Startup.s
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上传日期：2022-06-12
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- ;/*****************************************************************************
- ;* startup.s: startup file for NXP LPC230x Family Microprocessors
- ;*
- ;* Copyright(C) 2006, NXP Semiconductor
- ;* All rights reserved.
- ;*
- ;* History
- ;* 2006.09.01 ver 1.00 Prelimnary version, first Release
- ;*
- ;*****************************************************************************/
- PRESERVE8
- ;/*
- ; * The STARTUP.S code is executed after CPU Reset. This file may be
- ; * translated with the following SET symbols. In uVision these SET
- ; * symbols are entered under Options - ASM - Define.
- ; *
- ; * REMAP: when set the startup code initializes the register MEMMAP
- ; * which overwrites the settings of the CPU configuration pins. The
- ; * startup and interrupt vectors are remapped from:
- ; * 0x00000000 default setting (not remapped)
- ; * 0x40000000 when RAM_MODE is used
- ; *
- ; * RAM_MODE: when set the device is configured for code execution
- ; * from on-chip RAM starting at address 0x40000000.
- ; */
- ; Standard definitions of Mode bits and Interrupt (I & F) flags in PSRs
- Mode_USR EQU 0x10
- Mode_FIQ EQU 0x11
- Mode_IRQ EQU 0x12
- Mode_SVC EQU 0x13
- Mode_ABT EQU 0x17
- Mode_UND EQU 0x1B
- Mode_SYS EQU 0x1F
- I_Bit EQU 0x80 ; when I bit is set, IRQ is disabled
- F_Bit EQU 0x40 ; when F bit is set, FIQ is disabled
- ;// <h> Stack Configuration (Stack Sizes in Bytes)
- ;// <o0> Undefined Mode <0x0-0xFFFFFFFF:8>
- ;// <o1> Supervisor Mode <0x0-0xFFFFFFFF:8>
- ;// <o2> Abort Mode <0x0-0xFFFFFFFF:8>
- ;// <o3> Fast Interrupt Mode <0x0-0xFFFFFFFF:8>
- ;// <o4> Interrupt Mode <0x0-0xFFFFFFFF:8>
- ;// <o5> User/System Mode <0x0-0xFFFFFFFF:8>
- ;// </h>
- UND_Stack_Size EQU 0x00000000
- SVC_Stack_Size EQU 0x00000100
- ABT_Stack_Size EQU 0x00000000
- FIQ_Stack_Size EQU 0x00000000
- IRQ_Stack_Size EQU 0x00000120 ;每层嵌套需要9个字堆栈，允许8层嵌套
- USR_Stack_Size EQU 0x00000200
- Stack_Size EQU (UND_Stack_Size + SVC_Stack_Size + ABT_Stack_Size +
- FIQ_Stack_Size + IRQ_Stack_Size + USR_Stack_Size)
- AREA STACK, NOINIT, READWRITE, ALIGN=3
- Stack_Mem SPACE Stack_Size
- StackUsr EQU Stack_Mem+USR_Stack_Size
- Stack_Top EQU Stack_Mem + Stack_Size
- EXPORT StackUsr ;声明为外部标号，供IRQ.S调用。
- ;// <h> Heap Configuration
- ;// <o> Heap Size (in Bytes) <0x0-0xFFFFFFFF>
- ;// </h>
- Heap_Size EQU 0x00000001
-
- AREA HEAP, NOINIT, READWRITE, ALIGN=3
- Heap_Mem SPACE Heap_Size
- ; Area Definition and Entry Point
- ; Startup Code must be linked first at Address at which it expects to run.
- ;引入的外部标号在这声明
- IMPORT FIQ_Exception ;快速中断异常处理程序
- IMPORT __main ;C语言主程序入口
- IMPORT TargetResetInit ;目标板基本初始化
- IMPORT SoftwareInterrupt ;软件中断的处理函数
-
- AREA RESET, CODE, READONLY
- ARM
- ; Exception Vectors
- ; Mapped to Address 0.
- ; Absolute addressing mode must be used.
- ; Dummy Handlers are implemented as infinite loops which can be modified.
- ;;中断向量表
- ;;对于1.未定义指令 2.预取指中止 3.数据中止三种异常不做处理
- ;;
- Vectors LDR PC, Reset_Addr
- LDR PC, Undef_Addr
- LDR PC, SWI_Addr
- LDR PC, PAbt_Addr
- LDR PC, DAbt_Addr
- NOP ; Reserved Vector
- ; LDR PC, IRQ_Addr
- LDR PC, [PC, #-0x0120] ; Vector from VicVectAddr
- LDR PC, FIQ_Addr
- Reset_Addr DCD Reset_Handler
- Undef_Addr DCD Undef_Handler
- SWI_Addr DCD SoftwareInterrupt
- PAbt_Addr DCD PAbt_Handler
- DAbt_Addr DCD DAbt_Handler
- ;DCD 0xB9206E28 ; Reserved Address
- DCD 0xB9206E50 ;以保证前32字节指令相加和为0
- ;IRQ_Addr DCD IRQ_Handler
- FIQ_Addr DCD FIQ_Handler
- Undef_Handler B Undef_Handler
- ;SWI_Handler B SWI_Handler
- PAbt_Handler B PAbt_Handler
- DAbt_Handler B DAbt_Handler
- ;IRQ_Handler B IRQ_Handler
- FIQ_Handler
- STMFD SP!, {R0-R3, LR}
- BL FIQ_Exception
- LDMFD SP!, {R0-R3, LR}
- SUBS PC, LR, #4
- ; Reset Handler
- EXPORT Reset_Handler
- Reset_Handler
- ; Setup Stack for each mode
- LDR R0, =Stack_Top
- ; Enter Undefined Instruction Mode and set its Stack Pointer
- MSR CPSR_c, #Mode_UND:OR:I_Bit:OR:F_Bit
- MOV SP, R0
- SUB R0, R0, #UND_Stack_Size
- ; Enter Abort Mode and set its Stack Pointer
- MSR CPSR_c, #Mode_ABT:OR:I_Bit:OR:F_Bit
- MOV SP, R0
- SUB R0, R0, #ABT_Stack_Size
- ; Enter FIQ Mode and set its Stack Pointer
- MSR CPSR_c, #Mode_FIQ:OR:I_Bit:OR:F_Bit
- MOV SP, R0
- SUB R0, R0, #FIQ_Stack_Size
- ; Enter IRQ Mode and set its Stack Pointer
- MSR CPSR_c, #Mode_IRQ:OR:I_Bit:OR:F_Bit
- MOV SP, R0
- SUB R0, R0, #IRQ_Stack_Size
- ; Enter Supervisor Mode and set its Stack Pointer
- MSR CPSR_c, #Mode_SVC:OR:I_Bit:OR:F_Bit
- MOV SP, R0
- SUB R0, R0, #SVC_Stack_Size
- ; Enter User Mode and set its Stack Pointer
- MSR CPSR_c, #Mode_USR
- MOV SP, R0
- SUB SL, SP, #USR_Stack_Size
-
- ; IMPORT TargetResetInit
- BL TargetResetInit ;在target.c文件中
- ; Enter the C code
- ; IMPORT __main
- LDR R0, =__main
- BX R0
- ; User Initial Stack & Heap
- ;;函数说明参考RV_CC.PDF文件P291
- ;;function: __user_initial_stackheap
- ;;description:初始化堆栈(stack)和堆(heap),函数采用双存储器区域。
- ;;parameter:r0,sp,r2
- ;;return value:r0--堆的基址（heap base in r0）
- ;;r1--堆栈基址，堆栈区域的最高地址
- ;;r2--堆的限制地址(heap limit in r2)
- ;;r3--堆栈限制地址，堆栈区域的最低地址
- ;;
- AREA |.text|, CODE, READONLY
- IMPORT __use_two_region_memory ;select memory model of two memory region
- EXPORT __user_initial_stackheap
- __user_initial_stackheap
- LDR R0, = Heap_Mem
- LDR R1, =(Stack_Mem + USR_Stack_Size)
- LDR R2, = (Heap_Mem + Heap_Size)
- LDR R3, = Stack_Mem
- BX LR
- END
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