How to access C arrays from assembler for Windows x64?

Question

I wrote an assembler function to speed up the image processing (images are created using CreateDIBSection).

For Win32, the assembler code works without problems, but for Win64 I get a crash as soon as I try to access the array data.

I put the relevant information in a structure, and my assembler function gets a pointer to that structure. The structure pointer is placed in ebx / rbx and with indexing I read the data from the structure.

Any idea what I'm doing wrong? I use nasm with Visual Studio 2008, and for Win64 I set "default rel".

C ++ Code:

struct myData {
  tUInt32 ulParam1;
  void* pData;
};

CallMyAssemblerFunction(&myData);

Assembly code:

Win32:

...
  push ebp;
  mov ebp,esp
  mov ebx, [ebp + 8]; pointer to our struct
  mov eax, [ebx]; ulParam1
  mov esi, [ebx + 4]; pData, 4 byte pointer

  movd xmm0, [esi];
...

Win64:

...
  mov rbx, rcx; pointer to our struct
  mov eax, [rbx]; ulParam1
  mov rsi, [rbx + 4]; pData, 8 byte pointer

  movd xmm0, [rsi]; CRASH!
...

Answer 1

, pData [rbx + 8], [rbx + 4]. ( "" ) ulParam1 pData, pData 8 ( ).

Answer 2

. , x64