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;/***************************************************************************
; * Copyright (c) 2024 Microsoft Corporation
; *
; * This program and the accompanying materials are made available under the
; * terms of the MIT License which is available at
; * https://opensource.org/licenses/MIT.
; *
; * SPDX-License-Identifier: MIT
; **************************************************************************/
;
;
;/**************************************************************************/
;/**************************************************************************/
;/** */
;/** ThreadX Component */
;/** */
;/** Timer */
;/** */
;/**************************************************************************/
;/**************************************************************************/
;
;#define TX_SOURCE_CODE
;
;
;/* Include necessary system files. */
;
;#include "tx_api.h"
;#include "tx_timer.h"
;#include "tx_thread.h"
;
;
;Define Assembly language external references...
;
IMPORT _tx_timer_time_slice
IMPORT _tx_timer_system_clock
IMPORT _tx_timer_current_ptr
IMPORT _tx_timer_list_start
IMPORT _tx_timer_list_end
IMPORT _tx_timer_expired_time_slice
IMPORT _tx_timer_expired
IMPORT _tx_thread_time_slice
IMPORT _tx_timer_expiration_process
;
;
AREA ||.text||, CODE, READONLY
PRESERVE8
;/**************************************************************************/
;/* */
;/* FUNCTION RELEASE */
;/* */
;/* _tx_timer_interrupt Cortex-A8/AC5 */
;/* 6.1 */
;/* AUTHOR */
;/* */
;/* William E. Lamie, Microsoft Corporation */
;/* */
;/* DESCRIPTION */
;/* */
;/* This function processes the hardware timer interrupt. This */
;/* processing includes incrementing the system clock and checking for */
;/* time slice and/or timer expiration. If either is found, the */
;/* interrupt context save/restore functions are called along with the */
;/* expiration functions. */
;/* */
;/* INPUT */
;/* */
;/* None */
;/* */
;/* OUTPUT */
;/* */
;/* None */
;/* */
;/* CALLS */
;/* */
;/* _tx_timer_expiration_process Timer expiration processing */
;/* _tx_thread_time_slice Time slice interrupted thread */
;/* */
;/* CALLED BY */
;/* */
;/* interrupt vector */
;/* */
;/**************************************************************************/
;VOID _tx_timer_interrupt(VOID)
;{
EXPORT _tx_timer_interrupt
_tx_timer_interrupt
;
; /* Upon entry to this routine, it is assumed that context save has already
; been called, and therefore the compiler scratch registers are available
; for use. */
;
; /* Increment the system clock. */
; _tx_timer_system_clock++;
;
LDR r1, =_tx_timer_system_clock ; Pickup address of system clock
LDR r0, [r1, #0] ; Pickup system clock
ADD r0, r0, #1 ; Increment system clock
STR r0, [r1, #0] ; Store new system clock
;
; /* Test for time-slice expiration. */
; if (_tx_timer_time_slice)
; {
;
LDR r3, =_tx_timer_time_slice ; Pickup address of time-slice
LDR r2, [r3, #0] ; Pickup time-slice
CMP r2, #0 ; Is it non-active?
BEQ __tx_timer_no_time_slice ; Yes, skip time-slice processing
;
; /* Decrement the time_slice. */
; _tx_timer_time_slice--;
;
SUB r2, r2, #1 ; Decrement the time-slice
STR r2, [r3, #0] ; Store new time-slice value
;
; /* Check for expiration. */
; if (__tx_timer_time_slice == 0)
;
CMP r2, #0 ; Has it expired?
BNE __tx_timer_no_time_slice ; No, skip expiration processing
;
; /* Set the time-slice expired flag. */
; _tx_timer_expired_time_slice = TX_TRUE;
;
LDR r3, =_tx_timer_expired_time_slice ; Pickup address of expired flag
MOV r0, #1 ; Build expired value
STR r0, [r3, #0] ; Set time-slice expiration flag
;
; }
;
__tx_timer_no_time_slice
;
; /* Test for timer expiration. */
; if (*_tx_timer_current_ptr)
; {
;
LDR r1, =_tx_timer_current_ptr ; Pickup current timer pointer addr
LDR r0, [r1, #0] ; Pickup current timer
LDR r2, [r0, #0] ; Pickup timer list entry
CMP r2, #0 ; Is there anything in the list?
BEQ __tx_timer_no_timer ; No, just increment the timer
;
; /* Set expiration flag. */
; _tx_timer_expired = TX_TRUE;
;
LDR r3, =_tx_timer_expired ; Pickup expiration flag address
MOV r2, #1 ; Build expired value
STR r2, [r3, #0] ; Set expired flag
B __tx_timer_done ; Finished timer processing
;
; }
; else
; {
__tx_timer_no_timer
;
; /* No timer expired, increment the timer pointer. */
; _tx_timer_current_ptr++;
;
ADD r0, r0, #4 ; Move to next timer
;
; /* Check for wrap-around. */
; if (_tx_timer_current_ptr == _tx_timer_list_end)
;
LDR r3, =_tx_timer_list_end ; Pickup addr of timer list end
LDR r2, [r3, #0] ; Pickup list end
CMP r0, r2 ; Are we at list end?
BNE __tx_timer_skip_wrap ; No, skip wrap-around logic
;
; /* Wrap to beginning of list. */
; _tx_timer_current_ptr = _tx_timer_list_start;
;
LDR r3, =_tx_timer_list_start ; Pickup addr of timer list start
LDR r0, [r3, #0] ; Set current pointer to list start
;
__tx_timer_skip_wrap
;
STR r0, [r1, #0] ; Store new current timer pointer
; }
;
__tx_timer_done
;
;
; /* See if anything has expired. */
; if ((_tx_timer_expired_time_slice) || (_tx_timer_expired))
; {
;
LDR r3, =_tx_timer_expired_time_slice ; Pickup addr of expired flag
LDR r2, [r3, #0] ; Pickup time-slice expired flag
CMP r2, #0 ; Did a time-slice expire?
BNE __tx_something_expired ; If non-zero, time-slice expired
LDR r1, =_tx_timer_expired ; Pickup addr of other expired flag
LDR r0, [r1, #0] ; Pickup timer expired flag
CMP r0, #0 ; Did a timer expire?
BEQ __tx_timer_nothing_expired ; No, nothing expired
;
__tx_something_expired
;
;
STMDB sp!, {r0, lr} ; Save the lr register on the stack
; and save r0 just to keep 8-byte alignment
;
; /* Did a timer expire? */
; if (_tx_timer_expired)
; {
;
LDR r1, =_tx_timer_expired ; Pickup addr of expired flag
LDR r0, [r1, #0] ; Pickup timer expired flag
CMP r0, #0 ; Check for timer expiration
BEQ __tx_timer_dont_activate ; If not set, skip timer activation
;
; /* Process timer expiration. */
; _tx_timer_expiration_process();
;
BL _tx_timer_expiration_process ; Call the timer expiration handling routine
;
; }
__tx_timer_dont_activate
;
; /* Did time slice expire? */
; if (_tx_timer_expired_time_slice)
; {
;
LDR r3, =_tx_timer_expired_time_slice ; Pickup addr of time-slice expired
LDR r2, [r3, #0] ; Pickup the actual flag
CMP r2, #0 ; See if the flag is set
BEQ __tx_timer_not_ts_expiration ; No, skip time-slice processing
;
; /* Time slice interrupted thread. */
; _tx_thread_time_slice();
BL _tx_thread_time_slice ; Call time-slice processing
;
; }
;
__tx_timer_not_ts_expiration
;
LDMIA sp!, {r0, lr} ; Recover lr register (r0 is just there for
; the 8-byte stack alignment
;
; }
;
__tx_timer_nothing_expired
;
IF {INTER} = {TRUE}
BX lr ; Return to caller
ELSE
MOV pc, lr ; Return to caller
ENDIF
;
;}
END
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