sprintf 重新进入具有中断的 32 位 MCU 中的 64 位操作

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问题描述

参考 SO 问题:52164135

In reference to SO question: 52164135

设置:
我有一个函数可以将许多 double 值转换为预定义的字符串.输入是一个 struct 数组，我们从中将两个双精度值连接成一个字符串.double 的大小为 8 字节或 64 位，我的操作 MCU 是 STM32，一个 32 位 ARM 微控制器.
中断也在并行运行.

The setup:
I have a function which converts many double values into a predefined string. The input is a array of struct from which we concatenate two double values into a string. A double is of size 8 bytes or 64 bits and my MCU of operation is STM32, a 32 bit ARM micro-controller.
An interrupt is also running parallelly.

数据应如下所示:

[[[12.11111111,12.11111111],[12.22222222,12.22222222],...]

但我得到(很少):

[[[12.11111111,12.11111111],[55.01[12.33333333,12.33333333],...]

注意:我错过了[12.22222222,12.22222222]

sprintf 不会重新进入t:
根据此讨论，在 AVRFreaks 上，sprintf 不会重新(讨论的是在启用中断的硬件环境中使用 sprintf.)这意味着如果在 sprintf 操作之间发生中断，堆栈将无法继续它正在执行的操作.

sprintf is not re-entrant:
According to this discussion, on AVRFreaks, sprintf is not re-entrant. (The discussion is on using sprintf in a interrupt enabled hardware environment.) Which means if an interrupt occurs in-between a sprintf operation the stack fails to continue the operation it was doing.

由于我的 MCU 是 32 位的，所以要执行 64 位操作需要两个时钟周期.如果我们根据上面的讨论假设在 sprintf 操作之间发生了中断，sprintf 应该会失败.

Since my MCU is a 32 bit one, to perform a 64 bit operation it will take two clock cycles. And if we assume an interrupt occurred in between the sprintf operation according the the above discussion sprintf should fail.

问题
1.sprintf被打断会失败吗?

这里是字符串函数，一个中断例程也在后台运行，用于处理其他传感器数据(本地和全局)

Here is the string function, an interrupt routine also runs in the background which deals with other sensor data (local and global)

/* @brief From the array of GPS structs we create a string of the format
 * [[lat,long],[lat,long],..]
 * @param   input   The input array of GPS structs
 * @param   output  The output string which will contain lat, long
 * @param   sz      Size left in the output buffer
 * @return  0       Successfully completed operation
 *          1       Failed / Error
 */
int get_gps60secString(GPS_periodic_t input[GPS_PERIODIC_ARRAY_SIZE], 
                       char *output, size_t sz) 
{
    int cnt = snprintf(output, sz, "[");
    if (cnt < 0 || cnt >= sz)
        return 1;
    output += cnt;
    sz -= cnt;

    int i = 0;
    for (i = 0; i < GPS_PERIODIC_ARRAY_SIZE; i++) {
        cnt = snprintf(output, sz, "[%0.8f,%0.8f]%s", 
                input[i].point.latitude, input[i].point.longitude, 
                i + 1 == GPS_PERIODIC_ARRAY_SIZE ? "" : ",");
        if (cnt < 0 || cnt >= sz)
            return 1;
        output += cnt;
        sz -= cnt;
    }

    cnt = snprintf(output, sz, "]");
    if (cnt < 0 || cnt >= sz)
        return 1;
    return 0; // no error
}

中断例程

What's happening inside the interrupt routine

void GPS_InterruptHandler(UART_HandleTypeDef *UartHandle)
{
    gps_UART_RxInterrupt_Disable();
    GPS_t l_sGpsInfo;
    memset(&l_sGpsInfo,0,sizeof(GPS_t));
    status=Validate_get_gpsInfo((char*)g_gps_readBuff,&l_sGpsInfo,100);

    MEMS_interruptHandler(); //Inertial sensor ISR
    gps_UART_RxInterrupt_Enable();
}

the

sprintf 重新进入具有中断的 32 位 MCU 中的 64 位操作

问题描述

推荐答案