1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2014, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
18 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
30 ------------------------------------------------------------------------------
32 with Debug; use Debug;
33 with Output; use Output;
34 with Unchecked_Conversion;
36 package body Tree_IO is
37 Debug_Flag_Tree : Boolean := False;
38 -- Debug flag for debug output from tree read/write
40 -------------------------------------------
41 -- Compression Scheme Used for Tree File --
42 -------------------------------------------
44 -- We don't just write the data directly, but instead do a mild form
45 -- of compression, since we expect lots of compressible zeroes and
46 -- blanks. The compression scheme is as follows:
48 -- 00nnnnnn followed by nnnnnn bytes (non compressed data)
49 -- 01nnnnnn indicates nnnnnn binary zero bytes
50 -- 10nnnnnn indicates nnnnnn ASCII space bytes
51 -- 11nnnnnn bbbbbbbb indicates nnnnnnnn occurrences of byte bbbbbbbb
53 -- Since we expect many zeroes in trees, and many spaces in sources,
54 -- this compression should be reasonably efficient. We can put in
55 -- something better later on.
57 -- Note that this compression applies to the Write_Tree_Data and
58 -- Read_Tree_Data calls, not to the calls to read and write single
59 -- scalar values, which are written in memory format without any
62 C_Noncomp : constant := 2#00_000000#;
63 C_Zeros : constant := 2#01_000000#;
64 C_Spaces : constant := 2#10_000000#;
65 C_Repeat : constant := 2#11_000000#;
66 -- Codes for compression sequences
68 Max_Count : constant := 63;
69 -- Maximum data length for one compression sequence
71 -- The above compression scheme applies only to data written with the
72 -- Tree_Write routine and read with Tree_Read. Data written using the
73 -- Tree_Write_Char or Tree_Write_Int routines and read using the
74 -- corresponding input routines is not compressed.
76 type Int_Bytes is array (1 .. 4) of Byte;
77 for Int_Bytes'Size use 32;
79 function To_Int_Bytes is new Unchecked_Conversion (Int, Int_Bytes);
80 function To_Int is new Unchecked_Conversion (Int_Bytes, Int);
82 ----------------------
83 -- Global Variables --
84 ----------------------
86 Tree_FD : File_Descriptor;
87 -- File descriptor for tree
89 Buflen : constant Int := 8_192;
90 -- Length of buffer for read and write file data
92 Buf : array (Pos range 1 .. Buflen) of Byte;
93 -- Read/write file data buffer
96 -- Number of bytes read/written from/to buffer
99 -- Total number of bytes in input buffer containing valid data. Used only
100 -- for input operations. There is data left to be processed in the buffer
101 -- if Buft > Bufn. A value of zero for Buft means that the buffer is empty.
103 -----------------------
104 -- Local Subprograms --
105 -----------------------
107 procedure Read_Buffer;
108 -- Reads data into buffer, setting Bufn appropriately
110 function Read_Byte return Byte;
111 pragma Inline (Read_Byte);
112 -- Returns next byte from input file, raises Tree_Format_Error if none left
114 procedure Write_Buffer;
115 -- Writes out current buffer contents
117 procedure Write_Byte (B : Byte);
118 pragma Inline (Write_Byte);
119 -- Write one byte to output buffer, checking for buffer-full condition
125 procedure Read_Buffer is
127 Buft := Int (Read (Tree_FD, Buf (1)'Address, Integer (Buflen)));
130 raise Tree_Format_Error;
140 function Read_Byte return Byte is
154 procedure Tree_Read_Bool (B : out Boolean) is
156 B := Boolean'Val (Read_Byte);
158 if Debug_Flag_Tree then
173 procedure Tree_Read_Char (C : out Character) is
175 C := Character'Val (Read_Byte);
177 if Debug_Flag_Tree then
178 Write_Str ("==> transmitting Character = ");
188 procedure Tree_Read_Data (Addr : Address; Length : Int) is
190 type S is array (Pos) of Byte;
191 -- This is a big array, for which we have to suppress the warning
193 type SP is access all S;
195 function To_SP is new Unchecked_Conversion (Address, SP);
197 Data : constant SP := To_SP (Addr);
198 -- Data buffer to be read as an indexable array of bytes
201 -- Pointer to next byte of data buffer to be read into
208 if Debug_Flag_Tree then
209 Write_Str ("==> transmitting ");
211 Write_Str (" data bytes");
215 -- Verify data length
220 Write_Str ("==> transmitting, expected ");
222 Write_Str (" bytes, found length = ");
225 raise Tree_Format_Error;
230 while OP <= Length loop
232 -- Get compression control character
235 C := B and 2#00_111111#;
236 B := B and 2#11_000000#;
240 if B = C_Noncomp then
241 if Debug_Flag_Tree then
242 Write_Str ("==> uncompressed: ");
244 Write_Str (", starting at ");
250 Data (OP) := Read_Byte;
256 elsif B = C_Zeros then
257 if Debug_Flag_Tree then
258 Write_Str ("==> zeroes: ");
260 Write_Str (", starting at ");
272 elsif B = C_Spaces then
273 if Debug_Flag_Tree then
274 Write_Str ("==> spaces: ");
276 Write_Str (", starting at ");
282 Data (OP) := Character'Pos (' ');
286 -- Specified repeated character
291 if Debug_Flag_Tree then
292 Write_Str ("==> other char: ");
297 Write_Str (", starting at ");
309 -- At end of loop, data item must be exactly filled
311 if OP /= Length + 1 then
312 raise Tree_Format_Error;
317 --------------------------
318 -- Tree_Read_Initialize --
319 --------------------------
321 procedure Tree_Read_Initialize (Desc : File_Descriptor) is
326 Debug_Flag_Tree := Debug_Flag_5;
327 end Tree_Read_Initialize;
333 procedure Tree_Read_Int (N : out Int) is
338 N_Bytes (J) := Read_Byte;
341 N := To_Int (N_Bytes);
343 if Debug_Flag_Tree then
344 Write_Str ("==> transmitting Int = ");
354 procedure Tree_Read_Str (S : out String_Ptr) is
359 S := new String (1 .. Natural (N));
360 Tree_Read_Data (S.all (1)'Address, N);
363 -------------------------
364 -- Tree_Read_Terminate --
365 -------------------------
367 procedure Tree_Read_Terminate is
369 -- Must be at end of input buffer, so we should get Tree_Format_Error
370 -- if we try to read one more byte, if not, we have a format error.
374 pragma Warnings (Off, B);
380 when Tree_Format_Error => return;
383 raise Tree_Format_Error;
384 end Tree_Read_Terminate;
386 ---------------------
387 -- Tree_Write_Bool --
388 ---------------------
390 procedure Tree_Write_Bool (B : Boolean) is
392 if Debug_Flag_Tree then
393 Write_Str ("==> transmitting Boolean = ");
404 Write_Byte (Boolean'Pos (B));
407 ---------------------
408 -- Tree_Write_Char --
409 ---------------------
411 procedure Tree_Write_Char (C : Character) is
413 if Debug_Flag_Tree then
414 Write_Str ("==> transmitting Character = ");
419 Write_Byte (Character'Pos (C));
422 ---------------------
423 -- Tree_Write_Data --
424 ---------------------
426 procedure Tree_Write_Data (Addr : Address; Length : Int) is
428 type S is array (Pos) of Byte;
429 -- This is a big array, for which we have to suppress the warning
431 type SP is access all S;
433 function To_SP is new Unchecked_Conversion (Address, SP);
435 Data : constant SP := To_SP (Addr);
436 -- Pointer to data to be written, converted to array type
439 -- Input buffer pointer, next byte to be processed
441 NC : Nat range 0 .. Max_Count := 0;
442 -- Number of bytes of non-compressible sequence
446 procedure Write_Non_Compressed_Sequence;
447 -- Output currently collected sequence of non-compressible data
449 -----------------------------------
450 -- Write_Non_Compressed_Sequence --
451 -----------------------------------
453 procedure Write_Non_Compressed_Sequence is
456 Write_Byte (C_Noncomp + Byte (NC));
458 if Debug_Flag_Tree then
459 Write_Str ("==> uncompressed: ");
461 Write_Str (", starting at ");
466 for J in reverse 1 .. NC loop
467 Write_Byte (Data (IP - J));
472 end Write_Non_Compressed_Sequence;
474 -- Start of processing for Tree_Write_Data
477 if Debug_Flag_Tree then
478 Write_Str ("==> transmitting ");
480 Write_Str (" data bytes");
484 -- We write the count at the start, so that we can check it on
485 -- the corresponding read to make sure that reads and writes match
487 Tree_Write_Int (Length);
490 -- IP is index of next input character
491 -- NC is number of non-compressible bytes saved up
494 -- If input is completely processed, then we are all done
497 Write_Non_Compressed_Sequence;
501 -- Test for compressible sequence, must be at least three identical
502 -- bytes in a row to be worthwhile compressing.
505 and then Data (IP) = Data (IP + 1)
506 and then Data (IP) = Data (IP + 2)
508 Write_Non_Compressed_Sequence;
510 -- Count length of new compression sequence
516 and then Data (IP) = Data (IP - 1)
517 and then C < Max_Count
523 -- Output compression sequence
525 if Data (IP - 1) = 0 then
526 if Debug_Flag_Tree then
527 Write_Str ("==> zeroes: ");
529 Write_Str (", starting at ");
530 Write_Int (IP - Int (C));
534 Write_Byte (C_Zeros + C);
536 elsif Data (IP - 1) = Character'Pos (' ') then
537 if Debug_Flag_Tree then
538 Write_Str ("==> spaces: ");
540 Write_Str (", starting at ");
541 Write_Int (IP - Int (C));
545 Write_Byte (C_Spaces + C);
548 if Debug_Flag_Tree then
549 Write_Str ("==> other char: ");
552 Write_Int (Int (Data (IP - 1)));
554 Write_Str (", starting at ");
555 Write_Int (IP - Int (C));
559 Write_Byte (C_Repeat + C);
560 Write_Byte (Data (IP - 1));
563 -- No compression possible here
566 -- Output non-compressed sequence if at maximum length
568 if NC = Max_Count then
569 Write_Non_Compressed_Sequence;
579 ---------------------------
580 -- Tree_Write_Initialize --
581 ---------------------------
583 procedure Tree_Write_Initialize (Desc : File_Descriptor) is
588 Debug_Flag_Tree := Debug_Flag_5;
589 end Tree_Write_Initialize;
595 procedure Tree_Write_Int (N : Int) is
596 N_Bytes : constant Int_Bytes := To_Int_Bytes (N);
599 if Debug_Flag_Tree then
600 Write_Str ("==> transmitting Int = ");
606 Write_Byte (N_Bytes (J));
614 procedure Tree_Write_Str (S : String_Ptr) is
616 Tree_Write_Int (S'Length);
617 Tree_Write_Data (S (1)'Address, S'Length);
620 --------------------------
621 -- Tree_Write_Terminate --
622 --------------------------
624 procedure Tree_Write_Terminate is
629 end Tree_Write_Terminate;
635 procedure Write_Buffer is
637 if Integer (Bufn) = Write (Tree_FD, Buf'Address, Integer (Bufn)) then
642 Write_Str ("fatal error: disk full");
651 procedure Write_Byte (B : Byte) is
656 if Bufn = Buflen then