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192 | -- Usage: test_stream_performance <big_file>
-- Produces .tmp files that are copies of <big_file>.
--
-- Example of output with GNAT GPL 2008 / Win32:
--
-- xxx'Write / xxx'Read (Stream attributes)......... 9.282530042 seconds
-- Workarounds with Stream_Element_Array buffer:
-- copy........................................... 0.444120412 seconds
-- overlay (read), unchecked_conversion (write)... 0.156874407 seconds
-- overlay........................................ 0.150155676 seconds
-- Factor (Copy) 20.900930898
-- Factor (Overlay) 61.819374993
-- Buffer size in bits..... 8192
-- SE Buffer size in bits.. 8192
-- File size in megabytes..... 2.46367E+01
with Ada.Calendar; use Ada.Calendar;
with Ada.Text_IO;
with Ada.Streams.Stream_IO; use Ada.Streams.Stream_IO;
with Ada.Command_Line; use Ada.Command_Line;
with Ada.Unchecked_Conversion;
with Interfaces; use Interfaces;
procedure Test_Stream_Performance is
f_in, f_out : Ada.Streams.Stream_IO.File_Type;
type Buffer is array (Natural range <>) of Unsigned_8;
------------------------------------------------
-- 1) Stream attributes - xxx'Read, xxx'Write --
------------------------------------------------
-- NB: usually we would just have: Buffer'Read(Stream(f_in), b);
-- Here we care about end of file.
--
procedure Read_Attribute (b : out Buffer; last_read : out Natural) is
idx : constant Positive_Count := Index (f_in);
siz : constant Positive_Count := Size (f_in);
begin
if End_Of_File (f_in) then
last_read := b'First - 1;
else
last_read := Natural'Min (b'First + Natural (siz - idx), b'Last);
Buffer'Read (Stream (f_in), b (b'First .. last_read));
end if;
end Read_Attribute;
procedure Write_Attribute (b : in Buffer) is
begin
Buffer'Write (Stream (f_out), b);
end Write_Attribute;
---------------------------------------------
-- 2) The Stream_Element_Array workarounds --
---------------------------------------------
procedure Read_SE_Copy (b : out Buffer; last_read : out Natural) is
use Ada.Streams;
First : constant Stream_Element_Offset := Stream_Element_Offset (b'First);
Last : Stream_Element_Offset := Stream_Element_Offset (b'Last);
SE_Buffer : Stream_Element_Array (First .. Last);
begin
Read (Stream (f_in).all, SE_Buffer, Last);
for i in First .. Last loop
b (Natural (i)) := Unsigned_8 (SE_Buffer (i));
end loop;
last_read := Natural (Last);
end Read_SE_Copy;
procedure Write_SE_Copy (b : in Buffer) is
use Ada.Streams;
First : constant Stream_Element_Offset := Stream_Element_Offset (b'First);
Last : constant Stream_Element_Offset := Stream_Element_Offset (b'Last);
SE_Buffer : Stream_Element_Array (First .. Last);
begin
for i in SE_Buffer'Range loop
SE_Buffer (i) := Stream_Element (b (Natural (i)));
end loop;
Write (Stream (f_out).all, SE_Buffer);
end Write_SE_Copy;
-- Overlay idea by Jeff Carter
procedure Read_SE_Overlay (b : out Buffer; last_read : out Natural) is
use Ada.Streams;
Last : Stream_Element_Offset;
SE_Buffer : Stream_Element_Array (1 .. b'Length);
for SE_Buffer'Address use b'Address;
pragma Import (Ada, SE_Buffer);
begin
Read (Stream (f_in).all, SE_Buffer, Last);
last_read := b'First + Natural (Last) - 1;
end Read_SE_Overlay;
procedure Write_SE_Overlay (b : in Buffer) is
use Ada.Streams;
SE_Buffer : Stream_Element_Array (1 .. b'Length);
for SE_Buffer'Address use b'Address;
pragma Import (Ada, SE_Buffer);
begin
Write (Stream (f_out).all, SE_Buffer);
end Write_SE_Overlay;
-- Using Unchecked_Conversion
procedure Write_SE_UC (b : in Buffer) is
subtype My_SEA is Ada.Streams.Stream_Element_Array (1 .. b'Length);
function To_SEA is new Ada.Unchecked_Conversion (Buffer, My_SEA);
use Ada.Streams;
begin
Write (Stream (f_out).all, To_SEA (b));
end Write_SE_UC;
----------
-- Test --
----------
function name return String is
begin
return Argument (1);
end name;
generic
label : String;
with procedure Read (b : out Buffer; last_read : out Natural);
with procedure Write (b : in Buffer);
procedure Test (bytes : Positive);
procedure Test (bytes : Positive) is
b : Buffer (1 .. bytes);
l : Natural;
begin
Open (f_in, In_File, name);
Create (f_out, Out_File, name & "_$$$_" & label & ".tmp");
while not End_Of_File (f_in) loop
Read (b, l);
Write (b (1 .. l));
end loop;
Close (f_out);
Close (f_in);
end Test;
procedure Test_Attribute is new Test ("Attribute", Read_Attribute, Write_Attribute);
procedure Test_SE_Copy is new Test ("SE_Copy", Read_SE_Copy, Write_SE_Copy);
procedure Test_SE_Overlay is new Test ("SE_Overlay", Read_SE_Overlay, Write_SE_Overlay);
procedure Test_SE_UC is new Test ("SE_UC", Read_SE_Overlay, Write_SE_UC);
use Ada.Text_IO;
procedure All_Tests (buffer_bytes : Positive) is
T0, T1, T2, T3, T4 : Time;
begin
T0 := Clock;
Test_Attribute (buffer_bytes);
T1 := Clock;
Test_SE_Copy (buffer_bytes);
T2 := Clock;
Test_SE_UC (buffer_bytes);
T3 := Clock;
Test_SE_Overlay (buffer_bytes);
T4 := Clock;
Put_Line ("xxx'Write / xxx'Read (Stream attributes)........." & Duration'Image (T1 - T0) & " seconds");
Put_Line ("Workarounds with Stream_Element_Array buffer:");
Put_Line (" copy (byte buffer from/to SE buffer)..........." & Duration'Image (T2 - T1) & " seconds");
Put_Line (" overlay (read), unchecked_conversion (write)..." & Duration'Image (T3 - T2) & " seconds");
Put_Line (" overlay (read and write)......................." & Duration'Image (T4 - T3) & " seconds");
Put_Line ("Factor (Copy) " & Duration'Image ((T1 - T0) / (T2 - T1)));
Put_Line ("Factor (UC) " & Duration'Image ((T1 - T0) / (T3 - T2)));
Put_Line ("Factor (Overlay)" & Duration'Image ((T1 - T0) / (T4 - T3)));
New_Line;
Put_Line ("Buffer size in bytes....." & Integer'Image (buffer_bytes));
Open (f_in, In_File, name);
Put_Line ("File size in megabytes....." & Float'Image (Float (Size (f_in)) / (1024.0 * 1024.0)));
Close (f_in);
end All_Tests;
begin
if Argument_Count = 0 then
Put_Line (" Usage: test_stream_performance <big_file>");
Put_Line (" Produces .tmp files that are copies of <big_file>.");
return;
end if;
All_Tests (1024); -- 1 KB
All_Tests (32 * 1024); -- 32 KB
All_Tests (64 * 1024); -- 64 KB
All_Tests (128 * 1024); -- 128 KB
All_Tests (256 * 1024); -- 256 KB
All_Tests (1024 * 1024); -- 1 MB
end Test_Stream_Performance;
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