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+------------------------------------------------------------------------------
+-- --
+-- GNAT COMPILER COMPONENTS --
+-- --
+-- T R E E _ I O --
+-- --
+-- B o d y --
+-- --
+-- Copyright (C) 1992-2009 Free Software Foundation, Inc. --
+-- --
+-- GNAT is free software; you can redistribute it and/or modify it under --
+-- terms of the GNU General Public License as published by the Free Soft- --
+-- ware Foundation; either version 3, or (at your option) any later ver- --
+-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
+-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
+-- or FITNESS FOR A PARTICULAR PURPOSE. --
+-- --
+-- As a special exception under Section 7 of GPL version 3, you are granted --
+-- additional permissions described in the GCC Runtime Library Exception, --
+-- version 3.1, as published by the Free Software Foundation. --
+-- --
+-- You should have received a copy of the GNU General Public License and --
+-- a copy of the GCC Runtime Library Exception along with this program; --
+-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
+-- <http://www.gnu.org/licenses/>. --
+-- --
+-- GNAT was originally developed by the GNAT team at New York University. --
+-- Extensive contributions were provided by Ada Core Technologies Inc. --
+-- --
+------------------------------------------------------------------------------
+
+with Debug; use Debug;
+with Output; use Output;
+with Unchecked_Conversion;
+
+package body Tree_IO is
+ Debug_Flag_Tree : Boolean := False;
+ -- Debug flag for debug output from tree read/write
+
+ -------------------------------------------
+ -- Compression Scheme Used for Tree File --
+ -------------------------------------------
+
+ -- We don't just write the data directly, but instead do a mild form
+ -- of compression, since we expect lots of compressible zeroes and
+ -- blanks. The compression scheme is as follows:
+
+ -- 00nnnnnn followed by nnnnnn bytes (non compressed data)
+ -- 01nnnnnn indicates nnnnnn binary zero bytes
+ -- 10nnnnnn indicates nnnnnn ASCII space bytes
+ -- 11nnnnnn bbbbbbbb indicates nnnnnnnn occurrences of byte bbbbbbbb
+
+ -- Since we expect many zeroes in trees, and many spaces in sources,
+ -- this compression should be reasonably efficient. We can put in
+ -- something better later on.
+
+ -- Note that this compression applies to the Write_Tree_Data and
+ -- Read_Tree_Data calls, not to the calls to read and write single
+ -- scalar values, which are written in memory format without any
+ -- compression.
+
+ C_Noncomp : constant := 2#00_000000#;
+ C_Zeros : constant := 2#01_000000#;
+ C_Spaces : constant := 2#10_000000#;
+ C_Repeat : constant := 2#11_000000#;
+ -- Codes for compression sequences
+
+ Max_Count : constant := 63;
+ -- Maximum data length for one compression sequence
+
+ -- The above compression scheme applies only to data written with the
+ -- Tree_Write routine and read with Tree_Read. Data written using the
+ -- Tree_Write_Char or Tree_Write_Int routines and read using the
+ -- corresponding input routines is not compressed.
+
+ type Int_Bytes is array (1 .. 4) of Byte;
+ for Int_Bytes'Size use 32;
+
+ function To_Int_Bytes is new Unchecked_Conversion (Int, Int_Bytes);
+ function To_Int is new Unchecked_Conversion (Int_Bytes, Int);
+
+ ----------------------
+ -- Global Variables --
+ ----------------------
+
+ Tree_FD : File_Descriptor;
+ -- File descriptor for tree
+
+ Buflen : constant Int := 8_192;
+ -- Length of buffer for read and write file data
+
+ Buf : array (Pos range 1 .. Buflen) of Byte;
+ -- Read/write file data buffer
+
+ Bufn : Nat;
+ -- Number of bytes read/written from/to buffer
+
+ Buft : Nat;
+ -- Total number of bytes in input buffer containing valid data. Used only
+ -- for input operations. There is data left to be processed in the buffer
+ -- if Buft > Bufn. A value of zero for Buft means that the buffer is empty.
+
+ -----------------------
+ -- Local Subprograms --
+ -----------------------
+
+ procedure Read_Buffer;
+ -- Reads data into buffer, setting Bufn appropriately
+
+ function Read_Byte return Byte;
+ pragma Inline (Read_Byte);
+ -- Returns next byte from input file, raises Tree_Format_Error if none left
+
+ procedure Write_Buffer;
+ -- Writes out current buffer contents
+
+ procedure Write_Byte (B : Byte);
+ pragma Inline (Write_Byte);
+ -- Write one byte to output buffer, checking for buffer-full condition
+
+ -----------------
+ -- Read_Buffer --
+ -----------------
+
+ procedure Read_Buffer is
+ begin
+ Buft := Int (Read (Tree_FD, Buf (1)'Address, Integer (Buflen)));
+
+ if Buft = 0 then
+ raise Tree_Format_Error;
+ else
+ Bufn := 0;
+ end if;
+ end Read_Buffer;
+
+ ---------------
+ -- Read_Byte --
+ ---------------
+
+ function Read_Byte return Byte is
+ begin
+ if Bufn = Buft then
+ Read_Buffer;
+ end if;
+
+ Bufn := Bufn + 1;
+ return Buf (Bufn);
+ end Read_Byte;
+
+ --------------------
+ -- Tree_Read_Bool --
+ --------------------
+
+ procedure Tree_Read_Bool (B : out Boolean) is
+ begin
+ B := Boolean'Val (Read_Byte);
+
+ if Debug_Flag_Tree then
+ if B then
+ Write_Str ("True");
+ else
+ Write_Str ("False");
+ end if;
+
+ Write_Eol;
+ end if;
+ end Tree_Read_Bool;
+
+ --------------------
+ -- Tree_Read_Char --
+ --------------------
+
+ procedure Tree_Read_Char (C : out Character) is
+ begin
+ C := Character'Val (Read_Byte);
+
+ if Debug_Flag_Tree then
+ Write_Str ("==> transmitting Character = ");
+ Write_Char (C);
+ Write_Eol;
+ end if;
+ end Tree_Read_Char;
+
+ --------------------
+ -- Tree_Read_Data --
+ --------------------
+
+ procedure Tree_Read_Data (Addr : Address; Length : Int) is
+
+ type S is array (Pos) of Byte;
+ -- This is a big array, for which we have to suppress the warning
+
+ type SP is access all S;
+
+ function To_SP is new Unchecked_Conversion (Address, SP);
+
+ Data : constant SP := To_SP (Addr);
+ -- Data buffer to be read as an indexable array of bytes
+
+ OP : Pos := 1;
+ -- Pointer to next byte of data buffer to be read into
+
+ B : Byte;
+ C : Byte;
+ L : Int;
+
+ begin
+ if Debug_Flag_Tree then
+ Write_Str ("==> transmitting ");
+ Write_Int (Length);
+ Write_Str (" data bytes");
+ Write_Eol;
+ end if;
+
+ -- Verify data length
+
+ Tree_Read_Int (L);
+
+ if L /= Length then
+ Write_Str ("==> transmitting, expected ");
+ Write_Int (Length);
+ Write_Str (" bytes, found length = ");
+ Write_Int (L);
+ Write_Eol;
+ raise Tree_Format_Error;
+ end if;
+
+ -- Loop to read data
+
+ while OP <= Length loop
+
+ -- Get compression control character
+
+ B := Read_Byte;
+ C := B and 2#00_111111#;
+ B := B and 2#11_000000#;
+
+ -- Non-repeat case
+
+ if B = C_Noncomp then
+ if Debug_Flag_Tree then
+ Write_Str ("==> uncompressed: ");
+ Write_Int (Int (C));
+ Write_Str (", starting at ");
+ Write_Int (OP);
+ Write_Eol;
+ end if;
+
+ for J in 1 .. C loop
+ Data (OP) := Read_Byte;
+ OP := OP + 1;
+ end loop;
+
+ -- Repeated zeroes
+
+ elsif B = C_Zeros then
+ if Debug_Flag_Tree then
+ Write_Str ("==> zeroes: ");
+ Write_Int (Int (C));
+ Write_Str (", starting at ");
+ Write_Int (OP);
+ Write_Eol;
+ end if;
+
+ for J in 1 .. C loop
+ Data (OP) := 0;
+ OP := OP + 1;
+ end loop;
+
+ -- Repeated spaces
+
+ elsif B = C_Spaces then
+ if Debug_Flag_Tree then
+ Write_Str ("==> spaces: ");
+ Write_Int (Int (C));
+ Write_Str (", starting at ");
+ Write_Int (OP);
+ Write_Eol;
+ end if;
+
+ for J in 1 .. C loop
+ Data (OP) := Character'Pos (' ');
+ OP := OP + 1;
+ end loop;
+
+ -- Specified repeated character
+
+ else -- B = C_Repeat
+ B := Read_Byte;
+
+ if Debug_Flag_Tree then
+ Write_Str ("==> other char: ");
+ Write_Int (Int (C));
+ Write_Str (" (");
+ Write_Int (Int (B));
+ Write_Char (')');
+ Write_Str (", starting at ");
+ Write_Int (OP);
+ Write_Eol;
+ end if;
+
+ for J in 1 .. C loop
+ Data (OP) := B;
+ OP := OP + 1;
+ end loop;
+ end if;
+ end loop;
+
+ -- At end of loop, data item must be exactly filled
+
+ if OP /= Length + 1 then
+ raise Tree_Format_Error;
+ end if;
+
+ end Tree_Read_Data;
+
+ --------------------------
+ -- Tree_Read_Initialize --
+ --------------------------
+
+ procedure Tree_Read_Initialize (Desc : File_Descriptor) is
+ begin
+ Buft := 0;
+ Bufn := 0;
+ Tree_FD := Desc;
+ Debug_Flag_Tree := Debug_Flag_5;
+ end Tree_Read_Initialize;
+
+ -------------------
+ -- Tree_Read_Int --
+ -------------------
+
+ procedure Tree_Read_Int (N : out Int) is
+ N_Bytes : Int_Bytes;
+
+ begin
+ for J in 1 .. 4 loop
+ N_Bytes (J) := Read_Byte;
+ end loop;
+
+ N := To_Int (N_Bytes);
+
+ if Debug_Flag_Tree then
+ Write_Str ("==> transmitting Int = ");
+ Write_Int (N);
+ Write_Eol;
+ end if;
+ end Tree_Read_Int;
+
+ -------------------
+ -- Tree_Read_Str --
+ -------------------
+
+ procedure Tree_Read_Str (S : out String_Ptr) is
+ N : Nat;
+
+ begin
+ Tree_Read_Int (N);
+ S := new String (1 .. Natural (N));
+ Tree_Read_Data (S.all (1)'Address, N);
+ end Tree_Read_Str;
+
+ -------------------------
+ -- Tree_Read_Terminate --
+ -------------------------
+
+ procedure Tree_Read_Terminate is
+ begin
+ -- Must be at end of input buffer, so we should get Tree_Format_Error
+ -- if we try to read one more byte, if not, we have a format error.
+
+ declare
+ B : Byte;
+ pragma Warnings (Off, B);
+
+ begin
+ B := Read_Byte;
+
+ exception
+ when Tree_Format_Error => return;
+ end;
+
+ raise Tree_Format_Error;
+ end Tree_Read_Terminate;
+
+ ---------------------
+ -- Tree_Write_Bool --
+ ---------------------
+
+ procedure Tree_Write_Bool (B : Boolean) is
+ begin
+ if Debug_Flag_Tree then
+ Write_Str ("==> transmitting Boolean = ");
+
+ if B then
+ Write_Str ("True");
+ else
+ Write_Str ("False");
+ end if;
+
+ Write_Eol;
+ end if;
+
+ Write_Byte (Boolean'Pos (B));
+ end Tree_Write_Bool;
+
+ ---------------------
+ -- Tree_Write_Char --
+ ---------------------
+
+ procedure Tree_Write_Char (C : Character) is
+ begin
+ if Debug_Flag_Tree then
+ Write_Str ("==> transmitting Character = ");
+ Write_Char (C);
+ Write_Eol;
+ end if;
+
+ Write_Byte (Character'Pos (C));
+ end Tree_Write_Char;
+
+ ---------------------
+ -- Tree_Write_Data --
+ ---------------------
+
+ procedure Tree_Write_Data (Addr : Address; Length : Int) is
+
+ type S is array (Pos) of Byte;
+ -- This is a big array, for which we have to suppress the warning
+
+ type SP is access all S;
+
+ function To_SP is new Unchecked_Conversion (Address, SP);
+
+ Data : constant SP := To_SP (Addr);
+ -- Pointer to data to be written, converted to array type
+
+ IP : Pos := 1;
+ -- Input buffer pointer, next byte to be processed
+
+ NC : Nat range 0 .. Max_Count := 0;
+ -- Number of bytes of non-compressible sequence
+
+ C : Byte;
+
+ procedure Write_Non_Compressed_Sequence;
+ -- Output currently collected sequence of non-compressible data
+
+ -----------------------------------
+ -- Write_Non_Compressed_Sequence --
+ -----------------------------------
+
+ procedure Write_Non_Compressed_Sequence is
+ begin
+ if NC > 0 then
+ Write_Byte (C_Noncomp + Byte (NC));
+
+ if Debug_Flag_Tree then
+ Write_Str ("==> uncompressed: ");
+ Write_Int (NC);
+ Write_Str (", starting at ");
+ Write_Int (IP - NC);
+ Write_Eol;
+ end if;
+
+ for J in reverse 1 .. NC loop
+ Write_Byte (Data (IP - J));
+ end loop;
+
+ NC := 0;
+ end if;
+ end Write_Non_Compressed_Sequence;
+
+ -- Start of processing for Tree_Write_Data
+
+ begin
+ if Debug_Flag_Tree then
+ Write_Str ("==> transmitting ");
+ Write_Int (Length);
+ Write_Str (" data bytes");
+ Write_Eol;
+ end if;
+
+ -- We write the count at the start, so that we can check it on
+ -- the corresponding read to make sure that reads and writes match
+
+ Tree_Write_Int (Length);
+
+ -- Conversion loop
+ -- IP is index of next input character
+ -- NC is number of non-compressible bytes saved up
+
+ loop
+ -- If input is completely processed, then we are all done
+
+ if IP > Length then
+ Write_Non_Compressed_Sequence;
+ return;
+ end if;
+
+ -- Test for compressible sequence, must be at least three identical
+ -- bytes in a row to be worthwhile compressing.
+
+ if IP + 2 <= Length
+ and then Data (IP) = Data (IP + 1)
+ and then Data (IP) = Data (IP + 2)
+ then
+ Write_Non_Compressed_Sequence;
+
+ -- Count length of new compression sequence
+
+ C := 3;
+ IP := IP + 3;
+
+ while IP < Length
+ and then Data (IP) = Data (IP - 1)
+ and then C < Max_Count
+ loop
+ C := C + 1;
+ IP := IP + 1;
+ end loop;
+
+ -- Output compression sequence
+
+ if Data (IP - 1) = 0 then
+ if Debug_Flag_Tree then
+ Write_Str ("==> zeroes: ");
+ Write_Int (Int (C));
+ Write_Str (", starting at ");
+ Write_Int (IP - Int (C));
+ Write_Eol;
+ end if;
+
+ Write_Byte (C_Zeros + C);
+
+ elsif Data (IP - 1) = Character'Pos (' ') then
+ if Debug_Flag_Tree then
+ Write_Str ("==> spaces: ");
+ Write_Int (Int (C));
+ Write_Str (", starting at ");
+ Write_Int (IP - Int (C));
+ Write_Eol;
+ end if;
+
+ Write_Byte (C_Spaces + C);
+
+ else
+ if Debug_Flag_Tree then
+ Write_Str ("==> other char: ");
+ Write_Int (Int (C));
+ Write_Str (" (");
+ Write_Int (Int (Data (IP - 1)));
+ Write_Char (')');
+ Write_Str (", starting at ");
+ Write_Int (IP - Int (C));
+ Write_Eol;
+ end if;
+
+ Write_Byte (C_Repeat + C);
+ Write_Byte (Data (IP - 1));
+ end if;
+
+ -- No compression possible here
+
+ else
+ -- Output non-compressed sequence if at maximum length
+
+ if NC = Max_Count then
+ Write_Non_Compressed_Sequence;
+ end if;
+
+ NC := NC + 1;
+ IP := IP + 1;
+ end if;
+ end loop;
+
+ end Tree_Write_Data;
+
+ ---------------------------
+ -- Tree_Write_Initialize --
+ ---------------------------
+
+ procedure Tree_Write_Initialize (Desc : File_Descriptor) is
+ begin
+ Bufn := 0;
+ Tree_FD := Desc;
+ Set_Standard_Error;
+ Debug_Flag_Tree := Debug_Flag_5;
+ end Tree_Write_Initialize;
+
+ --------------------
+ -- Tree_Write_Int --
+ --------------------
+
+ procedure Tree_Write_Int (N : Int) is
+ N_Bytes : constant Int_Bytes := To_Int_Bytes (N);
+
+ begin
+ if Debug_Flag_Tree then
+ Write_Str ("==> transmitting Int = ");
+ Write_Int (N);
+ Write_Eol;
+ end if;
+
+ for J in 1 .. 4 loop
+ Write_Byte (N_Bytes (J));
+ end loop;
+ end Tree_Write_Int;
+
+ --------------------
+ -- Tree_Write_Str --
+ --------------------
+
+ procedure Tree_Write_Str (S : String_Ptr) is
+ begin
+ Tree_Write_Int (S'Length);
+ Tree_Write_Data (S (1)'Address, S'Length);
+ end Tree_Write_Str;
+
+ --------------------------
+ -- Tree_Write_Terminate --
+ --------------------------
+
+ procedure Tree_Write_Terminate is
+ begin
+ if Bufn > 0 then
+ Write_Buffer;
+ end if;
+ end Tree_Write_Terminate;
+
+ ------------------
+ -- Write_Buffer --
+ ------------------
+
+ procedure Write_Buffer is
+ begin
+ if Integer (Bufn) = Write (Tree_FD, Buf'Address, Integer (Bufn)) then
+ Bufn := 0;
+
+ else
+ Set_Standard_Error;
+ Write_Str ("fatal error: disk full");
+ OS_Exit (2);
+ end if;
+ end Write_Buffer;
+
+ ----------------
+ -- Write_Byte --
+ ----------------
+
+ procedure Write_Byte (B : Byte) is
+ begin
+ Bufn := Bufn + 1;
+ Buf (Bufn) := B;
+
+ if Bufn = Buflen then
+ Write_Buffer;
+ end if;
+ end Write_Byte;
+
+end Tree_IO;