cstartup.s文件
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Part one of the system initialization code,
;; contains low-level
;; initialization.
;;
;; Copyright 2006 IAR Systems. All rights reserved.
;;
;; $Revision: 21638 $
;;
MODULE ?cstartup
;; Forward declaration of sections.
SECTION IRQ_STACK:DATA:NOROOT(3)
SECTION FIQ_STACK:DATA:NOROOT(3)
SECTION SVC_STACK:DATA:NOROOT(3)
SECTION ABT_STACK:DATA:NOROOT(3)
SECTION UND_STACK:DATA:NOROOT(3)
SECTION CSTACK:DATA:NOROOT(3)
;
; The module in this file are included in the libraries, and may be
; replaced by any user-defined modules that define the PUBLIC symbol
; __iar_program_start or a user defined start symbol.
;
; To override the cstartup defined in the library, simply add your
; modified version to the workbench project.
SECTION .intvec:CODE:NOROOT(2)
PUBLIC __vector
PUBLIC __iar_program_start
PUBLIC __vector_0x14
EXTERN undef_handler, swi_handler, prefetch_handler
EXTERN data_handler, irq_handler, fiq_handler
ARM ; Always ARM mode after reset
__vector:
ldr pc,[pc,#24] ; Absolute jump can reach 4 GByte
__undef_handler:
ldr pc,[pc,#24] ; Branch to undef_handler
__swi_handler:
ldr pc,[pc,#24] ; Branch to swi_handler
__prefetch_handler:
ldr pc,[pc,#24] ; Branch to prefetch_handler
__data_handler
ldr pc,[pc,#24] ; Branch to data_handler
__vector_0x14
dc32 0xFFFFFFFF
__irq_handler:
ldr pc,[pc, #-0x0120] ; Branch to irq_handler
__fiq_handler:
ldr pc,[pc,#24] ; Branch to fiq_handler
; Constant table entries (for ldr pc) will be placed at 0x20
dc32 __iar_program_start
dc32 __undef_handler
dc32 __swi_handler
dc32 __prefetch_handler
dc32 __data_handler
dc32 0xFFFFFFFF
dc32 0xFFFFFFFF
dc32 __fiq_handler
; --------------------
; Mode, correspords to bits 0-5 in CPSR
MODE_MSK DEFINE 0x1F ; Bit mask for mode bits in CPSR
USR_MODE DEFINE 0x10 ; User mode
FIQ_MODE DEFINE 0x11 ; Fast Interrupt Request mode
IRQ_MODE DEFINE 0x12 ; Interrupt Request mode
SVC_MODE DEFINE 0x13 ; Supervisor mode
ABT_MODE DEFINE 0x17 ; Abort mode
UND_MODE DEFINE 0x1B ; Undefined Instruction mode
SYS_MODE DEFINE 0x1F ; System mode
CP_DIS_MASK DEFINE 0xFFFFFFF2
SECTION .text:CODE:NOROOT(2)
EXTERN ?main
REQUIRE __vector
EXTERN low_level_init
ARM
__iar_program_start:
?cstartup:
I_Bit DEFINE 0x80 ; when I bit is set, IRQ is disabled
F_Bit DEFINE 0x40 ; when F bit is set, FIQ is disabled
#define VIC_INT_ENABLE 0xFFFFF014
; Disable all interrupts
ldr r0,=VIC_INT_ENABLE
mov r1,#0xFFFFFFFF
str r1,[r0]
; Execution starts here.
; After a reset, the mode is ARM, Supervisor, interrupts disabled.
; Initialize the stack pointers.
; The pattern below can be used for any of the exception stacks:
; FIQ, IRQ, SVC, ABT, UND, SYS.
; The USR mode uses the same stack as SYS.
; The stack segments must be defined in the linker command file,
; and be declared above.
mrs r0,cpsr ; Original PSR value
bic r0,r0,#MODE_MSK ; Clear the mode bits
orr r0,r0,#SVC_MODE ; Set Supervisor mode bits
msr cpsr_c,r0 ; Change the mode
ldr sp,=SFE(SVC_STACK) ; End of SVC_STACK
bic r0,r0,#MODE_MSK ; Clear the mode bits
orr r0,r0,#UND_MODE ; Set Undefined mode bits
msr cpsr_c,r0 ; Change the mode
ldr sp,=SFE(UND_STACK) ; End of UND_MODE
bic r0,r0,#MODE_MSK ; Clear the mode bits
orr r0,r0,#ABT_MODE ; Set Data abort mode bits
msr cpsr_c,r0 ; Change the mode
ldr sp,=SFE(ABT_STACK) ; End of ABT_STACK
bic r0,r0,#MODE_MSK ; Clear the mode bits
orr r0,r0,#FIQ_MODE ; Set FIR mode bits
msr cpsr_c,r0 ; Change the mode
ldr sp,=SFE(FIQ_STACK) ; End of FIQ_STACK
bic r0,r0,#MODE_MSK ; Clear the mode bits
orr r0,r0,#IRQ_MODE ; Set IRQ mode bits
msr cpsr_c,r0 ; Change the mode
ldr sp,=SFE(IRQ_STACK) ; End of IRQ_STACK
bic r0,r0,#MODE_MSK | I_Bit | F_Bit ; Clear the mode bits
orr r0,r0,#SYS_MODE ; Set System mode bits
msr cpsr_c,r0 ; Change the mode
ldr sp,=SFE(CSTACK) ; End of CSTACK
#ifdef __ARMVFP__
; Enable the VFP coprocessor.
mov r0, #BASE_ARD_EIM ; Set EN bit in VFP
fmxr fpexc, r0 ; FPEXC, clear others.
; Disable underflow exceptions by setting flush to zero mode.
; For full IEEE 754 underflow compliance this code should be removed
; and the appropriate exception handler installed.
mov r0, #0x01000000 ; Set FZ bit in VFP
fmxr fpscr, r0 ; FPSCR, clear others.
#endif
; Add more initialization here
; Continue to ?main for more IAR specific system startup
ldr r0,=?main
bx r0
END
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