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-- Filename: fixed_extensions_pkg_sim.vhd
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-- Purpose : Package adding various extensions to the VHDL-2008 (VHDL'93, 2002
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-- compatibility versions) fixed-point arithmetic package by David
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-- Bishop.
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-- Supported operators:
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-- * ceil : round towards plus infinity.
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-- * fix : round towards zero.
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-- * floor : round towards minus infinity.
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-- * round : round to nearest; ties to greatest absolute value.
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-- * nearest : round to nearest; ties to plus infinity.
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-- * convergent: round to nearest; ties to closest even.
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-- * bitinsert : bit-field insertion to word
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-- * bitextract: bit-field extraction from word
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--
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-- Author : Nikolaos Kavvadias (C) 2011
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-- Date : 25-Jul-2011
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-- Revision: 0.0.0 (01/05/11)
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-- Initial version. Supports ceil, fix, floor, round, nearest,
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-- convergent based on their MATLAB documentation.
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-- 0.0.1 (03/05/11)
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-- Added bitinsert.
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-- 0.0.2 (16/07/11)
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-- Added bitextract (sfixed, ufixed), bitinsert (ufixed). Commented
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-- non-synthesizable part (assertions) of bitinsert.
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-- 0.0.3 (19/07/11)
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-- Fixed ceil bug with rounding integral (zero fractional part)
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-- values.
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-- 0.0.4 (21/07/11)
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-- Fixed more bugs regarding fix, round and convergent.
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-- 0.0.5 (25/07/11)
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-- Design edited for simulation-oriented use.
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--------------------------------------------------------------------------------
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use STD.TEXTIO.all;
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library IEEE;
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use IEEE.STD_LOGIC_1164.all;
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use IEEE.NUMERIC_STD.all;
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--library IEEE_PROPOSED;
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--use IEEE_PROPOSED.fixed_float_types.all;
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--use IEEE_PROPOSED.fixed_pkg.all;
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--use WORK.fixed_float_types.all;
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use WORK.fixed_pkg.all;
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package fixed_extensions_pkg is
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function ceil (arg : UNRESOLVED_sfixed) return UNRESOLVED_sfixed;
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function ceil (arg : UNRESOLVED_ufixed) return UNRESOLVED_ufixed;
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function fix (arg : UNRESOLVED_sfixed) return UNRESOLVED_sfixed;
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function fix (arg : UNRESOLVED_ufixed) return UNRESOLVED_ufixed;
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function floor (arg : UNRESOLVED_sfixed) return UNRESOLVED_sfixed;
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function floor (arg : UNRESOLVED_ufixed) return UNRESOLVED_ufixed;
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function round (arg : UNRESOLVED_sfixed) return UNRESOLVED_sfixed;
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function round (arg : UNRESOLVED_ufixed) return UNRESOLVED_ufixed;
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function nearest (arg : UNRESOLVED_sfixed) return UNRESOLVED_sfixed;
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function nearest (arg : UNRESOLVED_ufixed) return UNRESOLVED_ufixed;
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function convergent (arg : UNRESOLVED_sfixed) return UNRESOLVED_sfixed;
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function convergent (arg : UNRESOLVED_ufixed) return UNRESOLVED_ufixed;
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function bitinsert (a, y0 : UNRESOLVED_sfixed; bhi, blo : std_logic_vector) return UNRESOLVED_sfixed;
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function bitinsert (a, y0 : UNRESOLVED_ufixed; bhi, blo : std_logic_vector) return UNRESOLVED_ufixed;
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function bitextract (a : UNRESOLVED_sfixed; bhi, blo : std_logic_vector) return UNRESOLVED_sfixed;
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function bitextract (a : UNRESOLVED_ufixed; bhi, blo : std_logic_vector) return UNRESOLVED_ufixed;
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end package fixed_extensions_pkg;
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--library IEEE;
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--use IEEE.MATH_REAL.all;
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--use WORK.MATH_REAL.all;
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package body fixed_extensions_pkg is
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-- ceil: round towards plus infinity.
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function ceil (
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arg : UNRESOLVED_sfixed) -- fixed point input
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return UNRESOLVED_sfixed is
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variable result : UNRESOLVED_sfixed (arg'high downto arg'low);
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variable fract_zero : std_logic_vector(-arg'low-1 downto 0) := (others => '0');
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begin
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if (arg'high <= 0) then
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result := (others => '0');
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return result;
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end if;
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if (arg'low > 0) then
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result := arg;
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return result;
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end if;
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if (arg'low < 0) then
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if (to_slv(arg(-1 downto arg'low)) = fract_zero) then
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result := arg;
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else
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result := arg + 1;
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end if;
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result(-1 downto arg'low) := (others => '0');
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end if;
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return result;
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end function ceil;
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-- ceil: round towards plus infinity.
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function ceil (
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arg : UNRESOLVED_ufixed) -- fixed point input
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return UNRESOLVED_ufixed is
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variable result : UNRESOLVED_ufixed (arg'high downto arg'low);
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variable fract_zero : std_logic_vector(-arg'low-1 downto 0) := (others => '0');
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begin
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if (arg'high <= 0) then
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result := (others => '0');
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return result;
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end if;
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if (arg'low > 0) then
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result := arg;
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return result;
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end if;
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if (arg'low < 0) then
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if (to_slv(arg(-1 downto arg'low)) = fract_zero) then
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result := arg;
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else
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result := arg + 1;
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end if;
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result(-1 downto arg'low) := (others => '0');
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end if;
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return result;
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end function ceil;
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-- fix: round towards zero.
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function fix (
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arg : UNRESOLVED_sfixed) -- fixed point input
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return UNRESOLVED_sfixed is
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variable result : UNRESOLVED_sfixed (arg'high downto arg'low);
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variable fract_zero : std_logic_vector(-arg'low-1 downto 0) := (others => '0');
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begin
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if (arg'high <= 0) then
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result := (others => '0');
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return result;
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end if;
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if (arg'low > 0) then
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result := arg;
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return result;
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end if;
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if (arg'low < 0) then
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if (is_negative(arg)) then
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if (to_slv(arg(-1 downto arg'low)) = fract_zero) then
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result := arg;
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else
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result := arg + 1;
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end if;
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else
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result := arg;
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end if;
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result(-1 downto arg'low) := (others => '0');
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end if;
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return result;
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end function fix;
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-- fix: round towards zero.
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function fix (
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arg : UNRESOLVED_ufixed) -- fixed point input
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return UNRESOLVED_ufixed is
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variable result : UNRESOLVED_ufixed (arg'high downto arg'low);
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begin
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if (arg'high <= 0) then
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result := (others => '0');
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return result;
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end if;
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if (arg'low > 0) then
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result := arg;
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return result;
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end if;
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if (arg'low < 0) then
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result := arg;
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result(-1 downto arg'low) := (others => '0');
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end if;
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return result;
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end function fix;
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-- floor: round towards minus infinity.
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function floor (
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arg : UNRESOLVED_sfixed) -- fixed point input
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return UNRESOLVED_sfixed is
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variable result : UNRESOLVED_sfixed (arg'high downto arg'low);
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begin
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if (arg'high <= 0) then
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result := (others => '0');
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return result;
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end if;
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if (arg'low > 0) then
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result := arg;
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return result;
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end if;
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if (arg'low < 0) then
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result := arg;
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result(-1 downto arg'low) := (others => '0');
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end if;
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return result;
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end function floor;
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-- floor: round towards plus infinity.
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function floor (
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arg : UNRESOLVED_ufixed) -- fixed point input
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return UNRESOLVED_ufixed is
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variable result : UNRESOLVED_ufixed (arg'high downto arg'low);
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begin
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if (arg'high <= 0) then
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result := (others => '0');
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return result;
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end if;
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if (arg'low > 0) then
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result := arg;
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return result;
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end if;
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if (arg'low < 0) then
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result := arg;
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result(-1 downto arg'low) := (others => '0');
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end if;
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return result;
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end function floor;
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-- round: round to nearest; ties to greatest absolute value.
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function round (
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arg : UNRESOLVED_sfixed) -- fixed point input
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return UNRESOLVED_sfixed is
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variable result : UNRESOLVED_sfixed (arg'high downto arg'low);
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variable onehalf_vec : std_logic_vector(-arg'low-1 downto 0) := (others => '0');
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begin
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224 |
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if (arg'high <= 0) then
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result := (others => '0');
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return result;
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end if;
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if (arg'low > 0) then
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result := arg;
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return result;
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end if;
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if (arg'low < 0) then
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onehalf_vec(-arg'low-1) := '1';
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if (is_negative(arg)) then
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if (to_slv(arg(-1 downto arg'low)) > onehalf_vec) then
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result := arg + 1;
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else
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result := arg;
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end if;
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else
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241 |
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if (to_slv(arg(-1 downto arg'low)) >= onehalf_vec) then
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result := arg + 1;
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else
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result := arg;
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end if;
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end if;
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result(-1 downto arg'low) := (others => '0');
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end if;
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return result;
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end function round;
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251 |
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252 |
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-- round: round to nearest; ties to greatest absolute value.
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253 |
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function round (
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254 |
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arg : UNRESOLVED_ufixed) -- fixed point input
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255 |
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return UNRESOLVED_ufixed is
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256 |
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variable result : UNRESOLVED_ufixed (arg'high downto arg'low);
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257 |
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variable onehalf_vec : std_logic_vector(-arg'low-1 downto 0) := (others => '0');
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begin
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259 |
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if (arg'high <= 0) then
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result := (others => '0');
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return result;
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end if;
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if (arg'low > 0) then
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result := arg;
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return result;
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266 |
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end if;
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267 |
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if (arg'low < 0) then
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onehalf_vec(-arg'low-1) := '1';
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269 |
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if (to_slv(arg(-1 downto arg'low)) >= onehalf_vec) then
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result := arg + 1;
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else
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result := arg;
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273 |
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end if;
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result(-1 downto arg'low) := (others => '0');
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275 |
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end if;
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return result;
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end function round;
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278 |
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279 |
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-- nearest: round to nearest; ties to plus infinity.
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280 |
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function nearest (
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281 |
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arg : UNRESOLVED_sfixed) -- fixed point input
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282 |
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return UNRESOLVED_sfixed is
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283 |
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variable result : UNRESOLVED_sfixed (arg'high downto arg'low);
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284 |
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begin
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285 |
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if (arg'high <= 0) then
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result := (others => '0');
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287 |
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return result;
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288 |
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end if;
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289 |
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if (arg'low > 0) then
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290 |
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result := arg;
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291 |
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return result;
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292 |
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end if;
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293 |
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if (arg'low < 0) then
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294 |
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if (arg(-1) = '1') then
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295 |
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result := arg + 1;
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296 |
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else
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297 |
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result := arg;
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298 |
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end if;
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299 |
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result(-1 downto arg'low) := (others => '0');
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300 |
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else
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301 |
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result := arg;
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302 |
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result(-1 downto arg'low) := (others => '0');
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303 |
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end if;
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304 |
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return result;
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305 |
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end function nearest;
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306 |
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|
307 |
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-- nearest: round to nearest; ties to plus infinity.
|
308 |
|
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function nearest (
|
309 |
|
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arg : UNRESOLVED_ufixed) -- fixed point input
|
310 |
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return UNRESOLVED_ufixed is
|
311 |
|
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variable result : UNRESOLVED_ufixed (arg'high downto arg'low);
|
312 |
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begin
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313 |
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if (arg'high <= 0) then
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314 |
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result := (others => '0');
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315 |
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return result;
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316 |
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end if;
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317 |
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if (arg'low > 0) then
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318 |
|
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result := arg;
|
319 |
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return result;
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320 |
|
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end if;
|
321 |
|
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if (arg'low < 0) then
|
322 |
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if (arg(-1) = '1') then
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323 |
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result := arg + 1;
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324 |
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else
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325 |
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result := arg;
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326 |
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end if;
|
327 |
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result(-1 downto arg'low) := (others => '0');
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328 |
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else
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329 |
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result := arg;
|
330 |
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result(-1 downto arg'low) := (others => '0');
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331 |
|
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end if;
|
332 |
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return result;
|
333 |
|
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end function nearest;
|
334 |
|
|
|
335 |
|
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-- convergent: round to nearest; ties to closest even.
|
336 |
|
|
function convergent (
|
337 |
|
|
arg : UNRESOLVED_sfixed) -- fixed point input
|
338 |
|
|
return UNRESOLVED_sfixed is
|
339 |
|
|
variable result : UNRESOLVED_sfixed (arg'high downto arg'low);
|
340 |
|
|
variable onehalf_vec : std_logic_vector(-arg'low-1 downto 0) := (others => '0');
|
341 |
|
|
begin
|
342 |
|
|
if (arg'high <= 0) then
|
343 |
|
|
result := (others => '0');
|
344 |
|
|
return result;
|
345 |
|
|
end if;
|
346 |
|
|
if (arg'low > 0) then
|
347 |
|
|
result := arg;
|
348 |
|
|
return result;
|
349 |
|
|
end if;
|
350 |
|
|
if (arg'low < 0) then
|
351 |
|
|
onehalf_vec(-arg'low-1) := '1';
|
352 |
|
|
if (arg(0) = '1') then
|
353 |
|
|
if (to_slv(arg(-1 downto arg'low)) >= onehalf_vec) then
|
354 |
|
|
result := arg + 1;
|
355 |
|
|
else
|
356 |
|
|
result := arg;
|
357 |
|
|
end if;
|
358 |
|
|
else
|
359 |
|
|
if (to_slv(arg(-1 downto arg'low)) > onehalf_vec) then
|
360 |
|
|
result := arg + 1;
|
361 |
|
|
else
|
362 |
|
|
result := arg;
|
363 |
|
|
end if;
|
364 |
|
|
end if;
|
365 |
|
|
result(-1 downto arg'low) := (others => '0');
|
366 |
|
|
end if;
|
367 |
|
|
return result;
|
368 |
|
|
end function convergent;
|
369 |
|
|
|
370 |
|
|
-- convergent: round to nearest; ties to closest even.
|
371 |
|
|
function convergent (
|
372 |
|
|
arg : UNRESOLVED_ufixed) -- fixed point input
|
373 |
|
|
return UNRESOLVED_ufixed is
|
374 |
|
|
variable result : UNRESOLVED_ufixed (arg'high downto arg'low);
|
375 |
|
|
variable onehalf_vec : std_logic_vector(-arg'low-1 downto 0) := (others => '0');
|
376 |
|
|
begin
|
377 |
|
|
if (arg'high <= 0) then
|
378 |
|
|
result := (others => '0');
|
379 |
|
|
return result;
|
380 |
|
|
end if;
|
381 |
|
|
if (arg'low > 0) then
|
382 |
|
|
result := arg;
|
383 |
|
|
return result;
|
384 |
|
|
end if;
|
385 |
|
|
if (arg'low < 0) then
|
386 |
|
|
onehalf_vec(-arg'low-1) := '1';
|
387 |
|
|
if (arg(0) = '1') then
|
388 |
|
|
if (to_slv(arg(-1 downto arg'low)) >= onehalf_vec) then
|
389 |
|
|
result := arg + 1;
|
390 |
|
|
else
|
391 |
|
|
result := arg;
|
392 |
|
|
end if;
|
393 |
|
|
else
|
394 |
|
|
if (to_slv(arg(-1 downto arg'low)) > onehalf_vec) then
|
395 |
|
|
result := arg + 1;
|
396 |
|
|
else
|
397 |
|
|
result := arg;
|
398 |
|
|
end if;
|
399 |
|
|
end if;
|
400 |
|
|
result(-1 downto arg'low) := (others => '0');
|
401 |
|
|
end if;
|
402 |
|
|
return result;
|
403 |
|
|
end function convergent;
|
404 |
|
|
|
405 |
|
|
function bitinsert (a, y0 : UNRESOLVED_sfixed; bhi, blo : std_logic_vector) return UNRESOLVED_sfixed is
|
406 |
|
|
variable y : UNRESOLVED_sfixed(a'RANGE);
|
407 |
|
|
begin
|
408 |
|
|
-- if (bhi < blo) then
|
409 |
|
|
-- assert false
|
410 |
|
|
-- report "Error: Invalid range for bitfield insert."
|
411 |
|
|
-- severity failure;
|
412 |
|
|
-- end if;
|
413 |
|
|
-- if (to_integer(signed(bhi)) > y'HIGH) then
|
414 |
|
|
-- assert false
|
415 |
|
|
-- report "Error: High bound (bhi) is out of result range."
|
416 |
|
|
-- severity failure;
|
417 |
|
|
-- end if;
|
418 |
|
|
-- if (to_integer(signed(blo)) < y'LOW) then
|
419 |
|
|
-- assert false
|
420 |
|
|
-- report "Error: Low bound (blo) is out of result range."
|
421 |
|
|
-- severity failure;
|
422 |
|
|
-- end if;
|
423 |
|
|
y := y0;
|
424 |
|
|
y(to_integer(signed(bhi)) downto to_integer(signed(blo))) :=
|
425 |
|
|
a(to_integer(signed(bhi))-to_integer(signed(blo)) downto a'LOW);
|
426 |
|
|
return (y);
|
427 |
|
|
end bitinsert;
|
428 |
|
|
|
429 |
|
|
function bitinsert (a, y0 : UNRESOLVED_ufixed; bhi, blo : std_logic_vector) return UNRESOLVED_ufixed is
|
430 |
|
|
variable y : UNRESOLVED_ufixed(a'RANGE);
|
431 |
|
|
begin
|
432 |
|
|
y := y0;
|
433 |
|
|
y(to_integer(signed(bhi)) downto to_integer(signed(blo))) :=
|
434 |
|
|
a(to_integer(signed(bhi))-to_integer(signed(blo)) downto a'LOW);
|
435 |
|
|
return (y);
|
436 |
|
|
end bitinsert;
|
437 |
|
|
|
438 |
|
|
function bitextract (a : UNRESOLVED_sfixed; bhi, blo : std_logic_vector) return UNRESOLVED_sfixed is
|
439 |
|
|
variable y : sfixed(a'HIGH downto a'LOW);
|
440 |
|
|
begin
|
441 |
|
|
y := a;
|
442 |
|
|
y(to_integer(signed(bhi))-to_integer(signed(blo)) downto a'LOW) :=
|
443 |
|
|
a(to_integer(signed(bhi)) downto to_integer(signed(blo)));
|
444 |
|
|
return (y);
|
445 |
|
|
end bitextract;
|
446 |
|
|
|
447 |
|
|
function bitextract (a : UNRESOLVED_ufixed; bhi, blo : std_logic_vector) return UNRESOLVED_ufixed is
|
448 |
|
|
variable y : ufixed(a'HIGH downto a'LOW);
|
449 |
|
|
begin
|
450 |
|
|
y := a;
|
451 |
|
|
y(to_integer(signed(bhi))-to_integer(signed(blo)) downto a'LOW) :=
|
452 |
|
|
a(to_integer(signed(bhi)) downto to_integer(signed(blo)));
|
453 |
|
|
return (y);
|
454 |
|
|
end bitextract;
|
455 |
|
|
|
456 |
|
|
end package body fixed_extensions_pkg;
|