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/***************************************************************************
* Copyright (c) 2026 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.
*
* AI Disclosure: This file was largely AI-generated by Claude Code (Opus 5.5).
* The AI-generated portions may be considered public domain (CC0-1.0)
* and not subject to the project's licence. The human contributor has
* reviewed and verified that the code is correct.
*
* SPDX-License-Identifier: MIT and CC0-1.0
**************************************************************************/
@ Low-level initialisation for the module execution harness on QEMU's MPS2
@ AN385 (Cortex-M3) and AN386 (Cortex-M4) boards, both clocked at 25 MHz.
.syntax unified
.thumb
.global _tx_initialize_unused_memory
.global _tx_timer_interrupt
.global __RAM_segment_used_end__
SYSTEM_CLOCK = 25000000
SYSTICK_CYCLES = ((SYSTEM_CLOCK / 100) - 1)
.text
.align 2
@ VOID _tx_initialize_low_level(VOID)
.global _tx_initialize_low_level
.thumb_func
_tx_initialize_low_level:
CPSID i @ Interrupts stay off until the scheduler starts
@ First free memory follows everything the image uses.
LDR r0, =_tx_initialize_unused_memory
LDR r1, =__RAM_segment_used_end__
ADD r1, r1, #4
STR r1, [r0]
@ Vector table base, in case the board boots with another.
LDR r0, =0xE000ED08 @ VTOR
LDR r1, =_vectors
STR r1, [r0]
@ SysTick at 100 Hz.
LDR r0, =0xE000E000
MOV r1, #0
STR r1, [r0, #0x10] @ SysTick control: off
STR r1, [r0, #0x18] @ SysTick current value
LDR r1, =SYSTICK_CYCLES
STR r1, [r0, #0x14] @ SysTick reload
MOV r1, #0x7
STR r1, [r0, #0x10] @ SysTick control: on, interrupt, core clock
@ Handler priorities: the faults highest, SVCall and PendSV lowest, as the
@ module port requires.
LDR r1, =0x00000000 @ Reserved, UsageFault, BusFault, MemManage
STR r1, [r0, #0xD18]
LDR r1, =0xFF000000 @ SVCall, reserved x3
STR r1, [r0, #0xD1C]
LDR r1, =0x40FF0000 @ SysTick, PendSV, reserved, debug monitor
STR r1, [r0, #0xD20]
BX lr
@ SysTick: drive the ThreadX timer.
.global __tx_SysTickHandler
.global SysTick_Handler
.thumb_func
__tx_SysTickHandler:
.thumb_func
SysTick_Handler:
PUSH {r0, lr}
BL _tx_timer_interrupt
POP {r0, lr}
BX lr
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