zig/std/special/compiler_rt/aulldiv.zig

const builtin = @import("builtin");
const linkage = if (builtin.is_test) builtin.GlobalLinkage.Internal else builtin.GlobalLinkage.Strong;
const is_win32 = builtin.os == builtin.Os.windows and builtin.arch == builtin.Arch.i386;

export nakedcc fn _aulldiv() {
    if (is_win32) {
        @setDebugSafety(this, false);
        @setGlobalLinkage(_aulldiv, linkage);
        asm volatile (
            \\.intel_syntax noprefix
            \\
            \\         push        ebx
            \\         push        esi
            \\         mov         eax,dword ptr [esp+18h]
            \\         or          eax,eax
            \\         jne         L1
            \\         mov         ecx,dword ptr [esp+14h]
            \\         mov         eax,dword ptr [esp+10h]
            \\         xor         edx,edx
            \\         div         ecx
            \\         mov         ebx,eax
            \\         mov         eax,dword ptr [esp+0Ch]
            \\         div         ecx
            \\         mov         edx,ebx
            \\         jmp         L2
            \\ L1:
            \\         mov         ecx,eax
            \\         mov         ebx,dword ptr [esp+14h]
            \\         mov         edx,dword ptr [esp+10h]
            \\         mov         eax,dword ptr [esp+0Ch]
            \\ L3:
            \\         shr         ecx,1
            \\         rcr         ebx,1
            \\         shr         edx,1
            \\         rcr         eax,1
            \\         or          ecx,ecx
            \\         jne         L3
            \\         div         ebx
            \\         mov         esi,eax
            \\         mul         dword ptr [esp+18h]
            \\         mov         ecx,eax
            \\         mov         eax,dword ptr [esp+14h]
            \\         mul         esi
            \\         add         edx,ecx
            \\         jb          L4
            \\         cmp         edx,dword ptr [esp+10h]
            \\         ja          L4
            \\         jb          L5
            \\         cmp         eax,dword ptr [esp+0Ch]
            \\         jbe         L5
            \\ L4:
            \\         dec         esi
            \\ L5:
            \\         xor         edx,edx
            \\         mov         eax,esi
            \\ L2:
            \\         pop         esi
            \\         pop         ebx
            \\         ret         10h
        );
        unreachable;
    }

    @setGlobalLinkage(_aulldiv, builtin.GlobalLinkage.Internal);
    unreachable;
}