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repo2/common/zpu/zpu_config_regs.vhdl @ 7

---------------------------------------------------------------------------
-- (c) 2013 mark watson
-- I am happy for anyone to use this for non-commercial use.
-- If my vhdl files are used commercially or otherwise sold,
-- please contact me for explicit permission at scrameta (gmail).
-- This applies for source and binary form and derived works.
---------------------------------------------------------------------------
LIBRARY ieee;
USE ieee.std_logic_1164.all;
use ieee.numeric_std.all;

ENTITY zpu_config_regs IS
GENERIC
(
platform : integer := 1 -- So ROM can detect which type of system...
);
PORT
(
CLK : IN STD_LOGIC;
RESET_N : IN STD_LOGIC;
POKEY_ENABLE : in std_logic;
ADDR : IN STD_LOGIC_VECTOR(4 DOWNTO 0);
CPU_DATA_IN : IN STD_LOGIC_VECTOR(31 DOWNTO 0);
WR_EN : IN STD_LOGIC;
-- GENERIC INPUT REGS (need to synchronize upstream...)
IN1 : in std_logic_vector(31 downto 0);
IN2 : in std_logic_vector(31 downto 0);
IN3 : in std_logic_vector(31 downto 0);
IN4 : in std_logic_vector(31 downto 0);
-- GENERIC OUTPUT REGS
OUT1 : out std_logic_vector(31 downto 0);
OUT2 : out std_logic_vector(31 downto 0);
OUT3 : out std_logic_vector(31 downto 0);
OUT4 : out std_logic_vector(31 downto 0);
-- SDCARD
SDCARD_CLK : out std_logic;
SDCARD_CMD : out std_logic;
SDCARD_DAT : in std_logic;
SDCARD_DAT3 : out std_logic;
-- ATARI interface (in future we can also turbo load by directly hitting memory...)
SIO_DATA_IN : out std_logic;
SIO_COMMAND : in std_logic;
SIO_DATA_OUT : in std_logic;
-- CPU interface
DATA_OUT : OUT STD_LOGIC_VECTOR(31 DOWNTO 0);
PAUSE_ZPU : out std_logic
);
END zpu_config_regs;

ARCHITECTURE vhdl OF zpu_config_regs IS
function vectorize(s: std_logic) return std_logic_vector is
variable v: std_logic_vector(0 downto 0);
begin
v(0) := s;
return v;
end;
signal addr_decoded : std_logic_vector(15 downto 0);
signal out1_next : std_logic_vector(31 downto 0);
signal out1_reg : std_logic_vector(31 downto 0);
signal out2_next : std_logic_vector(31 downto 0);
signal out2_reg : std_logic_vector(31 downto 0);
signal out3_next : std_logic_vector(31 downto 0);
signal out3_reg : std_logic_vector(31 downto 0);
signal out4_next : std_logic_vector(31 downto 0);
signal out4_reg : std_logic_vector(31 downto 0);
signal spi_miso : std_logic;
signal spi_mosi : std_logic;
signal spi_busy : std_logic;
signal spi_enable : std_logic;
signal spi_chip_select : std_logic_vector(0 downto 0);
signal spi_clk_out : std_logic;
signal spi_tx_data : std_logic_vector(7 downto 0);
signal spi_rx_data : std_logic_vector(7 downto 0);
signal spi_addr_next : std_logic;
signal spi_addr_reg : std_logic;
signal spi_addr_reg_integer : integer;
signal spi_speed_next : std_logic_vector(7 downto 0);
signal spi_speed_reg : std_logic_vector(7 downto 0);
signal spi_speed_reg_integer : integer;

signal pokey_data_out : std_logic_vector(7 downto 0);
signal wr_en_pokey : std_logic;

signal pause_next : std_logic_vector(31 downto 0);
signal pause_reg : std_logic_vector(31 downto 0);
signal paused_next : std_logic;
signal paused_reg : std_logic;
begin
-- register
process(clk,reset_n)
begin
if (reset_n='0') then
out1_reg <= (others=>'0');
out2_reg <= (others=>'0');
out3_reg <= (others=>'0');
out4_reg <= (others=>'0');
spi_addr_reg <= '1';
spi_speed_reg <= X"80";

pause_reg <= (others=>'0');
paused_reg <= '0';
elsif (clk'event and clk='1') then
out1_reg <= out1_next;
out2_reg <= out2_next;
out3_reg <= out3_next;
out4_reg <= out4_next;
spi_addr_reg <= spi_addr_next;
spi_speed_reg <= spi_speed_next;

pause_reg <= pause_next;
paused_reg <= paused_next;
end if;
end process;

-- decode address
decode_addr1 : entity work.complete_address_decoder
generic map(width=>4)
port map (addr_in=>addr(3 downto 0), addr_decoded=>addr_decoded);

-- spi - for sd card access without bit banging...
-- 200KHz to start with - probably fine for 8-bit, can up it later after init
-- spi-programming model:
-- reg for write/read
-- data (send/receive)
-- busy
-- speed - 0=400KHz, 1=10MHz? Start with 400KHz then atari800core...
-- chip select
-- uart - another Pokey! Running at atari frequency.
wr_en_pokey <= addr(4) and wr_en;
pokey1 : entity work.pokey
port map (clk=>clk,CPU_MEMORY_READY=>pokey_enable,ANTIC_MEMORY_READY=>pokey_enable,addr=>addr(3 downto 0),data_in=>cpu_data_in(7 downto 0),wr_en=>wr_en_pokey,
reset_n=>reset_n,keyboard_response=>"11",pot_in=>X"00",
sio_in1=>sio_data_out,sio_in2=>'1',sio_in3=>'1', -- TODO, pokey dir...
data_out=>pokey_data_out,
sio_out1=>sio_data_in);

-- hardware regs for ZPU
--
-- 0-3: GENERIC INPUT (RO)
-- 4-7: GENERIC OUTPUT (R/W)
-- 8: PAUSE
-- 9: SPI_DATA
-- SPI_DATA (DONE)
-- W - write data (starts transmission)
-- R - read data (wait for complete first)
-- 10: SPI_STATE
-- SPI_STATE/SPI_CTRL (DONE)
-- R: 0=busy
-- W: 0=select_n, speed
-- 11: SIO
-- SIO
-- R: 0=CMD
-- 12: TYPE
-- FPGA board (DONE)
-- R(32 bits) 0=DE1
-- 16-31: POKEY! Low bytes only... i.e. pokey reg every 4 bytes...
-- Writes to registers
process(cpu_data_in,wr_en,addr,addr_decoded, spi_speed_reg, spi_addr_reg, out1_reg, out2_reg, out3_reg, out4_reg, pause_reg)
begin
spi_speed_next <= spi_speed_reg;
spi_addr_next <= spi_addr_reg;
spi_tx_data <= (others=>'0');
spi_enable <= '0';
paused_next <= '0';
if (not(pause_reg = X"00000000")) then
pause_next <= std_LOGIC_VECTOR(unsigned(pause_reg)-to_unsigned(1,32));
paused_next <= '1';
end if;
if (wr_en = '1' and addr(4) = '0') then
if(addr_decoded(4) = '1') then
out1_next <= cpu_data_in;
end if;
if(addr_decoded(5) = '1') then
out2_next <= cpu_data_in;
end if;

if(addr_decoded(6) = '1') then
out3_next <= cpu_data_in;
end if;

if(addr_decoded(7) = '1') then
out4_next <= cpu_data_in;
end if;

if(addr_decoded(8) = '1') then
pause_next <= cpu_data_in;
paused_next <= '1';
end if;

if(addr_decoded(9) = '1') then
-- TODO, check overrun?
spi_tx_data <= cpu_data_in(7 downto 0);
spi_enable <= '1';
end if;

if(addr_decoded(10) = '1') then
spi_addr_next <= cpu_data_in(0);
if (cpu_data_in(1) = '1') then
spi_speed_next <= X"80"; -- slow, for init
else
spi_speed_next <= X"04"; -- turbo!
end if;
end if;
end if;
end process;
-- Read from registers
process(addr,addr_decoded, in1, in2, in3, in4, out1_reg, out2_reg, out3_reg, out4_reg, SIO_COMMAND, spi_rx_data, spi_busy, pokey_data_out)
begin
data_out <= (others=>'0');

if (addr(4) = '0') then
if (addr_decoded(0) = '1') then
data_out <= in1;
end if;
if (addr_decoded(1) = '1') then
data_out <= in2;
end if;
if (addr_decoded(2) = '1') then
data_out <= in3;
end if;
if (addr_decoded(3) = '1') then
data_out <= in4;
end if;

if (addr_decoded(4) = '1') then
data_out <= out1_reg;
end if;
if (addr_decoded(5) = '1') then
data_out <= out2_reg;
end if;
if (addr_decoded(6) = '1') then
data_out <= out3_reg;
end if;
if (addr_decoded(7) = '1') then
data_out <= out4_reg;
end if;

if (addr_decoded(9) = '1') then
data_out(7 downto 0) <= spi_rx_data;
end if;

if (addr_decoded(10) = '1') then
data_out(0) <= spi_busy;
end if;

if(addr_decoded(11) = '1') then
data_out(0) <= SIO_COMMAND;
end if;
if (addr_decoded(12) = '1') then
data_out <= std_logic_vector(to_unsigned(platform,32));
end if;
else
data_out(7 downto 0) <= pokey_data_out;
end if;
end process;
-- outputs
PAUSE_ZPU <= paused_reg;

out1 <= out1_reg;
out2 <= out2_reg;
out3 <= out3_reg;
out4 <= out4_reg;
SDCARD_CLK <= spi_clk_out;
SDCARD_CMD <= spi_mosi;
spi_miso <= SDCARD_DAT; -- INPUT!! XXX
SDCARD_DAT3 <= spi_chip_select(0);
end vhdl;


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