Notes

@echo off
if "%~1" == "startGame" goto :game
if "%~1" == "startController" goto :controller


::------------------------------------------------------------
:: verify existence of CHOICE command
:: set up a macro appropriately depending on available version

set "choice="
2>nul >nul choice /c:yn /t 0 /d y
if errorlevel 1 if not errorlevel 2 set "choice=choice /cs"
if not defined choice (
2>nul >nul choice /c:yn /t:y,1
if errorlevel 1 if not errorlevel 2 set "choice=choice /s"
)
if not defined choice (
echo ERROR: This game requires the CHOICE command, but it is missing.
echo Game aborted. :(
echo(
echo A 16 bit port of CHOICE.EXE from FREEDOS is available at
echo http://winsupport.org/utilities/freedos-choice.html
echo(
echo A 32 bit version from ??? suitable for 64 bit machines is available at
echo http://hp.vector.co.jp/authors/VA007219/dkclonesup/choice.html
echo(
exit /b
)


::---------------------------------------------------------------------
:: setup some global variables used by both the game and the controller

set "keys=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
set "keyFile=key.txt"
set "cmdFile=cmd.txt"


::------------------------------------------
:: launch the game and the controller

copy nul "%keyFile%" >nul
start "" /b "%~f0" startController 9^>^>%keyFile% 2^>nul ^>nul
cmd /c "%~f0" startGame 9^<%keyFile% ^<nul
echo(

::--------------------------------------------------------------------------------
:: Upon exit, wait for the controller to close before deleting the temp input file

:close
2>nul (>>"%keyFile%" call )||goto :close
del "%keyFile%"
exit /b


::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:game
setlocal disableDelayedExpansion
title %~nx0
cls

::----------------------------
:: user configurable options

set "up=W"
set "down=S"
set "left=A"
set "right=D"

set "width=40" max=99
set "height=25" max=99
:: max playing field: (width-2)*(height-2) <= 1365

::----------------------------
:: resize the console window

set /a cols=width+1, lines=height+10, area=(width-2)*(height-2)
if %area% gtr 1365 (
echo ERROR: Playfield area too large
>"%cmdFile%" (echo quit)
exit
)
if %lines% lss 14 set lines=14
if %cols% lss 46 set cols=46
mode con: cols=%cols% lines=%lines%

::----------------------------
:: define variables

set "spinner1=-"
set "spinner2="
set "spinner3=|"
set "spinner4=/"
set "spinner= spinner1 spinner2 spinner3 spinner4 "

set "space= "
set "bound=#"
set "food=+"
set "head=@"
set "body=O"
set "death=X"
set "playerSpace=%space%%food%"

set "xDiff%up%=+0"
set "xDiff%down%=+0"
set "xDiff%left%=-1"
set "xDiff%right%=+1"

set "yDiff%up%=-1"
set "yDiff%down%=+1"
set "yDiff%left%=+0"
set "yDiff%right%=+0"

set "%up%Axis=Y"
set "%down%Axis=Y"
set "%left%Axis=X"
set "%right%Axis=X"

set "delay1=20"
set "delay2=15"
set "delay3=10"
set "delay4=7"
set "delay5=5"
set "delay6=3"
set "delay0=0"

set "desc1=Sluggard"
set "desc2=Crawl"
set "desc3=Slow"
set "desc4=Normal"
set "desc5=Fast"
set "desc6=Insane"
set "desc0=Unplayable"

set "spinnerDelay=3"

set /a "width-=1, height-=1"


::---------------------------
:: define macros

::define a Line Feed (newline) string (normally only used as !LF!)
set LF=^


::Above 2 blank lines are required - do not remove

::define a newline with line continuation
set ^"n=^^^%LF%%LF%^%LF%%LF%^^"

:: setErr
::: Sets the ERRORLEVEL to 1
set "setErr=(call)"

:: clrErr
::: Sets the ERRORLEVEL to 0
set "clrErr=(call )"


:: getKey ValidKeys
::: Check for keypress. Only accept keys listed in ValidKeys
::: Return result in Key variable. Key is undefined if no valid keypress.
set getKey=%n%
for %%# in (1 2) do if %%#==2 (for /f "eol= delims= " %%1 in ("!args!") do (%n%
set "validKeys=%%1"%n%
set "key="%n%
^<^&9 set /p "key="%n%
if defined key if "!key!" neq ":" (%n%
set /a key-=1%n%
for %%K in (!key!) do set "key=!keys:~%%K,1!"%n%
)%n%
for %%K in (!key!) do if "!validKeys:%%K=!" equ "!validKeys!" set "key="%n%
)) else set args=


:: draw
::: draws the board
set draw=%n%
cls%n%
for /l %%Y in (0,1,%height%) do echo(!line%%Y!%n%
echo Speed=!Difficulty!%n%
echo Score=!score!


:: test X Y ValueListVar
::: tests if value at coordinates X,Y is within contents of ValueListVar
set test=%n%
for %%# in (1 2) do if %%#==2 (for /f "tokens=1-3" %%1 in ("!args!") do (%n%
for %%A in ("!line%%2:~%%1,1!") do if "!%%3:%%~A=!" neq "!%%3!" %clrErr% else %setErr%%n%
)) else set args=


:: plot X Y ValueVar
::: places contents of ValueVar at coordinates X,Y
set plot=%n%
for %%# in (1 2) do if %%#==2 (for /f "tokens=1-3" %%1 in ("!args!") do (%n%
set "part2=!line%%2:~%%1!"%n%
set "line%%2=!line%%2:~0,%%1!!%%3!!part2:~1!"%n%
)) else set args=


::--------------------------------------
:: start the game
setlocal enableDelayedExpansion
call :initialize


::--------------------------------------
:: main loop (infinite loop)
for /l %%. in (1 0 1) do (

%=== compute time since last move ===%
for /f "tokens=1-4 delims=:.," %%a in ("!time: =0!") do set /a "t2=(((1%%a*60)+1%%b)*60+1%%c)*100+1%%d-36610100, tDiff=t2-t1"
if !tDiff! lss 0 set /a tDiff+=24*60*60*100

if !tDiff! geq !delay! (
%=== delay has expired, so time for movement ===%

%=== establish direction ===%
%getKey% ASDW
for %%K in (!key!) do if "!%%KAxis!" neq "!axis!" (
set /a "xDiff=xDiff%%K, yDiff=yDiff%%K"
set "axis=!%%KAxis!"
)

%=== erase the tail ===%
set "TX=!snakeX:~-2!"
set "TY=!snakeY:~-2!"
set "snakeX=!snakeX:~0,-2!"
set "snakeY=!snakeY:~0,-2!"
%plot% !TX! !TY! space

%=== compute new head location and attempt to move ===%
set /a "X=PX+xDiff, Y=PY+yDiff"
set "X= !X!"
set "Y= !Y!"
set "X=!X:~-2!"
set "Y=!Y:~-2!"
(%test% !X! !Y! playerSpace) && (

%=== move successful ===%

%=== remove the new head location from the empty list ===%
for %%X in ("!X!") do for %%Y in ("!Y!") do set "empty=!empty:#%%~X %%~Y=!"

(%test% !X! !Y! food) && (
%=== moving to food - eat it ===%

%=== restore the tail ===%
%plot% !TX! !TY! body
set "snakeX=!snakeX!!TX!"
set "snakeY=!snakeY!!TY!"

%=== increment score and locate and draw new food ===%
set /a "score+=1, F=(!random!%%(emptyCnt-=1))*6+1"
for %%F in (!F!) do (%plot% !empty:~%%F,5! food)

) || (
%=== moving to empty space ===%

%=== add the former tail position to the empty list ===%
set "empty=!empty!#!TX! !TY!"
)

%=== draw the new head ===%
if defined snakeX (%plot% !PX! !PY! body)
%plot% !X! !Y! head

%=== Add the new head position to the snake strings ===%
set "snakeX=!X!!snakeX!"
set "snakeY=!Y!!snakeY!"
set "PX=!X!"
set "PY=!Y!"

%draw%

) || (

%=== failed move - game over ===%
%plot% !TX! !TY! body
call :spinner !PX! !PY! death
%draw%
echo(
call :ask "Would you like to play again? (Y/N)" YN
if /i "!key!" equ "N" (
>"%cmdFile%" (echo quit)
exit
) else (
call :initialize
)
)

set /a t1=t2
)
)

:ask Prompt ValidKeys
:: Prompt for a keypress. ValidKeys is a list of acceptable keys
:: Wait until a valid key is pressed and return result in Key variable
>"%cmdFile%" (echo prompt)
<nul set /p "=%~1 "
:purge
(%getKey% :)
if not defined key goto :purge
:getResponse
(%getKey% %2)
if not defined key (
>"%cmdFile%" (echo one)
goto :getResponse
)
exit /b


:spinner X Y ValueVar
set /a d1=-1000000
for /l %%N in (1 1 5) do for %%C in (%spinner%) do (
call :spinnerDelay
%plot% %1 %2 %%C
%draw%
)
call :spinnerDelay
(%plot% %1 %2 %3)
exit /b

:spinnerDelay
for /f "tokens=1-4 delims=:.," %%a in ("!time: =0!") do set /a "d2=(((1%%a*60)+1%%b)*60+1%%c)*100+1%%d-36610100, dDiff=d2-d1"
if %dDiff% lss 0 set /a dDiff+=24*60*60*100
if %dDiff% lss %spinnerDelay% goto :spinnerDelay
set /a d1=d2
exit /b


::-------------------------------------
:initialize
cls

echo Speed Options:
echo delay
echo # Description (seconds)
echo --- ----------- ---------
echo 1 Sluggard 0.20
echo 2 Crawl 0.15
echo 3 Slow 0.10
echo 4 Normal 0.07
echo 5 Fast 0.05
echo 6 Insane 0.03
echo 0 Unplayable none
echo(
call :ask "Pick a speed (1-6, 0):" 1234560
set "difficulty=!desc%key%!"
set "delay=!delay%key%!"
echo %key% - %difficulty%
echo(
<nul set /p "=Initializing."
set "axis=X"
set "xDiff=+1"
set "yDiff=+0"
set "empty="
set /a "PX=1, PY=height/2, FX=width/2+1, FY=PY, score=0, emptyCnt=0, t1=-1000000"
set "snakeX= %PX%"
set "snakeY= %PY%"
set "snakeX=%snakeX:~-2%"
set "snakeY=%snakeY:~-2%"
for /l %%Y in (0 1 %height%) do (
<nul set /p "=."
set "line%%Y="
for /l %%X in (0,1,%width%) do (
set "cell="
if %%Y equ 0 set "cell=%bound%"
if %%Y equ %height% set "cell=%bound%"
if %%X equ 0 set "cell=%bound%"
if %%X equ %width% set "cell=%bound%"
if %%X equ %PX% if %%Y equ %PY% set "cell=%head%"
if not defined cell (
set "cell=%space%"
set "eX= %%X"
set "eY= %%Y"
set "empty=!empty!#!eX:~-2! !eY:~-2!"
set /a emptyCnt+=1
)
if %%X equ %FX% if %%Y equ %FY% set "cell=%food%"
set "line%%Y=!line%%Y!!cell!"
)
)
(%draw%)
echo(
echo Movement keys: %up%=up %down%=down %left%=left %right%=right
echo Avoid running into yourself (%body%%body%%head%) or wall (%bound%)
echo Eat food (%food%) to grow.
echo(
call :ask "Press any alpha-numeric key to start..." %keys%
>"%cmdFile%" (echo go)
exit /b


::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:controller

setlocal enableDelayedExpansion
set "cmd=hold"
set "key="
for /l %%. in (1 0 1) do (
if "!cmd!" neq "hold" (
%choice% /n /c:!keys!
set "key=!errorlevel!"
)
if exist "%cmdFile%" (
<"%cmdFile%" set /p "cmd="
del "%cmdFile%"
)
if "!cmd!" equ "quit" exit
if defined key (
if "!cmd!" equ "prompt" >&9 (echo :)
>&9 (echo !key!)
if "!cmd!" neq "go" set "cmd=hold"
set "key="
)
)