Move Generation: Castling - micro-Max by H.G. Muller

[Alexlaw1964]

Hello. Please help add castling to the move generator. I’m trying to generate all pseudo‑legal moves from a position obtained from a FEN string.

Code: Select all

// version 3.2 micro-Max by H.G. Muller
#include <stdio.h>
#define W while
#define WHITE 8
#define BLACK 16
//char *FEN = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w QKqk";
//char *FEN = "r4rk1/1pp1qppp/p1np1n2/2b1p1B1/2B1P1b1/P1NP1N2/1PP1QPPP/R4RK1 w - - ";
//char *FEN = "r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq -";
//char *FEN = "r3k2r/p2pqpb1/bn2pnp1/2pPN3/Pp2P3/2N2Q1p/1PPBBPPP/R3K2R w - c6";
char *FEN = "8/2p5/3p3k/1P5r/1R3pP1/1K6/4P3/8 b - g3";
char o[]={-16,-15,-17,0,1,16,0,1,16,15,17,0,14,18,31,33,0, /* step-vector lists */
 7,-1,11,6,8,3,6, /* 1st dir. in o[] per piece*/
 6,3,5,7,4,5,3,6}; /* initial piece setup */
char n[]=".?+nkbrq?*?NKBRQ"; /* piece symbols on printout*/
char b[129],t,x,y,u,p,H;
int M=136,r;
int K,N,cnt;
int E,F,S=128,V=112; /*E=e.p. sqr.*/
int ReadFEN(char *FEN){
 int row, file, i, col, nr, cc;
 char c, *p, epSqr[2];
 p = FEN;
 for(i=0; i<128; i++) b[i&0x77]=0;
 nr=0;
 cc=0;
 for(row=7; row>=0; row--)
    {   /* read one row of the FEN */
        file = 0;
        do{
          c = *p++;
          if(c>='1' && c<='8') { file += c - '0'; }
          else
          {
            col = WHITE;
            cc=8*(7-row)+file+nr;
            if(c >= 'a') { c += 'A'-'a'; col = BLACK; }
                        switch(c)
            {
            //{1,2,3,4,5,6,7} = {P+,P-,N,K,B,R,Q}
            case 'K':
                b[cc]=4|col;
                break;
            case 'R':
                b[cc]=6|col;
                break;
            case 'Q':
                b[cc]=7|col;
                break;
            case 'B':
                b[cc]=5|col;
                break;
            case 'P':
                b[cc]=9<<(1&(col>>4));
                break;
            case 'N':
                b[cc]=3|col;
                break;
            //default: return -15;
            }
          file++;
          }
          }while(file < 8);
        if(file >  8) return (-10); /* bad format */
        if(file == 8)
        {   c = *p++;
            nr+=8;
            if(row > 0 && c != '/') return(-10); /* bad format */
            if(row==0  && c != ' ') return (-10); /* bad format */
        }
    }
        while(c = *p++)
    {
        if(c>='0' && c<='9') continue; /* ignore move counts */
        if(c>='a' && c<='h') /* might be e.p. square */
        {    if(*p == '3' || *p == '6')
             {
                 epSqr[0]=c;
                 epSqr[1]=*p;
                 E=((8 - (epSqr[1] - '0')) * 16) + (epSqr[0] - 'a');
                 p++;
                 continue;
             }
             //else if(c != 'b') continue;
        }
        switch(c)
        {
        case 'K': break;
        case 'Q': break;
        case 'k': break;
        case 'q': break;
        case 'w': col = WHITE; break;
        case 'b': col = BLACK; break;
        case ' ':
        case '-': break;
        //default: return -10;
        }
    }

return col;
}
int main()
{
 int j,k=8;//k=8;  k=16; 

 K=8;W(K--)
 {
     b[K]=(b[K+112]=o[K+24]+8)+8;
     b[K+16]=18;
     b[K+96]=9;  /* initial board setup*/

 }
 k=ReadFEN(FEN);
   W(1)
 {
   N=-1;W(++N<121)
   printf(" %c",N&8&&(N+=7)?10:n[b[N]&15]);          /* print board        */
 W((getchar())>10); /* read input line */

 x=0;cnt=0;
 do{
         u=b[x]; /* scan board looking for */
         if(u&k) /* own piece (inefficient!)*/
 {r=p=u&7; /* p = piece type (set r>0) */
 j=o[p+16]; /* first step vector f.piece*/
 while(r=p>2&r<0?-r:-o[++j]) /* loop over directions o[] */
 {
    y=x;F=S;
    do{
      H=y+=r; /* y traverses ray */
      if(y&M)break; /* board edge hit */
      if(p<3&y==E)H=y^16; /* shift capt.sqr. H if e.p.*/
      t=b[H];
      if(t&k|p<3&!(r&7)!=!t)break; /* capt. own, bad pawn mode */
      cnt++;
      printf("%c%c%c%c\n",
       'a' + (x % 16),
       '0' + (8 - (x / 16)),
       'a' + (y % 16),
       '0' + (8 - (y / 16))
      );
      //printf(" %d-%d\n",x,y);
      t+=p<5; /* fake capt. for nonsliding*/
       if(p<3&6*k+(y&V)==S /* pawn on 3rd/6th, or */
          ){F=y;t--;} /* unfake capt., enable e.p.*/
    }while(!t); /* if not capt. continue ray*/
 }
 }}W(x=x+9&~M);/* next sqr. of board, wrap */
 printf("cnt=%d\n",cnt);
  }
}