;------------------------------------------------------------------------------
;-         ATMEL Microcontroller Software Support  -  ROUSSET  -
;------------------------------------------------------------------------------
; The software is delivered "AS IS" without warranty or condition of any
; kind, either express, implied or statutory. This includes without
; limitation any warranty or condition with respect to merchantability or
; fitness for any particular purpose, or against the infringements of
; intellectual property rights of others.
;-----------------------------------------------------------------------------
;- File source          : Cstartup.s79
;- Object               : Generic CStartup for IAR No Use REMAP
;- Compilation flag     : None
;-
;- 1.0 15/Jun/04 JPP    : Creation
;- 1.1 01/Apr/05 JPP    : save SPSR
;------------------------------------------------------------------------------

;------------------------------------------------------------------------------
;- Area Definition
;------------------------------------------------------------------------------

AT91C_BASE_AIC  EQU   0xFFFFF000
AIC_FVR         EQU   (260)
AIC_IVR         EQU   (256)
AIC_EOICR       EQU   (304)

;---------------------------------------------------------------
; ?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
    RSEG      INTRAMSTART_REMAP
    RSEG      INTRAMEND_REMAP

    RSEG      ICODE:CODE:ROOT(2)
    CODE32    ; Always ARM mode after reset	
    org       0
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.
;------------------------------------------------------------------------------

    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


InitReset:
;------------------------------------------------------------------------------
;- Low level Init (PMC, AIC, ? ....) by C function AT91F_LowLevelInit
;------------------------------------------------------------------------------
    EXTERN    AT91F_LowLevelInit

#define  __iramend    SFB(INTRAMEND_REMAP)

;- minumum C initialization
;- call  AT91F_LowLevelInit( void)

    ldr       r13, =__iramend            ; temporary stack in internal RAM

;--Call Low level init function in ABSOLUTE through the Interworking
    ldr       r0, =AT91F_LowLevelInit
    mov       lr, pc
    bx        r0

;------------------------------------------------------------------------------
;- Stack Sizes Definition
;------------------------
;- Interrupt Stack requires 2 words x 8 priority level x 4 bytes when using
;- the vectoring. This assume that the IRQ management.
;- The Interrupt Stack must be adjusted depending on the interrupt handlers.
;- Fast Interrupt not requires stack If in your application it required you must
;- be definehere.
;- The System stack size is not defined and is limited by the free internal
;- SRAM.
;------------------------------------------------------------------------------

;------------------------------------------------------------------------------
;- 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 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


;---------------------------------------------------------------
; ?CSTARTUP
;---------------------------------------------------------------
    EXTERN    __segment_init
    EXTERN    main
; 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).
    ldr       r0, =__segment_init
    mov       lr, pc
    bx        r0

    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


;------------------------------------------------------------------------------
;- Manage exception
;---------------
;- This module 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 SPSR need to be saved for nested interrupt
    mrs       r14, SPSR
    stmfd     sp!, {r14}

;- Save and r0 in IRQ stack
    stmfd     sp!, {r0}

;- 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

;- 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 R0
    ldmia     sp!, {r0}

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

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

;---------------------------------------------------------------
; ?EXEPTION_VECTOR
; This module is only linked if needed for closing files.
;---------------------------------------------------------------
    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

;---------------------------------------------------------------
; ?EXEPTION_VECTOR
; This module is only linked if needed for closing files.
;---------------------------------------------------------------
#define IRQ_MASK   0x00000080
#define FIQ_MASK   0x00000040
#define INTs_MASK  (IRQ_MASK | FIQ_MASK)

;---------------------------------------------------
; \fn extern void AT91F_enable_interrupt(void)
; \brief Enable Core interrupt
;---------------------------------------------------

    PUBLIC    AT91F_enable_interrupt

    CODE32    ; Always ARM mode after exeption

AT91F_enable_interrupt
    mrs       r0, CPSR
    bic       r0, r0, #INTs_MASK
    msr       CPSR_c, r0
    bx        lr

;---------------------------------------------------
; \fn extern void AT91F_disable_interrupt(void)
; \brief Disable Core interrupt
;---------------------------------------------------

    PUBLIC    AT91F_disable_interrupt

    CODE32    ; Always ARM mode after exeption

AT91F_disable_interrupt
    mrs       r0, CPSR
    orr       r0, r0, #INTs_MASK
    msr       CPSR_c, r0
    mrs       r0, CPSR
    ands      r0, r0, #INTs_MASK
    beq       AT91F_disable_interrupt
    bx        lr

    ENDMOD

  END