NSIS code if-else to stack operation - nsis

Question

I always get confused when it comes to nsis stack operation. Now I'm writing a small piece of code for trimming trailing space from a string.
Input:
C:\Program Files (x86)\COMPANY\ or C:\Program Files (x86)\COMPANY
Output:
C:\Program Files (x86)\COMPANY
Working code - with normal if-else
!define TrimPath '!insertmacro "_TrimPath"'
!macro _TrimPath _FOLDERPATH
StrCpy $0 `${_FOLDERPATH}` 1 -1
${If} $0 == "\"
StrCpy $1 `${_FOLDERPATH}` -1
StrCpy `${_FOLDERPATH}` $1
${EndIf}
!macroend
Wrong code - with stack operation
!define TrimPath '!insertmacro "_TrimPath"'
!macro _TrimPath _FOLDERPATH
Exch $0
StrCpy $2 $0 1 -1
StrCmp $2 "\" +2 +1
StrCpy $1 $0 -1
StrCpy $1 $0
Pop $0
Exch $1
!macroend
Can anyone correct me and point me whats wrong?

Answer 1

I think you're trying to use a macro as a function. Some comments/questions/hints:
Why are you using Exch which swaps the value in the top of the stack instead of using _FOLDERPATH ?
Are you pushing the parameter in the stack before calling the macro? Something like:
push $path
${Trimpath}
Pop $0 restores the value of $0 but then you call Exch $1 which will swap the value in top of the stack (unknow value, maybe the stack is empty) with $1. Why?? If you want to save the result in the stack, just push $1.