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;- ----------------------------------------------------------------------------
;- ATMEL Microcontroller Software Support - ROUSSET -
;- ----------------------------------------------------------------------------
;- 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.
;- ----------------------------------------------------------------------------
;- File source : Cstartup.s79
;- Object : Generic CStartup
;- 1.0 01/Sep/05 FBr : Creation
;- 1.1 09/Sep/05 JPP : Change Interrupt management
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
; Include your AT91 Library files
;------------------------------------------------------------------------------
#include "AT91SAM7X256_inc.h"
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
; ?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
RSEG INTRAMEND_REMAP ;- Begins a relocatable segment
RSEG ICODE:CODE (2) ;- Begins a relocatable segment : corresponding address is 32-bit aligned
CODE32 ;- Always ARM mode after reset
ORG 0 ;- Sets the location counter: corresponds to the RESET vector address
;------------------------------------------------------------------------------
;- 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
B 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:
B rsvdvec ; 0x14 reserved
irqvec:
B IRQ_Handler_Entry ; 0x18 IRQ
fiqvec: ; 0x1c FIQ
;------------------------------------------------------------------------------
;- Function : FIQ_Handler_Entry
;- Treatments : FIQ Controller Interrupt Handler.
;- Called Functions : AIC_FVR[interrupt]
;------------------------------------------------------------------------------
FIQ_Handler_Entry:
;- Switch in SVC/User Mode to allow User Stack access for C code
; because the FIQ is not yet acknowledged
;- Save and r0 in FIQ_Register
mov r9,r0
ldr r0 , [r8, #AIC_FVR]
msr CPSR_c,#I_BIT | F_BIT | ARM_MODE_SVC
;- Save scratch/used registers and LR in User Stack
stmfd sp!, { r1-r3, r12, lr}
;- Branch to the routine pointed by the AIC_FVR
mov r14, pc
bx r0
;- Restore scratch/used registers and LR from User Stack
ldmia sp!, { r1-r3, r12, lr}
;- Leave Interrupts disabled and switch back in FIQ mode
msr CPSR_c, #I_BIT | F_BIT | ARM_MODE_FIQ
;- Restore the R0 ARM_MODE_SVC register
mov r0,r9
;- Restore the Program Counter using the LR_fiq directly in the PC
subs pc,lr,#4
;------------------------------------------------------------------------------
;- 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}^
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
__iramend EQU SFB(INTRAMEND_REMAP) ;- Segment begin
EXTERN AT91F_LowLevelInit
ldr r13,=__iramend ;- Temporary stack in internal RAM for Low Level Init execution
ldr r0,=AT91F_LowLevelInit
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.
;------------------------------------------------------------------------------
IRQ_STACK_SIZE EQU (3*8*4) ; 3 words to be saved per interrupt priority level
ARM_MODE_FIQ EQU 0x11
ARM_MODE_IRQ EQU 0x12
ARM_MODE_SVC EQU 0x13
I_BIT EQU 0x80
F_BIT EQU 0x40
;------------------------------------------------------------------------------
;- Setup the stack for each mode
;------------------------------------------------------------------------------
ldr r0, =__iramend
;- Set up Fast Interrupt Mode and set FIQ Mode Stack
msr CPSR_c, #ARM_MODE_FIQ | I_BIT | F_BIT
;- Init the FIQ register
ldr r8, =AT91C_BASE_AIC
;- 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
mov r13, r0
;------------------------------------------------------------------------------
; Initialize segments.
;------------------------------------------------------------------------------
; __segment_init is assumed to use
; instruction set and to be reachable by BL from the ICODE segment
; (it is safest to link them in segment ICODE).
;------------------------------------------------------------------------------
EXTERN __segment_init
ldr r0,=__segment_init
mov lr, pc
bx 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
;------------------------------------------------------------------------------
;- Exception Vectors
;------------------------------------------------------------------------------
PUBLIC AT91F_Default_FIQ_handler
PUBLIC AT91F_Default_IRQ_handler
PUBLIC AT91F_Spurious_handler
CODE32 ; 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
ENDMOD ;- Terminates the assembly of the current module
END ;- Terminates the assembly of the last module in a file
|
