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[QUOTE="Paul, post: 4098766"]
Hi,

in the example attached I did try to set some filter coeffs constants
for a fir filter (direct form I second order structure). Modelsim
complains on

Type mark "coeefficient_type" cannot be actual parameter.
Illegal name (subtype declaration "coeefficient_type") in expression.

Is there a limitation or simple a syntax error. Is there a way to do
this - how to get it?

Thanks,
Olaf

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

library floatfixlib;
use floatfixlib.math_utility_pkg.all; -- ieee_proposed for VHDL-93 version
use floatfixlib.fixed_pkg.all; -- ieee_proposed for compatibility version

entity df1tsos is

port (
    clk       : in  std_ulogic;
    clk_en    : in  std_ulogic;
    reset     : in  std_ulogic;
    input     : in  sfixed(16 downto -14);  -- [-2 2)
    output    : out sfixed(16 downto -14)   -- [-2 2)
  );

end entity df1tsos;

architecture rtl of df1tsos is

subtype numerator_type is sfixed(16 downto -14);  -- [-2 2)
  subtype denominator_type is sfixed(16 downto -14);  -- [-2 2)
  subtype numerator_state_type is sfixed(16 downto -12); -- [-8 8)
  subtype denominator_state_type is sfixed(16 downto -12); -- [-8 8)
  subtype coeefficient_type is sfixed(16 downto -14); -- [-2 2)

signal numerator_s            : numerator_type;
  signal denominator_s          : denominator_type;

constant b0_coeff             : coeefficient_type := to_sfixed(
0.000000000000000, coeefficient_type);
  constant b1_coeff             : coeefficient_type := to_sfixed(
1.000000000000000, coeefficient_type);
  constant b2_coeff             : coeefficient_type := to_sfixed(
0.843811035156250, coeefficient_type);
  constant a0_coeff             : coeefficient_type := to_sfixed(
1.000000000000000, coeefficient_type);
  constant a1_coeff             : coeefficient_type :=
to_sfixed(-1.538757324218750, coeefficient_type);
  constant a2_coeff             : coeefficient_type := to_sfixed(
0.601013183593750, coeefficient_type);

begin

end architecture rtl;
[/QUOTE]

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