cstartup.s

来自「最新版IAR FOR ARM（EWARM）5.11中的代码例子」· S 代码 · 共 239 行

;* ----------------------------------------------------------------------------
;*         ATMEL Microcontroller Software Support  -  ROUSSET  -
;* ----------------------------------------------------------------------------
;* Copyright (c) 2006, Atmel Corporation
;
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;* this software without specific prior written permission.
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;* ----------------------------------------------------------------------------

;------------------------------------------------------------------------------
; Include your AT91 Library files
;------------------------------------------------------------------------------
#define __ASSEMBLY__
#include "project.h"
;------------------------------------------------------------------------------

#define AT91C_ISRAM_SIZE  0x00014000
#define AT91C_ISRAM       0x00300000

#define TOP_OF_MEMORY    (AT91C_ISRAM + AT91C_ISRAM_SIZE)
#define IRQ_STACK_SIZE   (3*8*4)
     ; 3 words to be saved per interrupt priority level

#define ARM_MODE_IRQ     0x12
#define ARM_MODE_SVC     0x13
#define I_BIT     0x80
#define F_BIT     0x40

;------------------------------------------------------------------------------
; ?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.
;------------------------------------------------------------------------------

    PROGRAM     ?RESET              ;- Begins a program module
    SECTION     PROGRAM_DATA:CODE
;    SECTION     INTRAMEND_REMAP     ;- Begins a relocatable segment
    SECTION     .intvec:CODE(2)     ;- Begins a relocatable segment : corresponding address is 32-bit aligned
    ARM                             ;- Always ARM mode after reset

;------------------------------------------------------------------------------
;- Exception vectors
;------------------------------------------------------------------------------
;- These vectors can be read at address 0 or at RAM address
;- They ABSOLUTELY requires to be in relative addresssing mode in order to
;- guarantee a valid jump. For the moment, all are just looping.
;- If an exception occurs before remap, this would result in an infinite loop.
;- To ensure if a exeption occurs before start application to infinite loop.
;------------------------------------------------------------------------------

reset
                ldr         pc, =InitReset      ; 0x00 Reset handler
undefvec:
                B           undefvec            ; 0x04 Undefined Instruction
swivec:
                B           swivec              ; 0x08 Software Interrupt
pabtvec:
                B           pabtvec             ; 0x0C Prefetch Abort
dabtvec:
                B           dabtvec             ; 0x10 Data Abort
rsvdvec:
                DCD         SFE(PROGRAM_DATA)
irqvec:
                B           IRQ_Handler_Entry   ; 0x18 IRQ
fiqvec:
                B           fiqvec              ; 0x1c FIQ

;------------------------------------------------------------------------------
;- Manage exception: The exception must be ensure in ARM mode
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
;- Function             : IRQ_Handler_Entry
;- Treatments           : IRQ Controller Interrupt Handler.
;- Called Functions     : AIC_IVR[interrupt]
;------------------------------------------------------------------------------
IRQ_Handler_Entry:

;-------------------------
;- Manage Exception Entry
;-------------------------
;- Adjust and save LR_irq in IRQ stack
    sub         lr, lr, #4
    stmfd       sp!, {lr}

;- Save r0 and SPSR (need to be saved for nested interrupt)
    mrs         r14, SPSR
    stmfd       sp!, {r0,r14}

;- Write in the IVR to support Protect Mode
;- No effect in Normal Mode
;- De-assert the NIRQ and clear the source in Protect Mode
    ldr         r14, =AT91C_BASE_AIC
    ldr         r0 , [r14, #AIC_IVR]
    str         r14, [r14, #AIC_IVR]

;- Enable Interrupt and Switch in Supervisor Mode
    msr         CPSR_c, #ARM_MODE_SVC

;- Save scratch/used registers and LR in User Stack
    stmfd       sp!, { r1-r3, r12, r14}

;----------------------------------------------
;- Branch to the routine pointed by the AIC_IVR
;----------------------------------------------
    mov         r14, pc
    bx          r0

;----------------------------------------------
;- Manage Exception Exit
;----------------------------------------------
;- Restore scratch/used registers and LR from User Stack
    ldmia       sp!, { r1-r3, r12, r14}

;- Disable Interrupt and switch back in IRQ mode
    msr         CPSR_c, #I_BIT | ARM_MODE_IRQ

;- Mark the End of Interrupt on the AIC
    ldr         r14, =AT91C_BASE_AIC
    str         r14, [r14, #AIC_EOICR]

;- Restore SPSR_irq and r0 from IRQ stack
    ldmia       sp!, {r0,r14}
    msr         SPSR_cxsf, r14

;- Restore adjusted  LR_irq from IRQ stack directly in the PC
    ldmia       sp!, {pc}^

;------------------------------------------------------------------------------
;- Exception Vectors
;------------------------------------------------------------------------------
    PUBLIC    AT91F_Default_FIQ_handler
    PUBLIC    AT91F_Default_IRQ_handler
    PUBLIC    AT91F_Spurious_handler

    ARM      ; Always ARM mode after exeption

AT91F_Default_FIQ_handler
    b         AT91F_Default_FIQ_handler

AT91F_Default_IRQ_handler
    b         AT91F_Default_IRQ_handler

AT91F_Spurious_handler
    b         AT91F_Spurious_handler


        LTORG

;------------------------------------------------------------------------------
; ?INIT
; Program entry.
;------------------------------------------------------------------------------
    SECTION     .text:CODE (2)      ;- Begins a relocatable segment : corresponding address is 32-bit aligned
InitReset:

;------------------------------------------------------------------------------
;- Low level Init is performed in a C function: AT91F_LowLevelInit
;- Init Stack Pointer to a valid memory area before calling AT91F_LowLevelInit
;------------------------------------------------------------------------------

;- Retrieve end of RAM address
    EXTERN   lowlevel_init
    msr     CPSR_c, #ARM_MODE_SVC | I_BIT | F_BIT
    ldr     r13,=TOP_OF_MEMORY              ;- Temporary stack in internal RAM for Low Level Init execution
    ldr     r0,=lowlevel_init
    mov     lr, pc
    bx      r0                          ;- Branch on C function (with interworking)

;------------------------------------------------------------------------------
;- Top of Stack Definition
;------------------------------------------------------------------------------
;- Interrupt and Supervisor Stack are located at the top of internal memory in
;- order to speed the exception handling context saving and restoring.
;- ARM_MODE_SVC (Application, C) Stack is located at the top of the external memory.
;------------------------------------------------------------------------------

;------------------------------------------------------------------------------
;- Setup the stack for each mode
;------------------------------------------------------------------------------
    ldr     r0, =TOP_OF_MEMORY

;- Set up Interrupt Mode and set IRQ Mode Stack
    msr     CPSR_c, #ARM_MODE_IRQ | I_BIT | F_BIT
    mov     r13, r0                     ; Init stack IRQ
    sub     r0, r0, #IRQ_STACK_SIZE

;- Enable interrupt & Set up Supervisor Mode and set Supervisor Mode Stack
    msr     CPSR_c, #ARM_MODE_SVC | F_BIT
    mov     r13, r0

;------------------------------------------------------------------------------
;- Branch on C code Main function (with interworking)
;------------------------------------------------------------------------------
    EXTERN      ?main
    PUBLIC      __main
?jump_to_main:
    ldr lr,=?call_exit
    ldr r0,=?main
__main:
    bx  r0

;------------------------------------------------------------------------------
;- Loop for ever
;------------------------------------------------------------------------------
;- End of application. Normally, never occur.
;- Could jump on Software Reset ( B 0x0 ).
;------------------------------------------------------------------------------
?call_exit:
End
    b       End

    END         ;- Terminates the assembly of the last module in a file