div 128

div128.cpp

#include <immintrin.h>

// https://stackoverflow.com/a/8456388
// https://docs.microsoft.com/en-us/cpp/intrinsics/div128?view=vs-2019

#pragma code_seg(".text")
const unsigned char sdiv128Data[] =
{
  0x48, 0x89, 0xD0, // mov rax,rdx
  0x48, 0x89, 0xCA, // mov rdx,rcx
  0x49, 0xF7, 0xF8, // idiv r8
  0x49, 0x89, 0x11, // mov [r9],rdx
  0xC3              // ret
};

__int64 (__fastcall *sdiv128)(__int64 numhi,
                              __int64 numlo,
                              __int64 den,
                              __int64* rem) =
  (__int64 (__fastcall *)(__int64,
                          __int64,
                          __int64,
                          __int64*))&sdiv128Data;

__int64 div_mod(__int64 hi, __int64 low, __int64 divisor, __int64* reminder) {
    return _div128(hi, low, divisor, reminder);
}

int main()
{
    __int64 sr;
    sdiv128(-1, -6, -2, &sr);
    return 0;
}