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vhdl-sincos-gen
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This commit is contained in:
Joris van Rantwijk 2016-04-14 00:42:58 +02:00
parent 2dbc6d44db
commit a3d8939440
1 changed files with 6 additions and 1 deletions
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rtl/sincos_gen.vhdl
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@ -78,15 +78,20 @@ architecture rtl of sincos_gen is
variable sin_int: integer; variable sin_int: integer;
begin begin
for i in 0 to table_size-1 loop for i in 0 to table_size-1 loop
-- Calculate ideal value for mid-point of the i-th section of
-- the first quadrant of the sine function.
sin_flt := sin(real(2*i + 1) / real(2 * table_size) * MATH_PI / 2.0); sin_flt := sin(real(2*i + 1) / real(2 * table_size) * MATH_PI / 2.0);
-- Multiply by nominal amplitude and round to nearest integer.
-- Note: The table contains UNSIGNED integers of table_width bits.
sin_int := integer(sin_flt * real(2**table_width - 2)); sin_int := integer(sin_flt * real(2**table_width - 2));
-- Store in table.
tbl(i) := std_logic_vector(to_unsigned(sin_int, table_width)); tbl(i) := std_logic_vector(to_unsigned(sin_int, table_width));
end loop; end loop;
return tbl; return tbl;
end function; end function;
-- Lookup table for the first quarter-period of the sine. -- Lookup table for the first quarter-period of the sine.
-- lookup_table(i) = sin( (i + 0.5) / table_size * pi / 2 ) -- lookup_table[i] == sin( (i + 0.5) / table_size * pi / 2 )
constant lookup_table: table_type := gen_table; constant lookup_table: table_type := gen_table;
-- Internal registers. -- Internal registers.