With Visual Studio I can read the clock cycle count from the processor as shown below.
How do I do the same thing with GCC?

```
#ifdef _MSC_VER             // Compiler: Microsoft Visual Studio

    #ifdef _M_IX86                      // Processor: x86

        inline uint64_t clockCycleCount()
        {
            uint64_t c;
            __asm {
                cpuid       // serialize processor
                rdtsc       // read time stamp counter
                mov dword ptr [c + 0], eax
                mov dword ptr [c + 4], edx
            }
            return c;
        }

    #elif defined(_M_X64)               // Processor: x64

        extern "C" unsigned __int64 __rdtsc();
        #pragma intrinsic(__rdtsc)
        inline uint64_t clockCycleCount()
        {
            return __rdtsc();
        }

    #endif

#endif

```