📄 lpc2xxx_cstartup.s79
字号:
;-----------------------------------------------------------------------------
; This file contains the startup code used by the ICCARM C compiler.
;
; The modules in this file are included in the libraries, and may be replaced
; by any user-defined modules that define the PUBLIC symbol _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.
;
; All code in the modules (except ?RESET) will be placed in the ICODE segment.
;
; $Revision: 1.1 $
;
;-----------------------------------------------------------------------------
;
; Naming covention of labels in this file:
;
; ?xxx - External labels only accessed from assembler.
; __xxx - External labels accessed from or defined in C.
; xxx - Labels local to one module (note: this file contains
; several modules).
; main - The starting point of the user program.
;
;---------------------------------------------------------------
; Macros and definitions for the whole file
;---------------------------------------------------------------
; Mode, correspords to bits 0-5 in CPSR
MODE_BITS 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
;---------------------------------------------------------------
; ?RESET
; Reset Vector.
; Normally, segment INTVEC is linked at address 0.
; For debugging purposes, INTVEC may be placed at other
; addresses.
; A debugger that honors the entry point will start the
; program in a normal way even if INTVEC is not at address 0.
;---------------------------------------------------------------
MODULE ?RESET
COMMON INTVEC:CODE:NOROOT(2)
PUBLIC __program_start
EXTERN ?cstartup
EXTERN undef_handler, swi_handler, prefetch_handler
EXTERN data_handler, irq_handler, fiq_handler
CODE32 ; Always ARM mode after reset
org 0x00
__program_start
ldr pc,[pc,#24] ; Absolute jump can reach 4 GByte
; ldr b,?cstartup ; Relative branch allows remap, limited to 32 MByte
; Vectors can be enabled by removing the comments below or by
; using #pragma vector from C code.
org 0x04
; ldr pc,[pc,#24] ; Branch to undef_handler
org 0x08
; ldr pc,[pc,#24] ; Branch to swi_handler
org 0x0c
; ldr pc,[pc,#24] ; Branch to prefetch_handler
org 0x10
; ldr pc,[pc,#24] ; Branch to data_handler
org 0x18
; ldr pc,[pc,#24] ; Branch to irq_handler
org 0x1c
; ldr pc,[pc,#24] ; Branch to fiq_handler
; Constant table entries (for ldr pc) will be placed at 0x20
; Exception vectors can be specified in C code by #pragma vector or by filling
; in the vectors below. The vector address is the ARM vector number + 0x20.
org 0x20
dc32 ?cstartup
org 0x24
; dc32 undef_handler
org 0x28
; dc32 swi_handler
org 0x2c
; dc32 prefetch_handler
org 0x30
; dc32 data_handler
org 0x38
; dc32 irq_handler
org 0x3c
; dc32 fiq_handler
LTORG
; ENDMOD __program_start
ENDMOD
;---------------------------------------------------------------
; ?CSTARTUP
;---------------------------------------------------------------
MODULE ?CSTARTUP
RSEG IRQ_STACK:DATA(2)
RSEG ABT_STACK:DATA:NOROOT(2)
RSEG UND_STACK:DATA:NOROOT(2)
RSEG FIR_STACK:DATA:NOROOT(2)
RSEG SVC_STACK:DATA:NOROOT(2)
RSEG CSTACK:DATA(2)
RSEG ICODE:CODE:NOROOT(2)
PUBLIC ?cstartup
EXTERN ?main
; Execution starts here.
; After a reset, the mode is ARM, Supervisor, interrupts disabled.
CODE32
?cstartup
; Add initialization nedded before setup of stackpointers here
; 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_BITS ; 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) & 0xFFFFFFF8 ; End of IRQ_STACK
bic r0,r0,#MODE_BITS ; Clear the mode bits
orr r0,r0,#ABT_MODE ; Set Abort mode bits
msr cpsr_c,r0 ; Change the mode
ldr sp,=SFE(ABT_STACK) & 0xFFFFFFF8 ; End of ABT_STACK
bic r0,r0,#MODE_BITS ; 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) & 0xFFFFFFF8 ; End of SVC_STACK
bic r0,r0,#MODE_BITS ; 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) & 0xFFFFFFF8 ; End of FIR_STACK
bic r0,r0,#MODE_BITS ; Clear the mode bits
orr r0,r0,#FIQ_MODE ; Set FIR mode bits
msr cpsr_c,r0 ; Change the mode
ldr sp,=SFE(FIR_STACK) & 0xFFFFFFF8 ; End of FIR_STACK
bic r0,r0,#MODE_BITS ; Clear the mode bits
orr r0,r0,#SYS_MODE ; Set System mode bits
msr cpsr_c,r0 ; Change the mode
ldr sp,=SFE(CSTACK) & 0xFFFFFFF8 ; End of CSTACK
#ifdef __ARMVFP__
; Enable the VFP coprocessor.
mov r0, #0x40000000 ; 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
LTORG
ENDMOD
END
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -