我正在尝试在STM32L476发现板ARM Cortex-M4 CPU上实现浮点运算。我所有的代码都只能用ARM Assembly编写。
首先，我通过激活CoProcesser 10和11来启用FPU，
.thumb
.thumb_func
.globl fpu_init
fpu_init:
ldr r0,=0xE000ED88
ldr r1,[r0]
ldr r2,=0xF00000
orr r1,r2, #(0xF << 20)
str r1,[r0]
dsb
isb
bx lr
这是程序的其余部分，我在其中实现浮点运算。
.syntax unified
.global main
.fpu vfpv4
.type main, %function
main:
bl fpu_init
LDR R0, =val1 @ load variable address
VLDR S0, [R0] @ load the value into the VFP register
LDR R0, =val2 @ load variable address
VLDR S1, [R0] @ load the value into the VFP register
VMUL.F32 S2, S0, S1 @ compute S2 = S0 * S1
VCVT.F64.F32 D4, S2 @ covert the result to double precision for printing
VMOV R1, R2, D4 @ split the double VFP register into two ARM registers
BL _printf_result @ print the result
B _exit @ branch to exit procedure with no return
.size main, .-main
_exit:
MOV R7, #4 @ write syscall, 4
MOV R0, #1 @ output stream to monitor, 1
MOV R2, #21 @ print string length
LDR R1, =exit_str @ string at label exit_str:
SWI 0 @ execute syscall
MOV R7, #1 @ terminate syscall, 1
SWI 0 @ execute syscall
_printf_result:
PUSH {LR} @ push LR to stack
LDR R0, =result_str @ R0 contains formatted string address
BL printf @ call printf
POP {PC} @ pop LR from stack and return
.data
result_str: .asciz "Multiplication result = %f \n"
exit_str: .ascii "Terminating program.\n"
val1: .float 3.14159
val2: .float 0.100
上面的代码都在我的main.s中。
当我的程序到达第一个VLDR函数并跳转到startup_stm32l476xx.s文件中的默认处理程序时，就会出现问题（我猜是浮点运算函数未定义）。
在我的startup_stm32l476xx.s中，FPU_IRQHandler映射到Default_Handler。
.weak FPU_IRQHandler
.thumb_set FPU_IRQHandler,Default_Handler
是因为未定义VLDR还是因为我没有在程序中编写Default_Handler而将VLDR跳转到FPU_IRQHandler。
如何仅在ARM汇编中编写FPU_IRQHandler，而无需任何其他C代码。
其他说明：文件startup_stm32l476xx.s已将.fpu设置为softvfp。即使我在.fpu vpfv4中设置了main.s，也会造成问题吗？
.syntax unified
.cpu cortex-m4
.fpu softvfp
.thumb
我刚开始组装，任何帮助将不胜感激。谢谢
编辑：我已经添加了启动代码。我正在使用PlatfromIO构建该项目。
启动代码如下：
/**
******************************************************************************
* @file startup_stm32l476xx.s
* @author MCD Application Team
* @brief STM32L476xx devices vector table GCC toolchain.
* This module performs:
* - Set the initial SP
* - Set the initial PC == Reset_Handler,
* - Set the vector table entries with the exceptions ISR address,
* - Configure the clock system
* - Branches to main in the C library (which eventually
* calls main()).
* After Reset the Cortex-M4 processor is in Thread mode,
* priority is Privileged, and the Stack is set to Main.
******************************************************************************
* @attention
*
* <h2><center>© COPYRIGHT(c) 2017 STMicroelectronics</center></h2>
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. Neither the name of STMicroelectronics nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
******************************************************************************
*/
.syntax unified
.cpu cortex-m4
.fpu softvfp
.thumb
.global g_pfnVectors
.global Default_Handler
/* start address for the initialization values of the .data section.
defined in linker script */
.word _sidata
/* start address for the .data section. defined in linker script */
.word _sdata
/* end address for the .data section. defined in linker script */
.word _edata
/* start address for the .bss section. defined in linker script */
.word _sbss
/* end address for the .bss section. defined in linker script */
.word _ebss
.equ BootRAM, 0xF1E0F85F
/**
* @brief This is the code that gets called when the processor first
* starts execution following a reset event. Only the absolutely
* necessary set is performed, after which the application
* supplied main() routine is called.
* @param None
* @retval : None
*/
.section .text.Reset_Handler
.weak Reset_Handler
.type Reset_Handler, %function
Reset_Handler:
ldr sp, =_estack /* Atollic update: set stack pointer */
/* Copy the data segment initializers from flash to SRAM */
movs r1, #0
b LoopCopyDataInit
CopyDataInit:
ldr r3, =_sidata
ldr r3, [r3, r1]
str r3, [r0, r1]
adds r1, r1, #4
LoopCopyDataInit:
ldr r0, =_sdata
ldr r3, =_edata
adds r2, r0, r1
cmp r2, r3
bcc CopyDataInit
ldr r2, =_sbss
b LoopFillZerobss
/* Zero fill the bss segment. */
FillZerobss:
movs r3, #0
str r3, [r2], #4
LoopFillZerobss:
ldr r3, = _ebss
cmp r2, r3
bcc FillZerobss
/* Call the clock system intitialization function.*/
bl SystemInit
/* Call static constructors */
bl __libc_init_array
/* Call the application's entry point.*/
bl main
LoopForever:
b LoopForever
.size Reset_Handler, .-Reset_Handler
/**
* @brief This is the code that gets called when the processor receives an
* unexpected interrupt. This simply enters an infinite loop, preserving
* the system state for examination by a debugger.
*
* @param None
* @retval : None
*/
.section .text.Default_Handler,"ax",%progbits
Default_Handler:
Infinite_Loop:
b Infinite_Loop
.size Default_Handler, .-Default_Handler
/******************************************************************************
*
* The minimal vector table for a Cortex-M4. Note that the proper constructs
* must be placed on this to ensure that it ends up at physical address
* 0x0000.0000.
*
******************************************************************************/
.section .isr_vector,"a",%progbits
.type g_pfnVectors, %object
.size g_pfnVectors, .-g_pfnVectors
g_pfnVectors:
.word _estack
.word Reset_Handler
.word NMI_Handler
.word HardFault_Handler
.word MemManage_Handler
.word BusFault_Handler
.word UsageFault_Handler
.word 0
.word 0
.word 0
.word 0
.word SVC_Handler
.word DebugMon_Handler
.word 0
.word PendSV_Handler
.word SysTick_Handler
.word WWDG_IRQHandler
.word PVD_PVM_IRQHandler
.word TAMP_STAMP_IRQHandler
.word RTC_WKUP_IRQHandler
.word FLASH_IRQHandler
.word RCC_IRQHandler
.word EXTI0_IRQHandler
.word EXTI1_IRQHandler
.word EXTI2_IRQHandler
.word EXTI3_IRQHandler
.word EXTI4_IRQHandler
.word DMA1_Channel1_IRQHandler
.word DMA1_Channel2_IRQHandler
.word DMA1_Channel3_IRQHandler
.word DMA1_Channel4_IRQHandler
.word DMA1_Channel5_IRQHandler
.word DMA1_Channel6_IRQHandler
.word DMA1_Channel7_IRQHandler
.word ADC1_2_IRQHandler
.word CAN1_TX_IRQHandler
.word CAN1_RX0_IRQHandler
.word CAN1_RX1_IRQHandler
.word CAN1_SCE_IRQHandler
.word EXTI9_5_IRQHandler
.word TIM1_BRK_TIM15_IRQHandler
.word TIM1_UP_TIM16_IRQHandler
.word TIM1_TRG_COM_TIM17_IRQHandler
.word TIM1_CC_IRQHandler
.word TIM2_IRQHandler
.word TIM3_IRQHandler
.word TIM4_IRQHandler
.word I2C1_EV_IRQHandler
.word I2C1_ER_IRQHandler
.word I2C2_EV_IRQHandler
.word I2C2_ER_IRQHandler
.word SPI1_IRQHandler
.word SPI2_IRQHandler
.word USART1_IRQHandler
.word USART2_IRQHandler
.word USART3_IRQHandler
.word EXTI15_10_IRQHandler
.word RTC_Alarm_IRQHandler
.word DFSDM1_FLT3_IRQHandler
.word TIM8_BRK_IRQHandler
.word TIM8_UP_IRQHandler
.word TIM8_TRG_COM_IRQHandler
.word TIM8_CC_IRQHandler
.word ADC3_IRQHandler
.word FMC_IRQHandler
.word SDMMC1_IRQHandler
.word TIM5_IRQHandler
.word SPI3_IRQHandler
.word UART4_IRQHandler
.word UART5_IRQHandler
.word TIM6_DAC_IRQHandler
.word TIM7_IRQHandler
.word DMA2_Channel1_IRQHandler
.word DMA2_Channel2_IRQHandler
.word DMA2_Channel3_IRQHandler
.word DMA2_Channel4_IRQHandler
.word DMA2_Channel5_IRQHandler
.word DFSDM1_FLT0_IRQHandler
.word DFSDM1_FLT1_IRQHandler
.word DFSDM1_FLT2_IRQHandler
.word COMP_IRQHandler
.word LPTIM1_IRQHandler
.word LPTIM2_IRQHandler
.word OTG_FS_IRQHandler
.word DMA2_Channel6_IRQHandler
.word DMA2_Channel7_IRQHandler
.word LPUART1_IRQHandler
.word QUADSPI_IRQHandler
.word I2C3_EV_IRQHandler
.word I2C3_ER_IRQHandler
.word SAI1_IRQHandler
.word SAI2_IRQHandler
.word SWPMI1_IRQHandler
.word TSC_IRQHandler
.word LCD_IRQHandler
.word 0
.word RNG_IRQHandler
.word FPU_IRQHandler
/*******************************************************************************
*
* Provide weak aliases for each Exception handler to the Default_Handler.
* As they are weak aliases, any function with the same name will override
* this definition.
*
*******************************************************************************/
.weak NMI_Handler
.thumb_set NMI_Handler,Default_Handler
.weak HardFault_Handler
.thumb_set HardFault_Handler,Default_Handler
.weak MemManage_Handler
.thumb_set MemManage_Handler,Default_Handler
.weak BusFault_Handler
.thumb_set BusFault_Handler,Default_Handler
.weak UsageFault_Handler
.thumb_set UsageFault_Handler,Default_Handler
.weak SVC_Handler
.thumb_set SVC_Handler,Default_Handler
.weak DebugMon_Handler
.thumb_set DebugMon_Handler,Default_Handler
.weak PendSV_Handler
.thumb_set PendSV_Handler,Default_Handler
.weak SysTick_Handler
.thumb_set SysTick_Handler,Default_Handler
.weak WWDG_IRQHandler
.thumb_set WWDG_IRQHandler,Default_Handler
.weak PVD_PVM_IRQHandler
.thumb_set PVD_PVM_IRQHandler,Default_Handler
.weak TAMP_STAMP_IRQHandler
.thumb_set TAMP_STAMP_IRQHandler,Default_Handler
.weak RTC_WKUP_IRQHandler
.thumb_set RTC_WKUP_IRQHandler,Default_Handler
.weak FLASH_IRQHandler
.thumb_set FLASH_IRQHandler,Default_Handler
.weak RCC_IRQHandler
.thumb_set RCC_IRQHandler,Default_Handler
.weak EXTI0_IRQHandler
.thumb_set EXTI0_IRQHandler,Default_Handler
.weak EXTI1_IRQHandler
.thumb_set EXTI1_IRQHandler,Default_Handler
.weak EXTI2_IRQHandler
.thumb_set EXTI2_IRQHandler,Default_Handler
.weak EXTI3_IRQHandler
.thumb_set EXTI3_IRQHandler,Default_Handler
.weak EXTI4_IRQHandler
.thumb_set EXTI4_IRQHandler,Default_Handler
.weak DMA1_Channel1_IRQHandler
.thumb_set DMA1_Channel1_IRQHandler,Default_Handler
.weak DMA1_Channel2_IRQHandler
.thumb_set DMA1_Channel2_IRQHandler,Default_Handler
.weak DMA1_Channel3_IRQHandler
.thumb_set DMA1_Channel3_IRQHandler,Default_Handler
.weak DMA1_Channel4_IRQHandler
.thumb_set DMA1_Channel4_IRQHandler,Default_Handler
.weak DMA1_Channel5_IRQHandler
.thumb_set DMA1_Channel5_IRQHandler,Default_Handler
.weak DMA1_Channel6_IRQHandler
.thumb_set DMA1_Channel6_IRQHandler,Default_Handler
.weak DMA1_Channel7_IRQHandler
.thumb_set DMA1_Channel7_IRQHandler,Default_Handler
.weak ADC1_2_IRQHandler
.thumb_set ADC1_2_IRQHandler,Default_Handler
.weak CAN1_TX_IRQHandler
.thumb_set CAN1_TX_IRQHandler,Default_Handler
.weak CAN1_RX0_IRQHandler
.thumb_set CAN1_RX0_IRQHandler,Default_Handler
.weak CAN1_RX1_IRQHandler
.thumb_set CAN1_RX1_IRQHandler,Default_Handler
.weak CAN1_SCE_IRQHandler
.thumb_set CAN1_SCE_IRQHandler,Default_Handler
.weak EXTI9_5_IRQHandler
.thumb_set EXTI9_5_IRQHandler,Default_Handler
.weak TIM1_BRK_TIM15_IRQHandler
.thumb_set TIM1_BRK_TIM15_IRQHandler,Default_Handler
.weak TIM1_UP_TIM16_IRQHandler
.thumb_set TIM1_UP_TIM16_IRQHandler,Default_Handler
.weak TIM1_TRG_COM_TIM17_IRQHandler
.thumb_set TIM1_TRG_COM_TIM17_IRQHandler,Default_Handler
.weak TIM1_CC_IRQHandler
.thumb_set TIM1_CC_IRQHandler,Default_Handler
.weak TIM2_IRQHandler
.thumb_set TIM2_IRQHandler,Default_Handler
.weak TIM3_IRQHandler
.thumb_set TIM3_IRQHandler,Default_Handler
.weak TIM4_IRQHandler
.thumb_set TIM4_IRQHandler,Default_Handler
.weak I2C1_EV_IRQHandler
.thumb_set I2C1_EV_IRQHandler,Default_Handler
.weak I2C1_ER_IRQHandler
.thumb_set I2C1_ER_IRQHandler,Default_Handler
.weak I2C2_EV_IRQHandler
.thumb_set I2C2_EV_IRQHandler,Default_Handler
.weak I2C2_ER_IRQHandler
.thumb_set I2C2_ER_IRQHandler,Default_Handler
.weak SPI1_IRQHandler
.thumb_set SPI1_IRQHandler,Default_Handler
.weak SPI2_IRQHandler
.thumb_set SPI2_IRQHandler,Default_Handler
.weak USART1_IRQHandler
.thumb_set USART1_IRQHandler,Default_Handler
.weak USART2_IRQHandler
.thumb_set USART2_IRQHandler,Default_Handler
.weak USART3_IRQHandler
.thumb_set USART3_IRQHandler,Default_Handler
.weak EXTI15_10_IRQHandler
.thumb_set EXTI15_10_IRQHandler,Default_Handler
.weak RTC_Alarm_IRQHandler
.thumb_set RTC_Alarm_IRQHandler,Default_Handler
.weak DFSDM1_FLT3_IRQHandler
.thumb_set DFSDM1_FLT3_IRQHandler,Default_Handler
.weak TIM8_BRK_IRQHandler
.thumb_set TIM8_BRK_IRQHandler,Default_Handler
.weak TIM8_UP_IRQHandler
.thumb_set TIM8_UP_IRQHandler,Default_Handler
.weak TIM8_TRG_COM_IRQHandler
.thumb_set TIM8_TRG_COM_IRQHandler,Default_Handler
.weak TIM8_CC_IRQHandler
.thumb_set TIM8_CC_IRQHandler,Default_Handler
.weak ADC3_IRQHandler
.thumb_set ADC3_IRQHandler,Default_Handler
.weak FMC_IRQHandler
.thumb_set FMC_IRQHandler,Default_Handler
.weak SDMMC1_IRQHandler
.thumb_set SDMMC1_IRQHandler,Default_Handler
.weak TIM5_IRQHandler
.thumb_set TIM5_IRQHandler,Default_Handler
.weak SPI3_IRQHandler
.thumb_set SPI3_IRQHandler,Default_Handler
.weak UART4_IRQHandler
.thumb_set UART4_IRQHandler,Default_Handler
.weak UART5_IRQHandler
.thumb_set UART5_IRQHandler,Default_Handler
.weak TIM6_DAC_IRQHandler
.thumb_set TIM6_DAC_IRQHandler,Default_Handler
.weak TIM7_IRQHandler
.thumb_set TIM7_IRQHandler,Default_Handler
.weak DMA2_Channel1_IRQHandler
.thumb_set DMA2_Channel1_IRQHandler,Default_Handler
.weak DMA2_Channel2_IRQHandler
.thumb_set DMA2_Channel2_IRQHandler,Default_Handler
.weak DMA2_Channel3_IRQHandler
.thumb_set DMA2_Channel3_IRQHandler,Default_Handler
.weak DMA2_Channel4_IRQHandler
.thumb_set DMA2_Channel4_IRQHandler,Default_Handler
.weak DMA2_Channel5_IRQHandler
.thumb_set DMA2_Channel5_IRQHandler,Default_Handler
.weak DFSDM1_FLT0_IRQHandler
.thumb_set DFSDM1_FLT0_IRQHandler,Default_Handler
.weak DFSDM1_FLT1_IRQHandler
.thumb_set DFSDM1_FLT1_IRQHandler,Default_Handler
.weak DFSDM1_FLT2_IRQHandler
.thumb_set DFSDM1_FLT2_IRQHandler,Default_Handler
.weak COMP_IRQHandler
.thumb_set COMP_IRQHandler,Default_Handler
.weak LPTIM1_IRQHandler
.thumb_set LPTIM1_IRQHandler,Default_Handler
.weak LPTIM2_IRQHandler
.thumb_set LPTIM2_IRQHandler,Default_Handler
.weak OTG_FS_IRQHandler
.thumb_set OTG_FS_IRQHandler,Default_Handler
.weak DMA2_Channel6_IRQHandler
.thumb_set DMA2_Channel6_IRQHandler,Default_Handler
.weak DMA2_Channel7_IRQHandler
.thumb_set DMA2_Channel7_IRQHandler,Default_Handler
.weak LPUART1_IRQHandler
.thumb_set LPUART1_IRQHandler,Default_Handler
.weak QUADSPI_IRQHandler
.thumb_set QUADSPI_IRQHandler,Default_Handler
.weak I2C3_EV_IRQHandler
.thumb_set I2C3_EV_IRQHandler,Default_Handler
.weak I2C3_ER_IRQHandler
.thumb_set I2C3_ER_IRQHandler,Default_Handler
.weak SAI1_IRQHandler
.thumb_set SAI1_IRQHandler,Default_Handler
.weak SAI2_IRQHandler
.thumb_set SAI2_IRQHandler,Default_Handler
.weak SWPMI1_IRQHandler
.thumb_set SWPMI1_IRQHandler,Default_Handler
.weak TSC_IRQHandler
.thumb_set TSC_IRQHandler,Default_Handler
.weak LCD_IRQHandler
.thumb_set LCD_IRQHandler,Default_Handler
.weak RNG_IRQHandler
.thumb_set RNG_IRQHandler,Default_Handler
.weak FPU_IRQHandler
.thumb_set FPU_IRQHandler,Default_Handler
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
我上面的启动代码中的Reset_Handler：
.section .text.Reset_Handler
.weak Reset_Handler
.type Reset_Handler, %function
Reset_Handler:
ldr sp, =_estack /* Atollic update: set stack pointer */
/* Copy the data segment initializers from flash to SRAM */
movs r1, #0
b LoopCopyDataInit
CopyDataInit:
ldr r3, =_sidata
ldr r3, [r3, r1]
str r3, [r0, r1]
adds r1, r1, #4
LoopCopyDataInit:
ldr r0, =_sdata
ldr r3, =_edata
adds r2, r0, r1
cmp r2, r3
bcc CopyDataInit
ldr r2, =_sbss
b LoopFillZerobss
/* Zero fill the bss segment. */
FillZerobss:
movs r3, #0
str r3, [r2], #4
LoopFillZerobss:
ldr r3, = _ebss
cmp r2, r3
bcc FillZerobss
/* Call the clock system intitialization function.*/
bl SystemInit
/* Call static constructors */
bl __libc_init_array
/* Call the application's entry point.*/
bl main
LoopForever:
b LoopForever
.size Reset_Handler, .-Reset_Handler
我的PlatformIO构建配置如下：
[env:disco_l476vg]
platform = ststm32@4.5.0
board = disco_l476vg
framework = stm32cube
build_flags = -g -O0 -mfloat-abi=softfp -mfpu=fpv5-d16
upload_protocol = stlink
extra_scripts = update_link_flags.py