Incorporate variant type in book hash key

[xboard.git] / book.c

diff --git a/book.c b/book.c
index e42b9c6..a5aa6ab 100644 (file)
--- a/book.c
+++ b/book.c
@@ -278,6 +278,23 @@ uint64 hash(int moveNr)
 {
     int r, f, p_enc, squareNr, pieceGroup;
     uint64 key=0, holdingsKey=0, Zobrist;
+    VariantClass v = gameInfo.variant;
+
+    switch(v) {
+       case VariantNormal:
+       case VariantFischeRandom: // compatible with normal
+       case VariantNoCastle:
+       case VariantXiangqi: // for historic reasons; does never collide anyway because of other King type
+           break;
+       case VariantGiveaway: // in opening same as suicide
+           key += VariantSuicide;
+           break;
+       case VariantGothic: // these are special cases of CRC, and can share book
+       case VariantCapablanca:
+           v = VariantCapaRandom;
+       default:
+           key += v; // variant type incorporated in key to allow mixed books without collisions
+    }
 
     for(f=0; f<BOARD_WIDTH; f++){
         for(r=0; r<BOARD_HEIGHT;r++){
@@ -676,8 +693,10 @@ void SaveToBook(char *text)
     if(count != currentCount) {
        do {
            for(i=0; i<len1; i++) buf2[i] = buf1[i]; len2 = len1;
-           fseek(f, readpos, SEEK_SET);
-           readpos += len1 = fread(buf1, 1, 4096, f);
+           if(readpos > writepos) {
+               fseek(f, readpos, SEEK_SET);
+               readpos += len1 = fread(buf1, 1, 4096, f);
+           } else len1 = 0; // wrote already past old EOF
            fseek(f, writepos, SEEK_SET);
            fwrite(buf2, 1, len2, f);
            writepos += len2;