updating a hardware cursor with assembly and ada

updating a hardware cursor with assembly and ada

[cl1]

I an trying to learn some operating system development. I have it
booting and printing text to the screen. However, I have an issue with
updating the hardware cursor. It does not update. I can provide the
whole sources if need be, but i believe i am missunderstanding
something in Ada. The tutorial I am learning from is written in C and
for the most part its pretty easy converting it to ada. The code i'm
having an issue with follows. The important parts are outportb in the
c files and Update_Cursor in the vga package body.

// this is the way the tutorial updated the hardware cursor. My
version is
// in the Vga package called Update_Cursor
// void move_csr(void)
// {
//   unsigned temp;
//   temp = csr_y * 80 + csr_x; // csr_y and csr_x are global
variables
//
//   outportb(0x3D4, 14);
//   outportb(0x3D5, temp >> 8);
//   outportb(0x3D4, 15);
//   outportb(0x3D5, temp);
// }

// port.h
#ifndef __PORT_H
#define __PORT_H
extern unsigned char inportb (unsigned short _port);
extern void outportb (unsigned short _port, usigned char _data);

// port.c
#include "port.h"

unsigned char inportb (unsigned short _port)
{
 unsigned char rv;
 __asm__ __volatile__ ("inb %1, %0" : "=a" (rv) : "dN" (_port));
 return rv;
}

unsigned char outportb (unsigned short _port, unsigned char _data)
{
 __asm__ __volatile__ ("outb %1, %0" : : "dN" (_port), "a" (_data));
}

-- vga.ads
package Vga is
 
-----------------------------------------------------------------------------
  type Color is (
     Black,         -- 0000
     Blue,          -- 0001
     Green,         -- 0010
     Cyan,          -- 0011
     Red,           -- 0100
     Magenta,       -- 0101
     Brown,         -- 0110
     Light_Grey,    -- 0111
     Dark_Grey,     -- 1000
     Light_Blue,    -- 1001
     Light_Green,   -- 1010
     Light_Cyan,    -- 1011
     Light_Red,     -- 1100
     Light_Magenta, -- 1101
     Light_Brown,   -- 1110
     White);        -- 1111

  for Color use (
     Black         => 16#0#,
     Blue          => 16#1#,
     Green         => 16#2#,
     Cyan          => 16#3#,
     Red           => 16#4#,
     Magenta       => 16#5#,
     Brown         => 16#6#,
     Light_Grey    => 16#7#,
     Dark_Grey     => 16#8#,
     Light_Blue    => 16#9#,
     Light_Green   => 16#A#,
     Light_Cyan    => 16#B#,
     Light_Red     => 16#C#,
     Light_Magenta => 16#D#,
     Light_Brown   => 16#E#,
     White         => 16#F#);

  for Color'Size use 4;
 
-----------------------------------------------------------------------------
  subtype Background_Color is Color range Color'First..Light_Grey;


  subtype Row is Positive range Positive'First..25;
  subtype Column is Positive range Positive'First..80;
 
-----------------------------------------------------------------------------
  type Video_Console is
     record
        Foreground : Color := White;
        Background : Background_Color := Black;
        Row : Vga.Row := Vga.Row'First;
        Column : Vga.Column := Vga.Column'First;
     end record;

  procedure Clear(Console : in out Video_Console);
  procedure Put(Console : in out Video_Console; S : String);
 
-----------------------------------------------------------------------------
end Vga;

-- vga.adb
with System;
package body Vga is
 
-----------------------------------------------------------------------------
  type Video_Character is
     record
        Foreground : Color;
        Background : Background_Color;
        Glyph      : Character;
     end record;

  for Video_Character use
     record
        Foreground at 0 range 8..11;
        Background at 0 range 12..15;
        Glyph      at 0 range 0..7;
     end record;

  for Video_Character'Size use 16;
 
-----------------------------------------------------------------------------
  Video_Memory : array (Row'Range, Column'Range) of Video_Character;

  for Video_Memory'Address use System'To_Address (16#000B8000#);

  pragma Import (Ada, Video_Memory);
 
-----------------------------------------------------------------------------
  procedure Update_Cursor (Console : Video_Console) is
     procedure OutportB (Port : Natural; Data : Natural);
     pragma Import(C, OutportB, "outportB");

     Data : Natural := Console.Column * 80 + Console.Row;
  begin
     OutportB ( 16#3D4#, 14);
     OutportB ( 16#3D5#, Data / 2 ** 8);
     OutportB ( 16#3D4#, 15);
     OutportB ( 16#3D5#, Data);
  end Update_Cursor;
 
-----------------------------------------------------------------------------
  procedure Clear (Console : in out Video_Console) is
     Clear_Character : Video_Character := (
       Foreground => Console.Foreground,
       Background => Console.Background,
       Glyph      => ' ');
  begin
     for R in Row'Range loop
        for C in Column'Range loop
           Video_Memory (R, C) := Clear_Character;
        end loop;
     end loop;
     Console.Row := Row'First;
     Console.Column := Column'First;
     Update_Cursor(Console);
  end Clear;
 
-----------------------------------------------------------------------------
  procedure Put (Console : in out Video_Console;
                        C           :        Character) is
     V : Video_Character := (
       Foreground => Console.Foreground,
       Background => Console.Background,
       Glyph      => C);
     Tmp : Positive := Console.Column + 1;
  begin
     Video_Memory(Console.Row, Console.Column) := V;
     if Tmp > Column'Last then
        Console.Column := Column'First;
        Console.Row := Row'Succ(Console.Row);
     else
        Console.Column := Column'Succ(Console.Column);
     end if;
     Update_Cursor(Console);
  end Put;
 
-----------------------------------------------------------------------------
  procedure Put (Console : in out Video_Console; S : String) is
  begin
     for I in S'Range loop
        Put (Console, S (I));
     end loop;
  end Put;
 
-----------------------------------------------------------------------------
end Vga;

Re: updating a hardware cursor with assembly and ada

[Georg Bauhaus]

cl1 schrieb:

> unsigned char outportb (unsigned short _port, unsigned char _data)
> {
>  __asm__ __volatile__ ("outb %1, %0" : : "dN" (_port), "a" (_data));
> }

> -----------------------------------------------------------------------------
>   procedure Update_Cursor (Console : Video_Console) is
>      procedure OutportB (Port : Natural; Data : Natural);

Does type Natural match C type unsigned short on your system?
(Just a guess.) Maybe Interfaces.Unsigned_N is better choice.

>      pragma Import(C, OutportB, "outportB");

Re: updating a hardware cursor with assembly and ada

[cl1]

On Mar 6, 11:26 am, Georg Bauhaus <rm.tsoh-plus.nicif-
bauh...@maps.futureapps.de> wrote:
> cl1 schrieb:
>
> > unsigned char outportb (unsigned short _port, unsigned char _data)
> > {
> >  __asm__ __volatile__ ("outb %1, %0" : : "dN" (_port), "a" (_data));
> > }
> > ---------------------------------------------------------------------------­--
> >   procedure Update_Cursor (Console : Video_Console) is
> >      procedure OutportB (Port : Natural; Data : Natural);
>
> Does type Natural match C type unsigned short on your system?

If it didn't, what problem would this pose?

> (Just a guess.) Maybe Interfaces.Unsigned_N is better choice.

I have no runtime (this is os development code). I don't know if i can
use the Interfaces packages in gnat with out it. I tried to implement
Unsigned_16 with out the operations and the compiler complained about
not having primitive operations defined on the part where i was doing
Data : Unsigned_16 := Console.Column * 80 + Console.Row; even when
Column and Row were of type Unsigned_16;

>
>
>
> >      pragma Import(C, OutportB, "outportB");- Hide quoted text -
>
> - Show quoted text -

Re: updating a hardware cursor with assembly and ada

[Jeffrey R. Carter]

cl1 wrote:
> unsigned char outportb (unsigned short _port, unsigned char _data)

>      procedure OutportB (Port : Natural; Data : Natural);
>      pragma Import(C, OutportB, "outportB");

I would recommend using the types in Interfaces.C and its children rather than 
the predefined types.

You should give the C name in the pragma Import exactly as it appears in C: 
"outportb".

-- 
Jeff Carter
"Saving keystrokes is the job of the text editor,
not the programming language."
Preben Randhol
64

Re: updating a hardware cursor with assembly and ada

[Gautier]

If it can help, you can look at the packages in dos_paqs.zip
here: http://www.mysunrise.ch/users/gdm/gsoft.htm
in the ./biblio directory.
You have:
- PC_TextScreen for text console
- VGA_Graphics for VGA
For examples of machine code insertions (GNAT flavour), look for "asm" in the 
Ada files.
In other directories you have also Super-VGA (VESA) and sound card libraries.
HTH
______________________________________________________________
Gautier         -- http://www.mysunrise.ch/users/gdm/index.htm
Ada programming -- http://www.mysunrise.ch/users/gdm/gsoft.htm

NB: For a direct answer, e-mail address on the Web site!

Re: updating a hardware cursor with assembly and ada

[Gautier]

If it can help, you can look at the packages in dos_paqs.zip
here: http://homepage.sunrise.ch/mysunrise/gdm/locaux.htm
in the ./biblio directory.
You have:
- PC_TextScreen for text console
- VGA_Graphics for VGA
For examples of machine code insertions (GNAT flavour), look for "asm" in the
Ada files.
In other directories you have also Super-VGA (./svga_lib) and sound card 
libraries (./sb_lib).
HTH
______________________________________________________________
Gautier         -- http://www.mysunrise.ch/users/gdm/index.htm
Ada programming -- http://www.mysunrise.ch/users/gdm/gsoft.htm

NB: For a direct answer, e-mail address on the Web site!

Re: updating a hardware cursor with assembly and ada

[Adam Beneschan]

On Mar 6, 9:51 am, cl1 <charles.w.lamb...@gmail.com> wrote:
> On Mar 6, 11:26 am, Georg Bauhaus <rm.tsoh-plus.nicif-
>
> bauh...@maps.futureapps.de> wrote:
> > cl1 schrieb:
>
> > > unsigned char outportb (unsigned short _port, unsigned char _data)
> > > {
> > >  __asm__ __volatile__ ("outb %1, %0" : : "dN" (_port), "a" (_data));
> > > }
> > > ---------------------------------------------------------------------------­--
> > >   procedure Update_Cursor (Console : Video_Console) is
> > >      procedure OutportB (Port : Natural; Data : Natural);
>
> > Does type Natural match C type unsigned short on your system?
>
> If it didn't, what problem would this pose?

Assuming Natural is 32 bits (I don't really know): If the code
generated for your Ada program thinks it's passing two 32-bit integers
as parameters, but the runtime code is expecting a 16-bit integer and
an 8-bit integer as parameters, the runtime code may not use correct
values for the parameters.


> > (Just a guess.) Maybe Interfaces.Unsigned_N is better choice.
>
> I have no runtime (this is os development code). I don't know if i can
> use the Interfaces packages in gnat with out it. I tried to implement
> Unsigned_16 with out the operations and the compiler complained about
> not having primitive operations defined on the part where i was doing
> Data : Unsigned_16 := Console.Column * 80 + Console.Row; even when
> Column and Row were of type Unsigned_16;

The operations "*" and "+" aren't automatically available, unless you
do something to make them visible.  Try "use type
Interfaces.Unsigned_16;".

                               -- Adam

Re: updating a hardware cursor with assembly and ada

[Ludovic Brenta]

Gautier <gautier@fakeaddress.nil> writes:

> If it can help, you can look at the packages in dos_paqs.zip
> here: http://homepage.sunrise.ch/mysunrise/gdm/locaux.htm
> in the ./biblio directory.
> You have:
> - PC_TextScreen for text console
> - VGA_Graphics for VGA
> For examples of machine code insertions (GNAT flavour), look for "asm" in the
> Ada files.
> In other directories you have also Super-VGA (./svga_lib) and sound
> card libraries (./sb_lib).
> HTH
> ______________________________________________________________
> Gautier         -- http://www.mysunrise.ch/users/gdm/index.htm
> Ada programming -- http://www.mysunrise.ch/users/gdm/gsoft.htm
>
> NB: For a direct answer, e-mail address on the Web site!

See also Lovelace OS:

http://www.ada-france.org:8081/revision/file/2707659158a6d459d8b83cb80437efe12f4aeea4/src/boards/x86/lovelace-outb.adb
http://www.ada-france.org:8081/revision/file/2707659158a6d459d8b83cb80437efe12f4aeea4/src/boards/qemu_x86/lovelace-stage1-console.adb

PS. Feel free to join the OS Lovelace project, see http://www.lovelace.fr.

-- 
Ludovic Brenta.

Re: updating a hardware cursor with assembly and ada

[cl1]

Thank you all for the advice. I haven't had a chance to try any of it,
but now I have several options to look at. I guess I just need to
figure out what i do and do not have access to at boot time. Based on
the suggestions I recieved, it is not quite as limited as i had
originally thought.

Re: updating a hardware cursor with assembly and ada

[cl1]

Okay I have updated the Update_Cursor method with the following
implementation, However I am getting the error:

i386-elf-gcc -fno-pic -c -nostdinc -ffunction-sections -fdata-sections
-I. -gnato -gnatp -gnatE vga.adb
vga.adb:3:06: "System.Machine_Code" is not a predefined library unit

I know the error message means there is no System.Machine_Code that it
can find. What i don't know is if there is a flag, or something i can
do to get access to it. I'm really lost at this point, because there
is no way i can implement that package with my current knowledge.


with System;
with Interfaces;
with System.Machine_Code;
package body Vga is
   ...
 
-----------------------------------------------------------------------------
   procedure Update_Cursor (Console : Video_Console) is
      use Interfaces;
      use System.Machine_Code;
      Data : Unsigned_16 := Console.Column * 80 + Console.Row;
      OutB : String := "outb 140x3D4, 14" & NL & "outb %0, 0x3D5";
      Part1 : Unsigned_8 :=
Ada.Unchecked_Conversion(Shift_Right(Data));
      Part2 : Unsigned_8 := Ada.Unchecked_Conversion(Data);
   begin
      Asm (Template => "outb 14, 0x3D4" & NL
                     & "outb %0, 0x3D5" & NL
                     & "outb 15, 0x3D4" & NL
                     & "outb %1, ox3D5",
           Input    => (Unsigned_8'Asm_Input(Part1),
                        Unsigned_8'Asm_Input(Part2));
   end Update_Cursor;
 
-----------------------------------------------------------------------------
   ...
end Vga;

Re: updating a hardware cursor with assembly and ada

[Ludovic Brenta]

cl1 writes:
> Okay I have updated the Update_Cursor method with the following
> implementation, However I am getting the error:
>
> i386-elf-gcc -fno-pic -c -nostdinc -ffunction-sections -fdata-sections
> -I. -gnato -gnatp -gnatE vga.adb
> vga.adb:3:06: "System.Machine_Code" is not a predefined library unit
>
> I know the error message means there is no System.Machine_Code that
> it can find. What i don't know is if there is a flag, or something i
> can do to get access to it. I'm really lost at this point, because
> there is no way i can implement that package with my current
> knowledge.

System.Machine_Code is normally part of the standard library.  Since
you don't have one, you have two possible solutions:

1) write your own minimalistic run-time library, consisting at least
   of System and System.Machine_Code (you can copy GNAT's library if
   you want to).  BTW, the compiler requires a package System that
   describes the target architecture.

2) Write procedure Update_Cursor directly in assembly language (as
   opposed to inline assembly in an Ada source file).

HTH

-- 
Ludovic Brenta.