lpc2xxx_cstartup.s79
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上传日期：2013-09-23
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- ;-----------------------------------------------------------------------------
- ; 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
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