Subversion Repositories g729a_codec

-----------------------------------------------------------------

--                                                             --

-----------------------------------------------------------------

--                                                             --

-- Copyright (C) 2013 Stefano Tonello                          --

--                                                             --

-- This source file may be used and distributed without        --

-- restriction provided that this copyright statement is not   --

-- removed from the file and that any derivative work contains --

-- the original copyright notice and the associated disclaimer.--

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-- THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY         --

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-----------------------------------------------------------------

---------------------------------------------------------

-- Pipe-B adder/subtractor

---------------------------------------------------------

library IEEE;

use IEEE.std_logic_1164.all;

use IEEE.numeric_std.all;

library WORK;

use WORK.G729A_ASIP_PKG.all;

use WORK.G729A_ASIP_BASIC_PKG.all;

use WORK.G729A_ASIP_ARITH_PKG.all;

entity G729A_ASIP_ADDSUB_PIPEB is

  port(

    OPA_i : in LDWORD_T;

    OPB_i : in LDWORD_T;

    CTRL_i : in ADD_CTRL;

    RES_o : out LDWORD_T;

    OVF_o : out std_logic

  );

end G729A_ASIP_ADDSUB_PIPEB;

architecture ARC of G729A_ASIP_ADDSUB_PIPEB is

  constant ZERO : LDWORD_T := to_signed(0,LDLEN);

  constant ONE : LDWORD_T := to_signed(1,LDLEN);

  component G729A_ASIP_ADDER_F is

    generic(

      LEN1 : integer := 16;

      LEN2 : integer := 16

    );

    port(

      OPA_i : in signed(LEN1+LEN2-1 downto 0);

      OPB_i : in signed(LEN1+LEN2-1 downto 0);

      CI_i : in std_logic;

      SUM_o : out signed(LEN1+LEN2-1 downto 0)

    );

  end component;

  function EXTS(S : signed; L : natural) return signed is

    variable XS : signed(L-1 downto 0);

  begin

    XS(S'HIGH downto 0) := S;

    XS(L-1 downto S'HIGH+1) := (others => S(S'HIGH));

    return(XS);

  end function;

  signal IOPA,IOPB,CI,SUM : LDWORD_T;

begin

  -- adder operands selection

  process(CTRL_i,OPB_i,OPA_i)

  begin

    case CTRL_i is

      when AC_ABS|AC_NEG =>

        -- tmp = -opa_i

        IOPA <= not(EXTS(OPA_i(SDLEN-1 downto 0),LDLEN));

        IOPB <= ZERO;

        CI <= ONE;

      when AC_LABS|AC_LNEG =>

        -- tmp = -opa_i

        IOPA <= not(OPA_i);

        IOPB <= ZERO;

        CI <= ONE;

      --when AC_ADD =>

      --  -- tmp = opa_i + opb_i

      --  IOPA <= EXTS(OPA_i(SDLEN-1 downto 0),LDLEN);

      --  IOPB <= EXTS(OPB_i(SDLEN-1 downto 0),LDLEN);

      --  CI <= ZERO;

      when AC_LADD =>

        -- tmp = opa_i + opb_i

        IOPA <= OPA_i;

        IOPB <= OPB_i;

        CI <= ZERO;

      --when AC_SUB =>

      --  -- tmp = opa_i - opb_i

      --  IOPA <= EXTS(OPA_i(SDLEN-1 downto 0),LDLEN);

      --  IOPB <= not(EXTS(OPB_i(SDLEN-1 downto 0),LDLEN));

      --  CI <= ONE;

      when AC_LSUB =>

        -- tmp = opa_i - opb_i

        IOPA <= OPA_i;

        IOPB <= not(OPB_i);

        CI <= ONE;

      when AC_LEXT =>

        -- tmp = opa_i - (opa_i(31:16)<<16)

        IOPA <= OPA_i;

        IOPB <= not(OPA_i(LDLEN-1 downto SDLEN) & to_signed(0,SDLEN));

        CI <= ONE;

      when others => -- RND

        -- tmp = opa_i + 0x00008000 

        IOPA <= OPA_i;

        IOPB <= (SDLEN-1 => '1',others => '0');

        CI <= ZERO;

      --when AC_INC =>

      --  -- tmp = opa_i + 1 

      --  IOPA <= EXTS(OPA_i(SDLEN-1 downto 0),LDLEN);

      --  IOPB <= (0 => '1',others => '0');

      --  CI <= ZERO;

      --when others => -- DEC

      --  -- tmp = opa_i - 1 

      --  IOPA <= EXTS(OPA_i(SDLEN-1 downto 0),LDLEN);

      --  IOPB <= (others => '1');

      --  CI <= ZERO;

    end case;

  end process;

  -- adder

  U_ADDF : G729A_ASIP_ADDER_F

    generic map(

      LEN1 => SDLEN,

      LEN2 => SDLEN

    )

    port map(

      OPA_i => IOPA,

      OPB_i => IOPB,

      CI_i => CI(0),

      SUM_o => SUM

    );

  -- result and overflow flag generation

  process(CTRL_i,OPA_i,OPB_i,SUM)

    variable SA,LSA,LSB,IOVF : std_logic;

    variable IRES,TMP : LDWORD_T;

  begin

    SA := OPA_i(SDLEN-1);

    LSA := OPA_i(LDLEN-1);

    LSB := OPB_i(LDLEN-1);

    case CTRL_i is

      when AC_ABS =>

        -- IRES upper half is set to all-0

        IRES(LDLEN-1 downto SDLEN) := (others => '0');

        -- overflow flag is unchanged

        IOVF := '0';

        -- check if input is min. signed integer

        if(OPA_i(SDLEN-1 downto 0) = MIN_16) then

          IRES(SDLEN-1 downto 0) := MAX_16;

        elsif(SA = '1') then

          IRES(SDLEN-1 downto 0) := SUM(SDLEN-1 downto 0);

        else

          IRES(SDLEN-1 downto 0) := OPA_i(SDLEN-1 downto 0);

        end if;

      --when AC_ADD =>

      --  -- IRES upper half is set to all-0

      --  IRES(LDLEN-1 downto SDLEN) := (others => '0');

      --  sature(SUM,IRES(SDLEN-1 downto 0),IOVF);

      when AC_NEG =>

        -- IRES upper half is set to all-0

        IRES(LDLEN-1 downto SDLEN) := (others => '0');

        if(OPA_i(SDLEN-1 downto 0) = MIN_16) then

          IRES(SDLEN-1 downto 0) := MAX_16;

        else

          IRES(SDLEN-1 downto 0) := SUM(SDLEN-1 downto 0);

        end if;

        IOVF := '0';

      --when AC_SUB =>

      --  -- IRES upper half is set to all-0

      --  IRES(LDLEN-1 downto SDLEN) := (others => '0');

      --  sature(SUM,IRES(SDLEN-1 downto 0),IOVF);

      when AC_LABS =>

        if(OPB_i = MIN_32) then

          IRES := MAX_32;

        elsif(LSA = '1') then

          IRES := SUM;

        else

          IRES := OPA_i;

        end if;

        IOVF := '0';

      when AC_LADD =>

        L_add_sub(SUM,'1',LSA,LSB,IRES,IOVF);

      when AC_LSUB =>

        L_add_sub(SUM,'0',LSA,LSB,IRES,IOVF);

      when AC_LNEG =>

        if(OPA_i = MIN_32) then

          IRES := MAX_32;

        else

          IRES := SUM;

        end if;

        IOVF := '0';

      when AC_LEXT =>

        IRES(LDLEN-1 downto SDLEN) := OPA_i(LDLEN-1 downto SDLEN);

        IRES(SDLEN-1 downto 0) := SUM(SDLEN downto 1);

        IOVF := '0';

      when others => -- AC_RND

        L_add_sub(SUM,'1',LSA,'0',TMP,IOVF);

        IRES(LDLEN-1 downto SDLEN) := (others => '0'); --TMP(LDLEN-1));

        IRES(SDLEN-1 downto 0) := TMP(LDLEN-1 downto SDLEN);

      --when others => -- AC_NIL

      --  IRES := SUM;

      --  IOVF := '0';

    end case;

    RES_o <= IRES;

    OVF_o <= IOVF;

  end process;

end ARC;