..  Licensed to the Apache Software Foundation (ASF) under one
    or more contributor license agreements.  See the NOTICE file
    distributed with this work for additional information
    regarding copyright ownership.  The ASF licenses this file
    to you under the Apache License, Version 2.0 (the
    "License"); you may not use this file except in compliance
    with the License.  You may obtain a copy of the License at

..    http://www.apache.org/licenses/LICENSE-2.0

..  Unless required by applicable law or agreed to in writing,
    software distributed under the License is distributed on an
    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    KIND, either express or implied.  See the License for the
    specific language governing permissions and limitations
    under the License.

VTA Configuration
=================

The VTA stack incorporates both a hardware accelerator stack and
a TVM based software stack.
VTA incorporates flexibility out of the box: by modifying the
``vta/config/vta_config.json`` high-level configuration file,
the user can change the shape of the tensor intrinsic,
clock frequency, pipelining, data type width, and on-chip buffer sizes.

Parameters Overview
-------------------

We explain the parameters listed in the ``vta_config.json`` file in the table
below.

+-----------------------+------------+--------------------------------------------------------+
| Attribute             | Format     | Description                                            |
+=======================+============+========================================================+
| ``TARGET``            | String     | The TVM device target.                                 |
+-----------------------+------------+--------------------------------------------------------+
| ``HW_VER``            | String     | VTA hardware version number.                           |
+-----------------------+------------+--------------------------------------------------------+
| ``LOG_INP_WIDTH``     | Int (log2) | Input data type signed integer width.                  |
+-----------------------+------------+--------------------------------------------------------+
| ``LOG_WGT_WIDTH``     | Int (log2) | Weight data type signed integer width.                 |
+-----------------------+------------+--------------------------------------------------------+
| ``LOG_ACC_WIDTH``     | Int (log2) | Accumulator data type signed integer width.            |
+-----------------------+------------+--------------------------------------------------------+
| ``LOG_BATCH``         | Int (log2) | VTA matrix multiply intrinsic input/output dimension 0.|
+-----------------------+------------+--------------------------------------------------------+
| ``LOG_BLOCK``         | Int (log2) | VTA matrix multiply inner dimensions.                  |
+-----------------------+------------+--------------------------------------------------------+
| ``LOG_UOP_BUFF_SIZE`` | Int (log2) | Micro-op on-chip buffer in Bytes.                      |
+-----------------------+------------+--------------------------------------------------------+
| ``LOG_INP_BUFF_SIZE`` | Int (log2) | Input on-chip buffer in Bytes.                         |
+-----------------------+------------+--------------------------------------------------------+
| ``LOG_WGT_BUFF_SIZE`` | Int (log2) | Weight on-chip buffer in Bytes.                        |
+-----------------------+------------+--------------------------------------------------------+
| ``LOG_ACC_BUFF_SIZE`` | Int (log2) | Accumulator on-chip buffer in Bytes.                   |
+-----------------------+------------+--------------------------------------------------------+


 .. note::

    When a parameter name is preceded with ``LOG``, it means that it describes a value that can only be expressed a power of two.
    For that reason we describe these parameters by their log2 value.
    For instance, to describe an integer width of 8-bits for the input data types, we set the ``LOG_INP_WIDTH`` to be 3, which is the log2 of 8.
    Similarly, to descibe a 64kB micro-op buffer, we would set ``LOG_UOP_BUFF_SIZE`` to be 16.

We provide additional detail below regarding each parameter:

 - ``TARGET``: Can be set to ``"pynq"``, ``"ultra96"``, ``"sim"`` (fast simulator), or ``"tsim"`` (cycle accurate sim with verilator).
 - ``HW_VER``: Hardware version which increments every time the VTA hardware design changes. This parameter is used to uniquely identity hardware bitstreams.
 - ``LOG_BATCH``: Equivalent to A in multiplication of shape (A, B) x (B, C), or typically, the batch dimension of inner tensor computation.
 - ``LOG_BLOCK``: Equivalent to B and C in multiplication of shape (A, B) x (B, C), or typically, the input/output channel dimensions of the inner tensor computation.

