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Platform-independent core collection
Commit ddf1319c authored by Tristan Gingold's avatar Tristan Gingold
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gencores_pkg: add f_log2 and f_max

parent 4273aed0
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modules/common/gencores_pkg.vhd
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......@@ -45,6 +45,11 @@ package gencores_pkg is
function f_gray_encode(x : std_logic_vector) return std_logic_vector;
function f_gray_decode(x : std_logic_vector; step : natural) return std_logic_vector;
-- Returns the log2 of N such that 2**f_log2(N) >= N.
-- The result is the minimum value. Can return 0.
function f_log2(N : positive) return natural;
-- Slightly incorrect version of log2: the result is at least 1.
function f_log2_ceil(N : natural) return positive;
-- kept for backwards compatibility, same as f_log2_ceil()
function log2_ceil(N : natural) return positive;
......@@ -72,6 +77,9 @@ package gencores_pkg is
function f_pick (cond : std_logic; if_1 : std_logic_vector; if_0 : std_logic_vector)
return std_logic_vector;
-- Return the maximum of L and R.
function f_max (l, r : natural) return natural;
-- Functions to convert characters and strings to upper/lower case
function to_upper(c : character) return character;
function to_lower(c : character) return character;
......@@ -885,6 +893,16 @@ package body gencores_pkg is
end if;
end f_gray_decode;
function f_log2(N : positive) return natural is
begin
for i in 0 to 30 loop
if N <= 2**i then
return i;
end if;
end loop;
report "N is too large" severity error;
end f_log2;
------------------------------------------------------------------------------
-- Returns log of 2 of a natural number
------------------------------------------------------------------------------
......@@ -1020,6 +1038,15 @@ package body gencores_pkg is
return f_pick (f_to_std_logic(cond), if_1, if_0);
end function f_pick;
function f_max (l, r : natural) return natural is
begin
if l >= r then
return l;
else
return r;
end if;
end f_max;
------------------------------------------------------------------------------
-- Functions to convert characters and strings to upper/lower case
------------------------------------------------------------------------------
......
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