Missing x64 Intrinsics and Windows API for ARM64

This is a list of x64 intrinsics used in many popular codebases but is lacking an ARM64 implementation and an alternative MSVC intrinsics.

An alternative ARM64 implementation in C is provided to help developers port code for windows arm64 targets.

	Intrinsics / Windows API	Description	ARM64 alternative implementation

	Intrinsics / Windows API	Description	ARM64 alternative implementation
1	_umul128	128-bit unsigned multiplication	`#pragma intrinsic(__umulh) uint64_t _umul128(uint64_t a, uint64_t b, uint64_t high) { high = __umulh(a, b); return a * b; }`
2	UnsignedMultiply128	128-bit unsigned multiplication
3	_addcarry_u64	64-bit add with carry returning the carry flag	`uint64_t addcarry(uint64_t x, uint64_t y, uint64_t carry_in, uint64_t sum) { sum = x + y + (carry_in !=0 ? 1 : 0); return x > UINT32_MAX - y; }`
4	__rdtsc	Processor time stamp - Number of clock cycles since reset	`int64_t processor_cycle_count() { const int64_t pmccntr_el0 = (((3 & 1) << 14) \| // op0 ((3 & 7) << 11) \| // op1 ((9 & 15) << 7) \| // crn ((13 & 15) << 3) \| // crm ((0 & 7) << 0)); // op2 return _ReadStatusReg (pmccntr_el0); }`
5	__popcnt and variants	Counts the number of `1` bits (population count) in a 16-, 32-, or 64-bit unsigned integer.

Windows On Arm (WOA)