From: Nick Bowler <nbowler@draconx.ca>
Date: Sat, 12 Mar 2022 21:31:12 +0000 (-0500)
Subject: Report changed positions from game_do_move.
X-Git-Url: http://git.draconx.ca/gitweb/rrace.git/commitdiff_plain/48cf657b615567153e5ed786b6034f9b46733f9a

Report changed positions from game_do_move.

Instead of manually comparing positions before and after the move,
we can just alter the definition of game_do_move to return this
information, since it has already done most of the work internally.
---

diff --git a/src/game.c b/src/game.c
index bdd8f2b..999d526 100644
--- a/src/game.c
+++ b/src/game.c
@@ -170,14 +170,14 @@ void game_reset(struct board *board)
 	}
 }
 
-int game_do_move(struct board *board, int x, int y)
+uint_fast32_t game_do_move(struct board *board, int x, int y)
 {
 	int bx = board->x, by = board->y;
-	uint_least32_t mask, val[4];
+	uint_least32_t ret = 0, mask, val[4];
 	int i, shl, shr;
 
 	if ((bx != x) == (by != y))
-		return -1;
+		return 0;
 
 	if (bx == x) {
 		mask = board_mask_v(x, by, y);
@@ -192,11 +192,13 @@ int game_do_move(struct board *board, int x, int y)
 	for (i = 0; i < 4; i++) {
 		board->game[i] ^= (val[i] = board->game[i] & mask);
 		board->game[i] |= val[i] << shl >> shr;
+		ret |= board->game[i] ^ val[i];
 	}
 
 	board->x = x;
 	board->y = y;
-	return 0;
+
+	return mask & ret;
 }
 
 uint_fast32_t game_check_goal(struct board *board)
diff --git a/src/game.h b/src/game.h
index a734e22..176cb36 100644
--- a/src/game.h
+++ b/src/game.h
@@ -161,9 +161,10 @@ static inline uint_fast32_t board_right(int x)
  * and update the location of the empty position which, if the move was valid
  * is now (x, y).
  *
- * Returns 0 if the move was valid (and board has been updated), -1 otherwise.
+ * Returns the board bitmap indicating which positions changed.  A return
+ * value of 0 therefore indicates an invalid move.
  */
-int game_do_move(struct board *board, int x, int y);
+uint_fast32_t game_do_move(struct board *board, int x, int y);
 
 /*
  * Returns the board bitmap setting game locations that differ from the goal.
diff --git a/src/motif_ui.c b/src/motif_ui.c
index dfe4e82..85241d8 100644
--- a/src/motif_ui.c
+++ b/src/motif_ui.c
@@ -217,12 +217,9 @@ static void goal_resize(Widget w, void *data, void *cb_data)
 
 static void do_input_move(struct app_state *state, int x, int y)
 {
-	uint_least32_t *gp = state->board.game, prev[4];
-
-	memcpy(prev, gp, sizeof prev);
-	if (game_do_move(&state->board, x, y) == 0) {
-		uint_least32_t mask;
+	uint_fast32_t mask;
 
+	if ((mask = game_do_move(&state->board, x, y)) != 0) {
 		if (game_check_goal(&state->board) == 0) {
 			int_fast32_t ms = game_finish(&state->board);
 			unsigned min, sec;
@@ -236,14 +233,9 @@ static void do_input_move(struct app_state *state, int x, int y)
 			min = sec / 60, sec %= 60;
 			printf("You won!  Time was %u:%.2u:%.3u\n",
 			       min, sec, (unsigned)ms);
+			mask |= ~GOAL_MASK;
 		}
 
-		/* Figure out which tiles changed */
-		prev[0] ^= gp[0];
-		prev[1] ^= gp[1];
-		prev[2] ^= gp[2];
-		mask = prev[0] | prev[1] | prev[2];
-
 		x11_redraw_game(state, mask);
 	}
 }