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URL https://opencores.org/ocsvn/potato/potato/trunk

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    from Rev 13 to Rev 14
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Rev 13 → Rev 14

/potato/trunk/src/pp_types.vhd
16,7 → 16,7
ALU_SLT, ALU_SLTU,
ALU_ADD, ALU_SUB,
ALU_SRL, ALU_SLL, ALU_SRA,
ALU_NOP
ALU_NOP, ALU_INVALID
);
 
--! Types of branches.
/potato/trunk/src/pp_control_unit.vhd
5,9 → 5,10
library ieee;
use ieee.std_logic_1164.all;
 
use work.pp_types.all;
use work.pp_constants.all;
use work.pp_csr.all;
use work.pp_types.all;
use work.pp_utilities.all;
 
--! @brief Unit decoding instructions and setting control signals apropriately.
entity pp_control_unit is
43,10 → 44,18
end entity pp_control_unit;
 
architecture behaviour of pp_control_unit is
signal exception : std_logic;
signal exception_cause : std_logic_vector(4 downto 0);
signal alu_op_temp : alu_operation;
begin
 
csr_imm <= funct3(2);
alu_op <= alu_op_temp;
 
decode_exception <= exception or to_std_logic(alu_op_temp = ALU_INVALID);
decode_exception_cause <= exception_cause when alu_op_temp /= ALU_INVALID
else CSR_CAUSE_INVALID_INSTR;
 
alu_control: entity work.pp_alu_control_unit
port map(
opcode => opcode,
54,7 → 63,7
funct7 => funct7,
alu_x_src => alu_x_src,
alu_y_src => alu_y_src,
alu_op => alu_op
alu_op => alu_op_temp
);
 
decode_ctrl: process(opcode, funct3, funct12)
62,53 → 71,53
case opcode is
when b"01101" => -- Load upper immediate
rd_write <= '1';
decode_exception <= '0';
decode_exception_cause <= CSR_CAUSE_NONE;
exception <= '0';
exception_cause <= CSR_CAUSE_NONE;
branch <= BRANCH_NONE;
when b"00101" => -- Add upper immediate to PC
rd_write <= '1';
decode_exception <= '0';
decode_exception_cause <= CSR_CAUSE_NONE;
exception <= '0';
exception_cause <= CSR_CAUSE_NONE;
branch <= BRANCH_NONE;
when b"11011" => -- Jump and link
rd_write <= '1';
decode_exception <= '0';
decode_exception_cause <= CSR_CAUSE_NONE;
exception <= '0';
exception_cause <= CSR_CAUSE_NONE;
branch <= BRANCH_JUMP;
when b"11001" => -- Jump and link register
rd_write <= '1';
decode_exception <= '0';
decode_exception_cause <= CSR_CAUSE_NONE;
exception <= '0';
exception_cause <= CSR_CAUSE_NONE;
branch <= BRANCH_JUMP_INDIRECT;
when b"11000" => -- Branch operations
rd_write <= '0';
decode_exception <= '0';
decode_exception_cause <= CSR_CAUSE_NONE;
exception <= '0';
exception_cause <= CSR_CAUSE_NONE;
branch <= BRANCH_CONDITIONAL;
when b"00000" => -- Load instructions
rd_write <= '1';
decode_exception <= '0';
decode_exception_cause <= CSR_CAUSE_NONE;
exception <= '0';
exception_cause <= CSR_CAUSE_NONE;
branch <= BRANCH_NONE;
when b"01000" => -- Store instructions
rd_write <= '0';
decode_exception <= '0';
decode_exception_cause <= CSR_CAUSE_NONE;
exception <= '0';
exception_cause <= CSR_CAUSE_NONE;
branch <= BRANCH_NONE;
when b"00100" => -- Register-immediate operations
rd_write <= '1';
decode_exception <= '0';
decode_exception_cause <= CSR_CAUSE_NONE;
exception <= '0';
exception_cause <= CSR_CAUSE_NONE;
branch <= BRANCH_NONE;
when b"01100" => -- Register-register operations
rd_write <= '1';
decode_exception <= '0';
decode_exception_cause <= CSR_CAUSE_NONE;
exception <= '0';
exception_cause <= CSR_CAUSE_NONE;
branch <= BRANCH_NONE;
when b"00011" => -- Fence instructions, ignored
rd_write <= '0';
decode_exception <= '0';
decode_exception_cause <= CSR_CAUSE_NONE;
exception <= '0';
exception_cause <= CSR_CAUSE_NONE;
branch <= BRANCH_NONE;
when b"11100" => -- System instructions
if funct3 = b"000" then
115,32 → 124,32
rd_write <= '0';
 
if funct12 = x"000" then
decode_exception <= '1';
decode_exception_cause <= CSR_CAUSE_SYSCALL;
exception <= '1';
exception_cause <= CSR_CAUSE_SYSCALL;
branch <= BRANCH_NONE;
elsif funct12 = x"001" then
decode_exception <= '1';
decode_exception_cause <= CSR_CAUSE_BREAKPOINT;
exception <= '1';
exception_cause <= CSR_CAUSE_BREAKPOINT;
branch <= BRANCH_NONE;
elsif funct12 = x"800" then
decode_exception <= '0';
decode_exception_cause <= CSR_CAUSE_NONE;
exception <= '0';
exception_cause <= CSR_CAUSE_NONE;
branch <= BRANCH_SRET;
else
decode_exception <= '1';
decode_exception_cause <= CSR_CAUSE_INVALID_INSTR;
exception <= '1';
exception_cause <= CSR_CAUSE_INVALID_INSTR;
branch <= BRANCH_NONE;
end if;
else
rd_write <= '1';
decode_exception <= '0';
decode_exception_cause <= CSR_CAUSE_NONE;
exception <= '0';
exception_cause <= CSR_CAUSE_NONE;
branch <= BRANCH_NONE;
end if;
when others =>
rd_write <= '0';
decode_exception <= '1';
decode_exception_cause <= CSR_CAUSE_INVALID_INSTR;
exception <= '1';
exception_cause <= CSR_CAUSE_INVALID_INSTR;
branch <= BRANCH_NONE;
end case;
end process decode_ctrl;
/potato/trunk/src/pp_alu_control_unit.vhd
89,7 → 89,7
when b"111" =>
alu_op <= ALU_AND;
when others =>
alu_op <= ALU_NOP;
alu_op <= ALU_INVALID;
end case;
when b"01100" => -- Register-register operations
alu_x_src <= ALU_SRC_REG;
121,8 → 121,12
when b"111" =>
alu_op <= ALU_AND;
when others =>
alu_op <= ALU_NOP;
alu_op <= ALU_INVALID;
end case;
when b"00011" => -- Fence instructions, ignored
alu_x_src <= ALU_SRC_REG;
alu_y_src <= ALU_SRC_REG;
alu_op <= ALU_NOP;
when b"11100" => -- System instructions
alu_x_src <= ALU_SRC_CSR;
alu_y_src <= ALU_SRC_NULL;
130,7 → 134,7
when others =>
alu_x_src <= ALU_SRC_REG;
alu_y_src <= ALU_SRC_REG;
alu_op <= ALU_NOP;
alu_op <= ALU_INVALID;
end case;
end process decode_alu;
 

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