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[/] [fpu100/] [tags/] [arelease/] [post_norm_sqrt.vhd] - Rev 27
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------------------------------------------------------------------------------- -- -- Project: <Floating Point Unit Core> -- -- Description: post-normalization entity for the square-root unit ------------------------------------------------------------------------------- -- -- 100101011010011100100 -- 110000111011100100000 -- 100000111011000101101 -- 100010111100101111001 -- 110000111011101101001 -- 010000001011101001010 -- 110100111001001100001 -- 110111010000001100111 -- 110110111110001011101 -- 101110110010111101000 -- 100000010111000000000 -- -- Author: Jidan Al-eryani -- E-mail: jidan@gmx.net -- -- Copyright (C) 2006 -- -- 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. -- -- THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY -- EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED -- TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS -- FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR -- OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, -- INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES -- (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE -- GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR -- BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF -- LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT -- (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT -- OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE -- POSSIBILITY OF SUCH DAMAGE. -- library ieee ; use ieee.std_logic_1164.all; use ieee.std_logic_unsigned.all; use ieee.std_logic_misc.all; library work; use work.fpupack.all; entity post_norm_sqrt is port( clk_i : in std_logic; opa_i : in std_logic_vector(FP_WIDTH-1 downto 0); fract_26_i : in std_logic_vector(FRAC_WIDTH+2 downto 0); -- hidden(1) & fraction(11) exp_i : in std_logic_vector(EXP_WIDTH-1 downto 0); ine_i : in std_logic; rmode_i : in std_logic_vector(1 downto 0); output_o : out std_logic_vector(FP_WIDTH-1 downto 0); ine_o : out std_logic ); end post_norm_sqrt; architecture rtl of post_norm_sqrt is signal s_expa, s_exp_i : std_logic_vector(EXP_WIDTH-1 downto 0); signal s_fract_26_i : std_logic_vector(FRAC_WIDTH+2 downto 0); signal s_ine_i : std_logic; signal s_rmode_i : std_logic_vector(1 downto 0); signal s_output_o : std_logic_vector(FP_WIDTH-1 downto 0); signal s_sign_i : std_logic; signal s_opa_i : std_logic_vector(FP_WIDTH-1 downto 0); signal s_ine_o : std_logic; signal s_expo : std_logic_vector(EXP_WIDTH-1 downto 0); signal s_fraco1 : std_logic_vector(FRAC_WIDTH+2 downto 0); signal s_guard, s_round, s_sticky, s_roundup : std_logic; signal s_frac_rnd : std_logic_vector(FRAC_WIDTH downto 0); signal s_infa : std_logic; signal s_nan_op, s_nan_a: std_logic; begin -- Input Register process(clk_i) begin if rising_edge(clk_i) then s_opa_i <= opa_i; s_expa <= opa_i(30 downto 23); s_sign_i <= opa_i(31); s_fract_26_i <= fract_26_i; s_ine_i <= ine_i; s_exp_i <= exp_i; s_rmode_i <= rmode_i; end if; end process; -- Output Register process(clk_i) begin if rising_edge(clk_i) then output_o <= s_output_o; ine_o <= s_ine_o; end if; end process; -- *** Stage 1 *** s_expo <= s_exp_i; s_fraco1 <= s_fract_26_i; -- ***Stage 2*** -- Rounding s_guard <= s_fraco1(1); s_round <= s_fraco1(0); s_sticky <= s_ine_i; s_roundup <= s_guard and ((s_round or s_sticky)or s_fraco1(3)) when s_rmode_i="00" else -- round to nearset even ( s_guard or s_round or s_sticky) and (not s_sign_i) when s_rmode_i="10" else -- round up ( s_guard or s_round or s_sticky) and (s_sign_i) when s_rmode_i="11" else -- round down '0'; -- round to zero(truncate = no rounding) process(clk_i) begin if rising_edge(clk_i) then if s_roundup='1' then s_frac_rnd <= s_fraco1(25 downto 2) + '1'; else s_frac_rnd <= s_fraco1(25 downto 2); end if; end if; end process; -- ***Stage 3*** -- Output s_infa <= '1' when s_expa="11111111" else '0'; s_nan_a <= '1' when (s_infa='1' and or_reduce (s_opa_i(22 downto 0))='1') else '0'; s_nan_op <= '1' when s_sign_i='1' and or_reduce(s_opa_i(30 downto 0))='1' else '0'; -- sqrt(-x) = NaN s_ine_o <= '1' when s_ine_i='1' and (s_infa or s_nan_a or s_nan_op)='0' else '0'; process( s_nan_a, s_nan_op, s_infa, s_sign_i, s_expo, s_frac_rnd) begin if (s_nan_a or s_nan_op)='1' then s_output_o <= s_sign_i & QNAN; elsif s_infa ='1' then s_output_o <= s_sign_i & INF; else s_output_o <= s_sign_i & s_expo & s_frac_rnd(22 downto 0); end if; end process; end rtl;
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