Boot/HAL.cortex4.qemu.Mod at main · io-core/Boot · GitHub

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(* begin-module-short-description
provides a Hardware Abstraction Layer for cortex-m4.
end-module-short-description *)

(* begin-module-use-description
Module HAL (.cm4) exercises features of the compiler in bringing Oberon up from bare metal on cortex-m4.

end-module-use-description *)
(* begin-module-develop-description
The HAL prepares the Oberon runtime and so cannot rely on it.

* No global variables
* No strings
* No heap allocation

The first thing HAL must do is set up its own stack.

Each platform should have its own HAL. This is the HAL for cortex-m4 on QEMU.

The HAL remains resident and may be used by other modules.

end-module-develop-description *)
MODULE* HAL;
  IMPORT SYSTEM;

  CONST
    stackOrg = 47FFF000H;
    MTOrg    = 40001000H;
    rsData   = 9000000H;
    FDTLoc   = 48000000H; (* At start R02 holds the location of the FDTB *)
    MT = 12; SP = 14; LNK = 15;   (*dedicated registers RISC5 ordinal*)

  TYPE

  VAR


  (* begin-procedure-description
---
**Greet** Transmits a greeting on the serial port.
  end-procedure-description *)
PROCEDURE Greet;
BEGIN
  SYSTEM.PUT(rsData,ORD("O"));
  SYSTEM.PUT(rsData,ORD("b"));
  SYSTEM.PUT(rsData,ORD("e"));
  SYSTEM.PUT(rsData,ORD("r"));
  SYSTEM.PUT(rsData,ORD("o"));
  SYSTEM.PUT(rsData,ORD("n"));
  SYSTEM.PUT(rsData,13);
  SYSTEM.PUT(rsData,10);
END Greet;

  (* begin-procedure-description
---
**Init** queries the system configuration, establishes the module store and the heap, and passes control to the Kernel.
  end-procedure-description *)
PROCEDURE Init;
  VAR x, y, z: INTEGER;
BEGIN

(*
  LED(1); z := 0;
  REPEAT LED(z); x := 1000;
     REPEAT y := 1000;
       REPEAT y := y-1 UNTIL y = 0;
       x := x-1
     UNTIL x = 0;
     z := z+1
  UNTIL FALSE
*)

END Init;


  (* begin-procedure-description
---
**The initialzation code for this module** establishes the stack and module table origin, transmits a greeting, and then calls Init.
  end-procedure-description *)
BEGIN SYSTEM.LDREG(0, stackOrg);
      SYSTEM.REGREG(SP,0); (*can't load constants to SP directly on aarch64*)
      SYSTEM.LDREG(MT, MTOrg);
      Greet;
      Init;
      WHILE TRUE DO END
END HAL.