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'''[[Main Page|Home]] * [[Engines]] * [[CPW-Engine]] * Algebraic'''
=Description=
When communicating with the [[GUI]], the Engine is supposed to use the [[Algebraic Chess Notation|algebraic game notation]]. The code on this page is used to translate the positions in the engine native form to the GUI friendly representation and back again.
The algebraic game notation first has 2 characters representing the square the piece comes from (eg.: "e2"). Then 2 characters to indicate the square the piece moves to (eg.: "e4"). And finally, in case of a promotion, the piece the pawn is promoted to ( q | r | b | n ). So a possible starting move for white could be "e2e4". And a possible promotion move could be "a7a8n".
=Code=
==int convert_0x88_a(sq, a)==
<pre>
int convert_0x88_a(int sq, char * a) {
a[0] = COL(sq) + 'a';
a[1] = ROW(sq) + '1';
a[2] = 0;
return 0;
}
</pre>
==int convert_a_0x88(a)==
<pre>
int convert_a_0x88(char * a) {
int sq = 0;
sq = a[0] - 'a';
sq += (a[1] - '1') * 16;
return sq;
}
</pre>
==int algebraic_moves(a)==
<pre>
int algebraic_moves(char * a) {
smoves m;
while ((a[0] >= 'a') && (a[0] <= 'h')) {
m.from = convert_a_0x88(a);
m.to = convert_a_0x88(a+2);
m.piece_from = b.pieces[m.from];
m.piece_to = b.pieces[m.from];
m.piece_cap = b.pieces[m.to];
m.flags = 0;
m.castle = 0;
m.ep = 0;
m.ply = 0;
m.score = 0;
switch (a[4]) {
case 'q': m.piece_to = PIECE_QUEEN; a++; break;
case 'r': m.piece_to = PIECE_ROOK; a++; break;
case 'b': m.piece_to = PIECE_BISHOP; a++; break;
case 'n': m.piece_to = PIECE_KNIGHT; a++; break;
}
//castling
if ((m.piece_from == PIECE_KING) &&
((m.from == E1 && (m.to == G1 || m.to == C1)) ||
(m.from == E8 && (m.to == G8 || m.to == C8)))) {
m.flags = MFLAG_CASTLE;
}
/*ep
if the moving-piece is a Pawn, the square it moves to is empty and
it was a diagonal move it has to be an en-passant capture.
*/
if ((m.piece_from == PIECE_PAWN) &&
(m.piece_cap == PIECE_EMPTY) &&
((abs(m.from-m.to)==15)||(abs(m.from-m.to)==17))) {
m.flags = MFLAG_EPCAPTURE;
}
move_make(m);
a += 4;
while (a[0]==' ') a++;
}
return 0;
}
</pre>
'''[[CPW-Engine|Up one Level]]'''
=Description=
When communicating with the [[GUI]], the Engine is supposed to use the [[Algebraic Chess Notation|algebraic game notation]]. The code on this page is used to translate the positions in the engine native form to the GUI friendly representation and back again.
The algebraic game notation first has 2 characters representing the square the piece comes from (eg.: "e2"). Then 2 characters to indicate the square the piece moves to (eg.: "e4"). And finally, in case of a promotion, the piece the pawn is promoted to ( q | r | b | n ). So a possible starting move for white could be "e2e4". And a possible promotion move could be "a7a8n".
=Code=
==int convert_0x88_a(sq, a)==
<pre>
int convert_0x88_a(int sq, char * a) {
a[0] = COL(sq) + 'a';
a[1] = ROW(sq) + '1';
a[2] = 0;
return 0;
}
</pre>
==int convert_a_0x88(a)==
<pre>
int convert_a_0x88(char * a) {
int sq = 0;
sq = a[0] - 'a';
sq += (a[1] - '1') * 16;
return sq;
}
</pre>
==int algebraic_moves(a)==
<pre>
int algebraic_moves(char * a) {
smoves m;
while ((a[0] >= 'a') && (a[0] <= 'h')) {
m.from = convert_a_0x88(a);
m.to = convert_a_0x88(a+2);
m.piece_from = b.pieces[m.from];
m.piece_to = b.pieces[m.from];
m.piece_cap = b.pieces[m.to];
m.flags = 0;
m.castle = 0;
m.ep = 0;
m.ply = 0;
m.score = 0;
switch (a[4]) {
case 'q': m.piece_to = PIECE_QUEEN; a++; break;
case 'r': m.piece_to = PIECE_ROOK; a++; break;
case 'b': m.piece_to = PIECE_BISHOP; a++; break;
case 'n': m.piece_to = PIECE_KNIGHT; a++; break;
}
//castling
if ((m.piece_from == PIECE_KING) &&
((m.from == E1 && (m.to == G1 || m.to == C1)) ||
(m.from == E8 && (m.to == G8 || m.to == C8)))) {
m.flags = MFLAG_CASTLE;
}
/*ep
if the moving-piece is a Pawn, the square it moves to is empty and
it was a diagonal move it has to be an en-passant capture.
*/
if ((m.piece_from == PIECE_PAWN) &&
(m.piece_cap == PIECE_EMPTY) &&
((abs(m.from-m.to)==15)||(abs(m.from-m.to)==17))) {
m.flags = MFLAG_EPCAPTURE;
}
move_make(m);
a += 4;
while (a[0]==' ') a++;
}
return 0;
}
</pre>
'''[[CPW-Engine|Up one Level]]'''
