change order of statements and make gender neutral

diff --git a/docs/examples/puzzles/wolf_goat_cabbage.sv b/docs/examples/puzzles/wolf_goat_cabbage.sv
index 9c9fe7a3c0d8becb3c182bc22e19f43780b93594..6821098d3f8d8188120fed52131810d901831f1a 100644 (file)
--- a/docs/examples/puzzles/wolf_goat_cabbage.sv
+++ b/docs/examples/puzzles/wolf_goat_cabbage.sv
@@ -1,38 +1,39 @@
-// A man needs to cross a river with a wolf, a goat and a cabbage. His boat is only large
-// enough to carry himself and one of his three possessions, so he must transport these
-// items one at a time. However, if he leaves the wolf and the goat together unattended,
-// then the wolf will eat the goat; similarly, if he leaves the goat and the cabbage together
-// unattended, then the goat will eat the cabbage. How can the man get across safely with
-// his three items?
+// A person needs to cross a river with a wolf, a goat and a cabbage. Their boat is only large
+// enough to carry themselves and one of their three possessions, so they must transport these
+// items one at a time. However, if they leave the wolf and the goat together unattended,
+// then the wolf will eat the goat; similarly, if they leave the goat and the cabbage together
+// unattended, then the goat will eat the cabbage. How can the person get across safely with
+// their three items?
 
 module wolf_goat_cabbage (input clk, input w, g, c);
        // everyone starts at the 1st river bank
        reg bank_w = 0; // wolf
        reg bank_g = 0; // goat
        reg bank_c = 0; // cabbage
-       reg bank_m = 0; // man
+       reg bank_person = 0; // person who drives the boat
 
        always @(posedge clk) begin
+               // person travels and takes the selected item with him
+               if (w && (bank_w == bank_person)) bank_w <= !bank_person;
+               if (g && (bank_g == bank_person)) bank_g <= !bank_person;
+               if (c && (bank_c == bank_person)) bank_c <= !bank_person;
+               bank_person <= !bank_person;
+
                // maximum one of the control signals must be high
                assume (w+g+c <= 1);
 
                // we want wolf, goat, and cabbage on the 2nd river bank
-               cover (bank_w && bank_g && bank_c);
+               // write a cover statement that will result in the desired combination
+               cover(bank_w == 1 && bank_g == 1 && bank_c == 1);
 
                // don't leave wolf and goat unattended
-               if (bank_w != bank_m) begin
+               if (bank_w != bank_person) begin
                        assume (bank_w != bank_g);
                end
 
                // don't leave goat and cabbage unattended
-               if (bank_g != bank_m) begin
+               if (bank_g != bank_person) begin
                        assume (bank_g != bank_c);
                end
-
-               // man travels and takes the selected item with him
-               if (w && (bank_w == bank_m)) bank_w <= !bank_m;
-               if (g && (bank_g == bank_m)) bank_g <= !bank_m;
-               if (c && (bank_c == bank_m)) bank_c <= !bank_m;
-               bank_m <= !bank_m;
        end
 endmodule