📄 cstartup.s
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;* ----------------------------------------------------------------------------
;* ATMEL Microcontroller Software Support - ROUSSET -
;* ----------------------------------------------------------------------------
;* Copyright (c) 2006, 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.
;*
;* - Redistributions in binary form must reproduce the above copyright notice,
;* this list of conditions and the disclaimer below in the documentation and/or
;* other materials provided with the distribution.
;*
;* 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.
;* ----------------------------------------------------------------------------
;------------------------------------------------------------------------------
; Include your AT91 Library files
;------------------------------------------------------------------------------
#include "AT91SAM7X256_inc.h"
;------------------------------------------------------------------------------
#define TOP_OF_MEMORY (AT91C_ISRAM + AT91C_ISRAM_SIZE)
#define IRQ_STACK_SIZE 200
; 3 words to be saved per interrupt priority level
; 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
I_BIT DEFINE 0x80
F_BIT DEFINE 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.
;------------------------------------------------------------------------------
SECTION .intvec:CODE:NOROOT(2)
PUBLIC __vector
PUBLIC __iar_program_start
EXTERN vPortYieldProcessor
ARM
__vector:
ldr pc,[pc,#+24] ;; Reset
__und_handler:
ldr pc,[pc,#+24] ;; Undefined instructions
__swi_handler:
ldr pc,[pc,#+24] ;; Software interrupt (SWI/SVC)
__prefetch_handler:
ldr pc,[pc,#+24] ;; Prefetch abort
__data_handler:
ldr pc,[pc,#+24] ;; Data abort
DC32 0xFFFFFFFF ;; RESERVED
__irq_handler:
LDR PC, [PC, #-0xF20]
__fiq_handler:
ldr pc,[pc,#+24] ;; FIQ
DC32 __iar_program_start
DC32 __und_handler
DC32 vPortYieldProcessor
DC32 __prefetch_handler
DC32 __data_handler
B .
DC32 IRQ_Handler_Entry
DC32 FIQ_Handler_Entry
;------------------------------------------------------------------------------
;- Manage exception: The exception must be ensure in ARM mode
;------------------------------------------------------------------------------
SECTION text:CODE:NOROOT(2)
ARM
;------------------------------------------------------------------------------
;- Function : FIQ_Handler_Entry
;- Treatments : FIQ Controller Interrupt Handler.
;- R8 is initialize in Cstartup
;- Called Functions : None only by FIQ
;------------------------------------------------------------------------------
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 | SVC_MODE
;- 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 | FIQ_MODE
;- 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
;------------------------------------------------------------------------------
;- 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, #SVC_MODE
;- 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 | IRQ_MODE
;- 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
;------------------------------------------------------------------------------
; ?INIT
; Program entry.
;------------------------------------------------------------------------------
SECTION FIQ_STACK:DATA:NOROOT(3)
SECTION IRQ_STACK:DATA:NOROOT(3)
SECTION SVC_STACK:DATA:NOROOT(3)
SECTION ABT_STACK:DATA:NOROOT(3)
SECTION UND_STACK:DATA:NOROOT(3)
SECTION CSTACK:DATA:NOROOT(3)
SECTION text:CODE:NOROOT(2)
REQUIRE __vector
EXTERN ?main
PUBLIC __iar_program_start
EXTERN AT91F_LowLevelInit
__iar_program_start:
;------------------------------------------------------------------------------
;- 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
ldr r13,=TOP_OF_MEMORY ;- 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)
; 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,#SVC_MODE ; Set SVC mode bits
msr cpsr_c,r0 ; Change the mode
ldr sp,=SFE(SVC_STACK) ; End of SVC_STACK
bic r0,r0,#MODE_BITS ; Clear the mode bits
orr r0,r0,#UND_MODE ; Set UND mode bits
msr cpsr_c,r0 ; Change the mode
ldr sp,=SFE(UND_STACK) ; End of UND_STACK
bic r0,r0,#MODE_BITS ; Clear the mode bits
orr r0,r0,#ABT_MODE ; Set ABT mode bits
msr cpsr_c,r0 ; Change the mode
ldr sp,=SFE(ABT_STACK) ; End of ABT_STACK
bic r0,r0,#MODE_BITS ; Clear the mode bits
orr r0,r0,#FIQ_MODE ; Set FIQ mode bits
msr cpsr_c,r0 ; Change the mode
ldr sp,=SFE(FIQ_STACK) ; End of FIQ_STACK
;- Init the FIQ register
ldr r8, =AT91C_BASE_AIC
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) ; End of IRQ_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) ; 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
msr CPSR_c,#I_BIT | F_BIT | SVC_MODE
; Continue to ?main for more IAR specific system startup
ldr r0,=?main
bx r0
END ;- Terminates the assembly of the last module in a file
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