📄 tct.s
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;/* DESCRIPTION */
;/* */
;/* This function checks the current stack for overflow conditions. */
;/* Additionally, this function keeps track of the minimum amount */
;/* of stack space for the calling thread and returns the current */
;/* available stack space. */
;/* */
;/* AUTHOR */
;/* */
;/* Barry Sellew, Accelerated Technology, Inc. */
;/* */
;/* CALLED BY */
;/* */
;/* TCC_Send_Signals Send signals to a task */
;/* */
;/* CALLS */
;/* */
;/* ERC_System_Error System error handler */
;/* */
;/* INPUTS */
;/* */
;/* None */
;/* */
;/* OUTPUTS */
;/* */
;/* available bytes in stack */
;/* */
;/* HISTORY */
;/* */
;/* NAME DATE REMARKS */
;/* */
;/* B. Sellew 02-21-1997 Created and verified version 1.0 */ */
;/* */
;/*************************************************************************/
XDEF _TCT_Check_Stack
_TCT_Check_Stack:
;UNSIGNED TCT_Check_Stack(void)
;{
;
;TC_TCB *thread;
;UNSIGNED remaining;
;
; /* Pickup the current task/HISR pointer. */
; thread = (TC_TCB *) TCD_Current_Thread;
;
; /* Determine if there is a current thread. */
; if (thread)
; {
;
MOVE.L _TCD_Current_Thread,D0 ; Pickup current thread pointer
BEQ _TCT_No_Stack_Check ; If task or HISR, skip stack check
MOVEA.L D0,A0 ; Point at the thread control block
;
; /* Determine if the stack pointers are out of range. */
; if ((thread -> tc_stack_pointer < thread -> tc_stack_start) ||
; (thread -> tc_stack_pointer > thread -> tc_stack_end))
;
MOVE.L A7,D0 ; Pickup the stack pointer
CMP.L 36(A0),D0 ; Compare with end of stack addr
BCS _TCT_Stack_Overflow ; Stack overflow condition
CMP.L 40(A0),D0 ; Compare with start of stack addr
BLS _TCT_No_Stack_Overflow ; If within limits, no overflow
;
; /* Stack overflow condition exits. */
; ERC_System_Error(NU_STACK_OVERFLOW);
;
_TCT_Stack_Overflow:
PEA 3 ; Put NU_STACK_OVERFLOW on stack
JSR _ERC_System_Error ; Call system error handler
;
_TCT_No_Stack_Overflow:
;
; /* Calculate the amount of available space on the stack. */
; remaining = (BYTE_PTR) thread -> tc_stack_pointer -
; (BYTE_PTR) thread -> tc_stack_start;
;
SUB.L 36(A0),D0 ; Calculate the remaining amount of
; stack space
;
; /* Determine if there is enough memory on the stack to save all of the
; registers. */
; if (remaining < 40)
;
CMPI.L #40,D0 ; Compare with a minimal amount of
; stack space to save context
BGT _TCT_Min_Available ; If remaining is greater, all is
; still okay
;
; /* Stack overflow condition is about to happen. */
; ERC_System_Error(NU_STACK_OVERFLOW);
;
PEA 3 ; Put NU_STACK_OVERFLOW on stack
JSR _ERC_System_Error ; Call system error handler
;
_TCT_Min_Available:
;
; /* Determine if this is a new minimum amount of stack space. */
; if (remaining < thread -> tc_stack_minimum)
;
CMP.L 52(A0),D0 ; Determine if a new minimum has
; been found
BCC _TCT_Stack_Check_Finished ; No, stack checking is finished
;
; /* Save the new stack minimum. */
; thread -> tc_stack_minimum = remaining;
;
MOVE.L D0,52(A0) ; Save new minimum
BRA _TCT_Stack_Check_Finished ; Finished
;
; }
; else
_TCT_No_Stack_Check:
;
; /* Set the remaining bytes to 0. */
; remaining = 0;
;
CLR.L D0 ; Clear return value
;
_TCT_Stack_Check_Finished:
;
; /* Return the remaining number of bytes on the stack. */
; return(remaining);
;
RTS ; Return to caller
;
;}
;
;/*************************************************************************/
;/* */
;/* FUNCTION */
;/* */
;/* TCC_Schedule */
;/* */
;/* DESCRIPTION */
;/* */
;/* This function waits for a thread to become ready. Once a thread */
;/* is ready, this function initiates a transfer of control to that */
;/* thread. */
;/* */
;/* AUTHOR */
;/* */
;/* Barry Sellew, Accelerated Technology, Inc. */
;/* */
;/* CALLED BY */
;/* */
;/* INC_Initialize Main initialization routine */
;/* */
;/* CALLS */
;/* */
;/* TCT_Control_To_Thread Transfer control to a thread */
;/* */
;/* INPUTS */
;/* */
;/* TCD_Execute_Task Pointer to task to execute */
;/* */
;/* OUTPUTS */
;/* */
;/* None */
;/* */
;/* HISTORY */
;/* */
;/* NAME DATE REMARKS */
;/* */
;/* B. Sellew 02-21-1997 Created and verified version 1.0 */ */
;/* */
;/*************************************************************************/
XDEF _TCT_Schedule
_TCT_Schedule:
;VOID TCT_Schedule(void)
;{
;
; /* Restore interrupts according to the value contained in
; TCD_Interrupt_Level. */
;
MOVE.W SR,D0 ; Pickup current SR
AND.L #$0000F8FF,D0 ; Clear the interrupt lockout
OR.L _TCD_Interrupt_Level,D0 ; Or-in the interrupt enable level
MOVE.W D0,SR ; Setup SR with interrupt level
;
; /* Wait until a thread (task or HISR) is available to execute. */
; do
; {
;
_TCT_Scheduling_Loop:
;
; } while ((!TCD_Execute_HISR) && (!TCD_Execute_Task));
;
MOVE.L _TCD_Execute_HISR,D0 ; Pickup the HISR pointer
BNE.S _TCT_Schedule_Thread ; If not NULL, found an HISR
MOVE.L _TCD_Execute_Task,D0 ; Pickup the Task pointer
BEQ.S _TCT_Scheduling_Loop ; Keep checking if task pointer is
; also NULL
_TCT_Schedule_Thread:
;
; /* Yes, either a task or an HISR is ready to execute. Lockout
; interrupts while the thread is transferred to. */
;
MOVE.W #LOCKOUT,SR ; Lockout interrupts
;
; /* Transfer control to the thread by falling through to the following
; routine. */
;}
;
;/*************************************************************************/
;/* */
;/* FUNCTION */
;/* */
;/* TCT_Control_To_Thread */
;/* */
;/* DESCRIPTION */
;/* */
;/* This function transfers control to the specified thread. Each */
;/* time control is transferred to a thread, its scheduled counter */
;/* is incremented. Additionally, time-slicing for task threads is */
;/* enabled in this routine. The TCD_Current_Thread pointer is */
;/* setup by this function. */
;/* */
;/* AUTHOR */
;/* */
;/* Barry Sellew, Accelerated Technology, Inc. */
;/* */
;/* CALLED BY */
;/* */
;/* TCT_Schedule Indirectly called */
;/* TCT_Protect Protection task switch */
;/* */
;/* CALLS */
;/* */
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