From: Joshua Wise <joshua@rebirth.joshuawise.com>
Date: Sat, 29 Mar 2008 08:12:10 +0000 (-0400)
Subject: PUSH and POP work
X-Git-Url: http://git.joshuawise.com/fpgaboy.git/commitdiff_plain/97649fedb7865d889dab2e20139bc887d871ed00?ds=sidebyside

PUSH and POP work
---

diff --git a/FPGABoy.ise b/FPGABoy.ise
index 5a47155..7770eb0 100644
Binary files a/FPGABoy.ise and b/FPGABoy.ise differ
diff --git a/GBZ80Core.v b/GBZ80Core.v
index fa9ed0b..cb80cb8 100644
--- a/GBZ80Core.v
+++ b/GBZ80Core.v
@@ -28,6 +28,8 @@
 `define INSN_LD_reg_reg		8'b01xxxxxx
 `define INSN_LD_reg_imm16	8'b00xx0001
 `define INSN_LD_SP_HL		8'b11111001
+`define INSN_PUSH_reg		8'b11xx0101
+`define INSN_POP_reg		8'b11xx0001
 `define INSN_reg_A		3'b111
 `define INSN_reg_B		3'b000
 `define INSN_reg_C		3'b001
@@ -40,6 +42,10 @@
 `define INSN_reg16_DE	2'b01
 `define INSN_reg16_HL	2'b10
 `define INSN_reg16_SP	2'b11
+`define INSN_stack_AF	2'b11
+`define INSN_stack_BC	2'b00
+`define INSN_stack_DE	2'b01
+`define INSN_stack_HL	2'b10
 module GBZ80Core(
 	input clk,
 	output reg [15:0] busaddress,	/* BUS_* is latched on STATE_FETCH. */
@@ -101,6 +107,10 @@ module GBZ80Core(
 				if (rd) rdata <= busdata;
 			buswr <= 0;
 			busrd <= 0;
+			wr <= 0;
+			rd <= 0;
+			address <= 16'bxxxxxxxxxxxxxxxx;	// Make it obvious if something of type has happened.
+			wdata <= 8'bxxxxxxxx;
 			state <= `STATE_EXECUTE;
 		end
 		`STATE_EXECUTE: begin
@@ -163,7 +173,7 @@ module GBZ80Core(
 				case(cycle)
 				0: begin
 						address <= {registers[`REG_H], registers[`REG_L]};
-						wr <= 0; rd <= 1;
+						rd <= 1;
 					end
 				1: begin
 						tmp <= rdata;
@@ -202,8 +212,6 @@ module GBZ80Core(
 			`INSN_LD_SP_HL: begin
 				case (cycle)
 				0:	begin
-						rd <= 0;
-						address <= 16'bxxxxxxxxxxxxxxxx;
 						tmp <= registers[`REG_H];
 					end
 				1:	begin
@@ -213,6 +221,51 @@ module GBZ80Core(
 					end
 				endcase
 			end
+			`INSN_PUSH_reg: begin	/* PUSH is 16 cycles! */
+				case (cycle)
+				0: begin
+						wr <= 1;
+						address <= {registers[`REG_SPH],registers[`REG_SPL]}-1;
+						case (opcode[5:4])
+						`INSN_stack_AF:	wdata <= registers[`REG_A];
+						`INSN_stack_BC:	wdata <= registers[`REG_B];
+						`INSN_stack_DE:	wdata <= registers[`REG_D];
+						`INSN_stack_HL:	wdata <= registers[`REG_H];
+						endcase
+					end
+				1: begin
+						wr <= 1;
+						address <= {registers[`REG_SPH],registers[`REG_SPL]}-1;
+						case (opcode[5:4])
+						`INSN_stack_AF:	wdata <= registers[`REG_F];
+						`INSN_stack_BC:	wdata <= registers[`REG_C];
+						`INSN_stack_DE:	wdata <= registers[`REG_E];
+						`INSN_stack_HL:	wdata <= registers[`REG_L];
+						endcase
+					end
+				2:	begin /* TWIDDLE OUR FUCKING THUMBS! */ end
+				3: begin
+						`EXEC_NEWCYCLE;
+						`EXEC_INC_PC;
+					end
+				endcase
+			end
+			`INSN_POP_reg: begin	/* POP is 12 cycles! */
+				case (cycle)
+				0: begin
+						rd <= 1;
+						address <= {registers[`REG_SPH],registers[`REG_SPL]};
+					end
+				1: begin
+						rd <= 1;
+						address <= {registers[`REG_SPH],registers[`REG_SPL]};
+					end
+				2: begin
+						`EXEC_NEWCYCLE;
+						`EXEC_INC_PC;
+					end
+				endcase
+			end
 			default:
 				$stop;
 			endcase
@@ -308,6 +361,51 @@ module GBZ80Core(
 					end
 				endcase
 			end
+			`INSN_PUSH_reg: begin	/* PUSH is 16 cycles! */
+				case (cycle)
+				0: begin
+						{registers[`REG_SPH],registers[`REG_SPL]} =
+							{registers[`REG_SPH],registers[`REG_SPL]} - 1;
+						cycle <= 1;
+					end
+				1:	begin
+						{registers[`REG_SPH],registers[`REG_SPL]} =
+							{registers[`REG_SPH],registers[`REG_SPL]} - 1;
+						cycle <= 2;
+					end
+				2:	cycle <= 3;
+				3:	cycle <= 0;
+				endcase
+			end
+			`INSN_POP_reg: begin	/* POP is 12 cycles! */
+				case (cycle)
+				0:	begin
+						cycle <= 1;
+						{registers[`REG_SPH],registers[`REG_SPL]} =
+							{registers[`REG_SPH],registers[`REG_SPL]} + 1;
+					end
+				1:	begin
+						case (opcode[5:4])
+						`INSN_stack_AF:	registers[`REG_F] <= rdata;
+						`INSN_stack_BC:	registers[`REG_C] <= rdata;
+						`INSN_stack_DE:	registers[`REG_E] <= rdata;
+						`INSN_stack_HL:	registers[`REG_L] <= rdata;
+						endcase
+						{registers[`REG_SPH],registers[`REG_SPL]} =
+							{registers[`REG_SPH],registers[`REG_SPL]} + 1;
+						cycle <= 2;
+					end
+				2:	begin
+						case (opcode[5:4])
+						`INSN_stack_AF:	registers[`REG_A] <= rdata;
+						`INSN_stack_BC:	registers[`REG_B] <= rdata;
+						`INSN_stack_DE:	registers[`REG_D] <= rdata;
+						`INSN_stack_HL:	registers[`REG_H] <= rdata;
+						endcase
+						cycle <= 0;
+					end
+				endcase
+			end	
 			endcase
 			state <= `STATE_FETCH;
 		end
diff --git a/rom.hex b/rom.hex
index a90b962..00214cd 100644
--- a/rom.hex
+++ b/rom.hex
@@ -4,8 +4,8 @@
 01
 // LD SP, HL
 F9
-// LD B, (HL)
-46
+// POP BC
+C1
 // LD A, 12h
 3E
 12
@@ -20,4 +20,5 @@ F9
 76
 
 @100
-56
\ No newline at end of file
+00
+56