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|
; * ----------------------------------------------------------------------------
; * ATMEL Microcontroller Software Support
; * ----------------------------------------------------------------------------
; * Copyright (c) 2008, Atmel Corporation
; *
; * All rights reserved.
; *
; * Redistribution and use in source and binary forms, with or without
; * modification, are permitted provided that the following conditions are met:
; *
; * - Redistributions of source code must retain the above copyright notice,
; * this list of conditions and the disclaimer below.
; *
; * Atmel's name may not be used to endorse or promote products derived from
; * this software without specific prior written permission.
; *
; * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR
; * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
; * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
; * DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,
; * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
; * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
; * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
; * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
; * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
; * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
; * ----------------------------------------------------------------------------
; KEIL startup file for AT91SAM7S microcontrollers.
; ------------------------------------------------------------------------------
; Definitions
; ------------------------------------------------------------------------------
; Standard definitions of Mode bits and Interrupt (I & F) flags in PSRs
ARM_MODE_USR EQU 0x10
ARM_MODE_FIQ EQU 0x11
ARM_MODE_IRQ EQU 0x12
ARM_MODE_SVC EQU 0x13
ARM_MODE_ABT EQU 0x17
ARM_MODE_UND EQU 0x1B
ARM_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
AT91C_BASE_AIC EQU 0xFFFFF000
AIC_IVR EQU 0x100
AIC_EOICR EQU 0x130
UND_Stack_Size EQU 0x00000000
SVC_Stack_Size EQU 0x00000100
ABT_Stack_Size EQU 0x00000000
FIQ_Stack_Size EQU 0x00000000
IRQ_Stack_Size EQU 0x00000080
USR_Stack_Size EQU 0x00000400
PRESERVE8
; Area Definition and Entry Point
; Startup Code must be linked first at Address at which it expects to run.
AREA VECTOR, CODE
ARM
; Exception Vectors
Vectors
LDR pc,=resetHandler
undefVector
b undefVector ; Undefined instruction
swiVector
b swiVector ; Software interrupt
prefetchAbortVector
b prefetchAbortVector ; Prefetch abort
dataAbortVector
b dataAbortVector ; Data abort
reservedVector
b reservedVector ; Reserved for future use
irqVector
b irqHandler ; Interrupt
fiqVector
; Fast interrupt
;------------------------------------------------------------------------------
; Handles a fast interrupt request by branching to the address defined in the
; AIC.
;------------------------------------------------------------------------------
fiqHandler
b fiqHandler
;------------------------------------------------------------------------------
; Handles incoming interrupt requests by branching to the corresponding
; handler, as defined in the AIC. Supports interrupt nesting.
;------------------------------------------------------------------------------
irqHandler
; Save interrupt context on the stack to allow nesting */
SUB lr, lr, #4
STMFD sp!, {lr}
MRS lr, SPSR
STMFD sp!, {r0,r1,lr}
; Write in the IVR to support Protect Mode */
LDR lr, =AT91C_BASE_AIC
LDR r0, [r14, #AIC_IVR]
STR lr, [r14, #AIC_IVR]
; Branch to interrupt handler in Supervisor mode */
MSR CPSR_c, #ARM_MODE_SVC
STMFD sp!, {r1-r4, r12, lr}
MOV lr, pc
BX r0
LDMIA sp!, {r1-r4, r12, lr}
MSR CPSR_c, #ARM_MODE_IRQ | I_BIT
; Acknowledge interrupt */
LDR lr, =AT91C_BASE_AIC
STR lr, [r14, #AIC_EOICR]
; Restore interrupt context and branch back to calling code
LDMIA sp!, {r0,r1,lr}
MSR SPSR_cxsf, lr
LDMIA sp!, {pc}^
;------------------------------------------------------------------------------
; After a reset, execution starts here, the mode is ARM, supervisor
; with interrupts disabled.
; Initializes the chip and branches to the main() function.
;------------------------------------------------------------------------------
AREA cstartup, CODE
ENTRY ; Entry point for the application
; Reset Handler
EXPORT resetHandler
IMPORT |Image$$Fixed_region$$Limit|
IMPORT |Image$$Relocate_region$$Base|
IMPORT |Image$$Relocate_region$$ZI$$Base|
IMPORT |Image$$Relocate_region$$ZI$$Limit|
IMPORT |Image$$ARM_LIB_STACK$$Base|
IMPORT |Image$$ARM_LIB_STACK$$ZI$$Limit|
; Perform low-level initialization of the chip using LowLevelInit()
IMPORT LowLevelInit
resetHandler
; Set pc to actual code location (i.e. not in remap zone)
LDR pc, =label
label
; Set up temporary stack (Top of the SRAM)
LDR r0, = |Image$$ARM_LIB_STACK$$ZI$$Limit|
MOV sp, r0
; Call Low level init
LDR r0, =LowLevelInit
MOV lr, pc
BX r0
;Initialize the Relocate_region segment
LDR r0, = |Image$$Fixed_region$$Limit|
LDR r1, = |Image$$Relocate_region$$Base|
LDR r3, = |Image$$Relocate_region$$ZI$$Base|
CMP r0, r1
BEQ %1
; Copy init data
0 CMP r1, r3
LDRCC r2, [r0], #4
STRCC r2, [r1], #4
BCC %0
1 LDR r1, =|Image$$Relocate_region$$ZI$$Limit|
MOV r2, #0
2 CMP r3, r1
STRCC r2, [r3], #4
BCC %2
; Setup Stack for each mode
LDR R0, = |Image$$ARM_LIB_STACK$$ZI$$Limit|
; Enter IRQ Mode and set its Stack Pointer
MSR CPSR_c, #ARM_MODE_IRQ:OR:I_BIT:OR:F_BIT
MOV SP, R0
SUB R4, SP, #IRQ_Stack_Size
; Supervisor mode (interrupts enabled)
MSR CPSR_c, #ARM_MODE_SVC | F_BIT
MOV SP, R4
; Enter the C code
IMPORT __main
LDR R0, =__main
BX R0
loop4
B loop4
END
|
