我正在尝试创建2个线程,它们与浮点数组一起工作。Howere编译器给了我这些错误:
/usr/include/c++/9/thread: In instantiation of ‘std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (&)(bool*, float*, float*, float*); _Args = {bool*, float (*)[10], float (*)[10], float (*)[10]}; <template-parameter-1-3> = void]’:
main.cpp:16:66: required from here
/usr/include/c++/9/thread:120:44: error: static assertion failed: std::thread arguments must be invocable after conversion to rvalues
120 | typename decay<_Args>::type...>::value,
| ^~~~~
/usr/include/c++/9/thread: In instantiation of ‘struct std::thread::_Invoker<std::tuple<void (*)(bool*, float*, float*, float*), bool*, float (*)[10], float (*)[10], float (*)[10]> >’:
/usr/include/c++/9/thread:131:22: required from ‘std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (&)(bool*, float*, float*, float*); _Args = {bool*, float (*)[10], float (*)[10], float (*)[10]}; <template-parameter-1-3> = void]’
main.cpp:16:66: required from here
/usr/include/c++/9/thread:243:4: error: no type named ‘type’ in ‘struct std::thread::_Invoker<std::tuple<void (*)(bool*, float*, float*, float*), bool*, float (*)[10], float (*)[10], float (*)[10]> >::__result<std::tuple<void (*)(bool*, float*, float*, float*), bool*, float (*)[10], float (*)[10], float (*)[10]> >’
243 | _M_invoke(_Index_tuple<_Ind...>)
| ^~~~~~~~~
/usr/include/c++/9/thread:247:2: error: no type named ‘type’ in ‘struct std::thread::_Invoker<std::tuple<void (*)(bool*, float*, float*, float*), bool*, float (*)[10], float (*)[10], float (*)[10]> >::__result<std::tuple<void (*)(bool*, float*, float*, float*), bool*, float (*)[10], float (*)[10], float (*)[10]> >’
247 | operator()()
| ^~~~~~~~
/usr/include/c++/9/thread: In instantiation of ‘std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (&)(float*); _Args = {float (*)[10]}; <template-parameter-1-3> = void]’:
main.cpp:17:43: required from here
/usr/include/c++/9/thread:120:44: error: static assertion failed: std::thread arguments must be invocable after conversion to rvalues
120 | typename decay<_Args>::type...>::value,
| ^~~~~
/usr/include/c++/9/thread: In instantiation of ‘struct std::thread::_Invoker<std::tuple<void (*)(float*), float (*)[10]> >’:
/usr/include/c++/9/thread:131:22: required from ‘std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (&)(float*); _Args = {float (*)[10]}; <template-parameter-1-3> = void]’
main.cpp:17:43: required from here
/usr/include/c++/9/thread:243:4: error: no type named ‘type’ in ‘struct std::thread::_Invoker<std::tuple<void (*)(float*), float (*)[10]> >::__result<std::tuple<void (*)(float*), float (*)[10]> >’
243 | _M_invoke(_Index_tuple<_Ind...>)
| ^~~~~~~~~
/usr/include/c++/9/thread:247:2: error: no type named ‘type’ in ‘struct std::thread::_Invoker<std::tuple<void (*)(float*), float (*)[10]> >::__result<std::tuple<void (*)(float*), float (*)[10]> >’
247 | operator()()
| ^~~~~~~~
我以为我忘记了dma线程的一些ctor参数,但事实并非如此。下面是我的代码:
#include <iostream>
#include <cstdint>
#include <thread>
void dma_service(bool*, float*, float*, float*);
void live_audio(float*);
void live_draw(float*);
constexpr int d_size = 10;
float data[d_size];
float pwm_cp[d_size];
float fft_cp[d_size];
bool drdy = 0;
std::thread dma_thrd(dma_service, &drdy, &data, &pwm_cp, &fft_cp);
std::thread audio_thrd(live_draw, &pwm_cp);
int main(){
for (auto i = 0; i < d_size; i++)
{
data[i] = 0;
pwm_cp[i] = 0;
}
printf("Hello, World!\n");
drdy = 1;
int k = 3;
while(k-->0)
{
audio_thrd.join();
printf("\n\n\n");
for (auto i = 0; i < d_size; i++)
{
data[i]++;
}
drdy = 1;
}
}
void dma_service(bool* flag, float* d_array, float* pwm_array, float* fft_array) {
while (!flag) ;
for (auto i = 0; i < d_size; i++)
{
pwm_array[i] = d_array[i];
fft_array[i] = d_array[i];
}
flag = 0;
}
void live_audio(float* pwm_array) {
dma_thrd.join();
printf("Audio Array:\n");
for (auto i = 0; i < d_size; i++)
{
printf("PWM_CP[%d] %f\n", i, pwm_array[i]);
}
}
我对lambda函数没有太多的经验,所以我不知道这里是否需要它们(并且很乐意避免它们)。谢谢你的建议!
给定浮点数据[d_size];
,&data
被推导为“指向数组的指针”类型。与float*
参数不匹配。
您可以简单地省略&
,那么数组到指针的衰减就会开始,类型就会匹配。
std::thread dma_thrd(dma_service, &drdy, data, pwm_cp, fft_cp);
std::thread audio_thrd(live_draw, pwm_cp);
或者传递第一个元素的地址:
std::thread dma_thrd(dma_service, &drdy, &data[0], &pwm_cp[0], &fft_cp[0]);
std::thread audio_thrd(live_draw, &pwm_cp[0]);
注意,这不足以使程序工作。我发现它缺少线程同步,在全局范围内启动线程是有问题的,因为它们将在main()
之前启动。此外,循环中的join()
也不能正常工作,因为join()
只能执行一次。