-- Abstract interface for SPI devices

-- Copyright (C)2016-2023, Philip Munts dba Munts Technologies.
--
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PACKAGE SPI IS

  -- Define an exception for SPI errors

  SPI_Error : EXCEPTION;

  -- Type definitions

  TYPE Byte IS MOD 256;

  TYPE Command IS ARRAY (Natural RANGE <>) OF Byte;

  TYPE Response IS ARRAY (Natural RANGE <>) OF Byte;

  TYPE MicroSeconds IS RANGE 0 .. 65536;

  -- Define an abstract interface for SPI devices

  TYPE DeviceInterface IS INTERFACE;

  -- Define an access type compatible with any subclass implementing
  -- SPI.DeviceInterface

  TYPE Device IS ACCESS ALL SPI.DeviceInterface'Class;

  -- Write only SPI bus cycle method

  PROCEDURE Write
   (Self     : DeviceInterface;
    cmd      : Command;
    cmdlen   : Natural) IS ABSTRACT;

  -- Read only SPI bus cycle method

  PROCEDURE Read
   (Self     : DeviceInterface;
    resp     : OUT Response;
    resplen  : Natural) IS ABSTRACT;

  -- Combined Write/Read SPI bus cycle method

  PROCEDURE Transaction
   (Self     : DeviceInterface;
    cmd      : Command;
    cmdlen   : Natural;
    resp     : OUT Response;
    resplen  : Natural;
    delayus  : MicroSeconds := 0) IS ABSTRACT;

END SPI;