CritSec - Critical section helper class for Raspberry Pi Pico SDK (RP2040)

CritSec.h

// CritSec - Critical section helper class for Raspberry Pi Pico SDK
// by Len Popp
//
// Usage
//
//  #include "CritSec.h"
//
//  {
//      CritSec<AnyType>::init();
//      /* ... */
//      {
//          CritSec<AnyType> cs;
//          /* ... critical section code ... */
//      }
//  }
//
// Notes
//
// To protect a block of code with a critical_section_t, declare a CritSec
// object at the start of the scope block. The CritSec will block in its
// constructor until the critical_section_t is available and it will release
// the critical_section_t in its destructor at the end of the block.
//
// All CritSec objects declared with the same template type, e.g. CritSec<AnyType>,
// will share a single critical_section_t object. CritSec objects declared with
// a different type, e.g. CritSec<SomeOtherType>, will use a different
// critical_section_t object.
//
// When compiling for the Raspberry Pi Pico, the C++ Standard Library does not have
// support for thread concurrency (std::mutex etc.). Therefore the Pi Pico SDK has
// its own concurrency support (spin_lock_t, critical_section_t, etc.).
// This helper class simplifies the use of critical sections and reduces errors by
// not requiring matching enter & exit calls. It generates efficient inlined code
// which is identical to using critical_section_t explicitly (tested with gcc 11.2).

#pragma once

#include "pico/sync.h"

template<typename T>
class CritSec
{
public:
    CritSec() { critical_section_enter_blocking(&cs); }
    ~CritSec() { critical_section_exit(&cs); }
    static void init() { critical_section_init(&cs); }
    static void deinit() { critical_section_deinit(&cs); }
private:
    static critical_section_t cs;
};

template<typename T> critical_section_t CritSec<T>::cs;

example.cpp

#include "pico/stdlib.h"
#include "CritSec.h"

struct Data
{
	int a = 1;
};

static Data data;

int main()
{
    CritSec<Data>::init();
    {
        CritSec<Data> cs;
        data.a = 17;
    }
    CritSec<Data>::deinit();
}