rem: u32 diff_usec(unsigned long long start,unsigned long long end)
add: u32 diff_usec(long long start,long long end)
context: u32 diff_usec(unsigned long long start,unsigned long long end){	u32 upper,lower;	upper = ((u32)(end>>32))-((u32)(start>>32));	if((u32)start > (u32)end)		upper--;	lower = ((u32)end)-((u32)start);	return ((upper*((u32)0x80000000/(TB_TIMER_CLOCK/2000)))+(lower/(TB_TIMER_CLOCK/1000)));}