RISC-V MCU启动文件分析
作者：互联网
启动文件由汇编语言编写，是MCU上电复位后第一个执行的程序。主要执行以下内容：
- 初始化gp(global pointer)全局指针寄存器、sp(stack pointer)栈指针寄存器
- 将data数据从flash中加载至RAM中
- 清空bss段数据
- 初始化中断向量表
- 配置系统时钟
- 从Machine模式切换到User模式，进入main函数运行
CH32V103启动文件如下：
/********************************** (C) COPYRIGHT *******************************
* File Name : startup_ch32v10x.s
* Author : WCH
* Version : V1.0.0
* Date : 2020/04/30
* Description : CH32V10x vector table for eclipse toolchain.
*******************************************************************************/
.section .init,"ax",@progbits /* 声明section 为 .init */
.global _start /* 指明标签_start的属性为全局性的 */
.align 1
_start: /* 标签_start处 */
j handle_reset /* 跳转至 handle_reset处 */
.word 0x00000013 /* 内核设计需要，不用关注 */
.word 0x00000013
.word 0x00000013
.word 0x00000013
.word 0x00000013
.word 0x00000013
.word 0x00000013
.word 0x00000013
.word 0x00000013
.word 0x00000013
.word 0x00000013
.word 0x00000013
.word 0x00100073
.section .vector,"ax",@progbits
.align 1
_vector_base: /* 中断向量表 */
.option norvc;
j _start
.word 0
j NMI_Handler /* NMI Handler */
j HardFault_Handler /* Hard Fault Handler */
.word 0
.word 0
.word 0
.word 0
.word 0
.word 0
.word 0
.word 0
j SysTick_Handler /* SysTick Handler */
.word 0
j SW_handler /* SW Handler */
.word 0
/* External Interrupts */
j WWDG_IRQHandler /* Window Watchdog */
j PVD_IRQHandler /* PVD through EXTI Line detect */
j TAMPER_IRQHandler /* TAMPER */
j RTC_IRQHandler /* RTC */
j FLASH_IRQHandler /* Flash */
j RCC_IRQHandler /* RCC */
j EXTI0_IRQHandler /* EXTI Line 0 */
j EXTI1_IRQHandler /* EXTI Line 1 */
j EXTI2_IRQHandler /* EXTI Line 2 */
j EXTI3_IRQHandler /* EXTI Line 3 */
j EXTI4_IRQHandler /* EXTI Line 4 */
j DMA1_Channel1_IRQHandler /* DMA1 Channel 1 */
j DMA1_Channel2_IRQHandler /* DMA1 Channel 2 */
j DMA1_Channel3_IRQHandler /* DMA1 Channel 3 */
j DMA1_Channel4_IRQHandler /* DMA1 Channel 4 */
j DMA1_Channel5_IRQHandler /* DMA1 Channel 5 */
j DMA1_Channel6_IRQHandler /* DMA1 Channel 6 */
j DMA1_Channel7_IRQHandler /* DMA1 Channel 7 */
j ADC1_2_IRQHandler /* ADC1_2 */
.word 0
.word 0
.word 0
.word 0
j EXTI9_5_IRQHandler /* EXTI Line 9..5 */
j TIM1_BRK_IRQHandler /* TIM1 Break */
j TIM1_UP_IRQHandler /* TIM1 Update */
j TIM1_TRG_COM_IRQHandler /* TIM1 Trigger and Commutation */
j TIM1_CC_IRQHandler /* TIM1 Capture Compare */
j TIM2_IRQHandler /* TIM2 */
j TIM3_IRQHandler /* TIM3 */
j TIM4_IRQHandler /* TIM4 */
j I2C1_EV_IRQHandler /* I2C1 Event */
j I2C1_ER_IRQHandler /* I2C1 Error */
j I2C2_EV_IRQHandler /* I2C2 Event */
j I2C2_ER_IRQHandler /* I2C2 Error */
j SPI1_IRQHandler /* SPI1 */
j SPI2_IRQHandler /* SPI2 */
j USART1_IRQHandler /* USART1 */
j USART2_IRQHandler /* USART2 */
j USART3_IRQHandler /* USART3 */
j EXTI15_10_IRQHandler /* EXTI Line 15..10 */
j RTCAlarm_IRQHandler /* RTC Alarm through EXTI Line */
j USBWakeUp_IRQHandler /* USB Wakeup from suspend */
j USBHD_IRQHandler /* USBHD */
.option rvc;
.section .text. , "ax", @progbits /* 中断服务程序弱定义 */
.weak NMI_Handler
.weak HardFault_Handler
.weak SysTick_Handler
.weak SW_handler
.weak WWDG_IRQHandler
.weak PVD_IRQHandler
.weak TAMPER_IRQHandler
.weak RTC_IRQHandler
.weak FLASH_IRQHandler
.weak RCC_IRQHandler
.weak EXTI0_IRQHandler
.weak EXTI1_IRQHandler
.weak EXTI2_IRQHandler
.weak EXTI3_IRQHandler
.weak EXTI4_IRQHandler
.weak DMA1_Channel1_IRQHandler
.weak DMA1_Channel2_IRQHandler
.weak DMA1_Channel3_IRQHandler
.weak DMA1_Channel4_IRQHandler
.weak DMA1_Channel5_IRQHandler
.weak DMA1_Channel6_IRQHandler
.weak DMA1_Channel7_IRQHandler
.weak ADC1_2_IRQHandler
.weak EXTI9_5_IRQHandler
.weak TIM1_BRK_IRQHandler
.weak TIM1_UP_IRQHandler
.weak TIM1_TRG_COM_IRQHandler
.weak TIM1_CC_IRQHandler
.weak TIM2_IRQHandler
.weak TIM3_IRQHandler
.weak TIM4_IRQHandler
.weak I2C1_EV_IRQHandler
.weak I2C1_ER_IRQHandler
.weak I2C2_EV_IRQHandler
.weak I2C2_ER_IRQHandler
.weak SPI1_IRQHandler
.weak SPI2_IRQHandler
.weak USART1_IRQHandler
.weak USART2_IRQHandler
.weak USART3_IRQHandler
.weak EXTI15_10_IRQHandler
.weak RTCAlarm_IRQHandler
.weak USBWakeUp_IRQHandler
.weak USBHD_IRQHandler
.section .text.handle_reset,"ax",@progbits
.weak handle_reset
.align 1
handle_reset: /* handle_reset起始位置 */
.option push
.option norelax
la gp, __global_pointer$ /* 将ld文件中的标签__global_pointer所处的地址值赋给gp寄存器 */
.option pop
1:
la sp, _eusrstack /* 将ld文件中的标签_eusrstack所处的地址值赋给sp寄存器 */
2:
/* Load data section from flash to RAM */
la a0, _data_lma
la a1, _data_vma
la a2, _edata
bgeu a1, a2, 2f
1:
lw t0, (a0)
sw t0, (a1)
addi a0, a0, 4
addi a1, a1, 4
bltu a1, a2, 1b
2:
/* clear bss section */
la a0, _sbss
la a1, _ebss
bgeu a0, a1, 2f
1:
sw zero, (a0)
addi a0, a0, 4
bltu a0, a1, 1b
2:
/* enable all interrupt */ /* csrs ，根据寄存器中每个为1的位，把CSR寄存器对应位置位 */
li t0, 0x88
csrs mstatus, t0 /* 状态寄存器mstatus赋值为0x88，打开所有中断，设置MPP值为00 */
la t0, _vector_base
ori t0, t0, 1
csrw mtvec, t0 /* 将中断向量表的首地址赋值给mtvec寄存器（中断发生时PC的地址） */
jal SystemInit /* 设置MCU系统时钟 */
la t0, main
csrw mepc, t0
mret
/*
mret返回指令(M模式特有的指令)，调用该指令会进行如下操作：
- 将PC指针设置为mepc的值
- 将mstatus的MPIE域复制到MIE来恢复之前的中断使能
- 将权限模式设置为mstatus的MPP域中的值。
芯片上电默认进入的是机器模式，通过将mstatus中的MPP值设置为00（00: User, 01: Supervisor, 11: Machine），
并将main函数的地址赋值给mepc，调用mret，使得用户在进入main函数运行时，芯片由机器模式切换为用户模式。
*/
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标签：0x00000013,TIM1,word,启动,weak,RISC,IRQHandler,DMA1,MCU 来源： https://www.cnblogs.com/zxyy-/p/16373322.html