Implement selection of game seeds, by reusing the config box

mechanism I've just invented (the midend handles the standard game
selection configuration). Each game is now required to validate its
own seed data before attempting to base a game on it and potentially
confusing itself.

[originally from svn r4186]

1 files changed, 30 insertions, 2 deletions

diff --git a/cube.c b/cube.c
index c867471..6c2658f 100644
--- a/cube.c
+++ b/cube.c
@@ -285,8 +285,8 @@ static void enum_grid_squares(game_params *params,
     if (solid->order == 4) {
         int x, y;
 
-        for (x = 0; x < params->d1; x++)
-            for (y = 0; y < params->d2; y++) {
+	for (y = 0; y < params->d2; y++)
+	    for (x = 0; x < params->d1; x++) {
                 struct grid_square sq;
 
                 sq.x = (float)x;
@@ -809,6 +809,34 @@ static struct solid *transform_poly(const struct solid *solid, int flip,
     return ret;
 }
 
+char *validate_seed(game_params *params, char *seed)
+{
+    int area = grid_area(params->d1, params->d2, solids[params->solid]->order);
+    int i, j;
+
+    i = (area + 3) / 4;
+    for (j = 0; j < i; j++) {
+	int c = seed[j];
+	if (c >= '0' && c <= '9') continue;
+	if (c >= 'A' && c <= 'F') continue;
+	if (c >= 'a' && c <= 'f') continue;
+	return "Not enough hex digits at start of string";
+	/* NB if seed[j]=='\0' that will also be caught here, so we're safe */
+    }
+
+    if (seed[i] != ':')
+	return "Expected ':' after hex digits";
+
+    i++;
+    do {
+	if (seed[i] < '0' || seed[i] > '9')
+	    return "Expected decimal integer after ':'";
+	i++;
+    } while (seed[i]);
+
+    return NULL;
+}
+
 game_state *new_game(game_params *params, char *seed)
 {
     game_state *state = snew(game_state);