External IO Python based generator
==================================
This example will demonstrate emulation of Xilinx Device's IO with a Python based external process.
**KEY CONCEPTS:** `Traffic Generator <https://docs.xilinx.com/r/en-US/ug1393-vitis-application-acceleration/Working-with-I/O-Traffic-Generators>`__, `Traffic generation using Python <https://docs.xilinx.com/r/en-US/ug1393-vitis-application-acceleration/Writing-Traffic-Generators-in-Python>`__
**KEYWORDS:** `sim_ipc_axis_master <https://docs.xilinx.com/r/en-US/ug1393-vitis-application-acceleration/Adding-Traffic-Generators-to-Your-Design>`__, `sim_ipc_axis_slave <https://docs.xilinx.com/r/en-US/ug1393-vitis-application-acceleration/Adding-Traffic-Generators-to-Your-Design>`__, `gt_master <https://docs.xilinx.com/r/en-US/ug1393-vitis-application-acceleration/Writing-Traffic-Generators-in-C>`__, `gt_slave <https://docs.xilinx.com/r/en-US/ug1393-vitis-application-acceleration/Writing-Traffic-Generators-in-C>`__
Some user applications make use of IO ports in Vitis flow to drive streaming traffic in and out of the platform . This example emulates such designs in HW-Emulation by mimicing the IO port behavior as in HW.
In this example, Master and Slave Stream IO models will be available as prepacked xo's with different data width configuration. In order to instantiate the IP's corresponding to the provided xo, the xos are specified in the v++ command line
::
XOS = $(XILINX_VITIS)/data/emulation/XO/sim_ipc_axis_master_32.xo $(XILINX_VITIS)/data/emulation/XO/sim_ipc_axis_slave_32.xo
$(VPP) $(VPP_FLAGS) -l $(VPP_LDFLAGS) $(XOS) --temp_dir $(TEMP_DIR) -o'$(LINK_OUTPUT)' $(+)
The Python-based Traffic Generator follows the following steps for blocking traffic generation, transportation and reception -
1. Instantiate AXI Master and Slave Utilities
.. code:: python
master_util = ipc_axis_master_util("gt_master")
slave_util = ipc_axis_slave_util("gt_slave")
2. Determine the number of transactions and create that many random packets
.. code:: python
#Create payload
payload = xtlm_ipc.axi_stream_packet()
#Generate Random Data length
#Here we are generating 1-25 random integers. Each integer can have any value
#We are multiplying by 4 as, each ineger will take 4 byes of memory
payload.data_length = 4*random.randint(1,25)
rand_int = [] #A list containing random numbers
for j in range(0, int(payload.data_length/4)):
#Generate a random integer and append to list
rand_int.append(random.randint(0, 10000)) #We can choose any range.
#Convert generated random number to byte form (as supported by C style struct),
#More features packing are available at https://docs.python.org/3/library/struct.html
#User is free to choose his own way of packing as long as it is in-line with C types
format_string = "<"+str(int(payload.data_length/4))+"I"
payload.data = bytes(bytearray(struct.pack(format_string, *tuple(rand_int))))
payload.tlast = True # to mark end of packet. This is user's choice based on application
3. Send the data over ipc socket. Here the function call is blocked until response is available.
.. code:: python
master_util.b_transport(payload)
4. Sample the data available on the socket.
.. code:: python
payload = slave_util.sample_transaction()
5. End the simulation using the following API.
.. code:: python
master_util.end_of_simulation()
The Python-based Traffic Generator follows the following steps for Non-blocking traffic generation, transportation and reception -
1. Instantiate AXI Master and Slave Utilities
.. code:: python
master_util = ipc_axis_master_nb_util("gt_master")
slave_util = ipc_axis_slave_nb_util("gt_slave")
2. Determine the number of transactions and create that many random packets
.. code:: python
#Create payload
payload = xtlm_ipc.axi_stream_packet()
#Generate Random Data length
#Here we are generating 1-25 random integers. Each integer can have any value
#We are multiplying by 4 as, each ineger will take 4 byes of memory
payload.data_length = 4*random.randint(1,25)
rand_int = [] #A list containing random numbers
for j in range(0, int(payload.data_length/4)):
#Generate a random integer and append to list
rand_int.append(random.randint(0, 10000)) #We can choose any range.
#Convert generated random number to byte form (as supported by C style struct),
#More features packing are available at https://docs.python.org/3/library/struct.html
#User is free to choose his own way of packing as long as it is in-line with C types
format_string = "<"+str(int(payload.data_length/4))+"I"
payload.data = bytes(bytearray(struct.pack(format_string, *tuple(rand_int))))
payload.tlast = True # to mark end of packet. This is user's choice based on application
3. Send the data over ipc socket. Here the function returns immediately without waiting for a response.
.. code:: python
master_util.nb_transport(payload)
4. Sample the data available on the socket.
.. code:: python
payload = slave_util.nb_sample_transaction()
5. End the simulation using the following API.
.. code:: python
master_util.end_of_simulation()
Connections to the Custom IP's specified in xo's are made using ``krnl_incr.cfg`` file as below:
::
[connectivity]
nk=sim_ipc_axis_master_32:1:gt_master
nk=sim_ipc_axis_slave_32:1:gt_slave
stream_connect=gt_master.M00_AXIS:increment_1.a
stream_connect=increment_1.output:gt_slave.S00_AXIS
Note : xo instance name specified on v++ command line becomes a key which will be used by the external process to refer to a particular stream port
**EXCLUDED PLATFORMS:**
- Versal VCK5000
- AWS VU9P F1
- Samsung SmartSSD Computation Storage Drive
- Samsung U.2 SmartSSD
DESIGN FILES
------------
Application code is located in the src directory. Accelerator binary files will be compiled to the xclbin directory. The xclbin directory is required by the Makefile and its contents will be filled during compilation. A listing of all the files in this example is shown below
::
src/b_test_master.py
src/b_test_slave.py
src/host.cpp
src/increment.cpp
src/nb_test_master.py
src/nb_test_slave.py
Access these files in the github repo by `clicking here <https://github.com/Xilinx/Vitis_Accel_Examples/tree/master/emulation/external_io_py>`__.
COMMAND LINE ARGUMENTS
----------------------
Once the environment has been configured, the application can be executed by
::
./external_io_py <increment XCLBIN>