RDTSC based timestamps

timestamp.h

#ifndef _TIMESTAMP_H_
#define _TIMESTAMP_H_

static inline uint64_t timestamp_start(void)
{
	union {
		uint64_t tsc_64;
		struct {
			uint32_t lo_32;
			uint32_t hi_32;
		};
	} tsc;

	asm volatile (
			"CPUID\n\t"/*serialize*/
			"RDTSC\n\t"/*read the clock*/
			"mov %%edx, %0\n\t"
			"mov %%eax, %1\n\t": "=r" (tsc.hi_32), "=r"
			(tsc.lo_32):: "%rax", "%rbx", "%rcx", "%rdx");
	return tsc.tsc_64;
}

static inline uint64_t timestamp_end(void)
{
	union {
		uint64_t tsc_64;
		struct {
			uint32_t lo_32;
			uint32_t hi_32;
		};
	} tsc;

	asm volatile (
		"RDTSCP\n\t"/*read the clock*/
		"mov %%edx, %0\n\t"
		"mov %%eax, %1\n\t"
		"CPUID\n\t": "=r" (tsc.hi_32), "=r"
		(tsc.lo_32):: "%rax", "%rbx", "%rcx", "%rdx");
	return tsc.tsc_64;
}

#endif