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feat(cortex-m4): 重定向 rt_interrupt_get_nest() 函数优化获取实现 #10614

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feat(cortex-m4): 重定向 rt_interrupt_get_nest() 函数优化获取实现 #10614

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37 changes: 37 additions & 0 deletions libcpu/arm/cortex-m4/cpuport.c
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@
* 2018-07-24 aozima enhancement hard fault exception handler.
* 2019-07-03 yangjie add __rt_ffs() for armclang.
* 2022-06-12 jonas fixed __rt_ffs() for armclang.
* 2025-08-18 wdfk_prog add rt_interrupt_get_nest() and __get_IPSR() support.
*/

#include <rtthread.h>
Expand Down Expand Up @@ -436,6 +437,42 @@ void rt_hw_cpu_reset(void)
SCB_AIRCR = SCB_RESET_VALUE;
}

/**
\brief Get IPSR Register
\details Returns the content of the IPSR Register.
\return IPSR Register value
*/
rt_inline rt_uint32_t __get_IPSR(void)
{
#if defined(__CC_ARM)
register uint32_t __regIPSR __asm("ipsr");
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Use rt_uint32_t instead of uint32_t to maintain consistency with RT-Thread's type naming conventions used elsewhere in the codebase.

Suggested change
register uint32_t __regIPSR __asm("ipsr");
register rt_uint32_t __regIPSR __asm("ipsr");

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return(__regIPSR);
#elif defined(__clang__)
uint32_t result;
__asm volatile ("MRS %0, ipsr" : "=r" (result) );
return(result);
#elif defined(__IAR_SYSTEMS_ICC__)
return __iar_builtin_rsr("IPSR");
#elif defined ( __GNUC__ )
uint32_t result;
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Use rt_uint32_t instead of uint32_t to maintain consistency with RT-Thread's type naming conventions used elsewhere in the codebase.

Suggested change
uint32_t result;
rt_uint32_t result;
__asm volatile ("MRS %0, ipsr" : "=r" (result) );
return(result);
#elif defined(__IAR_SYSTEMS_ICC__)
return __iar_builtin_rsr("IPSR");
#elif defined ( __GNUC__ )
rt_uint32_t result;

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Use rt_uint32_t instead of uint32_t to maintain consistency with RT-Thread's type naming conventions used elsewhere in the codebase.

Suggested change
uint32_t result;
rt_uint32_t result;
__asm volatile ("MRS %0, ipsr" : "=r" (result) );
return(result);
#elif defined(__IAR_SYSTEMS_ICC__)
return __iar_builtin_rsr("IPSR");
#elif defined ( __GNUC__ )
rt_uint32_t result;

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__asm volatile ("MRS %0, ipsr" : "=r" (result) );
return(result);
#endif
}

/**
* @brief This function will return the nest of interrupt.
*
* User application can invoke this function to get whether current
* context is interrupt context.
*
* @return the number of nested interrupts.
*/
rt_uint8_t rt_interrupt_get_nest(void)
{
return (__get_IPSR() != 0);
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The function return type is rt_uint8_t but this expression returns a boolean (0 or 1). While this works, it changes the semantic meaning from returning the actual nest count to returning a boolean. Consider either changing the return type to rt_bool_t or updating the function documentation to clarify that it returns 1 for interrupt context and 0 for thread context.

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@Rbb666 Rbb666 Aug 19, 2025

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@wdfk-prog 这块应该返回__get_IPSR()的数值？

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@wdfk-prog wdfk-prog Aug 20, 2025

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@wdfk-prog 这块应该返回__get_IPSR()的数值？

  • 函数返回值类型我会进行修改
  • 根据手册来看IPSR寄存器的值仅能代表当前是否处于中断,处于哪个中断源.不能识别进入了嵌套中断的层数.

https://developer.arm.com/documentation/dui0646/c/The-Cortex-M7-Processor/Programmers-model/Core-registers

image
  • 我进行全局搜索rt_interrupt_get_nest的用法.并未发现有对嵌套层数的判断.这样修改不会造成影响.
  • 硬件方案没有办法识别到中断嵌套的层数
  • 或许rt_interrupt_get_nest可以改为``rt_is_interrupt_mode`?

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@Rbb666 Rbb666 Aug 20, 2025

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rt_interrupt_get_nest 这种用法可能更好一些

我看到ut里面有类似使用 rt_interrupt_get_nest 的代码：

rt-thread/examples/utest/testcases/kernel/irq_tc.c

Line 21 in 60b3ccb

if(rt_interrupt_get_nest() > max_get_nest_count)

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@wdfk-prog wdfk-prog Aug 20, 2025 •
edited
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rt_interrupt_get_nest 这种用法可能更好一些

我看到ut里面有类似使用 rt_interrupt_get_nest 的代码：

rt-thread/examples/utest/testcases/kernel/irq_tc.c

Line 21 in 60b3ccb

if(rt_interrupt_get_nest() > max_get_nest_count)

  • 是,我也有看到.但是这种是实实在在的优化.大部分场景下并没有要获取中断嵌套层数的必要.
  • 有必要的话,也应该是重新定义两个函数,一个用于获取嵌套层数,另一个专门用来获取是否进入中断既可
  • 另外对于只用内核不使用驱动的方式,之前的rt_interrupt_get_nest 大概率失效.

}

#ifdef RT_USING_CPU_FFS
/**
* This function finds the first bit set (beginning with the least significant bit)
Expand Down
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