Redesign state machine

Signed-off-by: Warrick Lo <warrick.s.z.lo@gmail.com>

2 files changed, 50 insertions, 48 deletions

diff --git a/task5/datapath.sv b/task5/datapath.sv
index 03f408d..ea99794 100644
--- a/task5/datapath.sv
+++ b/task5/datapath.sv
@@ -12,6 +12,8 @@ module datapath(slow_clock, fast_clock, resetb,
 
 	logic [3:0] new_card, pcard1, pcard2, pcard3, dcard1, dcard2, dcard3;
 
+	assign pcard3_out = pcard3;
+
 	reg4 PCard1(new_card, load_pcard1, slow_clock, resetb, pcard1);
 	reg4 PCard2(new_card, load_pcard2, slow_clock, resetb, pcard2);
 	reg4 PCard3(new_card, load_pcard3, slow_clock, resetb, pcard3);
diff --git a/task5/statemachine.sv b/task5/statemachine.sv
index d6e9ae0..94dd95d 100644
--- a/task5/statemachine.sv
+++ b/task5/statemachine.sv
@@ -1,10 +1,10 @@
-`define STATE_DEAL_P1	3'b000
-`define STATE_DEAL_D1	3'b001
-`define STATE_DEAL_P2	3'b010
-`define STATE_DEAL_D2	3'b011
-`define STATE_DEAL_P3	3'b100
-`define STATE_DEAL_D3	3'b101
-`define STATE_END	3'b110
+`define STATE_DEAL_P1	3'd0
+`define STATE_DEAL_D1	3'd1
+`define STATE_DEAL_P2	3'd2
+`define STATE_DEAL_D2	3'd3
+`define STATE_DEAL_X1	3'd4
+`define STATE_DEAL_X2	3'd5
+`define STATE_END	3'd6
 
 module statemachine(slow_clock, resetb, dscore, pscore, pcard3,
 	load_pcard1, load_pcard2, load_pcard3,
@@ -17,47 +17,28 @@ module statemachine(slow_clock, resetb, dscore, pscore, pcard3,
 		load_dcard1, load_dcard2, load_dcard3,
 		player_win_light, dealer_win_light;
 
-	logic [2:0] state;
+	logic [2:0] state, state_next;
 
-	always_ff @(posedge slow_clock) casex ({resetb, state})
-		4'b0_xxx:
-			state <= `STATE_DEAL_P1;
-		{1'b1, `STATE_DEAL_P1}:
-			state <= `STATE_DEAL_D1;
-		{1'b1, `STATE_DEAL_D1}:
-			state <= `STATE_DEAL_P2;
-		{1'b1, `STATE_DEAL_P2}:
-			state <= `STATE_DEAL_D2;
-		{1'b1, `STATE_DEAL_D2}:
-			if ((pscore >= 8) || (dscore >= 8)) state <= `STATE_END;
-			else if (pscore <= 5) state <= `STATE_DEAL_P3;
-			else if (dscore <= 5) state <=`STATE_DEAL_D3;
-			else state = `STATE_END;
-		{1'b1, `STATE_DEAL_P3}: casex ({dscore, pcard3})
-			/* Banker 6 on a player's third card 6 or 7. */
-			{4'd6, 4'd6}, {4'd6, 4'd7},
-			/* Banker 5 on a player's third card 4 through 7. */
-			{4'd5, 4'd4}, {4'd5, 4'd5}, {4'd5, 4'd6}, {4'd5, 4'd7},
-			/* Banker 4 on a player's third card 2 through 7. */
-			{4'd4, 4'd2}, {4'd4, 4'd3}, {4'd4, 4'd4},
-			{4'd4, 4'd5}, {4'd4, 4'd6}, {4'd4, 4'd7},
-			/* Banker 3 on a player's third card 1 through 7. */
-			{4'd3, 4'd1}, {4'd3, 4'd2}, {4'd3, 4'd3}, {4'd3, 4'd4},
-			{4'd3, 4'd5}, {4'd3, 4'd6}, {4'd3, 4'd7},
-			/* Banker 0, 1, or 2. */
-			{4'd0, 4'bxxxx}, {4'd1, 4'bxxxx}, {4'd2, 4'bxxxx}:
-				state <= `STATE_DEAL_D3;
-			/* Banker stands otherwise. */
-			default: state <= `STATE_END;
-		endcase
-		{1'b1, `STATE_DEAL_D3}:
-			state <= `STATE_END;
-		{1'b1, `STATE_END}:
-			state <= `STATE_END;
-		default:
-			state <= `STATE_DEAL_P1;
+	/* Current state register. */
+	always_ff @(posedge slow_clock)
+		if (~resetb) state <= `STATE_DEAL_P1;
+		else state <= state_next;
+
+	/* Next state logic. */
+	always_comb case (state)
+		`STATE_DEAL_P1: state_next = `STATE_DEAL_D1;
+		`STATE_DEAL_D1: state_next = `STATE_DEAL_P2;
+		`STATE_DEAL_P2: state_next = `STATE_DEAL_D2;
+		`STATE_DEAL_D2: state_next = `STATE_DEAL_X1;
+		`STATE_DEAL_X1:
+			if ((dscore <= 7) && (pscore <= 5))
+				state_next = `STATE_DEAL_X2;
+			else
+				state_next = `STATE_END;
+		default: state_next = `STATE_END;
 	endcase
 
+	/* Output logic. */
 	always_comb begin
 		{player_win_light, dealer_win_light,
 			load_pcard1, load_pcard2, load_pcard3,
@@ -66,11 +47,30 @@ module statemachine(slow_clock, resetb, dscore, pscore, pcard3,
 
 		case (state)
 			`STATE_DEAL_P1: load_pcard1 = 1'b1;
-			`STATE_DEAL_P2: load_pcard2 = 1'b1;
-			`STATE_DEAL_P3: load_pcard3 = 1'b1;
 			`STATE_DEAL_D1: load_dcard1 = 1'b1;
+			`STATE_DEAL_P2: load_pcard2 = 1'b1;
 			`STATE_DEAL_D2: load_dcard2 = 1'b1;
-			`STATE_DEAL_D3: load_dcard3 = 1'b1;
+			`STATE_DEAL_X1:
+				/* Check for natural eight and nines first. */
+				if ((dscore <= 7) && (pscore <= 5))
+					load_pcard3 = 1'b1;
+				else if ((pscore <= 7) && (dscore <= 5))
+					load_dcard3 = 1'b1;
+			`STATE_DEAL_X2: casex ({dscore, pcard3})
+				/* Banker 6 on a player's third card 6 or 7. */
+				{4'd6, 4'd6}, {4'd6, 4'd7},
+				/* Banker 5 on a player's third card 4 through 7. */
+				{4'd5, 4'd4}, {4'd5, 4'd5}, {4'd5, 4'd6}, {4'd5, 4'd7},
+				/* Banker 4 on a player's third card 2 through 7. */
+				{4'd4, 4'd2}, {4'd4, 4'd3}, {4'd4, 4'd4},
+				{4'd4, 4'd5}, {4'd4, 4'd6}, {4'd4, 4'd7},
+				/* Banker 3 on a player's third card 1 through 7. */
+				{4'd3, 4'd1}, {4'd3, 4'd2}, {4'd3, 4'd3}, {4'd3, 4'd4},
+				{4'd3, 4'd5}, {4'd3, 4'd6}, {4'd3, 4'd7},
+				/* Banker 0, 1, or 2. */
+				{4'd0, 4'bxxxx}, {4'd1, 4'bxxxx}, {4'd2, 4'bxxxx}:
+					load_dcard3 = 1'b1;
+			endcase
 			`STATE_END: begin
 				if (pscore >= dscore) player_win_light = 1'b1;
 				if (dscore >= pscore) dealer_win_light = 1'b1;