machine_types

Foundational machine-level types for bare-metal Ada applications.

Overview

machine_types provides a comprehensive set of unsigned integer types with precise bit widths for embedded systems programming. It serves as a common dependency for hardware abstraction layers, enabling consistent type usage across peripheral drivers and register definitions.

Features

• Complete set of unsigned integer types from 1 to 64 bits
• Precise size specifications for hardware register mapping
• Pure package for maximum optimization and reusability
• Zero dependencies beyond standard Ada Interfaces
• Consistent naming convention (UInt1 through UInt64)

API

MT Package

with Interfaces;

package MT is
   pragma Pure;

   type Bit is mod 2**1 with Size => 1;
   type UInt2 is mod 2**2 with Size => 2;
   type UInt3 is mod 2**3 with Size => 3;
   type UInt4 is mod 2**4 with Size => 4;
   type UInt5 is mod 2**5 with Size => 5;
   type UInt6 is mod 2**6 with Size => 6;
   type UInt7 is mod 2**7 with Size => 7;
   subtype UInt8 is Interfaces.Unsigned_8;
   type UInt9 is mod 2**9 with Size => 9;
   type UInt10 is mod 2**10 with Size => 10;
   -- ... continues through UInt64
   subtype UInt16 is Interfaces.Unsigned_16;
   subtype UInt32 is Interfaces.Unsigned_32;
   subtype UInt64 is Interfaces.Unsigned_64;
end MT;

Usage

In Generic Peripheral Interfaces

with MT;

package Gpio_Types is
   type Logic_Level is (Low, High);
   
   function To_Bit (Level : Logic_Level) return MT.Bit is
     (case Level is
         when Low  => 0,
         when High => 1);
   
   function From_Bit (B : MT.Bit) return Logic_Level is
     (if B = 0 then Low else High);
end Gpio_Types;

In Driver Implementations

with MT;

package body STM32G431_GPIO is
   function Driver_Read (P : Pin) return MT.Bit is
      Port : GPIO_Port renames Get_Port (P);
      Mask : constant MT.UInt16 := Shift_Left (1, Get_Pin_Number (P));
   begin
      if (Port.IDR and Mask) /= 0 then
         return 1;
      else
         return 0;
      end if;
   end Driver_Read;
end STM32G431_GPIO;

Design Rationale

Pure Package

The pragma Pure directive allows the package to be used in any context, including other pure packages, and enables maximum compiler optimization through constant folding and elimination.

Comprehensive Type Coverage

Providing types for all bit widths from 1 to 64 eliminates the need for each project to define its own machine types, ensuring consistency across the ecosystem.

Standard Subtypes for Common Sizes

Using subtypes of Interfaces.Unsigned_8, Unsigned_16, Unsigned_32, and Unsigned_64 for standard sizes ensures compatibility with existing Ada code and libraries while maintaining naming consistency.

Explicit Size Specifications

Each type includes an explicit Size aspect, guaranteeing the compiler will reject any platform where the type cannot be represented with the specified bit width.

Integration

Add to your alire.toml:

[[depends-on]]
machine_types = "^0.1.0"

Dependencies

None (only standard Ada Interfaces package)

License

MIT OR Apache-2.0 WITH LLVM-exception