Ada Runtime Library: Difference between revisions

For more information regarding GNAT project configuration refer to the AdaCore documentation: [https://docs.adacore.com/gprbuild-docs/html/gprbuild_ug/gnat_project_manager.html]

 

library project Runtime is

-- Tells Gprbuild to create any missing directories in the build process.

for Target use "i686-elf";

end Runtime;

 

As noted in the source code comments above, in this setup the run-time sources are used as a run-time library during the build process. One method to implement this is to include a pre-requisite step in your makefile to copy the sources to the final build destination <tt>adainclude</tt> directory, then to specify this build directory as the run-time for the project. An example makefile for facilitating this can be seen below.

''Please note that this makefile may not be fit for all projects and purposes.''

 

RUNTIME_BINARY := ${LIB_DIR}/libgnat.a

RUNTIME_PROJ := runtime

${LIB_DIR}:

mkdir -p ${LIB_DIR}

 

 

Also, add the following line in the private part of the package:

 

private

Run_Time_Name : constant String := "Bare Bones Run Time";

 

According to <tt>targparm.ads</tt>, this directive should be the first thing after the private keyword.

 

'''x86.ads'''

-------------------------------------------------------------------------------

-- X86

pragma Preelaborate (x86);

end x86;

 

'''x86-port_io.ads'''

with Interfaces;

with System;

);

end x86.Port_IO;

 

 

'''x86-port_io.adb'''

with System.Machine_Code;

 

end Outb;

end x86.Port_IO;

 

Fundamentally, the role of the runtime library is to implement the features defined in the Ada language standard for the particular target platform. This requires the creation of target-specific packages to interface with platform features such as internal clocks, [[UART|UARTs]] and [[PIT|timers]], among other things. These packages can then be used by language-defined packages in the runtime library to expose this functionality to the linked application.

A practical usage of this would be to define a <tt>runtime.xml</tt> file, placed within the final <tt>adainclude</tt> directory of the run-time library. This is used to automatically use a linker script for the target platform when the kernel is linked against the library.

 

<?xml version="1.0" ?>

<gprconfig>

</configuration>

</gprconfig>

 

Where <tt>${RUNTIME}</tt> is a predefined variable made available by Gprbuild.

 

'''s-imguns.ads'''

with System.Unsigned_Types;

 

 

end System.Img_Uns;

 

'''s-imguns.adb'''

with System.Unsigned_Types; use System.Unsigned_Types;

 

 

end System.Img_Uns;

 

User-defined images for a given type can be implemented by overriding the default implementation of the <tt>Put_Image</tt> attribute.