Re: newbie problem

[Olivier Scalbert <olivier.scalbert@algosyn.com>]

Finally I have done some changes. Als_Create is now a procedure.

Here is the code:

--------------------------------------
-- adasound.ads
--------------------------------------
private with Ada.Sequential_Io;

package adasound is

     type Amplitude_T is new Float;
     type Frequency_T is new Float;
     type Time_T      is new Float;

     type Stereo_Amplitude_T is record
         Left : Amplitude_T;
         Right: Amplitude_T;
     end record;

     type Als_File_T is limited private;

     procedure Als_Create(Als_File: out Als_File_T; File_Name: String);
     procedure Als_Write(Als_File: Als_File_T; Stereo_Amplitude: 
Stereo_Amplitude_T);
     procedure Als_Close(Als_File: out Als_File_T);

private
     package Stereo_Amplitude_Io is new Ada.Sequential_Io 
(Stereo_Amplitude_T);

     type Als_File_T is record
         File_Type: Stereo_Amplitude_Io.File_Type;
         -- perhaps more stuff later
     end record;

end adasound;

--------------------------------------
-- adasound.adb
--------------------------------------
package body adasound is

procedure Als_Create(Als_File: out Als_File_T; File_Name: String) is
     File: Stereo_Amplitude_Io.File_Type;
begin
     Stereo_Amplitude_Io.Create(Als_File.File_Type, 
Stereo_Amplitude_Io.Out_File, File_Name);
end Als_Create;

procedure Als_Write(Als_File: Als_File_T; Stereo_Amplitude: 
Stereo_Amplitude_T) is
begin
     Stereo_Amplitude_Io.Write(Als_File.File_Type, Stereo_Amplitude);
end Als_Write;

procedure Als_Close(Als_File: out Als_File_T) is
begin
     Stereo_Amplitude_Io.Close(Als_File.File_Type);
end Als_Close;

end adasound;

--------------------------------------
-- driver.adb
--------------------------------------
with adasound;
use adasound;

procedure driver is
     Als_File : Als_File_T;
     Stereo : Stereo_Amplitude_T;
     Sample_Rate : constant Integer := 44_100;
     Nb_Seconds  : constant Integer :=  3_600;
begin
     Stereo.Left  := 0.0;
     Stereo.Right := 0.0;
     Als_Create(Als_File, "test.als");
     for i in 1..Sample_Rate * Nb_Seconds loop
         Als_Write(Als_File, Stereo);
     end loop;
     Als_Close(Als_File);
end driver;

I do not know if the design is better or not but at least it works.

I am also very pleased with the performance. Of course, it is nearly 
only IO but ...

time ./driver
real    0m15.648s
user    0m10.305s
sys     0m3.364s

ls -l test.als
-rw-r--r-- 1 ols ols 1270080000 2009-05-13 18:41 test.als


Olivier.