mkxp-z/binding/miniffi.cpp

#include "miniffi.h"
#include <assert.h>

#if defined(__MINGW64__) || defined(__linux__) || defined(__APPLE__)
mffi_value miniffi_call_intern(MINIFFI_FUNC target, MiniFFIFuncArgs *p, int nparams) {
    assert(nparams <= 10);
    return target(p->params[0], p->params[1], p->params[2], p->params[3],
                                 p->params[4], p->params[5], p->params[6],
                                 p->params[7], p->params[8], p->params[9]);
}
#else // 32-bit Windows
#define INTEL_ASM ".intel_syntax noprefix\n"
__attribute__((noinline))
mffi_value miniffi_call_intern(MINIFFI_FUNC target, MiniFFIFuncArgs *p, int nparams) {
    mffi_value ret;
    void *old_esp = 0;

    asm volatile(INTEL_ASM

                "mov [edi], esp\n"
                "test ebx, ebx\n"
                "jz mffi_call_void\n"
                
                "shl ebx, 2\n"
                "mov ecx, ebx\n"
                
                "mffi_call_loop:\n"
                "sub ecx, 4\n"
                "mov ebx, [esi+ecx]\n"
                "push ebx\n"
                "test ecx, ecx\n"
                "jnz mffi_call_loop\n"
                
                "mffi_call_void:\n"
                "call edx\n"
                
                : "=a"(ret)
                : "b"(nparams), "S"(p), "d"(target), "D"(&old_esp)
                : "ecx"
    );


    // If esp doesn't match, this was probably a cdecl and not a stdcall.
    // Move the stack pointer back to where it should be
    asm volatile(INTEL_ASM
                "mov edx, [edi]\n"
                "cmp edx, esp\n"
                "cmovne esp, edx"
                :
                : "D"(&old_esp)
                : "edx"
    );
    return ret;
}
#endif