mrm332/start/start.S

0001 /**
0002  *  @file
0003  *
0004  *  MRM332 Assembly Start Up Code
0005  */
0006
0007 /*
0008  *  COPYRIGHT (c) 2000.
0009  *  Matt Cross <profesor@gweep.net>
0010  *
0011  *  The license and distribution terms for this file may be
0012  *  found in the file LICENSE in this distribution or at
0013  *  http://www.rtems.org/license/LICENSE.
0014  *
0015  */
0016
0017 #include "mrm332.h"
0018 #include <rtems/asm.h>
0019 #include <rtems/m68k/sim.h>
0020
0021 BEGIN_CODE
0022
0023   /* Put the header necessary for the modified CPU32bug to automatically
0024      start up rtems: */
0025 #if 1
0026 .long 0xbeefbeef ;
0027 #endif
0028 .long 0 ;
0029 .long start ;
0030
0031 .global start
0032     start:
0033
0034     oriw   #0x0700,sr           /* Mask off interupts */
0035
0036     // Set VBR to CPU32Bug vector table address
0037     movel   #0x0,d0             /* Use the initial vectors until we get going */
0038     movecl  d0,vbr
0039
0040     /* Set stack pointer */
0041     movel   #_ISR_Stack_area_end,d0
0042     movel   d0,sp
0043     movel   d0,a6
0044
0045   /* include in ram_init.S */
0046   /*
0047    * Initalize the SIM module.
0048    * The stack pointer is not usable until the RAM chip select lines
0049    * are configured. The following code must remain inline.
0050    */
0051
0052   /* Module Configuration Register */
0053   /*    see section(s) 3.1.3-3.1.6 of the SIM Reference Manual */
0054   /* SIMCR etc and SAM macro all defined in sim.h found at     */
0055   /* /cpukit/score/cpu/m68k/rtems/m68k/sim.h                   */
0056   /* The code below does the following:                        */
0057   /*    - Sets Freeze Software Enable                          */
0058   /*    - Turns off Show Cycle Enable                          */
0059   /*    - Sets the location of SIM module mapping              */
0060   /*    - Sets the SIM Interrupt Arbitration Field             */
0061     lea SIMCR, a0
0062     movew   #FRZSW,d0
0063     oriw    #SAM(0,8,SHEN),d0
0064     oriw    #(MM*SIM_MM),d0
0065     oriw    #SAM(SIM_IARB,0,IARB),d0
0066     movew   d0, a0@
0067
0068     jsr start_c /* Jump to the C startup code */
0069
0070 END_CODE
0071