = off lsr 3 in
358 (* Optimize the common (byte-aligned) case. *)
359 if off land 7 = 0 then (
360 let byte = Char.code data.[byteoff] in
361 byte lsr (8 - flen), off+flen, len-flen
363 (* Extract the 16 bits at byteoff and byteoff+1 (note that the
364 * second byte might not exist in the original string).
366 let strlen = String.length data in
369 (_get_byte data byteoff strlen lsl 8) +
370 _get_byte data (byteoff+1) strlen in
372 (* Mask off the top bits. *)
373 let bitmask = (1 lsl (16 - (off land 7))) - 1 in
374 let word = word land bitmask in
375 (* Shift right to get rid of the bottom bits. *)
376 let shift = 16 - ((off land 7) + flen) in
377 let word = word lsr shift in
379 word, off+flen, len-flen
382 (* Extract [9..31] bits. We have to consider endianness and signedness. *)
383 let extract_int_be_unsigned data off len flen =
384 let byteoff = off lsr 3 in
386 let strlen = String.length data in
389 (* Optimize the common (byte-aligned) case. *)
390 if off land 7 = 0 then (
392 (_get_byte data byteoff strlen lsl 23) +
393 (_get_byte data (byteoff+1) strlen lsl 15) +
394 (_get_byte data (byteoff+2) strlen lsl 7) +
395 (_get_byte data (byteoff+3) strlen lsr 1) in
397 ) else if flen <= 24 then (
398 (* Extract the 31 bits at byteoff .. byteoff+3. *)
400 (_get_byte data byteoff strlen lsl 23) +
401 (_get_byte data (byteoff+1) strlen lsl 15) +
402 (_get_byte data (byteoff+2) strlen lsl 7) +
403 (_get_byte data (byteoff+3) strlen lsr 1) in
404 (* Mask off the top bits. *)
405 let bitmask = (1 lsl (31 - (off land 7))) - 1 in
406 let word = word land bitmask in
407 (* Shift right to get rid of the bottom bits. *)
408 let shift = 31 - ((off land 7) + flen) in
411 (* Extract the next 31 bits, slow method. *)
413 let c0, off, len = extract_char_unsigned data off len 8 in
414 let c1, off, len = extract_char_unsigned data off len 8 in
415 let c2, off, len = extract_char_unsigned data off len 8 in
416 let c3, off, len = extract_char_unsigned data off len 7 in
417 (c0 lsl 23) + (c1 lsl 15) + (c2 lsl 7) + c3 in
420 word, off+flen, len-flen
422 let extract_int_le_unsigned data off len flen =
423 let v, off, len = extract_int_be_unsigned data off len flen in
424 let v = I.byteswap v flen in
427 let extract_int_ne_unsigned =
428 if nativeendian = BigEndian
429 then extract_int_be_unsigned
430 else extract_int_le_unsigned
432 let extract_int_ee_unsigned = function
433 | BigEndian -> extract_int_be_unsigned
434 | LittleEndian -> extract_int_le_unsigned
435 | NativeEndian -> extract_int_ne_unsigned
437 let _make_int32_be c0 c1 c2 c3 =
441 (Int32.shift_left c0 24)
442 (Int32.shift_left c1 16))
443 (Int32.shift_left c2 8))
446 let _make_int32_le c0 c1 c2 c3 =
450 (Int32.shift_left c3 24)
451 (Int32.shift_left c2 16))
452 (Int32.shift_left c1 8))
455 (* Extract exactly 32 bits. We have to consider endianness and signedness. *)
456 let extract_int32_be_unsigned data off len flen =
457 let byteoff = off lsr 3 in
459 let strlen = String.length data in
462 (* Optimize the common (byte-aligned) case. *)
463 if off land 7 = 0 then (
465 let c0 = _get_byte32 data byteoff strlen in
466 let c1 = _get_byte32 data (byteoff+1) strlen in
467 let c2 = _get_byte32 data (byteoff+2) strlen in
468 let c3 = _get_byte32 data (byteoff+3) strlen in
469 _make_int32_be c0 c1 c2 c3 in
470 Int32.shift_right_logical word (32 - flen)
472 (* Extract the next 32 bits, slow method. *)
474 let c0, off, len = extract_char_unsigned data off len 8 in
475 let c1, off, len = extract_char_unsigned data off len 8 in
476 let c2, off, len = extract_char_unsigned data off len 8 in
477 let c3, _, _ = extract_char_unsigned data off len 8 in
478 let c0 = Int32.of_int c0 in
479 let c1 = Int32.of_int c1 in
480 let c2 = Int32.of_int c2 in
481 let c3 = Int32.of_int c3 in
482 _make_int32_be c0 c1 c2 c3 in
483 Int32.shift_right_logical word (32 - flen)
485 word, off+flen, len-flen
487 let extract_int32_le_unsigned data off len flen =
488 let v, off, len = extract_int32_be_unsigned data off len flen in
489 let v = I32.byteswap v flen in
492 let extract_int32_ne_unsigned =
493 if nativeendian = BigEndian
494 then extract_int32_be_unsigned
495 else extract_int32_le_unsigned
497 let extract_int32_ee_unsigned = function
498 | BigEndian -> extract_int32_be_unsigned
499 | LittleEndian -> extract_int32_le_unsigned
500 | NativeEndian -> extract_int32_ne_unsigned
502 let _make_int64_be c0 c1 c2 c3 c4 c5 c6 c7 =
510 (Int64.shift_left c0 56)
511 (Int64.shift_left c1 48))
512 (Int64.shift_left c2 40))
513 (Int64.shift_left c3 32))
514 (Int64.shift_left c4 24))
515 (Int64.shift_left c5 16))
516 (Int64.shift_left c6 8))
519 let _make_int64_le c0 c1 c2 c3 c4 c5 c6 c7 =
520 _make_int64_be c7 c6 c5 c4 c3 c2 c1 c0
522 (* Extract [1..64] bits. We have to consider endianness and signedness. *)
523 let extract_int64_be_unsigned data off len flen =
524 let byteoff = off lsr 3 in
526 let strlen = String.length data in
529 (* Optimize the common (byte-aligned) case. *)
530 if off land 7 = 0 then (
532 let c0 = _get_byte64 data byteoff strlen in
533 let c1 = _get_byte64 data (byteoff+1) strlen in
534 let c2 = _get_byte64 data (byteoff+2) strlen in
535 let c3 = _get_byte64 data (byteoff+3) strlen in
536 let c4 = _get_byte64 data (byteoff+4) strlen in
537 let c5 = _get_byte64 data (byteoff+5) strlen in
538 let c6 = _get_byte64 data (byteoff+6) strlen in
539 let c7 = _get_byte64 data (byteoff+7) strlen in
540 _make_int64_be c0 c1 c2 c3 c4 c5 c6 c7 in
541 Int64.shift_right_logical word (64 - flen)
543 (* Extract the next 64 bits, slow method. *)
545 let c0, off, len = extract_char_unsigned data off len 8 in
546 let c1, off, len = extract_char_unsigned data off len 8 in
547 let c2, off, len = extract_char_unsigned data off len 8 in
548 let c3, off, len = extract_char_unsigned data off len 8 in
549 let c4, off, len = extract_char_unsigned data off len 8 in
550 let c5, off, len = extract_char_unsigned data off len 8 in
551 let c6, off, len = extract_char_unsigned data off len 8 in
552 let c7, _, _ = extract_char_unsigned data off len 8 in
553 let c0 = Int64.of_int c0 in
554 let c1 = Int64.of_int c1 in
555 let c2 = Int64.of_int c2 in
556 let c3 = Int64.of_int c3 in
557 let c4 = Int64.of_int c4 in
558 let c5 = Int64.of_int c5 in
559 let c6 = Int64.of_int c6 in
560 let c7 = Int64.of_int c7 in
561 _make_int64_be c0 c1 c2 c3 c4 c5 c6 c7 in
562 Int64.shift_right_logical word (64 - flen)
564 word, off+flen, len-flen
566 let extract_int64_le_unsigned data off len flen =
567 let byteoff = off lsr 3 in
569 let strlen = String.length data in
572 (* Optimize the common (byte-aligned) case. *)
573 if off land 7 = 0 then (
575 let c0 = _get_byte64 data byteoff strlen in
576 let c1 = _get_byte64 data (byteoff+1) strlen in
577 let c2 = _get_byte64 data (byteoff+2) strlen in
578 let c3 = _get_byte64 data (byteoff+3) strlen in
579 let c4 = _get_byte64 data (byteoff+4) strlen in
580 let c5 = _get_byte64 data (byteoff+5) strlen in
581 let c6 = _get_byte64 data (byteoff+6) strlen in
582 let c7 = _get_byte64 data (byteoff+7) strlen in
583 _make_int64_le c0 c1 c2 c3 c4 c5 c6 c7 in
584 Int64.logand word (I64.mask flen)
586 (* Extract the next 64 bits, slow method. *)
588 let c0, off, len = extract_char_unsigned data off len 8 in
589 let c1, off, len = extract_char_unsigned data off len 8 in
590 let c2, off, len = extract_char_unsigned data off len 8 in
591 let c3, off, len = extract_char_unsigned data off len 8 in
592 let c4, off, len = extract_char_unsigned data off len 8 in
593 let c5, off, len = extract_char_unsigned data off len 8 in
594 let c6, off, len = extract_char_unsigned data off len 8 in
595 let c7, _, _ = extract_char_unsigned data off len 8 in
596 let c0 = Int64.of_int c0 in
597 let c1 = Int64.of_int c1 in
598 let c2 = Int64.of_int c2 in
599 let c3 = Int64.of_int c3 in
600 let c4 = Int64.of_int c4 in
601 let c5 = Int64.of_int c5 in
602 let c6 = Int64.of_int c6 in
603 let c7 = Int64.of_int c7 in
604 _make_int64_le c0 c1 c2 c3 c4 c5 c6 c7 in
605 Int64.logand word (I64.mask flen)
607 word, off+flen, len-flen
609 let extract_int64_ne_unsigned =
610 if nativeendian = BigEndian
611 then extract_int64_be_unsigned
612 else extract_int64_le_unsigned
614 let extract_int64_ee_unsigned = function
615 | BigEndian -> extract_int64_be_unsigned
616 | LittleEndian -> extract_int64_le_unsigned
617 | NativeEndian -> extract_int64_ne_unsigned
619 (*----------------------------------------------------------------------*)
620 (* Constructor functions. *)
622 module Buffer = struct
625 mutable len : int; (* Length in bits. *)
626 (* Last byte in the buffer (if len is not aligned). We store
627 * it outside the buffer because buffers aren't mutable.
633 (* XXX We have almost enough information in the generator to
634 * choose a good initial size.
636 { buf = Buffer.create 128; len = 0; last = 0 }
638 let contents { buf = buf; len = len; last = last } =
640 if len land 7 = 0 then
643 Buffer.contents buf ^ (String.make 1 (Char.chr last)) in
646 (* Add exactly 8 bits. *)
647 let add_byte ({ buf = buf; len = len; last = last } as t) byte =
648 if byte < 0 || byte > 255 then invalid_arg "Bitmatch.Buffer.add_byte";
649 let shift = len land 7 in
651 (* Target buffer is byte-aligned. *)
652 Buffer.add_char buf (Char.chr byte)
654 (* Target buffer is unaligned. 'last' is meaningful. *)
655 let first = byte lsr shift in
656 let second = (byte lsl (8 - shift)) land 0xff in
657 Buffer.add_char buf (Char.chr (last lor first));
662 (* Add exactly 1 bit. *)
663 let add_bit ({ buf = buf; len = len; last = last } as t) bit =
664 let shift = 7 - (len land 7) in
666 (* Somewhere in the middle of 'last'. *)
667 t.last <- last lor ((if bit then 1 else 0) lsl shift)
669 (* Just a single spare bit in 'last'. *)
670 let last = last lor if bit then 1 else 0 in
671 Buffer.add_char buf (Char.chr last);
676 (* Add a small number of bits (definitely < 8). This uses a loop
677 * to call add_bit so it's slow.
679 let _add_bits t c slen =
680 if slen < 1 || slen >= 8 then invalid_arg "Bitmatch.Buffer._add_bits";
681 for i = slen-1 downto 0 do
682 let bit = c land (1 lsl i) <> 0 in
686 let add_bits ({ buf = buf; len = len } as t) str slen =
688 if len land 7 = 0 then (
689 if slen land 7 = 0 then
690 (* Common case - everything is byte-aligned. *)
691 Buffer.add_substring buf str 0 (slen lsr 3)
693 (* Target buffer is aligned. Copy whole bytes then leave the
694 * remaining bits in last.
696 let slenbytes = slen lsr 3 in
697 if slenbytes > 0 then Buffer.add_substring buf str 0 slenbytes;
698 let last = Char.code str.[slenbytes] in (* last char *)
699 let mask = 0xff lsl (8 - (slen land 7)) in
700 t.last <- last land mask
704 (* Target buffer is unaligned. Copy whole bytes using
705 * add_byte which knows how to deal with an unaligned
706 * target buffer, then call add_bit for the remaining < 8 bits.
708 * XXX This is going to be dog-slow.
710 let slenbytes = slen lsr 3 in
711 for i = 0 to slenbytes-1 do
712 let byte = Char.code str.[i] in
715 let bitsleft = slen - (slenbytes lsl 3) in
716 if bitsleft > 0 then (
717 let c = Char.code str.[slenbytes] in
718 for i = 0 to bitsleft - 1 do
719 let bit = c land (0x80 lsr i) <> 0 in
727 (* Construct a single bit. *)
728 let construct_bit buf b _ _ =
731 (* Construct a field, flen = [2..8]. *)
732 let construct_char_unsigned buf v flen exn =
733 let max_val = 1 lsl flen in
734 if v < 0 || v >= max_val then raise exn;
736 Buffer.add_byte buf v
738 Buffer._add_bits buf v flen
740 (* Construct a field of up to 31 bits. *)
741 let construct_int_be_unsigned buf v flen exn =
742 (* Check value is within range. *)
743 if not (I.range_unsigned v flen) then raise exn;
745 I.map_bytes_be (Buffer._add_bits buf) (Buffer.add_byte buf) v flen
747 let construct_int_ne_unsigned =
748 if nativeendian = BigEndian
749 then construct_int_be_unsigned
750 else (*construct_int_le_unsigned*)
751 fun _ _ _ _ -> failwith "construct_int_le_unsigned"
753 let construct_int_ee_unsigned = function
754 | BigEndian -> construct_int_be_unsigned
755 | LittleEndian -> (*construct_int_le_unsigned*)
756 (fun _ _ _ _ -> failwith "construct_int_le_unsigned")
757 | NativeEndian -> construct_int_ne_unsigned
759 (* Construct a field of exactly 32 bits. *)
760 let construct_int32_be_unsigned buf v flen _ =
762 (Int32.to_int (Int32.shift_right_logical v 24));
764 (Int32.to_int ((Int32.logand (Int32.shift_right_logical v 16) 0xff_l)));
766 (Int32.to_int ((Int32.logand (Int32.shift_right_logical v 8) 0xff_l)));
768 (Int32.to_int (Int32.logand v 0xff_l))
770 let construct_int32_le_unsigned buf v flen _ =
772 (Int32.to_int (Int32.logand v 0xff_l));
774 (Int32.to_int ((Int32.logand (Int32.shift_right_logical v 8) 0xff_l)));
776 (Int32.to_int ((Int32.logand (Int32.shift_right_logical v 16) 0xff_l)));
778 (Int32.to_int (Int32.shift_right_logical v 24))
780 let construct_int32_ne_unsigned =
781 if nativeendian = BigEndian
782 then construct_int32_be_unsigned
783 else construct_int32_le_unsigned
785 let construct_int32_ee_unsigned = function
786 | BigEndian -> construct_int32_be_unsigned
787 | LittleEndian -> construct_int32_le_unsigned
788 | NativeEndian -> construct_int32_ne_unsigned
790 (* Construct a field of up to 64 bits. *)
791 let construct_int64_be_unsigned buf v flen exn =
792 (* Check value is within range. *)
793 if not (I64.range_unsigned v flen) then raise exn;
795 I64.map_bytes_be (Buffer._add_bits buf) (Buffer.add_byte buf) v flen
797 let construct_int64_ne_unsigned =
798 if nativeendian = BigEndian
799 then construct_int64_be_unsigned
800 else (*construct_int64_le_unsigned*)
801 fun _ _ _ _ -> failwith "construct_int64_le_unsigned"
803 let construct_int64_ee_unsigned = function
804 | BigEndian -> construct_int64_be_unsigned
805 | LittleEndian -> (*construct_int64_le_unsigned*)
806 (fun _ _ _ _ -> failwith "construct_int64_le_unsigned")
807 | NativeEndian -> construct_int64_ne_unsigned
809 (* Construct from a string of bytes, exact multiple of 8 bits
810 * in length of course.
812 let construct_string buf str =
813 let len = String.length str in
814 Buffer.add_bits buf str (len lsl 3)
816 (* Construct from a bitstring. *)
817 let construct_bitstring buf (data, off, len) =
818 (* Add individual bits until we get to the next byte boundary of
819 * the underlying string.
821 let blen = 7 - ((off + 7) land 7) in
822 let blen = min blen len in
823 let rec loop off len blen =
824 if blen = 0 then (off, len)
826 let b, off, len = extract_bit data off len 1 in
827 Buffer.add_bit buf b;
828 loop off len (blen-1)
831 let off, len = loop off len blen in
832 assert (len = 0 || (off land 7) = 0);
834 (* Add the remaining 'len' bits. *)
836 let off = off lsr 3 in
837 (* XXX dangerous allocation *)
839 else String.sub data off (String.length data - off) in
841 Buffer.add_bits buf data len
843 (*----------------------------------------------------------------------*)
844 (* Extract a string from a bitstring. *)
846 let string_of_bitstring (data, off, len) =
847 if off land 7 = 0 && len land 7 = 0 then
848 (* Easy case: everything is byte-aligned. *)
849 String.sub data (off lsr 3) (len lsr 3)
851 (* Bit-twiddling case. *)
852 let strlen = (len + 7) lsr 3 in
853 let str = String.make strlen '\000' in
854 let rec loop data off len i =
856 let c, off, len = extract_char_unsigned data off len 8 in
857 str.[i] <- Char.chr c;
858 loop data off len (i+1)
859 ) else if len > 0 then (
860 let c, _, _ = extract_char_unsigned data off len len in
861 str.[i] <- Char.chr (c lsl (8-len))
870 let bitstring_to_chan ((data, off, len) as bits) chan =
871 (* Fail if the bitstring length isn't a multiple of 8. *)
872 if len land 7 <> 0 then invalid_arg "bitstring_to_chan";
874 if off land 7 = 0 then
875 (* Easy case: string is byte-aligned. *)
876 output chan data (off lsr 3) (len lsr 3)
878 (* Bit-twiddling case: reuse string_of_bitstring *)
879 let str = string_of_bitstring bits in
880 output_string chan str
883 let bitstring_to_file bits filename =
884 let chan = open_out_bin filename in
886 bitstring_to_chan bits chan;
892 (*----------------------------------------------------------------------*)
893 (* Display functions. *)
896 let c = Char.code c in
899 let hexdump_bitstring chan (data, off, len) =
903 let linelen = ref 0 in
904 let linechars = String.make 16 ' ' in
906 fprintf chan "00000000 ";
909 let bits = min !len 8 in
910 let byte, off', len' = extract_char_unsigned data !off !len bits in
911 off := off'; len := len';
913 let byte = byte lsl (8-bits) in
914 fprintf chan "%02x " byte;
917 linechars.[!linelen] <-
918 (let c = Char.chr byte in
919 if isprint c then c else '.');
921 if !linelen = 8 then fprintf chan " ";
922 if !linelen = 16 then (
923 fprintf chan " |%s|\n%08x " linechars !count;
925 for i = 0 to 15 do linechars.[i] <- ' ' done
929 if !linelen > 0 then (
930 let skip = (16 - !linelen) * 3 + if !linelen < 8 then 1 else 0 in
931 for i = 0 to skip-1 do fprintf chan " " done;
932 fprintf chan " |%s|\n%!" linechars