From 09af5a0331f744f3dec83173be53835c53bba3c8 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Tue, 9 Dec 2014 20:22:33 +0100
Subject: [PATCH] Store sum and number of Elo values instead of averages, for
 easier merging.

---
 book/binloader.cpp | 12 +++---------
 book/binlookup.cpp |  5 ++++-
 book/count.h       |  5 +++--
 3 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/book/binloader.cpp b/book/binloader.cpp
index e4b40a6..88fb5ff 100644
--- a/book/binloader.cpp
+++ b/book/binloader.cpp
@@ -82,8 +82,6 @@ int main(int argc, char **argv)
 	printf("Writing SSTable...\n");
 	mtbl_writer* mtbl = mtbl_writer_init("open.mtbl", NULL);
 	Count c;
-	int num_elo = 0;
-	double sum_white_elo = 0.0, sum_black_elo = 0.0;
 	for (int i = 0; i < elems.size(); ++i) {
 		if (elems[i].result == WHITE) {
 			++c.white;
@@ -94,19 +92,15 @@ int main(int argc, char **argv)
 		}
 		c.opening_num = elems[i].opening_num;
 		if (elems[i].white_elo >= 100 && elems[i].black_elo >= 100) {
-			sum_white_elo += elems[i].white_elo;
-			sum_black_elo += elems[i].black_elo;
-			++num_elo;
+			c.sum_white_elo += elems[i].white_elo;
+			c.sum_black_elo += elems[i].black_elo;
+			++c.num_elo;
 		}
 		if (i == elems.size() - 1 || elems[i].bpfen_and_move != elems[i + 1].bpfen_and_move) {
-			c.avg_white_elo = sum_white_elo / num_elo;
-			c.avg_black_elo = sum_black_elo / num_elo;
 			mtbl_writer_add(mtbl,
 				(const uint8_t *)elems[i].bpfen_and_move.data(), elems[i].bpfen_and_move.size(),
 				(const uint8_t *)&c, sizeof(c));
 			c = Count();
-			num_elo = 0;
-			sum_white_elo = sum_black_elo = 0.0;
 		}
 	}
 	mtbl_writer_destroy(&mtbl);
diff --git a/book/binlookup.cpp b/book/binlookup.cpp
index 5ed372d..363e8dc 100644
--- a/book/binlookup.cpp
+++ b/book/binlookup.cpp
@@ -36,6 +36,9 @@ int main(int argc, char **argv)
 	while (mtbl_iter_next(it, &key, &len_key, &val, &len_val)) {
 		string move((char *)(key + prefix_len), len_key - prefix_len);
 		const Count* c = (Count *)val;
-		printf("%s %d %d %d %d %f %f\n", move.c_str(), c->white, c->draw, c->black, c->opening_num, c->avg_white_elo, c->avg_black_elo);
+		printf("%s %d %d %d %d %f %f\n", move.c_str(),
+			c->white, c->draw, c->black, c->opening_num,
+			float(c->sum_white_elo) / c->num_elo,
+			float(c->sum_black_elo) / c->num_elo);
 	}
 }
diff --git a/book/count.h b/book/count.h
index 1d8043f..3024b89 100644
--- a/book/count.h
+++ b/book/count.h
@@ -4,6 +4,7 @@ struct Count {
 	int draw = 0;
 	int black = 0;
 	int opening_num = -1;
-	float avg_white_elo = 0.0;
-	float avg_black_elo = 0.0;
+	unsigned long long sum_white_elo = 0;
+	unsigned long long sum_black_elo = 0;
+	int num_elo = 0;
 };
-- 
2.39.2