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Diffstat (limited to 'T65/T65.vhd')
| -rw-r--r-- | T65/T65.vhd | 551 |
1 files changed, 551 insertions, 0 deletions
diff --git a/T65/T65.vhd b/T65/T65.vhd new file mode 100644 index 0000000..f02a5b6 --- /dev/null +++ b/T65/T65.vhd @@ -0,0 +1,551 @@ +-- ****
+-- T65(b) core. In an effort to merge and maintain bug fixes ....
+--
+--
+-- Ver 301 more merging
+-- Ver 300 Bugfixes by ehenciak added, started tidyup *bust*
+-- MikeJ March 2005
+-- Latest version from www.fpgaarcade.com (original www.opencores.org)
+--
+-- ****
+--
+-- 65xx compatible microprocessor core
+--
+-- Version : 0246
+--
+-- Copyright (c) 2002 Daniel Wallner (jesus@opencores.org)
+--
+-- All rights reserved
+--
+-- Redistribution and use in source and synthezised forms, with or without
+-- modification, are permitted provided that the following conditions are met:
+--
+-- Redistributions of source code must retain the above copyright notice,
+-- this list of conditions and the following disclaimer.
+--
+-- Redistributions in synthesized form must reproduce the above copyright
+-- notice, this list of conditions and the following disclaimer in the
+-- documentation and/or other materials provided with the distribution.
+--
+-- Neither the name of the author nor the names of other contributors may
+-- be used to endorse or promote products derived from this software without
+-- specific prior written permission.
+--
+-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+-- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+-- THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+-- PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE
+-- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+-- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+-- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+-- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+-- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+-- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+-- POSSIBILITY OF SUCH DAMAGE.
+--
+-- Please report bugs to the author, but before you do so, please
+-- make sure that this is not a derivative work and that
+-- you have the latest version of this file.
+--
+-- The latest version of this file can be found at:
+-- http://www.opencores.org/cvsweb.shtml/t65/
+--
+-- Limitations :
+--
+-- 65C02 and 65C816 modes are incomplete
+-- Undocumented instructions are not supported
+-- Some interface signals behaves incorrect
+--
+-- File history :
+--
+-- 0246 : First release
+--
+
+library IEEE;
+ use IEEE.std_logic_1164.all;
+ use IEEE.numeric_std.all;
+ use work.T65_Pack.all;
+
+-- ehenciak 2-23-2005 : Added the enable signal so that one doesn't have to use
+-- the ready signal to limit the CPU.
+entity T65 is
+ port(
+ Mode : in std_logic_vector(1 downto 0); -- "00" => 6502, "01" => 65C02, "10" => 65C816
+ Res_n : in std_logic;
+ Enable : in std_logic;
+ Clk : in std_logic;
+ Rdy : in std_logic;
+ Abort_n : in std_logic;
+ IRQ_n : in std_logic;
+ NMI_n : in std_logic;
+ SO_n : in std_logic;
+ R_W_n : out std_logic;
+ Sync : out std_logic;
+ EF : out std_logic;
+ MF : out std_logic;
+ XF : out std_logic;
+ ML_n : out std_logic;
+ VP_n : out std_logic;
+ VDA : out std_logic;
+ VPA : out std_logic;
+ A : out std_logic_vector(23 downto 0);
+ DI : in std_logic_vector(7 downto 0);
+ DO : out std_logic_vector(7 downto 0)
+ );
+end T65;
+
+architecture rtl of T65 is
+
+ -- Registers
+ signal ABC, X, Y, D : std_logic_vector(15 downto 0);
+ signal P, AD, DL : std_logic_vector(7 downto 0) := x"00";
+ signal BAH : std_logic_vector(7 downto 0);
+ signal BAL : std_logic_vector(8 downto 0);
+ signal PBR : std_logic_vector(7 downto 0);
+ signal DBR : std_logic_vector(7 downto 0);
+ signal PC : unsigned(15 downto 0);
+ signal S : unsigned(15 downto 0);
+ signal EF_i : std_logic;
+ signal MF_i : std_logic;
+ signal XF_i : std_logic;
+
+ signal IR : std_logic_vector(7 downto 0);
+ signal MCycle : std_logic_vector(2 downto 0);
+
+ signal Mode_r : std_logic_vector(1 downto 0);
+ signal ALU_Op_r : std_logic_vector(3 downto 0);
+ signal Write_Data_r : std_logic_vector(2 downto 0);
+ signal Set_Addr_To_r : std_logic_vector(1 downto 0);
+ signal PCAdder : unsigned(8 downto 0);
+
+ signal RstCycle : std_logic;
+ signal IRQCycle : std_logic;
+ signal NMICycle : std_logic;
+
+ signal B_o : std_logic;
+ signal SO_n_o : std_logic;
+ signal IRQ_n_o : std_logic;
+ signal NMI_n_o : std_logic;
+ signal NMIAct : std_logic;
+
+ signal Break : std_logic;
+
+ -- ALU signals
+ signal BusA : std_logic_vector(7 downto 0);
+ signal BusA_r : std_logic_vector(7 downto 0);
+ signal BusB : std_logic_vector(7 downto 0);
+ signal ALU_Q : std_logic_vector(7 downto 0);
+ signal P_Out : std_logic_vector(7 downto 0);
+
+ -- Micro code outputs
+ signal LCycle : std_logic_vector(2 downto 0);
+ signal ALU_Op : std_logic_vector(3 downto 0);
+ signal Set_BusA_To : std_logic_vector(2 downto 0);
+ signal Set_Addr_To : std_logic_vector(1 downto 0);
+ signal Write_Data : std_logic_vector(2 downto 0);
+ signal Jump : std_logic_vector(1 downto 0);
+ signal BAAdd : std_logic_vector(1 downto 0);
+ signal BreakAtNA : std_logic;
+ signal ADAdd : std_logic;
+ signal AddY : std_logic;
+ signal PCAdd : std_logic;
+ signal Inc_S : std_logic;
+ signal Dec_S : std_logic;
+ signal LDA : std_logic;
+ signal LDP : std_logic;
+ signal LDX : std_logic;
+ signal LDY : std_logic;
+ signal LDS : std_logic;
+ signal LDDI : std_logic;
+ signal LDALU : std_logic;
+ signal LDAD : std_logic;
+ signal LDBAL : std_logic;
+ signal LDBAH : std_logic;
+ signal SaveP : std_logic;
+ signal Write : std_logic;
+
+ signal really_rdy : std_logic;
+ signal R_W_n_i : std_logic;
+
+begin
+ -- ehenciak : gate Rdy with read/write to make an "OK, it's
+ -- really OK to stop the processor now if Rdy is
+ -- deasserted" signal
+ really_rdy <= Rdy or not(R_W_n_i);
+
+ -- ehenciak : Drive R_W_n_i off chip.
+ R_W_n <= R_W_n_i;
+
+ Sync <= '1' when MCycle = "000" else '0';
+ EF <= EF_i;
+ MF <= MF_i;
+ XF <= XF_i;
+ ML_n <= '0' when IR(7 downto 6) /= "10" and IR(2 downto 1) = "11" and MCycle(2 downto 1) /= "00" else '1';
+ VP_n <= '0' when IRQCycle = '1' and (MCycle = "101" or MCycle = "110") else '1';
+ VDA <= '1' when Set_Addr_To_r /= "000" else '0'; -- Incorrect !!!!!!!!!!!!
+ VPA <= '1' when Jump(1) = '0' else '0'; -- Incorrect !!!!!!!!!!!!
+
+ mcode : T65_MCode
+ port map(
+ Mode => Mode_r,
+ IR => IR,
+ MCycle => MCycle,
+ P => P,
+ LCycle => LCycle,
+ ALU_Op => ALU_Op,
+ Set_BusA_To => Set_BusA_To,
+ Set_Addr_To => Set_Addr_To,
+ Write_Data => Write_Data,
+ Jump => Jump,
+ BAAdd => BAAdd,
+ BreakAtNA => BreakAtNA,
+ ADAdd => ADAdd,
+ AddY => AddY,
+ PCAdd => PCAdd,
+ Inc_S => Inc_S,
+ Dec_S => Dec_S,
+ LDA => LDA,
+ LDP => LDP,
+ LDX => LDX,
+ LDY => LDY,
+ LDS => LDS,
+ LDDI => LDDI,
+ LDALU => LDALU,
+ LDAD => LDAD,
+ LDBAL => LDBAL,
+ LDBAH => LDBAH,
+ SaveP => SaveP,
+ Write => Write
+ );
+
+ alu : T65_ALU
+ port map(
+ Mode => Mode_r,
+ Op => ALU_Op_r,
+ BusA => BusA_r,
+ BusB => BusB,
+ P_In => P,
+ P_Out => P_Out,
+ Q => ALU_Q
+ );
+
+ process (Res_n, Clk)
+ begin
+ if Res_n = '0' then
+ PC <= (others => '0'); -- Program Counter
+ IR <= "00000000";
+ S <= (others => '0'); -- Dummy !!!!!!!!!!!!!!!!!!!!!
+ D <= (others => '0');
+ PBR <= (others => '0');
+ DBR <= (others => '0');
+
+ Mode_r <= (others => '0');
+ ALU_Op_r <= "1100";
+ Write_Data_r <= "000";
+ Set_Addr_To_r <= "00";
+
+ R_W_n_i <= '1';
+ EF_i <= '1';
+ MF_i <= '1';
+ XF_i <= '1';
+
+ elsif Clk'event and Clk = '1' then
+ if (Enable = '1') then
+ if (really_rdy = '1') then
+ R_W_n_i <= not Write or RstCycle;
+
+ D <= (others => '1'); -- Dummy
+ PBR <= (others => '1'); -- Dummy
+ DBR <= (others => '1'); -- Dummy
+ EF_i <= '0'; -- Dummy
+ MF_i <= '0'; -- Dummy
+ XF_i <= '0'; -- Dummy
+
+ if MCycle = "000" then
+ Mode_r <= Mode;
+
+ if IRQCycle = '0' and NMICycle = '0' then
+ PC <= PC + 1;
+ end if;
+
+ if IRQCycle = '1' or NMICycle = '1' then
+ IR <= "00000000";
+ else
+ IR <= DI;
+ end if;
+ end if;
+
+ ALU_Op_r <= ALU_Op;
+ Write_Data_r <= Write_Data;
+ if Break = '1' then
+ Set_Addr_To_r <= "00";
+ else
+ Set_Addr_To_r <= Set_Addr_To;
+ end if;
+
+ if Inc_S = '1' then
+ S <= S + 1;
+ end if;
+ if Dec_S = '1' and RstCycle = '0' then
+ S <= S - 1;
+ end if;
+ if LDS = '1' then
+ S(7 downto 0) <= unsigned(ALU_Q);
+ end if;
+
+ if IR = "00000000" and MCycle = "001" and IRQCycle = '0' and NMICycle = '0' then
+ PC <= PC + 1;
+ end if;
+ --
+ -- jump control logic
+ --
+ case Jump is
+ when "01" =>
+ PC <= PC + 1;
+
+ when "10" =>
+ PC <= unsigned(DI & DL);
+
+ when "11" =>
+ if PCAdder(8) = '1' then
+ if DL(7) = '0' then
+ PC(15 downto 8) <= PC(15 downto 8) + 1;
+ else
+ PC(15 downto 8) <= PC(15 downto 8) - 1;
+ end if;
+ end if;
+ PC(7 downto 0) <= PCAdder(7 downto 0);
+
+ when others => null;
+ end case;
+ end if;
+ end if;
+ end if;
+ end process;
+
+ PCAdder <= resize(PC(7 downto 0),9) + resize(unsigned(DL(7) & DL),9) when PCAdd = '1'
+ else "0" & PC(7 downto 0);
+
+ process (Clk)
+ begin
+ if Clk'event and Clk = '1' then
+ if (Enable = '1') then
+ if (really_rdy = '1') then
+ if MCycle = "000" then
+ if LDA = '1' then
+ ABC(7 downto 0) <= ALU_Q;
+ end if;
+ if LDX = '1' then
+ X(7 downto 0) <= ALU_Q;
+ end if;
+ if LDY = '1' then
+ Y(7 downto 0) <= ALU_Q;
+ end if;
+ if (LDA or LDX or LDY) = '1' then
+ P <= P_Out;
+ end if;
+ end if;
+ if SaveP = '1' then
+ P <= P_Out;
+ end if;
+ if LDP = '1' then
+ P <= ALU_Q;
+ end if;
+ if IR(4 downto 0) = "11000" then
+ case IR(7 downto 5) is
+ when "000" =>
+ P(Flag_C) <= '0';
+ when "001" =>
+ P(Flag_C) <= '1';
+ when "010" =>
+ P(Flag_I) <= '0';
+ when "011" =>
+ P(Flag_I) <= '1';
+ when "101" =>
+ P(Flag_V) <= '0';
+ when "110" =>
+ P(Flag_D) <= '0';
+ when "111" =>
+ P(Flag_D) <= '1';
+ when others =>
+ end case;
+ end if;
+ if IR = "00000000" and MCycle = "011" and RstCycle = '0' and NMICycle = '0' and IRQCycle = '0' then
+ P(Flag_B) <= '1';
+ end if;
+ if IR = "00000000" and MCycle = "100" and RstCycle = '0' and (NMICycle = '1' or IRQCycle = '1') then
+ P(Flag_I) <= '1';
+ P(Flag_B) <= B_o;
+ end if;
+ if SO_n_o = '1' and SO_n = '0' then
+ P(Flag_V) <= '1';
+ end if;
+ if RstCycle = '1' and Mode_r /= "00" then
+ P(Flag_1) <= '1';
+ P(Flag_D) <= '0';
+ P(Flag_I) <= '1';
+ end if;
+ P(Flag_1) <= '1';
+
+ B_o <= P(Flag_B);
+ SO_n_o <= SO_n;
+ IRQ_n_o <= IRQ_n;
+ NMI_n_o <= NMI_n;
+ end if;
+ end if;
+ end if;
+ end process;
+
+---------------------------------------------------------------------------
+--
+-- Buses
+--
+---------------------------------------------------------------------------
+
+ process (Res_n, Clk)
+ begin
+ if Res_n = '0' then
+ BusA_r <= (others => '0');
+ BusB <= (others => '0');
+ AD <= (others => '0');
+ BAL <= (others => '0');
+ BAH <= (others => '0');
+ DL <= (others => '0');
+ elsif Clk'event and Clk = '1' then
+ if (Enable = '1') then
+ if (Rdy = '1') then
+ BusA_r <= BusA;
+ BusB <= DI;
+
+ case BAAdd is
+ when "01" =>
+ -- BA Inc
+ AD <= std_logic_vector(unsigned(AD) + 1);
+ BAL <= std_logic_vector(unsigned(BAL) + 1);
+ when "10" =>
+ -- BA Add
+ BAL <= std_logic_vector(resize(unsigned(BAL(7 downto 0)),9) + resize(unsigned(BusA),9));
+ when "11" =>
+ -- BA Adj
+ if BAL(8) = '1' then
+ BAH <= std_logic_vector(unsigned(BAH) + 1);
+ end if;
+ when others =>
+ end case;
+
+ -- ehenciak : modified to use Y register as well (bugfix)
+ if ADAdd = '1' then
+ if (AddY = '1') then
+ AD <= std_logic_vector(unsigned(AD) + unsigned(Y(7 downto 0)));
+ else
+ AD <= std_logic_vector(unsigned(AD) + unsigned(X(7 downto 0)));
+ end if;
+ end if;
+
+ if IR = "00000000" then
+ BAL <= (others => '1');
+ BAH <= (others => '1');
+ if RstCycle = '1' then
+ BAL(2 downto 0) <= "100";
+ elsif NMICycle = '1' then
+ BAL(2 downto 0) <= "010";
+ else
+ BAL(2 downto 0) <= "110";
+ end if;
+ if Set_addr_To_r = "11" then
+ BAL(0) <= '1';
+ end if;
+ end if;
+
+
+ if LDDI = '1' then
+ DL <= DI;
+ end if;
+ if LDALU = '1' then
+ DL <= ALU_Q;
+ end if;
+ if LDAD = '1' then
+ AD <= DI;
+ end if;
+ if LDBAL = '1' then
+ BAL(7 downto 0) <= DI;
+ end if;
+ if LDBAH = '1' then
+ BAH <= DI;
+ end if;
+ end if;
+ end if;
+ end if;
+ end process;
+
+ Break <= (BreakAtNA and not BAL(8)) or (PCAdd and not PCAdder(8));
+
+
+ with Set_BusA_To select
+ BusA <= DI when "000",
+ ABC(7 downto 0) when "001",
+ X(7 downto 0) when "010",
+ Y(7 downto 0) when "011",
+ std_logic_vector(S(7 downto 0)) when "100",
+ P when "101",
+ (others => '-') when others;
+
+ with Set_Addr_To_r select
+ A <= "0000000000000001" & std_logic_vector(S(7 downto 0)) when "01",
+ DBR & "00000000" & AD when "10",
+ "00000000" & BAH & BAL(7 downto 0) when "11",
+ PBR & std_logic_vector(PC(15 downto 8)) & std_logic_vector(PCAdder(7 downto 0)) when others;
+
+ with Write_Data_r select
+ DO <= DL when "000",
+ ABC(7 downto 0) when "001",
+ X(7 downto 0) when "010",
+ Y(7 downto 0) when "011",
+ std_logic_vector(S(7 downto 0)) when "100",
+ P when "101",
+ std_logic_vector(PC(7 downto 0)) when "110",
+ std_logic_vector(PC(15 downto 8)) when others;
+
+-------------------------------------------------------------------------
+--
+-- Main state machine
+--
+-------------------------------------------------------------------------
+
+ process (Res_n, Clk)
+ begin
+ if Res_n = '0' then
+ MCycle <= "001";
+ RstCycle <= '1';
+ IRQCycle <= '0';
+ NMICycle <= '0';
+ NMIAct <= '0';
+ elsif Clk'event and Clk = '1' then
+ if (Enable = '1') then
+ if (really_rdy = '1') then
+ if MCycle = LCycle or Break = '1' then
+ MCycle <= "000";
+ RstCycle <= '0';
+ IRQCycle <= '0';
+ NMICycle <= '0';
+ if NMIAct = '1' then
+ NMICycle <= '1';
+ elsif IRQ_n_o = '0' and P(Flag_I) = '0' then
+ IRQCycle <= '1';
+ end if;
+ else
+ MCycle <= std_logic_vector(unsigned(MCycle) + 1);
+ end if;
+
+ if NMICycle = '1' then
+ NMIAct <= '0';
+ end if;
+ if NMI_n_o = '1' and NMI_n = '0' then
+ NMIAct <= '1';
+ end if;
+ end if;
+ end if;
+ end if;
+ end process;
+
+end;
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