Implement Betza g modifier for non-final legs

The g modifier is implemented as a p that turns a rider into the
corresponding leaper when it hops, and vice versa. This is done by
stripping off any existing range indicator, and making the range
infinite by suffixing '0' when the old range was 1 (whether implied
or explicitly written). Except that for sliders/steppers this is done
by atom-name conversion after stripping off the range. Limited range
thus in general turns into leaper (D -> D0, Dn -> D), but with FWK
W3 -> R and R3 -> W, etc.

diff --git a/moves.c b/moves.c
index 787ab57..8c09e23 100644 (file)
--- a/moves.c
+++ b/moves.c
@@ -235,6 +235,8 @@ char symmetry[] = "FBNW.FFW.NKN.NW.QR....W..N";
 char xStep[]    = "2110.130.102.10.00....0..2";
 char yStep[]    = "2132.133.313.20.11....1..3";
 char dirType[]  = "01000104000200000260050000";
+char upgrade[]  = "AFCD.BGH.JQL.NO.KW....R..Z";
+
 //  alphabet   "a b    c d e f    g h    i j k l    m n o p q r    s    t u v    w x y z "
 int dirs1[] = { 0,0x3C,0,0,0,0xC3,0,0,   0,0,0,0xF0,0,0,0,0,0,0x0F,0   ,0,0,0   ,0,0,0,0 };
 int dirs2[] = { 0,0x18,0,0,0,0x81,0,0xFF,0,0,0,0x60,0,0,0,0,0,0x06,0x66,0,0,0x99,0,0,0,0 };
@@ -259,7 +261,7 @@ OK (Board board, int flags, ChessMove kind, int rf, int ff, int rt, int ft, VOID
 void
 MovesFromString (Board board, int flags, int f, int r, int tx, int ty, int angle, char *desc, MoveCallback cb, VOIDSTAR cl)
 {
-    char *p = desc;
+    char buf[80], *p = desc;
     int mine, his, dir, bit, occup, i;
     if(flags & F_WHITE_ON_MOVE) his = 2, mine = 1; else his = 1, mine = 2;
     while(*p) {                  // more moves to go
@@ -323,12 +325,6 @@ MovesFromString (Board board, int flags, int f, int r, int tx, int ty, int angle
        if(*desc == 'n') jump = 0, desc++;
        while(*desc == 'j') jump++, desc++;
        if(*desc == 'a') cont = ++desc;
-        if(!cont) {
-           if(!(mode & 15)) mode = his + 4;          // no mode spec, use default = mc
-       } else {
-           if(mode & 32) mode ^= 256 + 32;           // in non-final legs 'p' means 'pass through'
-           if(!(mode & 0x10F)) mode = his + 0x104;   // and default = mcp
-       }
        dx = xStep[*p-'A'] - '0';                     // step vector of atom
        dy = yStep[*p-'A'] - '0';
        if(isdigit(*++p)) expo = atoi(p++);           // read exponent
@@ -340,6 +336,21 @@ MovesFromString (Board board, int flags, int f, int r, int tx, int ty, int angle
        if(expo > 1 && dx == 0 && dy == 0) {          // castling indicated by O + number
            mode |= 16; dy = 1;
        }
+        if(!cont) {
+           if(!(mode & 15)) mode = his + 4;          // no mode spec, use default = mc
+       } else {
+           if(mode & 32) mode ^= 256 + 32;           // in non-final legs 'p' means 'pass through'
+           if(mode & 64) {
+               mode |= 256;                          // and 'g' too, but converts leaper <-> slider
+               strncpy(buf, cont, 80); cont = buf;   // copy next leg(s), so we can modify
+               while(islower(*cont)) cont++;         // skip to atom
+               *cont = upgrade[*cont-'A'];           // replace atom, BRQ <-> FWK
+               if(expo == 1) *++cont = '0';          // turn other leapers into riders 
+               *++cont = '\0';                       // make sure any old range is stripped off
+               cont = buf;                           // use modified string for continuation leg
+           }
+           if(!(mode & 0x10F)) mode = his + 0x104;   // and default = mcp
+       }
        if(dy == 1) skip = jump - 1, jump = 1;        // on W & F atoms 'j' = skip first square
         do {
          for(dir=0, bit=1; dir<8; dir++, bit += bit) { // loop over directions