STRPTR in asm

[Aslan Babakhanov]

Naked STRPTR in assembler

Code: [Select]

MACRO Sptr( pString, retPtr)
 ! push ebx
 ! lea ebx, pString
 ! mov edi, dword ptr [ebx]
 ! pop ebx
 ! mov retPtr, edi
END MACRO 
...
LOCAL s AS STRING, R AS DWORD
S = "STRPTR"
SPTR (S,R)

? STR$(R)

Using stackless function may replace macro and increase readability of the code.

[Charles Pegge]

Hi Aslan

This can be simplified to

Code: [Select]

MACRO Sptr( pString, retPtr)
 ! mov eax,pString
 ! mov retPtr,eax
END MACRO

Charles

[Aslan Babakhanov]

and this is really short.
Nice!

[Charles Pegge]

While I have not peeked into PB compiled code, I believe VARPTR() and STRPTR() are not functions but generate inline instructions.

A simple VARPTR translates to

lea eax,var

whereas STRPTR becomes

mov eax,var

Then assigning the result to a local variable would be something like:

mov [ebp-8],eax

Charles

[Bob Zale]

That would be true for pure scalar variables.  But that couldn't account for variables which require multiple operations to locate.  Arrays, pointer targets, Threaded, Instance...

Bob Zale
PowerBASIC Inc.