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/***************************************************************************
* Copyright (c) 2024 Microsoft Corporation
* Copyright (c) 2026-present Eclipse ThreadX contributors
*
* 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 */
/** */
/**************************************************************************/
/**************************************************************************/
#ifdef TX_INCLUDE_USER_DEFINE_FILE
#include "tx_user.h"
#endif
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _tx_timer_interrupt Cortex-M55/AC6 */
/* 6.2.1 */
/* AUTHOR */
/* */
/* Scott Larson, 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 */
/* expiration functions are called. */
/* */
/* 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)
// {
.section .text
.balign 4
.syntax unified
.eabi_attribute Tag_ABI_align_preserved, 1
.global _tx_timer_interrupt
.thumb_func
.type _tx_timer_interrupt, function
_tx_timer_interrupt:
/* Upon entry to this routine, it is assumed that 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
CBZ r2, __tx_timer_no_time_slice // Is it non-active?
// 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)
CBNZ r2, __tx_timer_no_time_slice // Has it expired?
// 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 address
LDR r0, [r1, #0] // Pickup current timer
LDR r2, [r0, #0] // Pickup timer list entry
CBZ r2, __tx_timer_no_timer // Is there anything in the list?
// 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
CBNZ r2, __tx_something_expired // Did a time-slice expire?
// 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
CBZ r0, __tx_timer_nothing_expired // Did a timer expire?
// No, nothing expired
__tx_something_expired:
PUSH {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
CBZ r0, __tx_timer_dont_activate // Check for timer expiration
// 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
CBZ r2, __tx_timer_not_ts_expiration // See if the flag is set
// No, skip time-slice processing
/* Time slice interrupted thread. */
// _tx_thread_time_slice();
BL _tx_thread_time_slice // Call time-slice processing
LDR r0, =_tx_thread_preempt_disable // Build address of preempt disable flag
LDR r1, [r0] // Is the preempt disable flag set?
CBNZ r1, __tx_timer_skip_time_slice // Yes, skip the PendSV logic
LDR r0, =_tx_thread_current_ptr // Build current thread pointer address
LDR r1, [r0] // Pickup the current thread pointer
LDR r2, =_tx_thread_execute_ptr // Build execute thread pointer address
LDR r3, [r2] // Pickup the execute thread pointer
LDR r0, =0xE000ED04 // Build address of control register
LDR r2, =0x10000000 // Build value for PendSV bit
CMP r1, r3 // Are they the same?
BEQ __tx_timer_skip_time_slice // If the same, there was no time-slice performed
STR r2, [r0] // Not the same, issue the PendSV for preemption
__tx_timer_skip_time_slice:
// }
__tx_timer_not_ts_expiration:
POP {r0, lr} // Recover lr register (r0 is just there for
// the 8-byte stack alignment
// }
__tx_timer_nothing_expired:
DSB // Complete all memory access
BX lr // Return to caller
// }
.end
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