URL
https://opencores.org/ocsvn/pcounter/pcounter/trunk
Subversion Repositories pcounter
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/pcounter
- from Rev 2 to Rev 1
- ↔ Reverse comparison
Rev 2 → Rev 1
/trunk/pcount_tb.vhdl
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/trunk/pdchain.vhdl
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/trunk/doc/pcounter_sch.pdf
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Index: trunk/doc/pcounter_4bit_trace.pdf
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Index: trunk/doc/pcounter_4bit_trace.pdf
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--- trunk/doc/pcounter_4bit_trace.pdf (revision 2)
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trunk/doc/pcounter_4bit_trace.pdf
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Index: trunk/doc/README
===================================================================
--- trunk/doc/README (revision 2)
+++ trunk/doc/README (nonexistent)
@@ -1,85 +0,0 @@
---
--- * pipelined synchronous pulse counter *
---
--- fast counter for slow-carry architectures
--- non-monotonic counting, value calculable by HDL/CPU
---
--- idea&code by Marek Peca 08/2012
--- Vyzkumny a zkusebni letecky ustav, a.s. http://vzlu.cz/
--- thanks to Michael Vacek for testing
---
-
-Pipelined Synchronous Pulse Counter
-===================================
-
-is a proposal of binary counter, designed to minimize logic path
-length in between flip-flops to one gate (MUX/AND) only, at the
-expense of not so straightforward binary counting. The reason for this
-design has emerged while using Actel (MicroSemi) ProASIC/IGLOO
-architecture, lacking any hardwired support for fast carry.
-
-During our work on Actel FPGAs (basically, 3-LUT & DFF only), we were
-aware of following types of faster counters:
-- LFSR counter
-- Johnson counter
-- "RLA counter" (as tailored using Actel's SmartGen core generator)
-
-Johnson due to its O(2^n) (n as number of bits) can not be used for
-longer counts; LFSR's are hard to invert (table lookup seems to be
-only known method), therefore also impractical for wider counters. RLA
-counter is still too slow and complex for wider counters and moderate
-speeds (e.g. > 24bits @ >100MHz).
-
-As a consequence, the proposed counter uses synchronous divide-by-two
-blocks, each using 1-bit pipeline and carry by single-clock
-pulse. Design is simple and fast, preliminary results from Synplify
-and Actel Designer shows 32bits @200MHz feasible.
-
-However, output bit lines are non-proportionaly delayed by discrete
-number of clock periods. Therefore, to obtain linear bit word, an
-inversion formula needs to be applied. Fortunately, the inversion is
-simple (unlike LFSR's), in C (pcount.c):
-
- for (k = 1; k < n; k++)
- if ((y & ((1<
\ No newline at end of file
Index: trunk/pdivtwo.vhdl
===================================================================
--- trunk/pdivtwo.vhdl (revision 2)
+++ trunk/pdivtwo.vhdl (nonexistent)
@@ -1,41 +0,0 @@
---
--- * pipelined synchronous pulse counter *
--- pdivtwo -- core 1-stage element (pipelined f/2 divider)
---
--- fast counter for slow-carry architectures
--- non-monotonic counting, value calculable by HDL/CPU
---
--- idea&code by Marek Peca 08/2012
--- Vyzkumny a zkusebni letecky ustav, a.s. http://vzlu.cz/
--- thanks to Michael Vacek for testing
---
-
-library ieee;
-use ieee.std_logic_1164.all;
-use ieee.numeric_std.all;
-
-entity pdivtwo is
- port (
- clock: in std_logic;
- en: in std_logic;
- q, p: out std_logic
- );
-end pdivtwo;
-
-architecture behavioral of pdivtwo is
- signal state: std_logic := '1';
- signal pipe: std_logic := '0';
- signal next_state, next_pipe: std_logic;
-begin
- next_state <= not state when en = '1' else state;
- next_pipe <= state and en;
- p <= pipe;
- q <= state;
-
- process
- begin
- wait until clock'event and clock = '1';
- state <= next_state;
- pipe <= next_pipe;
- end process;
-end behavioral;
Index: trunk/COPYING
===================================================================
--- trunk/COPYING (revision 2)
+++ trunk/COPYING (nonexistent)
@@ -1,165 +0,0 @@
- GNU LESSER GENERAL PUBLIC LICENSE
- Version 3, 29 June 2007
-
- Copyright (C) 2007 Free Software Foundation, Inc.
-#include
-#include
-#include
-
-typedef unsigned long count_t;
-
-count_t pcount_decode(unsigned n, count_t b) {
- count_t y = b;
- unsigned k;
- for (k = 1; k < n; k++)
- if ((y & ((1< 0; k--)
- if ((b & ((1< %08lx -> %08lx\n", b, y, z);
- }
- return 0;
-}
Index: trunk/Makefile
===================================================================
--- trunk/Makefile (revision 2)
+++ trunk/Makefile (nonexistent)
@@ -1,27 +0,0 @@
-UNITS=pdchain.vhdl pdivtwo.vhdl
-UNIT_TOP=pcount_tb.vhdl
-
-TOP_EXE=$(patsubst %.vhdl,%,$(UNIT_TOP))
-COPT=--ieee=synopsys -g
-ROPT=--vcd=$(TOP_EXE).vcd --stop-time=10us
-
-
-all: $(TOP_EXE) pcount
-
-testvcd: $(TOP_EXE)
- ghdl -r $(TOP_EXE) $(ROPT)
-
-testrun: $(TOP_EXE) pcount
- ghdl -r $(TOP_EXE) | ./pcount
-
-$(TOP_EXE): $(UNITS) $(UNIT_TOP)
- ghdl -i $(UNITS) $(UNIT_TOP)
- ghdl -a $(COPT) $(UNIT_TOP)
- ghdl -m $(COPT) $(TOP_EXE)
-
-pcount: pcount.c
- $(CC) -Wall -O -o $@ $<
-
-clean:
- rm -rf $(TOP_EXE) pcount
- ghdl --remove