init.s

Sirf/Centrality公司GPS平台AtlasIII芯片AT640的Nboot源码

;
; Copyright (c) 2002 Palmmicro Communications Inc.  All rights reserved.
;
; --------------------------------------------------------------------
; Module Name:
;	
;   init.s
;	  
; Abstract:
;	
;   This file is the first code running on RAM. It initialize 
;   the usermode stack and jump to C_Entry
;

        INCLUDE at4x0f.inc

        AREA    Init, CODE, READONLY
        EXPORT InitDevice

InitDevice

; --- Now enable IRQs, change to user mode and set up user mode stack.
        MOV     r0, #Mode_SVC:OR:F_Bit ; IRQ enabled
        MSR     cpsr_c, r0
        LDR     sp, =USR_Stack

; --- Now we enter the main C application code

        IMPORT  C_Entry
; If the main C code is in Thumb code rather than ARM, 
; we would need to change to Thumb state here.

        BL      C_Entry ; in C_main.c

; If above subroutine ever returns, just sit in an endless loop
here    B       here

        END