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|
ENTITY amd2901_ctl IS
PORT(
-- Input/Output from and to the data-path.
-- Command for selecting operands R and S.
ops_mx : out BIT_VECTOR(2 downto 0);
opr_mx : out BIT_VECTOR(1 downto 0);
-- ALU commands and auxiliary terminals.
alu_k : out BIT_VECTOR(4 downto 0);
alu_cout : in BIT;
alu_over : in BIT;
-- RAM, ACCU shifter commands and auxiliary terminals.
-- ("acc_sh" is same as "ram_sh")
ram_sh : out BIT_VECTOR(1 downto 0);
-- Output multiplexer commnand (for X bus).
out_mx : out BIT;
-- ACCU controls terminals.
-- ("acc_ck", "acc_test" and "acc_scin" directly comes from the plots)
acc_wen : out BIT;
-- Data bus terminals.
alu_f : in BIT_VECTOR(3 downto 0);
alu_np : in BIT_VECTOR(3 downto 0);
alu_ng : in BIT_VECTOR(3 downto 0);
-- Input/Output from and to the plots.
-- Test terminals from/to plots.
core_test : in BIT;
core_fonc : in BIT;
-- ALU terminals from/to plots.
-- core_ncout : out BIT;
core_np : out BIT;
core_ng : out BIT;
core_over : out BIT;
core_zero : out BIT;
-- core_nsign : out BIT;
-- RAM, ACCU shifter terminals from/to plots.
-- RAM and ACCU I/O plots controls.
core_sh_right : out BIT;
core_sh_left : out BIT;
-- Data bus terminals from/to the plots.
i : in BIT_VECTOR(8 downto 0);
noe : in BIT;
oe : out BIT;
-- -
-- ram_wri : out BIT;
-- +
a : in BIT_VECTOR(3 downto 0);
b : in BIT_VECTOR(3 downto 0);
deca : out BIT_VECTOR(15 downto 0);
decb : out BIT_VECTOR(15 downto 0);
decwb : out BIT_VECTOR(15 downto 0);
-- Power supply connectors.
vdd : in BIT;
vss : in BIT
-- -
);
END amd2901_ctl;
ARCHITECTURE behavior_data_flow OF amd2901_ctl IS
-- Internals bus.
SIGNAL alu_p : BIT_VECTOR(3 downto 0);
SIGNAL alu_g : BIT_VECTOR(3 downto 0);
-- Internals signals.
SIGNAL fonc_mode : BIT;
SIGNAL ram_wri : BIT;
SIGNAL interm : BIT_VECTOR (15 downto 0);
BEGIN
-- ******************** Miscellaneous controls *******************
-- Select between normal and test mode.
fonc_mode <= core_fonc and (not core_test);
-- *************** ACCU and RAM multiplexer control **************
WITH i(8 DOWNTO 6) SELECT
ram_sh <= "00" WHEN B"110"
| B"111",
"01" WHEN B"100"
| B"101",
"11" WHEN OTHERS;
-- ******************** S multiplexer control ********************
WITH i(2 downto 0) SELECT
ops_mx <= "000" WHEN B"110",
"000" WHEN B"010",
"000" WHEN B"000",
"010" WHEN B"101"
| B"100",
"001" WHEN B"001",
"001" WHEN B"011",
"100" WHEN B"111";
-- ******************** R multiplexer control ********************
WITH i(2 downto 0) SELECT
opr_mx <= "11" WHEN B"100"
| B"010"
| B"011",
"01" WHEN B"101"
| B"110"
| B"111",
"00" WHEN B"000"
| B"001";
-- ******************** X multiplexer control ********************
WITH i(8 downto 6) SELECT
out_mx <= "1" WHEN B"010",
"0" WHEN OTHERS;
-- ************************* ALU control *************************
-- ALU commands.
alu_k(4) <= ( i(5) or ( i(4) and i(3)));
alu_k(3) <= (not i(5) and ( i(4) and i(3)));
alu_k(2) <= ( i(5) and not i(4)) ;
alu_k(1) <= i(5) xor i(4);
alu_k(0) <= i(5) xor i(3);
-- Compute of ALU flags.
-- Propagate.
alu_p(3 downto 0) <= not alu_np(3 downto 0);
core_np <= not ( alu_p(0)
and alu_p(1)
and alu_p(2)
and alu_p(3));
-- Generate.
alu_g(3 downto 0) <= not alu_ng(3 downto 0);
core_ng <= not ( alu_g(3)
or (alu_p(3) and alu_g(2))
or (alu_p(3) and alu_p(2) and alu_g(1))
or (alu_p(3) and alu_p(2) and alu_p(1) and alu_g(0)));
-- Sign, zero, overflow and carry out.
-- core_nsign <= not alu_f(3);
core_zero <= not ( alu_f(3)
or alu_f(2)
or alu_f(1)
or alu_f(0));
core_over <= alu_cout xor alu_over;
-- ************************* ACCU control ************************
-- Compute of ACCU write enable.
acc_wen <= (not i(6)) and ((not i(7)) or i(8));
-- ACCU shifter I/O.
-- acc_i_up <= not core_acc_i_nup;
-- acc_i_down <= not core_acc_i_ndown;
-- core_acc_o_nup <= not acc_scout;
-- core_acc_o_ndown <= not acc_q_down;
-- ************************** RAM control ************************
-- Compute of RAM write enable.
ram_wri <= fonc_mode and (i(8) or i(7));
-- RAM and ACCU I/O plots controls.
core_sh_right <= i(8) and (not i(7));
core_sh_left <= i(8) and i(7) ;
-- RAM shifter I/O.
-- ram_i_up <= not core_ram_i_nup;
-- ram_i_down <= not core_ram_i_ndown;
-- core_ram_o_ndown <= not alu_f(0);
-- core_ram_o_nup <= not alu_f(3);
oe <= not noe;
-- +
WITH a(3 downto 0) SELECT
deca<= B"0000000000000001" WHEN X"0",
B"0000000000000010" WHEN X"1",
B"0000000000000100" WHEN X"2",
B"0000000000001000" WHEN X"3",
B"0000000000010000" WHEN X"4",
B"0000000000100000" WHEN X"5",
B"0000000001000000" WHEN X"6",
B"0000000010000000" WHEN X"7",
B"0000000100000000" WHEN X"8",
B"0000001000000000" WHEN X"9",
B"0000010000000000" WHEN X"A",
B"0000100000000000" WHEN X"B",
B"0001000000000000" WHEN X"C",
B"0010000000000000" WHEN X"D",
B"0100000000000000" WHEN X"E",
B"1000000000000000" WHEN OTHERS;
WITH b(3 downto 0) SELECT
interm<= B"0000000000000001" WHEN X"0",
B"0000000000000010" WHEN X"1",
B"0000000000000100" WHEN X"2",
B"0000000000001000" WHEN X"3",
B"0000000000010000" WHEN X"4",
B"0000000000100000" WHEN X"5",
B"0000000001000000" WHEN X"6",
B"0000000010000000" WHEN X"7",
B"0000000100000000" WHEN X"8",
B"0000001000000000" WHEN X"9",
B"0000010000000000" WHEN X"A",
B"0000100000000000" WHEN X"B",
B"0001000000000000" WHEN X"C",
B"0010000000000000" WHEN X"D",
B"0100000000000000" WHEN X"E",
B"1000000000000000" WHEN OTHERS;
decb <= interm;
WITH ram_wri SELECT
decwb<= interm WHEN B"1",
B"0000000000000000" WHEN OTHERS;
END behavior_data_flow;
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