xiuos/Ubiquitous/XiUOS/arch/arm/cortex-m7/boot.S

148 lines
4.4 KiB
ArmAsm

/* ------------------------------------------------------------------------- */
/* @file: startup_MIMXRT1052.s */
/* @purpose: CMSIS Cortex-M7 Core Device Startup File */
/* MIMXRT1052 */
/* @version: 1.0 */
/* @date: 2018-9-21 */
/* @build: b180921 */
/* ------------------------------------------------------------------------- */
/* */
/* Copyright 1997-2016 Freescale Semiconductor, Inc. */
/* Copyright 2016-2018 NXP */
/* All rights reserved. */
/* */
/* SPDX-License-Identifier: BSD-3-Clause */
/*****************************************************************************/
/* Version: GCC for ARM Embedded Processors */
/*****************************************************************************/
/**
* @file boot.S
* @brief Contex-M7 start function
* @version 1.0
* @author AIIT XUOS Lab
* @date 2021-05-28
*/
/*************************************************
File name: boot.S
Description: Contex-M7 start function function
Others: take startup_MIMXRT1052.s for references
History:
1. Date: 2021-05-28
Author: AIIT XUOS Lab
Modification:
1. add OS entry function
*************************************************/
.syntax unified
.arch armv7-m
.text
.thumb
/* Reset Handler */
.thumb_func
.align 2
.globl Reset_Handler
.weak Reset_Handler
.type Reset_Handler, %function
Reset_Handler:
cpsid i /* Mask interrupts */
.equ VTOR, 0xE000ED08
ldr r0, =VTOR
ldr r1, =__isr_vector
str r1, [r0]
ldr r2, [r1]
msr msp, r2
#ifndef __NO_SYSTEM_INIT
ldr r0,=SystemInit
blx r0
#endif
/* Loop to copy data from read only memory to RAM. The ranges
* of copy from/to are specified by following symbols evaluated in
* linker script.
* __etext: End of code section, i.e., begin of data sections to copy from.
* __data_start__/__data_end__: RAM address range that data should be
* __noncachedata_start__/__noncachedata_end__ : none cachable region
* copied to. Both must be aligned to 4 bytes boundary. */
ldr r1, =__etext
ldr r2, =__data_start__
ldr r3, =__data_end__
#if 1
/* Here are two copies of loop implemenations. First one favors code size
* and the second one favors performance. Default uses the first one.
* Change to "#if 0" to use the second one */
.LC0:
cmp r2, r3
ittt lt
ldrlt r0, [r1], #4
strlt r0, [r2], #4
blt .LC0
#else
subs r3, r2
ble .LC1
.LC0:
subs r3, #4
ldr r0, [r1, r3]
str r0, [r2, r3]
bgt .LC0
.LC1:
#endif
#ifdef __STARTUP_INITIALIZE_NONCACHEDATA
ldr r2, =__noncachedata_start__
ldr r3, =__noncachedata_init_end__
#if 1
.LC2:
cmp r2, r3
ittt lt
ldrlt r0, [r1], #4
strlt r0, [r2], #4
blt .LC2
#else
subs r3, r2
ble .LC3
.LC2:
subs r3, #4
ldr r0, [r1, r3]
str r0, [r2, r3]
bgt .LC2
.LC3:
#endif
/* zero inited ncache section initialization */
ldr r3, =__noncachedata_end__
movs r0,0
.LC4:
cmp r2,r3
itt lt
strlt r0,[r2],#4
blt .LC4
#endif /* __STARTUP_INITIALIZE_NONCACHEDATA */
#ifdef __STARTUP_CLEAR_BSS
/* This part of work usually is done in C library startup code. Otherwise,
* define this macro to enable it in this startup.
*
* Loop to zero out BSS section, which uses following symbols
* in linker script:
* __bss_start__: start of BSS section. Must align to 4
* __bss_end__: end of BSS section. Must align to 4
*/
ldr r1, =__bss_start__
ldr r2, =__bss_end__
movs r0, 0
.LC5:
cmp r1, r2
itt lt
strlt r0, [r1], #4
blt .LC5
#endif /* __STARTUP_CLEAR_BSS */
ldr r0,=entry
blx r0
.size Reset_Handler, . - Reset_Handler