cmd: Windows 7 batch loop file renumber with leading zeroes

renumber.cmd

@echo off 
echo renumber.cmd folder start total
echo ===============================

setlocal EnableDelayedExpansion
set /a start  = %2

if NOT DEFINED [%3] (
	for %%a in (.\%1\*.png) do ( set /a i+=1 )
	echo Total files in folder %1: !i!
	set /a total = i
) ELSE (
	set /a total  = %3
)

if !start! LSS 0 ( set /a start=total+start )

set /a end = total - start
set /a i=start

REM echo i=!i!, start=!start!, total=!total!, end=!end!

echo Renumber *.png in _folder_ from _start_ (will be named as zero) and loop after _total_
echo ---------------------------------------------------------------------------------------

for %%a in (.\%1\*.png) do (

REM templete for leading zeroes goes here:
SET newname=0000!i!
SET newname=!newname:~-4!

set /a i+=1
if !i! GEQ !total! ( set /a i=0 )

REM filename template goes here:
ren %%a !newname!.new
)
echo ---------------------------------------------------------------------------------------
REM final renaming
ren .\%1\*.new *.png