Updated readme

README

@@ -0,0 +1 @@
+README.md

README.md

@@ -0,0 +1,205 @@
+# Verilog AXI Stream Components Readme
+
+For more information and updates: http://alexforencich.com/wiki/en/verilog/axis/start
+
+GitHub repository: https://github.com/alexforencich/verilog-axis
+
+## Introduction
+
+Collection of AXI Stream bus components.  Most components are fully
+parametrizable in interface widths.  Includes full MyHDL testbench with
+intelligent bus cosimulation endpoints.
+
+## Documentation
+
+### axis_adapter module
+
+The axis_adapter module bridges AXI stream busses of differing widths.  The
+module is parametrizable, but there are certain restrictions.  First, the bus
+word widths must be identical (e.g. one 8-bit lane and eight 8-bit lanes, but
+not one 16-bit lane and one 32-bit lane).  Second, the bus widths must be
+related by an integer multiple (e.g. 2 words and 6 words, but not 4 words
+and 6 words).  Wait states will be inserted on the wider bus side when
+necessary.
+
+### axis_async_fifo module
+
+Basic word-based asynchronous FIFO with parametrizable data width and depth.
+Supports power of two depths only.
+
+### axis_async_fifo_64 module
+
+Basic word-based asynchronous FIFO with tkeep signal and parametrizable data
+width and depth.  Supports power of two depths only.
+
+### axis_async_frame_fifo module
+
+Basic frame-based asynchronous FIFO with parametrizable data width and depth.
+Supports power of two depths only.
+
+### axis_async_fifo_64 module
+
+Basic frame-based asynchronous FIFO with tkeep signal and parametrizable data
+width and depth.  Supports power of two depths only.
+
+### axis_fifo module
+
+Basic word-based synchronous FIFO with parametrizable data width and depth.
+Supports power of two depths only.
+
+### axis_fifo_64 module
+
+Basic word-based synchronous FIFO with tkeep signal and parametrizable data
+width and depth.  Supports power of two depths only.
+
+### axis_frame_fifo module
+
+Basic frame-based synchronous FIFO with parametrizable data width and depth.
+Supports power of two depths only.
+
+### axis_fifo_64 module
+
+Basic frame-based synchronous FIFO with tkeep signal and parametrizable data
+width and depth.  Supports power of two depths only.
+
+### axis_frame_join_N module
+
+Frame joiner with optional tag.  8 bit data path only.
+
+Can be generated with arbitrary port counts with axis_frame_join.py.
+
+### axis_ll_bringe module
+
+AXI stream to LocalLink bridge.
+
+### axis_rate_limit module
+
+Fractional rate limiter, supports word and frame modes.  Inserts wait states
+to limit data rate to specified ratio.  Frame mode inserts wait states at end
+of frames, word mode ignores frames and inserts wait states at any point.
+Parametrizable data width.  Rate and mode are configurable at run time.
+
+### axis_rate_limit_64 module
+
+Fractional rate limiter with tkeep signal, supports word and frame modes.
+Inserts wait states to limit data rate to specified ratio.  Frame mode inserts
+wait states at end of frames, word mode ignores frames and inserts wait states
+at any point.  Parametrizable data width.  Rate and mode are configurable at
+run time.
+
+### axis_register module
+
+Datapath register.  Use to improve timing for long routes.  
+
+### axis_register_64 module
+
+Datapath register with tkeep signal.  Use to improve timing for long routes.
+
+### axis_stat_counter module
+
+Statistics counter module.  Counts bytes and frames passing through monitored
+AXI stream interface.  Trigger signal used to reset and dump counts out of AXI
+interface, along with tag value.  Use with axis_frame_join_N to form a single
+monolithic frame from multiple monitored points with the same trigger.
+
+### ll_axis_bridge module
+
+LocalLink to AXI stream bridge.
+
+### Common signals
+
+    tdata   : Data (width generally DATA_WIDTH)
+    tkeep   : Data word valid (width generally KEEP_WIDTH, present on _64 modules)
+    tvalid  : Data valid
+    tready  : Sink ready
+    tlast   : End-of-frame
+    tuser   : Bad frame (valid with tlast & tvalid)
+
+### Source Files
+
+    rtl/axis_adapter.v              : Parametrizable bus width adapter
+    rtl/axis_async_fifo.v           : Asynchronous FIFO
+    rtl/axis_async_fifo_64.v        : Asynchronous FIFO (64 bit)
+    rtl/axis_async_frame_fifo.v     : Asynchronous frame FIFO
+    rtl/axis_async_frame_fifo_64.v  : Asynchronous frame FIFO (64 bit)
+    rtl/axis_fifo.v                 : Synchronous FIFO
+    rtl/axis_fifo_64.v              : Synchronous FIFO (64 bit)
+    rtl/axis_frame_fifo.v           : Synchronous frame FIFO
+    rtl/axis_frame_fifo_64.v        : Synchronous frame FIFO (64 bit)
+    rtl/axis_frame_join.py          : Frame joiner generator
+    rtl/axis_frame_join_4.v         : 4 port frame joiner
+    rtl/axis_ll_bridge.v            : AXI stream to LocalLink bridge
+    rtl/axis_rate_limit.v           : Fractional rate limiter
+    rtl/axis_rate_limit_64.v        : Fractional rate limiter (64 bit)
+    rtl/axis_register.v             : AXI Stream register
+    rtl/axis_register_64.v          : AXI Stream register (64 bit)
+    rtl/axis_stat_counter.v         : Statistics counter
+    rtl/ll_axis_bridge.v            : LocalLink to AXI stream bridge
+
+### AXI Stream Interface Example
+
+two byte transfer with sink pause after each byte
+
+              __    __    __    __    __    __    __    __    __
+    clk    __/  \__/  \__/  \__/  \__/  \__/  \__/  \__/  \__/  \__
+                    _____ _________________
+    tdata  XXXXXXXXX_D0__X_D1______________XXXXXXXXXXXXXXXXXXXXXXXX
+                    _____ _________________
+    tkeep  XXXXXXXXX_K0__X_K1______________XXXXXXXXXXXXXXXXXXXXXXXX
+                    _______________________
+    tvalid ________/                       \_______________________
+           ______________             _____             ___________
+    tready               \___________/     \___________/
+                          _________________
+    tlast  ______________/                 \_______________________
+
+    tuser  ________________________________________________________
+
+
+two back-to-back packets, no pauses
+
+              __    __    __    __    __    __    __    __    __
+    clk    __/  \__/  \__/  \__/  \__/  \__/  \__/  \__/  \__/  \__
+                    _____ _____ _____ _____ _____ _____
+    tdata  XXXXXXXXX_A0__X_A1__X_A2__X_B0__X_B1__X_B2__XXXXXXXXXXXX
+                    _____ _____ _____ _____ _____ _____
+    tkeep  XXXXXXXXX_K0__X_K1__X_K2__X_K0__X_K1__X_K2__XXXXXXXXXXXX
+                    ___________________________________
+    tvalid ________/                                   \___________
+           ________________________________________________________
+    tready
+                                _____             _____
+    tlast  ____________________/     \___________/     \___________
+
+    tuser  ________________________________________________________
+
+
+bad frame
+
+              __    __    __    __    __    __
+    clk    __/  \__/  \__/  \__/  \__/  \__/  \__
+                    _____ _____ _____
+    tdata  XXXXXXXXX_A0__X_A1__X_A2__XXXXXXXXXXXX
+                    _____ _____ _____
+    tkeep  XXXXXXXXX_K0__X_K1__X_K2__XXXXXXXXXXXX
+                    _________________
+    tvalid ________/                 \___________
+           ______________________________________
+    tready
+                                _____
+    tlast  ____________________/     \___________
+                                _____
+    tuser  ____________________/     \___________
+
+
+## Testing
+
+Running the included testbenches requires MyHDL and Icarus Verilog.  Make sure
+that myhdl.vpi is installed properly for cosimulation to work correctly.  The
+testbenches can be run with a Python test runner like nose or py.test, or the
+individual test scripts can be run with python directly.
+
+### Testbench Files
+
+    tb/axis_ep.py        : MyHDL AXI Stream endpoints
+    tb/ll_ep.py          : MyHDL LocalLink endpoints