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-- $Id: nxcramlib.vhd 641 2015-02-01 22:12:15Z mueller $
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-- $Id: nxcramlib.vhd 788 2016-07-16 22:23:23Z mueller $
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--
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--
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-- Copyright 2011- by Walter F.J. Mueller <W.F.J.Mueller@gsi.de>
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-- Copyright 2011-2016 by Walter F.J. Mueller <W.F.J.Mueller@gsi.de>
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--
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--
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-- This program is free software; you may redistribute and/or modify it under
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-- This program is free software; you may redistribute and/or modify it under
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-- the terms of the GNU General Public License as published by the Free
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-- the terms of the GNU General Public License as published by the Free
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-- Software Foundation, either version 2, or at your option any later version.
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-- Software Foundation, either version 2, or at your option any later version.
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--
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--
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------------------------------------------------------------------------------
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------------------------------------------------------------------------------
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-- Package Name: nxcramlib
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-- Package Name: nxcramlib
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-- Description: Nexys 2/3 CRAM drivers
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-- Description: Nexys 2/3 CRAM drivers
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--
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--
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-- Dependencies: -
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-- Dependencies: -
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-- Tool versions: ise 11.4-14.7; viv 2014.4; ghdl 0.26-0.31
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-- Tool versions: ise 11.4-14.7; viv 2014.4-2016.2; ghdl 0.26-0.33
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--
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--
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-- Revision History:
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-- Revision History:
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-- Date Rev Version Comment
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-- Date Rev Version Comment
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-- 2016-07-16 788 1.1 add cram_(read0|read1|write)delay functions
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-- 2011-11-26 433 1.0 Initial version (extracted from nexys2lib)
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-- 2011-11-26 433 1.0 Initial version (extracted from nexys2lib)
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------------------------------------------------------------------------------
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------------------------------------------------------------------------------
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library ieee;
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library ieee;
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use ieee.std_logic_1164.all;
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use ieee.std_logic_1164.all;
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use work.slvtypes.all;
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use work.slvtypes.all;
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package nxcramlib is
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package nxcramlib is
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pure function cram_delay(clk_mhz : positive;
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delay_ps : positive) return positive;
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pure function cram_read0delay(clk_mhz : positive) return positive;
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pure function cram_read1delay(clk_mhz : positive) return positive;
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pure function cram_writedelay(clk_mhz : positive) return positive;
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constant cram_read0delay_ps : positive := 80000; -- initial read delay
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constant cram_read1delay_ps : positive := 30000; -- page read delay
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constant cram_writedelay_ps : positive := 75000; -- write delay
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component nx_cram_dummy is -- CRAM protection dummy
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component nx_cram_dummy is -- CRAM protection dummy
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port (
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port (
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O_MEM_CE_N : out slbit; -- cram: chip enable (act.low)
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O_MEM_CE_N : out slbit; -- cram: chip enable (act.low)
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O_MEM_BE_N : out slv2; -- cram: byte enables (act.low)
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O_MEM_BE_N : out slv2; -- cram: byte enables (act.low)
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O_MEM_WE_N : out slbit; -- cram: write enable (act.low)
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O_MEM_WE_N : out slbit; -- cram: write enable (act.low)
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);
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);
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end component;
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end component;
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component nx_cram_memctl_as is -- CRAM driver (async+page mode)
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component nx_cram_memctl_as is -- CRAM driver (async+page mode)
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generic (
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generic (
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READ0DELAY : positive := 2; -- read word 0 delay in clock cycles
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READ0DELAY : positive := 4; -- read word 0 delay in clock cycles
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READ1DELAY : positive := 2; -- read word 1 delay in clock cycles
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READ1DELAY : positive := 2; -- read word 1 delay in clock cycles
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WRITEDELAY : positive := 3); -- write delay in clock cycles
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WRITEDELAY : positive := 4); -- write delay in clock cycles
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port (
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port (
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CLK : in slbit; -- clock
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CLK : in slbit; -- clock
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RESET : in slbit; -- reset
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RESET : in slbit; -- reset
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REQ : in slbit; -- request
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REQ : in slbit; -- request
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WE : in slbit; -- write enable
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WE : in slbit; -- write enable
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);
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);
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end component;
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end component;
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end package nxcramlib;
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end package nxcramlib;
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-- ----------------------------------------------------------------------------
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package body nxcramlib is
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-- -------------------------------------
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pure function cram_delay( -- calculate delay in clock cycles
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clk_mhz : positive; -- clock frequency in MHz
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delay_ps : positive) -- delay in ps
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return positive is
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variable period_ps : natural := 0; -- clk period in ps
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begin
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period_ps := 1000000 / clk_mhz;
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return (delay_ps + period_ps - 10) / period_ps;
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end function cram_delay;
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-- -------------------------------------
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pure function cram_read0delay( -- read0 delay in clock cycles
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clk_mhz : positive) -- clock frequency in MHz
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return positive is
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begin
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return cram_delay(clk_mhz, cram_read0delay_ps);
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end function cram_read0delay;
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-- -------------------------------------
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pure function cram_read1delay( -- read1 delay in clock cycles
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clk_mhz : positive) -- clock frequency in MHz
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return positive is
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begin
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return cram_delay(clk_mhz, cram_read1delay_ps);
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end function cram_read1delay;
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-- -------------------------------------
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pure function cram_writedelay( -- write delay in clock cycles
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clk_mhz : positive) -- clock frequency in MHz
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return positive is
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begin
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return cram_delay(clk_mhz, cram_writedelay_ps);
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end function cram_writedelay;
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end package body nxcramlib;
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