GetCaretPos Error Invalid Access Memory Location - winapi

Question

I'm trying to call the GetCaretPos function in User32.dll from an NSIS installer, and the only thing I can seem to get is an invalid access to memory location error.
Here is my code:
Function fixUpRegKeyText
Exch $0 ; HWND to text box
Push $1 ; text of edit box
Push $2 ; pointer to point structure
Push $3 ; getlasterror result
System::Alloc 16 ;struct long, long
pop $2
;messageBox MB_OK $2
;get the caret position
System::Call "User32::GetCaretPos(p .r2) i.. ? e"
pop $3
messageBox MB_OK $3 ; 998!
${NSD_GetText} $0 $1
Push $1
call StrUpper
Pop $1
${NSD_SetText} $0 $1
; now set the caret position
;System::call "user32::SetCaretPos(p s.) i .."
Pop $3
Pop $2
Pop $1
Pop $0
FunctionEnd
Edit In case anyone is interested in using Windows API to move the text caret, I blogged about it. Using anders' answer, it's straightforward to do this in NSIS script.

Answer 1

The p pointer type does not work in 2.46, use i. (Use your offline helpfile, the online helpfile has features only available in SVN)
Also, when a function needs a pointer to a struct that you have allocated, use "i register", not "i .register" (The function needs to know the memory address so it can fill it with data)
System::Call '*(i,i)i.r0'
System::Call "USER32::GetCaretPos(i r0)i.r3"
System::Call '*$0(i.r1,i.r2)'
DetailPrint "$1x$2 return=$3"
System::Free $0