kolibrios/programs/games/c4/trunk/ai.inc
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; C4
; Copyright (c) 2002 Thomas Mathys
; killer@vantage.ch
;
; This file is part of C4.
;
; C4 is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation; either version 2 of the License, or
; (at your option) any later version.
;
; C4 is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with C4; if not, write to the Free Software
; Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
%ifndef _AI_INC
%define _AI_INC
INFTY equ 1000000000
section .data
; table used to perform some primitive move "ordering":
; middle columns which are usually more important are
; searched first.
moveorder dd 1,7,2,6,3,5,4
; table used for static evaluation.
; this table is taken from 4st attack: it is ways better
; than the table i used before =)
evaltable: dd 0, 0, 0, 0, 0, 0, 0, 0, 0
dd 0, 3, 4, 5, 7, 5, 4, 3, 0
dd 0, 4, 6, 8,10, 8, 6, 4, 0
dd 0, 5, 8,12,13,12, 8, 5, 0
dd 0, 5, 8,12,13,12, 8, 5, 0
dd 0, 4, 6, 8,10, 8, 6, 4, 0
dd 0, 3, 4, 5, 7, 5, 4, 3, 0
dd 0, 0, 0, 0, 0, 0, 0, 0, 0
section .bss
cpulevel resd 1 ; level of current cpu player
bestval resd 1 ; value of best move found so far
nbestmoves resd 1 ; # of best moves found so far
bestmoves resd 7 ; array to hold all best moves
section .text
;**********************************************************
; aiGetMove
; returns a move for a computer player
;
; input : eax = cpu level ( >= 1)
; output : eax = move
; destroys : everything
;**********************************************************
aiGetMove:
; initialize variables
mov [cpulevel],eax
mov dword [bestval],-INFTY
mov dword [nbestmoves],0
; try every move
mov ecx,6
.evalmoves:
; get move to make from move order table
mov eax,[moveorder+ecx*4]
; if this is an invalid move, continue with next move
BOARDISVALIDMOVE eax
jz .nextmove
; make move for current player
mov ebx,[currentplayer]
call boardMakeMove
; evaluate move
push eax ; save move #
push ecx ; save loop counter
push dword [cpulevel] ; ply
mov ebx,[currentplayer] ; player
BOARDGETOTHERPLAYER ebx
push ebx
push dword -INFTY ; alpha
push dword INFTY ; beta
call alphabeta
neg eax ; damn, how could i forget this ???
mov ebx,eax ; save result for later
pop ecx ; restore loop counter
pop eax ; restore move #
; undo move (eax = move #)
call boardUndoMove
; let's see wether we have a new best move
cmp ebx,[bestval] ; new best value found ?
jle .nonewbestval
mov [bestval],ebx ; yes -> save it
mov dword [nbestmoves],1 ; delete everything that was in the list
mov [bestmoves+0],eax ; save move number in list
jmp short .nextmove ; continue with next move
.nonewbestval:
cmp ebx,[bestval] ; another best value found ?
jne .nextmove
mov ebx,[nbestmoves] ; yes -> add move to list
mov [bestmoves+ebx*4],eax
inc dword [nbestmoves]
.nextmove:
dec ecx
js .done
jmp .evalmoves
.done:
; randomly pick one of the best moves
call rand ; rand() % nbestmoves
xor edx,edx
div dword [nbestmoves]
mov eax,[bestmoves+edx*4] ; get move from list
ret
; test code : pick first move from list
mov eax,[bestmoves+0]
ret
;**********************************************************
; alphabeta
;
; input : see below
; output : eax = move value
; destroys : everything
;**********************************************************
alphabeta:
%define ply (ebp+20)
%define player (ebp+16)
%define alpha (ebp+12)
%define beta (ebp+ 8)
enter 0,0
; win for other player -> end search
mov eax,[player]
BOARDGETOTHERPLAYER eax
call boardIsWin
or eax,eax
jz .nowin
mov eax,-1000000
mov ebx,[ply]
shl ebx,10
sub eax,ebx
leave
ret 4*4
.nowin:
; board full but no win -> draw -> end search
BOARDISFULL
jnz .notfull
xor eax,eax
leave
ret 4*4
.notfull
; max search depth reached -> do static evaluation
cmp dword [ply],0
je .staticeval
; for each move
mov ecx,6
.evalmoves:
; while (alpha < beta)
mov eax,[alpha]
cmp eax,[beta]
jge .done
; pick move from move order table
mov eax,[moveorder+ecx*4]
; invalid move ? if so, continue with next move
BOARDISVALIDMOVE eax
jz .nextmove
; make move for current player
mov ebx,[player]
call boardMakeMove
; evaluate move
push eax
push ecx
mov eax,[ply] ; ply = ply-1
dec eax
push eax
mov ebx,[player] ; player = other player
BOARDGETOTHERPLAYER ebx
push ebx
mov ecx,[beta] ; alpha = -beta
neg ecx
push ecx
mov edx,[alpha] ; beta = -alpha
neg edx
push edx
call alphabeta
neg eax
; new alpha ?
cmp eax,[alpha]
jle .nonewalpha
mov [alpha],eax ; yes -> save it
.nonewalpha:
pop ecx
pop eax
; undo move
call boardUndoMove
.nextmove: ; evaluate next move
dec ecx
jns .evalmoves
.done:
mov eax,[alpha]
leave
ret 4*4
; static evaluation
.staticeval:
xor eax,eax
mov esi,BWIDTH*BHEIGHT-1
.l:
mov ebx,[board+esi*4] ; get stone from board
cmp ebx,[player] ; player's stone ?
jne .notplayer ; nope -> go on
add eax,[evaltable+esi*4] ; yes -> add stone value to eax
jmp .next ; next stone
.notplayer:
cmp ebx,EMPTY ; other player's stone ?
je .empty ; nope -> go on
sub eax,[evaltable+esi*4] ; yes -> sub stone value from eax
.empty:
.next: ; next stone
dec esi
jns .l
leave ; eax contains static value
ret 4*4
%undef ply
%undef player
%undef alpha
%undef beta
%endif