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--! @file
--! @brief ControlUnit http://en.wikipedia.org/wiki/Control_unit
 
--! Use standard library and import the packages (std_logic_1164,std_logic_unsigned,std_logic_arith)
library IEEE;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
use ieee.std_logic_arith.all;
 
--! Use CPU Definitions package
use work.pkgOpenCPU32.all;
 
--! The control unit coordinates the input and output devices of a computer system. It fetches the code of all of the instructions \n
--! in the microprograms. It directs the operation of the other units by providing timing and control signals. \n
--! all computer resources are managed by the Control Unit.It directs the flow of data between the cpu and the other devices.\n
--! The outputs of the control unit control the activity of the rest of the device. A control unit can be thought of as a finite-state machine.
 
--! The purpose of datapaths is to provide routes for data to travel between functional units.
entity ControlUnit is
    generic (n : integer := nBits - 1);                                                                 --! Generic value (Used to easily change the size of the Alu on the package)
         Port ( reset : in  STD_LOGIC;
           clk : in  STD_LOGIC;                                                                                         --! Main system clock
           FlagsDp : in  STD_LOGIC_VECTOR (2 downto 0);                          --! Flags comming from the Datapath
           DataDp : in  STD_LOGIC_VECTOR (n downto 0);                           --! Data comming from the Datapath
                          outEnDp : out  typeEnDis;                                                                             --! Enable/Disable datapath output
           MuxDp : out  dpMuxInputs;                                                                            --! Select on datapath data from (Memory, Imediate, RegFileA, RegFileB, AluOut)
                          MuxRegDp : out dpMuxAluIn;                                                                            --! Select Alu InputA (Memory,Imediate,RegFileA)
           ImmDp : out  STD_LOGIC_VECTOR (n downto 0);                           --! Imediate value passed to the Datapath
           DpAluOp : out  aluOps;                                                                                       --! Alu operations
                          DpRegFileWriteAddr : out  generalRegisters;                           --! General register address to write
           DpRegFileWriteEn : out  STD_LOGIC;                                                   --! Enable register write
           DpRegFileReadAddrA : out  generalRegisters;                          --! General register address to read
           DpRegFileReadAddrB : out  generalRegisters;                          --! General register address to read
           DpRegFileReadEnA : out  STD_LOGIC;                                                   --! Enable register read (PortA)
           DpRegFileReadEnB : out  STD_LOGIC;                                                   --! Enable register read (PortB)
           MemoryDataReadEn : out std_logic;                                                            --! Enable Main memory read
                          MemoryDataWriteEn: out std_logic;                                                             --! Enable Main memory write
                          MemoryDataInput : in  STD_LOGIC_VECTOR (n downto 0);   --! Incoming data from main memory
           MemoryDataRdAddr : out  STD_LOGIC_VECTOR (n downto 0);        --! Main memory Read address
                          MemoryDataWrAddr : out  STD_LOGIC_VECTOR (n downto 0); --! Main memory Write address
           MemoryDataOut : out  STD_LOGIC_VECTOR (n downto 0));  --! Data to write on main memory
end ControlUnit;
 
--! @brief ControlUnit http://en.wikipedia.org/wiki/Control_unit
--! @details The control unit receives external instructions or commands which it converts into a sequence of control signals that the control \n
--! unit applies to data path to implement a sequence of register-transfer level operations.
architecture Behavioral of ControlUnit is
 
signal currentCpuState : controlUnitStates;                                     -- CPU states
signal nextCpuState    : controlUnitStates;                                     -- CPU states
 
signal currentExState  : executionStates;                                               -- Execution states
signal nextExState     : executionStates;                                               -- Execution states
 
signal PC              : std_logic_vector(n downto 0);   -- Program Counter
signal IR              : std_logic_vector(n downto 0);   -- Intruction register
signal currInstruction : std_logic_vector(n downto 0);   -- Current Intruction
begin
 
        -- Next state logic (CPU, fetch, decode, execute states)
        process (clk, reset)
        begin
                if (reset = '1') then
                        currentCpuState <= initial;
                elsif rising_edge(clk) then
                        currentCpuState <= nextCpuState;
                end if;
        end process;
 
        -- Next state logic (Execution states)
        process (clk, currentCpuState)
        begin
                if (reset = '1') then
                        currentExState <= initInstructionExecution;
                elsif rising_edge(clk) then
                        currentExState <= nextExState;
                end if;
        end process;
 
        -- States Fetch, decode, execute from the processor (Also handles the execution of jump instructions)
        process (currentCpuState)
        variable cyclesExecute : integer range 0 to 20;          -- Cycles to wait while executing instruction
        variable opcodeIR : std_logic_vector(5 downto 0);
        variable operand_reg1 : std_logic_vector(3 downto 0);
        variable operand_imm  : std_logic_vector(21 downto 0);
        variable accDp : std_logic_vector(n downto 0);                   -- Value stored from DataPath
        begin
                opcodeIR := IR((IR'HIGH) downto (IR'HIGH - 5));
                operand_reg1 := IR((IR'HIGH - 6) downto (IR'HIGH - 9));         -- 4 bits register operand1 (Max 16 registers)
                operand_imm  := IR((IR'HIGH - 10) downto (IR'LOW));                     -- 22 bits imediate value (Max value 4194304)
                case currentCpuState is
                        -- Initial state left from reset ...
                        when initial =>
                                cyclesExecute := 0;
                                PC <= (others => '0');
                                IR <= (others => '0');
                                MemoryDataRdAddr <= (others => '0');
                                MemoryDataReadEn <= '0';
                                MemoryDataWriteEn <= '0';
                                nextCpuState <= fetch;
 
                        -- Fetch state (Go to memory and get a instruction)
                        when fetch =>
                                -- Increment program counter (Remember that PC will be update only on the next cycle...
                                PC <= PC + conv_std_logic_vector(1, nBits);
                                MemoryDataRdAddr <= PC; -- Warning PC is not 1 yet...
                                IR <= MemoryDataInput;
                                MemoryDataReadEn <= '1';
                                MemoryDataWriteEn <= '0';
                                nextCpuState <= decode;
 
                        -- Detect with instruction came from memory, set the number of cycles to execute...
                        when decode =>
                                MemoryDataReadEn <= '0';
                                MemoryDataWriteEn <= '0';
 
                                -- The high attribute points to the highes bit position
                                case opcodeIR is
                                        when mov_reg | mov_val | add_reg | add_val | sub_reg | and_reg | or_reg | xor_reg =>
                                                        nextCpuState <= execute;
                                                        cyclesExecute := 1;     -- Wait 1 cycles
                                                        currInstruction <= IR;
 
                                        when ld_reg | ld_val | stom_reg | stom_val =>
                                                        nextCpuState <= execute;
                                                        cyclesExecute := 2;     -- Wait 2 cycles
                                                        currInstruction <= IR;
 
                                        when jmp_val | jmpr_val =>
                                                nextCpuState <= execute;
                                                cyclesExecute := 0;              -- No Wait cycle
 
                                        -- Invalid instruction (Now will be ignored, but latter should raise a trap
                                        when others =>
                                                null;
                                end case;
 
                        -- Wait while the process that handles the execution works..
                        when execute =>
                                -- On the case of jump instructions, it's execution will be handled on this process
                                case opcodeIR is
 
                                        when jmp_val =>
                                                PC      <= "0000000000" & operand_imm;
 
                                        when jmpr_val =>
                                                PC      <= PC + ("0000000000" & operand_imm);
 
                                        -- ld r5,20 (Load into r5 register the content of the memory at address 20)
                                        when ld_val =>
                                                MemoryDataRdAddr <= "0000000000" & operand_imm;
                                                MemoryDataReadEn <= '1';
                                                if cyclesExecute = 0 then
                                                        MemoryDataReadEn <= '0';
                                                end if;
 
                                        -- STORE r1,10 (Store the value 10 on memory address pointed by r1)
                                        when stom_val =>
                                                -- And put the imediate value ...                                                       
                                                        MemoryDataOut <= "0000000000" & operand_imm;
                                                        if cyclesExecute = 1 then
                                                                -- After the register data is avaible in DataDp we put it's address and                                                         
                                                                accDp := DataDp;
                                                                MemoryDataWrAddr <= accDp;
                                                        elsif cyclesExecute = 0 then
                                                                -- strobe in to enter the data
                                                                MemoryDataWriteEn <= '1';
                                                        end if;
 
                                        when others =>
                                                null;
                                end case;
 
                                if cyclesExecute = 0 then
                                        -- Finish the instruction execution get next
                                        nextCpuState <= fetch;
                                else
                                        nextCpuState <= executing;
                                end if;
 
                        -- Just wait a cycle and back again to execute state which verify if still need to wait some cycles
                        when executing =>
                                cyclesExecute := cyclesExecute - 1;
                                nextCpuState <= execute;
 
                        when others =>
                                null;
                end case;
        end process;
 
        -- Process that handles the execution of each instruction (Excluding the call,jump,load,store instructions)
        process (currentExState)
        --variable operando1_reg : std_logic_vector(generalRegisters'range);
        variable opcodeIR     : std_logic_vector(5 downto 0);
        variable operand_reg1 : std_logic_vector(3 downto 0);
        variable operand_reg2 : std_logic_vector(3 downto 0);
        variable operand_imm  : std_logic_vector(21 downto 0);
        begin
                -- Parse the common operands
                opcodeIR := IR((IR'HIGH) downto (IR'HIGH - 5));                                 -- 6 Bits opcode (Max 64 instructions)
                operand_reg1 := IR((IR'HIGH - 6) downto (IR'HIGH - 9));         -- 4 bits register operand1 (Max 16 registers)
                operand_reg2 := IR((IR'HIGH - 10) downto (IR'HIGH - 13));   -- 4 bits register operand2 (Max 16 registers
                operand_imm  := IR((IR'HIGH - 10) downto (IR'LOW));                     -- 22 bits imediate value (Max value 4194304)
 
                -- Select the instruction and init it's execution
                case currentExState is
                        when initInstructionExecution =>
                                nextExState <= waitToExecute;
 
                        when waitToExecute =>
                                if ( (currentCpuState /= execute) and (currentCpuState /= executing) ) then
                                        nextExState <= initInstructionExecution;
                                else
                                        case opcodeIR is
                                        -- MOV r2,r1 (See the testDatapath to see how to drive the datapath for this function)
                                        when mov_reg =>
                                                MuxDp <= fromRegFileB;
                                                DpRegFileReadAddrB <= Num2reg(conv_integer(UNSIGNED(operand_reg2)));
                                                DpRegFileWriteAddr <= Num2reg(conv_integer(UNSIGNED(operand_reg1)));
                                                DpRegFileReadEnB <= '1';
                                                nextExState <= writeRegister;
 
                                        -- LOAD r1,10 (Load into r1, the value in the main memory located at address 10)
                                        when ld_val =>
                                                MuxDp <= fromMemory;
                                                DpRegFileWriteAddr <= Num2reg(conv_integer(UNSIGNED(operand_reg1)));
                                                -- The part that interface with the memory is located on the first process
                                                nextExState <= writeRegister;
 
                                        -- STORE r1,10 (Store the value 10 on the main memory pointed by r1)
                                        when stom_val =>
                                        MuxDp <= fromRegFileB;
                                        DpRegFileReadAddrB <= Num2reg(conv_integer(UNSIGNED(operand_reg1)));
                                        DpRegFileReadEnB <= '1';
                                        -- The part that interface with the memory is located on the first process
                                        nextExState <= readRegisterB;
 
                                        -- ADD r2,r0 (See the testDatapath to see how to drive the datapath for this function)
                                        when add_reg | sub_reg | and_reg | or_reg | xor_reg =>
                                                MuxDp <= fromAlu;
                                                MuxRegDp <= fromRegFileA;
                                                DpRegFileReadAddrA <= Num2reg(conv_integer(UNSIGNED(operand_reg1)));    -- Read first operand
                                                DpRegFileReadAddrB <= Num2reg(conv_integer(UNSIGNED(operand_reg2))); -- Read second operand
                                                DpRegFileReadEnA <= '1';
                                                DpRegFileReadEnB <= '1';
                                                DpRegFileWriteAddr <= Num2reg(conv_integer(UNSIGNED(operand_reg1)));    -- Point to write in first operand (pointing to register)                                       
                                                DpAluOp <= opcode2AluOp(opcodeIR);      -- Select the alu operation from the operand
                                                nextExState <= writeRegister;
 
                                        -- MOV r0,10d (See the testDatapath to see how to drive the datapath for this function)
                                        when mov_val =>
                                                MuxDp <= fromImediate;
                                                DpRegFileWriteAddr <= Num2reg(conv_integer(UNSIGNED(operand_reg1)));
                                                ImmDp <= "0000000000" & operand_imm;    -- & is used to concatenate signals
                                                nextExState <= writeRegister;
 
                                        -- ADD r3,2 (r2 <= r2+2) (See the testDatapath to see how to drive the datapath for this function)
                                        when add_val | sub_val | and_val | or_val | xor_val =>
                                                MuxDp <= fromAlu;
                                                MuxRegDp <= fromImediate;
                                                DpRegFileWriteAddr <= Num2reg(conv_integer(UNSIGNED(operand_reg1)));
                                                DpRegFileReadAddrB <= Num2reg(conv_integer(UNSIGNED(operand_reg1)));    -- Read first operand
                                                DpRegFileReadEnB <= '1';
                                                ImmDp <= "0000000000" & operand_imm;    -- & is used to concatenate signals                                             
                                                DpAluOp <= opcode2AluOp(opcodeIR);      -- Select the alu operation from the operand
                                                nextExState <= writeRegister;
 
                                        when others =>
                                                null;
                                        end case;
                                end if;
 
                        -- Write something on the register files
                        when writeRegister =>
                                DpRegFileWriteEn <= '1';
                                nextExState <= releaseWriteRead;
 
                        when readRegisterB =>
                                DpRegFileReadEnB <= '1';
                                outEnDp <= enable;
                                nextExState <= releaseWriteRead;
 
                        when readRegisterA =>
                                DpRegFileReadEnA <= '1';
                                outEnDp <= enable;
                                nextExState <= releaseWriteRead;
 
                        -- Release lines (Reset Datapath lines to something that does nothing...)
                        when releaseWriteRead =>
                                DpRegFileReadEnB <= '0';
                                DpRegFileReadEnA <= '0';
                                DpRegFileWriteEn <= '0';
                                outEnDp <= disable;
                                -- Come back to waiting state
                                nextExState <= waitToExecute;
 
                        when others =>
                                null;
                end case;
        end process;
 
end Behavioral;
 

Line No.	Rev	Author	Line
1	22	leonardoar	`--! @file`
2			`--! @brief ControlUnit http://en.wikipedia.org/wiki/Control_unit`
3
4			`--! Use standard library and import the packages (std_logic_1164,std_logic_unsigned,std_logic_arith)`
5			`library IEEE;`
6			`use ieee.std_logic_1164.all;`
7			`use ieee.std_logic_unsigned.all;`
8			`use ieee.std_logic_arith.all;`
9
10			`--! Use CPU Definitions package`
11			`use work.pkgOpenCPU32.all;`
12
13			`--! The control unit coordinates the input and output devices of a computer system. It fetches the code of all of the instructions \n`
14			`--! in the microprograms. It directs the operation of the other units by providing timing and control signals. \n`
15			`--! all computer resources are managed by the Control Unit.It directs the flow of data between the cpu and the other devices.\n`
16			`--! The outputs of the control unit control the activity of the rest of the device. A control unit can be thought of as a finite-state machine.`
17
18			`--! The purpose of datapaths is to provide routes for data to travel between functional units.`
19			`entity ControlUnit is`
20	24	leonardoar	`generic (n : integer := nBits - 1); --! Generic value (Used to easily change the size of the Alu on the package)`
21			`Port ( reset : in STD_LOGIC;`
22	28	leonardoar	`clk : in STD_LOGIC; --! Main system clock`
23	30	leonardoar	`FlagsDp : in STD_LOGIC_VECTOR (2 downto 0); --! Flags comming from the Datapath`
24	28	leonardoar	`DataDp : in STD_LOGIC_VECTOR (n downto 0); --! Data comming from the Datapath`
25	31	leonardoar	`outEnDp : out typeEnDis; --! Enable/Disable datapath output`
26	42	leonardoar	`MuxDp : out dpMuxInputs; --! Select on datapath data from (Memory, Imediate, RegFileA, RegFileB, AluOut)`
27	47	leonardoar	`MuxRegDp : out dpMuxAluIn; --! Select Alu InputA (Memory,Imediate,RegFileA)`
28	28	leonardoar	`ImmDp : out STD_LOGIC_VECTOR (n downto 0); --! Imediate value passed to the Datapath`
29	27	leonardoar	`DpAluOp : out aluOps; --! Alu operations`
30	28	leonardoar	`DpRegFileWriteAddr : out generalRegisters; --! General register address to write`
31			`DpRegFileWriteEn : out STD_LOGIC; --! Enable register write`
32			`DpRegFileReadAddrA : out generalRegisters; --! General register address to read`
33			`DpRegFileReadAddrB : out generalRegisters; --! General register address to read`
34			`DpRegFileReadEnA : out STD_LOGIC; --! Enable register read (PortA)`
35			`DpRegFileReadEnB : out STD_LOGIC; --! Enable register read (PortB)`
36			`MemoryDataReadEn : out std_logic; --! Enable Main memory read`
37			`MemoryDataWriteEn: out std_logic; --! Enable Main memory write`
38			`MemoryDataInput : in STD_LOGIC_VECTOR (n downto 0); --! Incoming data from main memory`
39	30	leonardoar	`MemoryDataRdAddr : out STD_LOGIC_VECTOR (n downto 0); --! Main memory Read address`
40			`MemoryDataWrAddr : out STD_LOGIC_VECTOR (n downto 0); --! Main memory Write address`
41	28	leonardoar	`MemoryDataOut : out STD_LOGIC_VECTOR (n downto 0)); --! Data to write on main memory`
42	22	leonardoar	`end ControlUnit;`
43
44			`--! @brief ControlUnit http://en.wikipedia.org/wiki/Control_unit`
45			`--! @details The control unit receives external instructions or commands which it converts into a sequence of control signals that the control \n`
46			`--! unit applies to data path to implement a sequence of register-transfer level operations.`
47			`architecture Behavioral of ControlUnit is`
48	26	leonardoar
49	25	leonardoar	`signal currentCpuState : controlUnitStates; -- CPU states`
50			`signal nextCpuState : controlUnitStates; -- CPU states`
51	26	leonardoar
52			`signal currentExState : executionStates; -- Execution states`
53			`signal nextExState : executionStates; -- Execution states`
54
55	25	leonardoar	`signal PC : std_logic_vector(n downto 0); -- Program Counter`
56			`signal IR : std_logic_vector(n downto 0); -- Intruction register`
57			`signal currInstruction : std_logic_vector(n downto 0); -- Current Intruction`
58	22	leonardoar	`begin`
59	24	leonardoar
60	26	leonardoar	`-- Next state logic (CPU, fetch, decode, execute states)`
61	24	leonardoar	`process (clk, reset)`
62			`begin`
63			`if (reset = '1') then`
64	26	leonardoar	`currentCpuState <= initial;`
65	24	leonardoar	`elsif rising_edge(clk) then`
66			`currentCpuState <= nextCpuState;`
67			`end if;`
68			`end process;`
69
70	26	leonardoar	`-- Next state logic (Execution states)`
71			`process (clk, currentCpuState)`
72			`begin`
73	33	leonardoar	`if (reset = '1') then`
74	27	leonardoar	`currentExState <= initInstructionExecution;`
75	26	leonardoar	`elsif rising_edge(clk) then`
76			`currentExState <= nextExState;`
77			`end if;`
78			`end process;`
79
80	29	leonardoar	`-- States Fetch, decode, execute from the processor (Also handles the execution of jump instructions)`
81	24	leonardoar	`process (currentCpuState)`
82	44	leonardoar	`variable cyclesExecute : integer range 0 to 20; -- Cycles to wait while executing instruction`
83	29	leonardoar	`variable opcodeIR : std_logic_vector(5 downto 0);`
84			`variable operand_reg1 : std_logic_vector(3 downto 0);`
85			`variable operand_imm : std_logic_vector(21 downto 0);`
86	44	leonardoar	`variable accDp : std_logic_vector(n downto 0); -- Value stored from DataPath`
87	24	leonardoar	`begin`
88	29	leonardoar	`opcodeIR := IR((IR'HIGH) downto (IR'HIGH - 5));`
89			`operand_reg1 := IR((IR'HIGH - 6) downto (IR'HIGH - 9)); -- 4 bits register operand1 (Max 16 registers)`
90			`operand_imm := IR((IR'HIGH - 10) downto (IR'LOW)); -- 22 bits imediate value (Max value 4194304)`
91	24	leonardoar	`case currentCpuState is`
92			`-- Initial state left from reset ...`
93			`when initial =>`
94	25	leonardoar	`cyclesExecute := 0;`
95	24	leonardoar	`PC <= (others => '0');`
96	25	leonardoar	`IR <= (others => '0');`
97	30	leonardoar	`MemoryDataRdAddr <= (others => '0');`
98	28	leonardoar	`MemoryDataReadEn <= '0';`
99	30	leonardoar	`MemoryDataWriteEn <= '0';`
100	24	leonardoar	`nextCpuState <= fetch;`
101
102			`-- Fetch state (Go to memory and get a instruction)`
103			`when fetch =>`
104			`-- Increment program counter (Remember that PC will be update only on the next cycle...`
105			`PC <= PC + conv_std_logic_vector(1, nBits);`
106	30	leonardoar	`MemoryDataRdAddr <= PC; -- Warning PC is not 1 yet...`
107	24	leonardoar	`IR <= MemoryDataInput;`
108	28	leonardoar	`MemoryDataReadEn <= '1';`
109	44	leonardoar	`MemoryDataWriteEn <= '0';`
110	24	leonardoar	`nextCpuState <= decode;`
111
112	25	leonardoar	`-- Detect with instruction came from memory, set the number of cycles to execute...`
113	24	leonardoar	`when decode =>`
114	28	leonardoar	`MemoryDataReadEn <= '0';`
115			`MemoryDataWriteEn <= '0';`
116	25	leonardoar
117			`-- The high attribute points to the highes bit position`
118	26	leonardoar	`case opcodeIR is`
119	44	leonardoar	`when mov_reg \| mov_val \| add_reg \| add_val \| sub_reg \| and_reg \| or_reg \| xor_reg =>`
120	25	leonardoar	`nextCpuState <= execute;`
121	34	leonardoar	`cyclesExecute := 1; -- Wait 1 cycles`
122	25	leonardoar	`currInstruction <= IR;`
123	44	leonardoar
124			`when ld_reg \| ld_val \| stom_reg \| stom_val =>`
125			`nextCpuState <= execute;`
126			`cyclesExecute := 2; -- Wait 2 cycles`
127			`currInstruction <= IR;`
128	29	leonardoar
129			`when jmp_val \| jmpr_val =>`
130			`nextCpuState <= execute;`
131	34	leonardoar	`cyclesExecute := 0; -- No Wait cycle`
132	29	leonardoar
133	26	leonardoar	`-- Invalid instruction (Now will be ignored, but latter should raise a trap`
134	29	leonardoar	`when others =>`
135			`null;`
136	25	leonardoar	`end case;`
137	24	leonardoar
138	25	leonardoar	`-- Wait while the process that handles the execution works..`
139			`when execute =>`
140	29	leonardoar	`-- On the case of jump instructions, it's execution will be handled on this process`
141			`case opcodeIR is`
142	31	leonardoar
143	29	leonardoar	`when jmp_val =>`
144			`PC <= "0000000000" & operand_imm;`
145	31	leonardoar
146	29	leonardoar	`when jmpr_val =>`
147			`PC <= PC + ("0000000000" & operand_imm);`
148	31	leonardoar
149	46	leonardoar	`-- ld r5,20 (Load into r5 register the content of the memory at address 20)`
150	31	leonardoar	`when ld_val =>`
151			`MemoryDataRdAddr <= "0000000000" & operand_imm;`
152	46	leonardoar	`MemoryDataReadEn <= '1';`
153			`if cyclesExecute = 0 then`
154			`MemoryDataReadEn <= '0';`
155			`end if;`
156	31	leonardoar
157	44	leonardoar	`-- STORE r1,10 (Store the value 10 on memory address pointed by r1)`
158			`when stom_val =>`
159			`-- And put the imediate value ...`
160			`MemoryDataOut <= "0000000000" & operand_imm;`
161			`if cyclesExecute = 1 then`
162			`-- After the register data is avaible in DataDp we put it's address and`
163			`accDp := DataDp;`
164			`MemoryDataWrAddr <= accDp;`
165			`elsif cyclesExecute = 0 then`
166			`-- strobe in to enter the data`
167			`MemoryDataWriteEn <= '1';`
168			`end if;`
169	31	leonardoar
170	29	leonardoar	`when others =>`
171			`null;`
172			`end case;`
173
174	26	leonardoar	`if cyclesExecute = 0 then`
175			`-- Finish the instruction execution get next`
176	25	leonardoar	`nextCpuState <= fetch;`
177	26	leonardoar	`else`
178	44	leonardoar	`nextCpuState <= executing;`
179	26	leonardoar	`end if;`
180
181			`-- Just wait a cycle and back again to execute state which verify if still need to wait some cycles`
182			`when executing =>`
183			`cyclesExecute := cyclesExecute - 1;`
184	44	leonardoar	`nextCpuState <= execute;`
185	26	leonardoar
186	24	leonardoar	`when others =>`
187			`null;`
188			`end case;`
189	25	leonardoar	`end process;`
190
191	31	leonardoar	`-- Process that handles the execution of each instruction (Excluding the call,jump,load,store instructions)`
192	26	leonardoar	`process (currentExState)`
193			`--variable operando1_reg : std_logic_vector(generalRegisters'range);`
194	27	leonardoar	`variable opcodeIR : std_logic_vector(5 downto 0);`
195			`variable operand_reg1 : std_logic_vector(3 downto 0);`
196			`variable operand_reg2 : std_logic_vector(3 downto 0);`
197			`variable operand_imm : std_logic_vector(21 downto 0);`
198	25	leonardoar	`begin`
199	27	leonardoar	`-- Parse the common operands`
200			`opcodeIR := IR((IR'HIGH) downto (IR'HIGH - 5)); -- 6 Bits opcode (Max 64 instructions)`
201			`operand_reg1 := IR((IR'HIGH - 6) downto (IR'HIGH - 9)); -- 4 bits register operand1 (Max 16 registers)`
202			`operand_reg2 := IR((IR'HIGH - 10) downto (IR'HIGH - 13)); -- 4 bits register operand2 (Max 16 registers`
203			`operand_imm := IR((IR'HIGH - 10) downto (IR'LOW)); -- 22 bits imediate value (Max value 4194304)`
204
205			`-- Select the instruction and init it's execution`
206	26	leonardoar	`case currentExState is`
207	27	leonardoar	`when initInstructionExecution =>`
208	33	leonardoar	`nextExState <= waitToExecute;`
209
210			`when waitToExecute =>`
211			`if ( (currentCpuState /= execute) and (currentCpuState /= executing) ) then`
212	44	leonardoar	`nextExState <= initInstructionExecution;`
213	33	leonardoar	`else`
214			`case opcodeIR is`
215	27	leonardoar	`-- MOV r2,r1 (See the testDatapath to see how to drive the datapath for this function)`
216			`when mov_reg =>`
217	42	leonardoar	`MuxDp <= fromRegFileB;`
218	27	leonardoar	`DpRegFileReadAddrB <= Num2reg(conv_integer(UNSIGNED(operand_reg2)));`
219			`DpRegFileWriteAddr <= Num2reg(conv_integer(UNSIGNED(operand_reg1)));`
220			`DpRegFileReadEnB <= '1';`
221			`nextExState <= writeRegister;`
222
223	31	leonardoar	`-- LOAD r1,10 (Load into r1, the value in the main memory located at address 10)`
224			`when ld_val =>`
225	42	leonardoar	`MuxDp <= fromMemory;`
226	31	leonardoar	`DpRegFileWriteAddr <= Num2reg(conv_integer(UNSIGNED(operand_reg1)));`
227			`-- The part that interface with the memory is located on the first process`
228			`nextExState <= writeRegister;`
229
230	44	leonardoar	`-- STORE r1,10 (Store the value 10 on the main memory pointed by r1)`
231	31	leonardoar	`when stom_val =>`
232	42	leonardoar	`MuxDp <= fromRegFileB;`
233	31	leonardoar	`DpRegFileReadAddrB <= Num2reg(conv_integer(UNSIGNED(operand_reg1)));`
234	44	leonardoar	`DpRegFileReadEnB <= '1';`
235	31	leonardoar	`-- The part that interface with the memory is located on the first process`
236	44	leonardoar	`nextExState <= readRegisterB;`
237	31	leonardoar
238	27	leonardoar	`-- ADD r2,r0 (See the testDatapath to see how to drive the datapath for this function)`
239			`when add_reg \| sub_reg \| and_reg \| or_reg \| xor_reg =>`
240	42	leonardoar	`MuxDp <= fromAlu;`
241	47	leonardoar	`MuxRegDp <= fromRegFileA;`
242	27	leonardoar	`DpRegFileReadAddrA <= Num2reg(conv_integer(UNSIGNED(operand_reg1))); -- Read first operand`
243			`DpRegFileReadAddrB <= Num2reg(conv_integer(UNSIGNED(operand_reg2))); -- Read second operand`
244			`DpRegFileReadEnA <= '1';`
245			`DpRegFileReadEnB <= '1';`
246			`DpRegFileWriteAddr <= Num2reg(conv_integer(UNSIGNED(operand_reg1))); -- Point to write in first operand (pointing to register)`
247			`DpAluOp <= opcode2AluOp(opcodeIR); -- Select the alu operation from the operand`
248			`nextExState <= writeRegister;`
249
250			`-- MOV r0,10d (See the testDatapath to see how to drive the datapath for this function)`
251			`when mov_val =>`
252	42	leonardoar	`MuxDp <= fromImediate;`
253	27	leonardoar	`DpRegFileWriteAddr <= Num2reg(conv_integer(UNSIGNED(operand_reg1)));`
254			`ImmDp <= "0000000000" & operand_imm; -- & is used to concatenate signals`
255			`nextExState <= writeRegister;`
256
257			`-- ADD r3,2 (r2 <= r2+2) (See the testDatapath to see how to drive the datapath for this function)`
258			`when add_val \| sub_val \| and_val \| or_val \| xor_val =>`
259	42	leonardoar	`MuxDp <= fromAlu;`
260	47	leonardoar	`MuxRegDp <= fromImediate;`
261	27	leonardoar	`DpRegFileWriteAddr <= Num2reg(conv_integer(UNSIGNED(operand_reg1)));`
262			`DpRegFileReadAddrB <= Num2reg(conv_integer(UNSIGNED(operand_reg1))); -- Read first operand`
263			`DpRegFileReadEnB <= '1';`
264			`ImmDp <= "0000000000" & operand_imm; -- & is used to concatenate signals`
265			`DpAluOp <= opcode2AluOp(opcodeIR); -- Select the alu operation from the operand`
266			`nextExState <= writeRegister;`
267
268	26	leonardoar	`when others =>`
269			`null;`
270	33	leonardoar	`end case;`
271			`end if;`
272	27	leonardoar
273			`-- Write something on the register files`
274			`when writeRegister =>`
275			`DpRegFileWriteEn <= '1';`
276			`nextExState <= releaseWriteRead;`
277
278	31	leonardoar	`when readRegisterB =>`
279			`DpRegFileReadEnB <= '1';`
280			`outEnDp <= enable;`
281			`nextExState <= releaseWriteRead;`
282
283			`when readRegisterA =>`
284			`DpRegFileReadEnA <= '1';`
285			`outEnDp <= enable;`
286			`nextExState <= releaseWriteRead;`
287
288	27	leonardoar	`-- Release lines (Reset Datapath lines to something that does nothing...)`
289			`when releaseWriteRead =>`
290			`DpRegFileReadEnB <= '0';`
291			`DpRegFileReadEnA <= '0';`
292	31	leonardoar	`DpRegFileWriteEn <= '0';`
293	33	leonardoar	`outEnDp <= disable;`
294			`-- Come back to waiting state`
295	34	leonardoar	`nextExState <= waitToExecute;`
296	27	leonardoar
297	26	leonardoar	`when others =>`
298			`null;`
299			`end case;`
300	24	leonardoar	`end process;`
301	22	leonardoar
302			`end Behavioral;`
303

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