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173 | -- Test_LZ77 runs a choice of LZ77 encoders for comparing them.
--
-- - Output of the encoder is dumped as readable text with DLE codes
-- or Literals (.lz77)
-- - LZ77 stream is decoded and written as .out for checking integrity:
-- should be identical to input file.
with Ada.Characters.Handling; use Ada.Characters.Handling;
with Ada.Command_Line; use Ada.Command_Line;
with Ada.Sequential_IO;
with Ada.Text_IO; use Ada.Text_IO;
with LZ77;
procedure Test_LZ77 is
package BIO is new Ada.Sequential_IO (LZ77.Byte);
use LZ77, BIO;
f_in, f_out : BIO.File_Type;
f_dump : Ada.Text_IO.File_Type;
function Read_byte return Byte is
b : Byte;
begin
Read (f_in, b);
return b;
end Read_byte;
function More_bytes return Boolean is
begin
return not End_Of_File (f_in);
end More_bytes;
----- LZSS Parameters -----
String_buffer_size : constant := 2**15; -- 2**15 for Deflate
Look_Ahead_Test : constant := 258; -- 258 for Deflate
Threshold : constant := 2; -- 2 for Deflate
type Text_Buffer is array (0 .. String_buffer_size + Look_Ahead_Test - 1) of Byte;
Text_Buf : Text_Buffer;
R : Natural;
procedure Write_and_record_literal (literal : Byte) is
begin
Write (f_out, literal);
Text_Buf (R) := literal;
R := (R + 1) mod String_buffer_size;
end Write_and_record_literal;
procedure Emit_literal (literal : Byte) is
begin
Write_and_record_literal (literal);
--
Put (f_dump, "Lit" & Byte'Image (literal));
if literal in 32 .. 126 then
Put (f_dump, " '" & Character'Val (literal) & ''');
end if;
New_Line (f_dump);
end Emit_literal;
min_dis, min_len, max_dis, max_len : Natural;
sum_dist, dl_count, len_258 : Natural;
has_DL : Boolean;
procedure Emit_DL_code (distance, length : Natural) is
b : Byte;
I : Natural;
begin
has_DL := True;
dl_count := dl_count + 1;
sum_dist := sum_dist + distance;
max_dis := Natural'Max (max_dis, distance);
max_len := Natural'Max (max_len, length);
min_dis := Natural'Min (min_dis, distance);
min_len := Natural'Min (min_len, length);
if length = 258 then
len_258 := len_258 + 1;
end if;
--
Put_Line (f_dump, "DLE" & Integer'Image (distance) & Integer'Image (length));
--
-- Expand DL code:
I := (R - distance) mod String_buffer_size;
for K in 0 .. length - 1 loop
b := Text_Buf ((I + K) mod String_buffer_size);
Write_and_record_literal (b);
end loop;
end Emit_DL_code;
procedure Dummy_Estimate_DL_Codes (
matches : in out LZ77.Matches_Array;
old_match_index : in Natural;
prefixes : in LZ77.Byte_Array;
best_score_index : out Positive;
best_score_set : out LZ77.Prefetch_Index_Type;
match_trace : out LZ77.DLP_Array
)
is null;
type Method_Set is array (Method_Type) of Boolean;
-- consider: constant Method_Set:= (others => True);
-- consider: constant Method_Set:= (IZ_5 | IZ_7 | IZ_8 => False, others => True);
consider : constant Method_Set := (LZHuf | IZ_10 | Rich | BT4 => True, others => False);
begin
Put_Line ("Test_LZ77");
New_Line;
Put_Line ("test_lz77 [input file]");
New_Line;
Put_Line ("Outputs:");
Put_Line (" *.lz77 are dump of the LZ77 stream");
Put_Line (" *.out are decoded streams, should match input file");
for m in Method_Type loop
if consider (m) then
max_dis := 0;
max_len := 0;
min_dis := Natural'Last;
min_len := Natural'Last;
has_DL := False;
dl_count := 0;
sum_dist := 0;
len_258 := 0;
declare
procedure My_LZ77 is
new LZ77.Encode (
String_buffer_size, Look_Ahead_Test, Threshold,
m,
Read_byte, More_bytes,
Emit_literal, Emit_DL_code,
False, Dummy_Estimate_DL_Codes
);
begin
if Argument_Count < 1 then
Open (f_in, In_File, "test/test_lz77.adb");
else
Open (f_in, In_File, Argument (1));
end if;
R := String_buffer_size - Look_Ahead_Test;
Create (f_out, Out_File, "lz77_" & To_Lower (Method_Type'Image (m)) & "_decode.out");
-- The dump.lz77 file is used in various places:
--
-- - Input:
-- LZ77_Stats
-- Zip.Compress.Deflate (bypass_LZ77 mode)
--
-- - Output:
-- Test_LZ77 (this program)
-- UnZip.Decompress
--
Create (f_dump, Out_File, "dump_" & To_Lower (Method_Type'Image (m)) & ".lz77");
New_Line;
Put_Line ("Method: " & Method_Type'Image (m) & " - Encoding file " & Name (f_in));
My_LZ77;
Close (f_in);
Close (f_out);
Close (f_dump);
if has_DL then
Put_Line (" DL codes:" & Integer'Image (dl_count));
Put_Line (" Min distance:" & Integer'Image (min_dis));
Put_Line (" Max distance:" & Integer'Image (max_dis));
Put_Line (" Average distance:" & Integer'Image (sum_dist / dl_count));
Put_Line (" Cases where length is exactly 258 (Deflate-friendly):" &
Integer'Image (len_258));
Put_Line (" Min length:" & Integer'Image (min_len));
Put_Line (" Max length:" & Integer'Image (max_len));
end if;
end;
end if;
end loop;
end Test_LZ77;
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