Runtime Initialization

The default init function is the bootstrap or glue code that sets up the DSP56800E environment before your code executes. This function is in the init file for each board-specific stationery project. The routines defined in the init file performs other tasks such as clearing the hardware stack, creating an interrupt table, and retrieving the stack start and exception handler addresses.

The final task performed by the init function is to call the main() function.

The starting point for a program is set in the Entry Point field in the DSC Linker > Input settings panel.

The project for the DSP56800E runtime is: CodeWarrior\M56800E Support\runtime_56800E\projects\Runtime 56800E.mcp

When creating a project from R1.1 or later Stationery, the associated init code is specific to the DSP56800E board. See the startup folder in the new project folder for the init code.

#



; -------------------------------------------------------

;

;       56852_init.asm



;       sample

        description:  main entry point to C code.

;                 setup runtime for C and call main

;

; -------------------------------------------------------





;===============================

; OMR mode bits

;===============================

NL_MODE                 EQU              $8000

CM_MODE                 EQU              $0100

XP_MODE                 EQU              $0080

R_MODE                  EQU              $0020

SA_MODE                 EQU              $0010



        section rtlib



        XREF F_stack_addr

        org p:





        GLOBAL Finit_M56852_



        SUBROUTINE "Finit_M56852_",Finit_M56852_,Finit_M56852END-Finit_M56852_



Finit_M56852_:



;

; setup the OMr with the values required by C

;

      bfset   #NL_MODE,omr     ; ensure NL=1  (enables nsted DO loops)

        nop

        nop

   bfclr   #(CM_MODE|XP_MODE|R_MODE|SA_MODE),omr ; ensure CM=0 (optional for C)

                   ; ensure XP=0 to enable harvard architecture

                   ; ensure R=0  (required for C)

                   ; ensure SA=0 (required for C)



; Setup the m01 register for linear addressing

        move.w  #-1,x0

        moveu.w x0,m01       ; Set the m register to linear addressing



        moveu.w hws,la        ; Clear the hardware stack

        moveu.w hws,la        nop

        nop





CALLMAIN:                           ; Initialize compiler environment





;Initialize the Stack

        move.l #>>F_Lstack_addr,r0

        bftsth #$0001,r0

        bcc noinc

        adda #1,r0

noinc:

        tfra    r0,sp                ; set stack pointer too

        move.w  #0,r1

        nop

        move.w  r1,x:(sp)

        adda    #1,sp



  jsr                   F__init_sections



; Call main()

        move.w  #0,y0               ; Pass parameters to main()

        move.w  #0,R2

        move.w  #0,R3



        jsr            Fmain        ; Call the Users program

;

;  The fflush calls where removed because they added code

;  growth in cases where the user is not using any debugger IO.

;  Users should now make these calls at the end of main if they use debugger IO

;

;       move.w  #0,r2

;       jsr     Ffflush             ; Flush File IO

;       jsr     Ffflush_console     ; Flush Console IO



;       end of program; halt CPU

        debughlt

        rts

Finit_M56852END:



       endsec