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;************************************************************************
;*
;*               Copyright Mentor Graphics Corporation 2002
;*                         All Rights Reserved.
;*
;* THIS WORK CONTAINS TRADE SECRET AND PROPRIETARY INFORMATION WHICH IS
;* THE PROPERTY OF MENTOR GRAPHICS CORPORATION OR ITS LICENSORS AND IS
;* SUBJECT TO LICENSE TERMS.
;*
;************************************************************************
;************************************************************************
;*
;* FILE NAME                              VERSION
;*
;*      tmt.s                   Nucleus PLUS\ARM925\Code Composer 1.14.1
;*
;* COMPONENT
;*
;*      TM - Timer Management
;*
;* DESCRIPTION
;*
;*      This file contains the target dependent routines of the timer
;*      management component.
;*
;* FUNCTIONS
;*
;*      TMT_Set_Clock                       Set system clock
;*      TMT_Retrieve_Clock                  Retrieve system clock
;*      TMT_Read_Timer                      Read count-down timer
;*      TMT_Enable_Timer                    Enable count-down timer
;*      TMT_Adjust_Timer                    Adjust count-down timer
;*      TMT_Disable_Timer                   Disable count-down timer
;*      TMT_Retrieve_TS_Task                Retrieve time-sliced task ptr
;*      TMT_Timer_Interrupt                 Process timer interrupt
;*
;* DEPENDENCIES
;*
;*      tc_extr.h                           Thread Control functions
;*      tm_extr.h                           Timer functions
;*
;* HISTORY
;*
;*         NAME            DATE                    REMARKS
;*
;*      B. Ronquillo     08-28-2002           Released version 1.14.1
;*
;*
;************************************************************************
;#define         NU_SOURCE_FILE
;******************************
;* INCLUDE ASSEMBLY CONSTANTS *
;******************************
; Define constants used in low-level initialization.
LOCKOUT                     .equ    00C0h   ; Interrupt lockout value

	.state32

;**********************************
;* EXTERNAL VARIABLE DECLARATIONS *
;**********************************
; Define external inner-component global data references.
;extern VOID           *TCD_Current_Thread;
;extern UNSIGNED        TMD_System_Clock;
;extern UNSIGNED        TMD_Timer;
;extern INT             TMD_Timer_State;
;extern UNSIGNED        TMD_Time_Slice;
;extern TC_TCB         *TMD_Time_Slice_Task;
;extern INT             TMD_Time_Slice_State;
;extern TC_HCB          TMD_HISR;

        .ref  _TCD_Current_Thread
        .ref  _TMD_System_Clock
        .ref  _TMD_Timer
        .ref  _TMD_Timer_State
        .ref  _TMD_Time_Slice
        .ref  _TMD_Time_Slice_Task
        .ref  _TMD_Time_Slice_State
        .ref  _TMD_HISR
        .ref  _TCD_Interrupt_Level

; Define activate HISR function.
;STATUS  TCT_Activate_HISR(TC_HCB *hisr);

        .ref  _TCT_Activate_HISR

    .text
;**********************************
;* LOCAL VARIABLE DECLARATIONS    *
;**********************************
; Define various data structure pointers so their addresses
; can be obtained in a PC-relative manner.

System_Clock
        .word     _TMD_System_Clock

Timer
        .word     _TMD_Timer

Timer_State
        .word     _TMD_Timer_State

Slice_State
        .word     _TMD_Time_Slice_State

Time_Slice
        .word     _TMD_Time_Slice

Current_Thread
        .word     _TCD_Current_Thread

Slice_Task
        .word     _TMD_Time_Slice_Task

HISR
        .word     _TMD_HISR

Int_Level
        .word     _TCD_Interrupt_Level

;************************************************************************
;*
;* FUNCTION
;*
;*      TMT_Set_Clock
;*
;* DESCRIPTION
;*
;*      This function sets the system clock to the specified value.
;*
;* CALLED BY
;*
;*      Application
;*
;* CALLS
;*
;*      None
;*
;* INPUTS
;*
;*      new_value                           New value for the clock
;*
;* OUTPUTS
;*
;*      None
;*
;* HISTORY
;*
;*         NAME            DATE                    REMARKS
;*
;*      W. Lamie        02-15-1994      Created initial version 1.0
;*      D. Lamie        02-15-1994      Verified version 1.0
;*
;************************************************************************
;VOID  TMT_Set_Clock(UNSIGNED new_value)
;{
    .def    $TMT_Set_Clock
$TMT_Set_Clock                              ; Dual-state interworking veneer
    .state16
    BX  r15
    NOP
    .state32
    B   _TMT_Set_Clock

        .def    _TMT_Set_Clock
_TMT_Set_Clock

; Set the system clock to the specified value.
;    TMD_System_Clock =  new_value;

        LDR     r1,System_Clock             ; Build address of system clock
        STR     r0,[r1,#0]                  ; Store new system clock value

        BX      r14                         ; Return to caller

;}

;************************************************************************
;*
;* FUNCTION
;*
;*      TMT_Retrieve_Clock
;*
;* DESCRIPTION
;*
;*      This function returns the current value of the system clock.
;*
;* CALLED BY
;*
;*      Application
;*
;* CALLS
;*
;*      None
;*
;* INPUTS
;*
;*      None
;*
;* OUTPUTS
;*
;*      TMD_System_Clock                    Value of system clock
;*
;* HISTORY
;*
;*         NAME            DATE                    REMARKS
;*
;*      W. Lamie        02-15-1994      Created initial version 1.0
;*      D. Lamie        02-15-1994      Verified version 1.0
;*
;************************************************************************
;UNSIGNED  TMT_Retrieve_Clock(void)
;{
    .def    $TMT_Retrieve_Clock
$TMT_Retrieve_Clock                         ; Dual-state interworking veneer
    .state16
    BX  r15
    NOP
    .state32
    B   _TMT_Retrieve_Clock

        .def    _TMT_Retrieve_Clock
_TMT_Retrieve_Clock

; Return the current value of the system clock.
;    return(TMD_System_Clock);

        LDR     r0,System_Clock             ; Build address to system clock
        LDR     r0,[r0,#0]                  ; Pickup system clock contents

        BX      r14                         ; Return to caller

;}

;************************************************************************
;*
;* FUNCTION
;*
;*      TMT_Read_Timer
;*
;* DESCRIPTION
;*
;*      This function returns the current value of the count-down timer.
;*
;* CALLED BY
;*
;*      TMC_Start_Timer                     Start timer function
;*
;* CALLS
;*
;*      None
;*
;* INPUTS
;*
;*      None
;*
;* OUTPUTS
;*
;*      TMD_Timer                           Value of count-down timer
;*
;* HISTORY
;*
;*         NAME            DATE                    REMARKS
;*
;*      W. Lamie        02-15-1994      Created initial version 1.0
;*      D. Lamie        02-15-1994      Verified version 1.0
;*
;************************************************************************
;UNSIGNED  TMT_Read_Timer(void)
;{
    .def    $TMT_Read_Timer
$TMT_Read_Timer                             ; Dual-state interworking veneer
    .state16
    BX  r15
    NOP
    .state32
    B   _TMT_Read_Timer

        .def    _TMT_Read_Timer
_TMT_Read_Timer

; Return the current value of the count-down timer.
;    return(TMD_Timer);

        LDR     r0,Timer                    ; Build address to timer
        LDR     r0,[r0,#0]                  ; Pickup timer contents

        BX      r14                         ; Return to caller

;}

;************************************************************************
;*
;* FUNCTION
;*
;*      TMT_Enable_Timer
;*
;* DESCRIPTION
;*
;*      This function enables the count-down timer with the specified
;*      value.
;*
;* CALLED BY
;*
;*      TMC_Start_Timer                     Start timer function
;*      TMC_Timer_Task                      Timer expiration task
;*
;* CALLS
;*
;*      None
;*
;* INPUTS
;*
;*      time                                New count-down time
;*
;* OUTPUTS
;*
;*      None
;*
;* HISTORY
;*
;*         NAME            DATE                    REMARKS
;*
;*      W. Lamie        02-15-1994      Created initial version 1.0
;*      D. Lamie        02-15-1994      Verified version 1.0
;*
;************************************************************************
;VOID  TMT_Enable_Timer(UNSIGNED time)
;{
    .def    $TMT_Enable_Timer
$TMT_Enable_Timer                           ; Dual-state interworking veneer
    .state16
    BX  r15
    NOP
    .state32
    B   _TMT_Enable_Timer

        .def    _TMT_Enable_Timer
_TMT_Enable_Timer

; Place the new time value into the count-down timer.
;    TMD_Timer =  time;

        LDR     r1,Timer                    ; Build address of timer
        STR     r0,[r1,#0]                  ; Store new timer value

; Indicate that the timer is active.
;    TMD_Timer_State =  TM_ACTIVE;

        MOV     r0,#0                       ; Build TM_ACTIVE value
        LDR     r1,Timer_State              ; Build address of timer state var
        STR     r0,[r1,#0]                  ; Change the state to active

        BX      r14                         ; Return to caller

;}

;************************************************************************
;*
;* FUNCTION
;*
;*      TMT_Adjust_Timer
;*
;* DESCRIPTION
;*
;*      This function adjusts the count-down timer with the specified
;*      value, if the new value is less than the current.
;*
;* CALLED BY
;*
;*      None
;*
;* CALLS
;*
;*      None
;*
;* INPUTS
;*
;*      time                                New count-down time.
;*
;* OUTPUTS
;*
;*      None
;*
;* HISTORY
;*
;*         NAME            DATE                    REMARKS
;*
;*      C. Meredith     03-01-1994      Created initial version 1.1
;*      D. Lamie        03-18-1994      Verified version 1.1
;*      C. Meredith     08-27-1994      Corrected bug in new timer
;*                                        adjust routine, resulting in
;*                                        version 1.1a
;*      W. Lamie        08-27-1994      Verified version 1.1a
;*
;************************************************************************
;VOID  TMT_Adjust_Timer(UNSIGNED time)
;{
    .def    $TMT_Adjust_Timer
$TMT_Adjust_Timer                           ; Dual-state interworking veneer
    .state16
    BX  r15
    NOP
    .state32
    B   _TMT_Adjust_Timer

        .def    _TMT_Adjust_Timer
_TMT_Adjust_Timer

; Lockout all interrupts
;    TMD_Timer_State =  TM_NOT_ACTIVE;

        MRS     r3,CPSR                     ; Pickup current CPSR
        ORR     r2,r3,#LOCKOUT              ; Build lockout CPSR
        MSR     CPSR,r2                     ; Setup new CPSR interrupt bits

; Check for the new value is less than the current time value
;    if (time < TMD_Timer)

        LDR     r1,Timer                    ; Build address to timer var
        LDR     r2,[r1,#0]                  ; read value of the timer
        CMP     r2,r0                       ; Do Timer - time > 0, means
        BLT     TMT_No_Adjust               ; time < Timer.

;        Adjust the time
;        TMD_Timer = time;

        STR     r0,[r1,#0]                  ; load passed in timer value

; Return to caller after restoring interrupts

TMT_No_Adjust:

        MSR     CPSR,r3                     ; Setup new CPSR enable bits

        BX      r14                         ; Return to caller
;}

;************************************************************************
;*
;* FUNCTION
;*
;*      TMT_Disable_Timer
;*
;* DESCRIPTION
;*
;*      This function disables the count-down timer.
;*
;* CALLED BY
;*
;*      TMC_Start_Timer                     Start timer function
;*      TMC_Timer_Task                      Timer expiration task
;*
;* CALLS
;*
;*      None
;*
;* INPUTS
;*
;*      None
;*
;* OUTPUTS
;*
;*      None
;*
;* HISTORY
;*
;*         NAME            DATE                    REMARKS
;*
;*      W. Lamie        02-15-1994      Created initial version 1.0
;*      D. Lamie        02-15-1994      Verified version 1.0
;*
;************************************************************************
;VOID  TMT_Disable_Timer(void)
;{
    .def    $TMT_Disable_Timer
$TMT_Disable_Timer                          ; Dual-state interworking veneer
    .state16
    BX  r15
    NOP
    .state32
    B   _TMT_Disable_Timer

        .def    _TMT_Disable_Timer
_TMT_Disable_Timer

; Disable the count-down timer.
;    TMD_Timer_State =  TM_NOT_ACTIVE;

        MOV     r1,#1                       ; Build TM_NOT_ACTIVE value
        LDR     r0,Timer_State              ; Build address to timer state var
        STR     r1,[r0,#0]                  ; Change timer state to not active

        BX      r14                         ; Return to caller
;}

;************************************************************************
;*
;* FUNCTION
;*
;*      TMT_Retreive_TS_Timer
;*
;* DESCRIPTION
;*
;*      This function returns the time-sliced task pointer.
;*
;* CALLED BY
;*
;*      TMC_Timer_HISR                      Timer HISR
;*
;* CALLS
;*
;*      None
;*
;* INPUTS
;*
;*      None
;*
;* OUTPUTS
;*
;*      TMD_Time_Slice_Task                 Time sliced task pointer
;*
;* HISTORY
;*
;*         NAME            DATE                    REMARKS
;*
;*      C. Meredith     03-01-1994      Created initial version 1.1
;*      D. Lamie        03-18-1994      Verified version 1.1
;*
;************************************************************************
;NU_TASK TMT_Retrieve_TS_Task (VOID)
;{
    .def    $TMT_Retrieve_TS_Task
$TMT_Retrieve_TS_Task                        ; Dual-state interworking veneer
    .state16
    BX  r15
    NOP
    .state32
    B   _TMT_Retrieve_TS_Task

        .def    _TMT_Retrieve_TS_Task
_TMT_Retrieve_TS_Task

; Read the current TMD_Time_Slice_Task variable and load for
; return to caller.

        LDR     r1,Slice_Task                ; Build address to timer slice var
        LDR     r0,[r1,#0]                   ; Get task pointer to be returned

; Return to caller time slice value back to caller

        BX      r14                          ; Return to caller

;}

;************************************************************************
;*
;* FUNCTION
;*
;*      TMT_Timer_Interrupt
;*
;* DESCRIPTION
;*
;*      This function processes the actual hardware interrupt.
;*      Processing includes updating the system clock and the count-
;*      down timer and the time-slice timer.  If one or both of the
;*      timers expire, the timer HISR is activated.
;*
;* CALLED BY
;*
;*      Interrupt Vector
;*
;* CALLS
;*
;*      TCT_Activate_HISR                   Activate timer HISR
;*      TCT_Interrupt_Context_Save          Save interrupted context
;*      TCT_Interrupt_Context_Restore       Restore interrupted context
;*
;* INPUTS
;*
;*      None
;*
;* OUTPUTS
;*
;*      None
;*
;* HISTORY
;*
;*         NAME            DATE                    REMARKS
;*
;*      W. Lamie        02-15-1994      Created initial version 1.0
;*      D. Lamie        02-15-1994      Verified version 1.0
;*
;************************************************************************
;VOID  TMT_Timer_Interrupt(void)
;{
        .def  _TMT_Timer_Interrupt
_TMT_Timer_Interrupt

        MRS     r1,CPSR                         ; Pickup current CPSR
        ORR     r1,r1,#LOCKOUT                  ; Set the interrupt lockout bits
        MSR     CPSR,r1                         ; Lockout interrupts

; Increment the system clock.
;    TMD_System_Clock++;

        LDR     r0,System_Clock                 ; Pickup system clock address
        LDR     r1,[r0,#0]                      ; Pickup system clock contents
        ADD     r1,r1,#1                        ; Increment system clock
        STR     r1,[r0,#0]                      ; Store new system clock value

; Determine if the count-down timer is active.
;    if (TMD_Timer_State == TM_ACTIVE)
;    {

        LDR     r1,Timer_State                  ; Build address to timer state flag
        LDR     r0,[r1,#0]                      ; Pickup timer state
        MOV     r3,#2                           ; Build expired value
        CMP     r0,#0                           ; Is there a timer active?
        BNE     TMT_No_Timer_Active             ; No, skip timer processing

; Decrement the count-down timer.
;        TMD_Timer--;

        LDR     r0,Timer                        ; Build timer address
        LDR     r2,[r0,#0]                      ; Pickup the current timer value

; Test if the Timer is at 0 and if so skip the decrement
        cmp     r2,#1
        beq     EXPIRED

        SUBS    r2,r2,#1                        ; Decrement the timer value
        STR     r2,[r0,#0]                      ; Store the new timer value

        bne     TMT_No_Timer_Active             ; Skip over the Set Timer State

; Determine if the timer has expired. If so, modify the state
; to indicate that it has expired.
;        if (TMD_Timer == 0)

;            TMD_Timer_State =  TM_EXPIRED;

EXPIRED:
        STREQ   r3,[r1,#0]                      ; Change the timer state to
                                                ; expired

;    }
TMT_No_Timer_Active:

; Determine if the time-slice timer is active.  Note that the parameters
; for the time-slice are controlled by the Thread Control (TC)
; component.
;    if (TMD_Time_Slice_State == TM_ACTIVE)
;    {
        LDR     r0,Slice_State                  ; Build time slice state address
        LDR     r2,[r0,#0]                      ; Pickup time slice state
        CMP     r2,#0                           ; Is there a time slice active?
        BNE     TMT_No_Time_Slice_Active        ; No, skip time slice processing

; Decrement the time slice counter.
;        TMD_Time_Slice--;

        LDR     r2,Time_Slice                   ; Build time slice address
        LDR     r3,[r2,#0]                      ; Pickup the time slice value
        SUBS    r3,r3,#1                        ; Decrement the time slice
        STR     r3,[r2,#0]                      ; Store the new time slice value

        ; Determine if the time-slice timer has expired. If so, modify the
        ; time-slice state to indicate that it has.
;        if (TMD_Time_Slice == 0)
;        {

        BNE     TMT_No_Time_Slice_Active        ; Has time slice expired?

;            TMD_Time_Slice_State =  TM_EXPIRED;

        MOV     r3,#2                           ; Build TM_EXPIRED value
        STR     r3,[r0,#0]                      ; Indicate time slice is expired

        ; Copy the current thread into the time-slice task pointer.
;            TMD_Time_Slice_Task =  TCD_Current_Thread;

        LDR     r2,Current_Thread               ; Pickup current thread pointer adr
        LDR     r2,[r2,#0]                      ; Pickup current thread pointer
        LDR     r3,Slice_Task                   ; Pickup time slice task pointer ad
        STR     r2,[r3,#0]                      ; Store current thread pointer

;            ((TC_TCB *) TCD_Current_Thread) -> tc_cur_time_slice =  1;

        MOV     r3,#1                           ; For safety, place a minimal time-
        STR     a4,[a3,#20h]!                   ; slice into the task's control
                                                ; block

;        }
;    }
TMT_No_Time_Slice_Active:

    ; Determine if either of the basic timers have expired.  If so,
    ; activate the timer HISR.
;    if ((TMD_Timer_State == TM_EXPIRED) ||
;        (TMD_Time_Slice_State == TM_EXPIRED))
;    {

        LDR     r1,[r1,#0]                      ; Pickup timer state
        CMP     r1,#2                           ; Does it indicate expiration?
        LDRNE   r0,[r0,#0]                      ; Pickup time slice state
        CMPNE   r0,#2                           ; Does it indicate expiration?

        BXNE    r14                             ; Return if no expiration

        ; Activate the HISR timer function.
;        TCT_Activate_HISR(&TMD_HISR);

        STR     r14,[r13, #-4]!                 ; Save r14 on the stack
        LDR     r0,HISR                         ; Build address of timer HISR
        BL      _TCT_Activate_HISR              ; Activate timer HISR
        LDR     r14,[r13], #4                   ; Recover return address
;    }

        BX      r14                             ; Return to caller

;}
        .end
author	Mychaela Falconia <falcon@freecalypso.org>
date	Fri, 15 May 2020 01:28:16 +0000
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