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- added helper functions for DCM frequency synthesis

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git-svn-id: http://moon:8086/svn/vhdl/trunk@576 cc03376c-175c-47c8-b038-4cd826a8556b
This commit is contained in:
jens
2009-11-03 20:38:30 +00:00
parent 6f27bf0c89
commit ee04924d42
1 changed files with 43 additions and 1 deletions
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lib/misc/utils_pkg.vhd
+43 -1
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@@ -1,5 +1,5 @@
-----------------------------------------------------------------------
-- $Header: /tmp/cvsroot/VHDL/lib/misc/utils_pkg.vhd,v 1.2 2009-01-02 15:28:01 Jens Exp $
-- $Header: /tmp/cvsroot/VHDL/lib/misc/utils_pkg.vhd,v 1.3 2009-11-03 20:38:30 Jens Exp $
-----------------------------------------------------------------------
library IEEE;
@@ -18,6 +18,9 @@ package utils_pkg is
function NextExpBaseTwo(x : natural) return natural;
function GCD(a, b : natural) return natural;
function LCM(a, b : natural) return natural;
function UTILS_PERIOD_NS(f_in_hz : natural) return real;
function UTILS_FREQ_M(f_in_hz, f_out_hz : natural) return natural;
function UTILS_FREQ_D(f_in_hz, f_out_hz : natural) return natural;
end utils_pkg;
@@ -71,6 +74,45 @@ package body utils_pkg is
end LCM;
function UTILS_PERIOD_NS(f_in_hz : natural) return real is
begin
return 1.0E9/real(f_in_hz);
end UTILS_PERIOD_NS;
function UTILS_FREQ_M(f_in_hz, f_out_hz : natural) return natural is
variable f_in_mhz : natural;
variable f_out_mhz : natural;
variable m : natural;
begin
f_in_mhz := f_in_hz/1E6;
f_out_mhz := f_out_hz/1E6;
m := f_out_mhz/GCD(f_in_mhz, f_out_mhz);
if m = 1 then
m := 2;
end if;
return m;
end UTILS_FREQ_M;
function UTILS_FREQ_D(f_in_hz, f_out_hz : natural) return natural is
variable f_in_mhz : natural;
variable f_out_mhz : natural;
variable m : natural;
variable d : natural;
begin
m := UTILS_FREQ_M(f_in_hz, f_out_hz);
f_in_mhz := f_in_hz/1E6;
f_out_mhz := f_out_hz/1E6;
d := m*f_in_mhz/f_out_mhz;
return d;
end UTILS_FREQ_D;
end utils_pkg;