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package mips_pkg is
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package mips_pkg is
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---- Basic types ---------------------------------------------------------------
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---- Basic types ---------------------------------------------------------------
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subtype t_word is std_logic_vector(31 downto 0);
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subtype t_word is std_logic_vector(31 downto 0);
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subtype t_halfword is std_logic_vector(15 downto 0);
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subtype t_byte is std_logic_vector(7 downto 0);
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---- System configuration constants --------------------------------------------
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---- System configuration constants --------------------------------------------
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-- True to use standard-ish MIPS-1 memory map, false to use Plasma's
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-- True to use standard-ish MIPS-1 memory map, false to use Plasma's
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-- (see implementation of function decode_addr below).
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-- (see implementation of function decode_addr below).
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constant RESET_VECTOR_M4 : t_word := X"bfbffffc";
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constant RESET_VECTOR_M4 : t_word := X"bfbffffc";
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-- Trap vector address (0x0000003c for Plasma, 0xbfc00180 for mips1)
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-- Trap vector address (0x0000003c for Plasma, 0xbfc00180 for mips1)
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constant TRAP_VECTOR : t_word := X"bfc00180";
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constant TRAP_VECTOR : t_word := X"bfc00180";
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-- Object code in bytes, i.e. as read from a binary or HEX file.
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-- This type is used to define BRAM init constants from external scripts.
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type t_obj_code is array(integer range <>) of std_logic_vector(7 downto 0);
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-- Types used to define memories for synthesis or simulation.
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type t_word_table is array(integer range <>) of t_word;
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type t_hword_table is array(integer range <>) of t_halfword;
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type t_byte_table is array(integer range <>) of t_byte;
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---- Object code management -- initialization helper functions -----------------
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-- Dummy t_obj_code constant, to be used essentially as a syntactic placeholder.
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constant default_object_code : t_obj_code(0 to 3) := (
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X"00", X"00", X"00", X"00"
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);
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-- Builds BRAM initialization constant from a constant CONSTRAINED byte array
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-- containing the application object code.
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-- The constant is a 32-bit, big endian word table.
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-- The object code is placed at the beginning of the BRAM and the rest is
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-- filled with zeros.
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-- The object code is truncated if it doesn't fit the given table size.
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-- CAN BE USED IN SYNTHESIZABLE CODE to compute a BRAM initialization constant
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-- from a constant argument.
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function objcode_to_wtable(oC : t_obj_code; size : integer) return t_word_table;
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-- Builds BRAM initialization constant from a constant CONSTRAINED byte array
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-- containing the application object code.
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-- The constant is a 32-bit, big endian word table.
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-- The object code is placed at the beginning of the BRAM and the rest is
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-- filled with zeros.
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-- The object code is truncated if it doesn't fit the given table size.
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-- CAN BE USED IN SYNTHESIZABLE CODE to compute a BRAM initialization constant
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-- from a constant argument.
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function objcode_to_htable(oC : t_obj_code; size : integer) return t_hword_table;
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-- Builds BRAM initialization constant from a constant CONSTRAINED byte array
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-- containing the application object code.
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-- The constant is an 8-bit byte table.
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-- The object code is placed at the beginning of the BRAM and the rest is
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-- filled with zeros.
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-- The object code is truncated if it doesn't fit the given table size.
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-- CAN BE USED IN SYNTHESIZABLE CODE to compute a BRAM initialization constant
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-- from a constant argument.
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function objcode_to_btable(oC : t_obj_code; size : integer) return t_byte_table;
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---- Address decoding ----------------------------------------------------------
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---- Address decoding ----------------------------------------------------------
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-- Note: it is the cache module that does all internal address decoding --------
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-- Note: it is the cache module that does all internal address decoding --------
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return decode_addr_plasma(addr);
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return decode_addr_plasma(addr);
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end if;
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end if;
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end function decode_addr;
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end function decode_addr;
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function objcode_to_wtable(oC : t_obj_code;
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size : integer)
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return t_word_table is
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variable br : t_word_table(integer range 0 to size-1):=(others => X"00000000");
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variable i, address, index : integer;
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begin
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-- Copy object code to start of BRAM...
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i := 0;
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for i in 0 to oC'length-1 loop
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case i mod 4 is
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when 0 => index := 24;
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when 1 => index := 16;
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when 2 => index := 8;
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when others => index := 0;
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end case;
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address := i / 4;
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if address >= size then
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exit;
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end if;
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br(address)(index+7 downto index) := oC(i);
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end loop;
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return br;
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end function objcode_to_wtable;
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function objcode_to_htable(oC : t_obj_code;
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size : integer)
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return t_hword_table is
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variable br : t_hword_table(integer range 0 to size-1):=(others => X"0000");
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variable i, address, index : integer;
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begin
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-- Copy object code to start of BRAM...
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i := 0;
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for i in 0 to oC'length-1 loop
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case i mod 2 is
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when 1 => index := 8;
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when others => index := 0;
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end case;
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address := i / 2;
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if address >= size then
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exit;
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end if;
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br(address)(index+7 downto index) := oC(i);
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end loop;
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return br;
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end function objcode_to_htable;
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function objcode_to_btable(oC : t_obj_code;
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size : integer)
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return t_byte_table is
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variable br : t_byte_table(integer range 0 to size-1):=(others => X"00");
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variable i, address, index : integer;
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begin
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-- Copy object code to start of table, leave the rest of the table
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for i in 0 to oC'length-1 loop
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if i >= size then
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exit;
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end if;
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br(i) := oC(i);
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end loop;
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return br;
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end function objcode_to_btable;
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end package body;
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end package body;
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