Incorporate variant type in book hash key

[xboard.git] / book.c

diff --git a/book.c b/book.c
index 3650b01..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++){
@@ -468,7 +485,8 @@ void move_to_string(char move_s[6], uint16 move)
 
 int GetBookMoves(int moveNr, char *book, entry_t entries[])
 {   // retrieve all entries for given position from book in 'entries', return number.
-    FILE *f;
+    static FILE *f = NULL;
+    static char curBook[MSG_SIZ];
     entry_t entry;
     int offset;
     uint64 key;
@@ -477,7 +495,11 @@ int GetBookMoves(int moveNr, char *book, entry_t entries[])
 
     if(book == NULL || moveNr >= 2*appData.bookDepth) return -1; 
 //    if(gameInfo.variant != VariantNormal) return -1; // Zobrist scheme only works for normal Chess, so far
-    f=fopen(book,"rb");
+    if(!f || strcmp(book, curBook)){ // keep book file open until book changed
+       strncpy(curBook, book, MSG_SIZ);
+       if(f) fclose(f);
+       f = fopen(book,"rb");
+    }
     if(!f){
        DisplayError("Polyglot book not valid", 0);
        appData.usePolyglotBook = FALSE;
@@ -489,7 +511,6 @@ int GetBookMoves(int moveNr, char *book, entry_t entries[])
 
     offset=find_key(f, key, &entry);
     if(entry.key != key) {
-         fclose(f);
          return FALSE;
     }
     entries[0] = entry;
@@ -506,7 +527,6 @@ int GetBookMoves(int moveNr, char *book, entry_t entries[])
         if(count == MOVE_BUF) break;
         entries[count++] = entry;
     }
-    fclose(f);
     return count;
 }
 
@@ -534,6 +554,7 @@ char *ProbeBook(int moveNr, char *book)
     for(i=0; i<count; i++){
         total_weight += entries[i].weight;
     }
+    if(total_weight == 0) return NULL; // force book miss rather than playing moves with weight 0.
     j = (random() & 0xFFF) * total_weight >> 12; // create random < total_weight
     total_weight = 0;
     for(i=0; i<count; i++){
@@ -672,8 +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;