//
// This confidential and proprietary software may be used only as
// authorised by a licensing agreement from ARM Limited
// (C) COPYRIGHT 2020-2021 ARM Limited
// ALL RIGHTS RESERVED
// The entire notice above must be reproduced on all authorised
// copies and copies may only be made to the extent permitted
// by a licensing agreement from ARM Limited.

== Operators

=== Operator Parameters

An operator processes input operands to produce output operands. An operator can have three types of parameters:

* An input operand. This must be a tensor or a list of tensors and data is read by the operation.
* An output operand. This must be a tensor or a list of tensors and data is written by the operation.
* An attribute. This is a parameter that is constant for a particular instance of the operator. It may have any data type supported by TOSA. It is expected to be set at compile time.

=== Operator Graphs

A TOSA graph is a collection of TOSA operators where:

* The output of an operator in the graph may be connected to one or more inputs of other operators in the graph
* When an output is connected to an input the tensor list shapes must match
* The attributes of the operators are defined and considered part of the graph
* The attributes must be in the valid range permitted for the operator
* The tensor dimensions must be in the valid range permitted for the operator

Some operators, such as control flow operators, take a graph of other operators as an attribute. The type tosa_graph_t will denote a graph of operators and the following functions define the tensor shape list for the graph input and outputs:

[source,c++]
----
shape_list_t tosa_input_shape(tosa_graph_t graph);
shape_list_t tosa_output_shape(tosa_graph_t graph);
----

Similarly the type tensor_list_t will be used for a list of tensors and the following function returns the shape of a tensor list:
[source,c++]
----
shape_list_t tensor_list_shape(tosa_list_t tensor_list);
----

The following function denotes the execution of a TOSA graph, on an input tensor list to produce an output tensor list.

[source,c++]
----
tosa_execute_graph(tosa_graph_t graph, tosa_list_t input_list, tosa_list_t output_list, tosa_level_t level) {
    ERROR_IF(tensor_list_shape(input_list) != tosa_input_shape(graph));
    ERROR_IF(tensor_list_shape(output_list) != tosa_output_shape(graph));
    for_each(operator in graph order) {
        ERROR_IF(operator input tensors do not meet requirement of operator Arguments inputs)
        ERROR_IF(operator attributes do not meet requirement of operator Arguments attributes)
        ERROR_IF(operator output tensors do not meet requirement of operator Arguments outputs)
        ERROR_IF(operator data types do not meet requirement of operator Supported Data Types)
        // Execute the operator as defined by the operation function pseduo-code
        tosa_execute_operator(operator, level);
    }
}
----

include::tensor_ops.adoc[]

include::activation_funcs.adoc[]

include::ewise_binary.adoc[]

include::ewise_unary.adoc[]

include::ewise_ternary.adoc[]

include::comparison.adoc[]

include::reduction.adoc[]

include::data_layout.adoc[]

include::scatter_gather.adoc[]

include::image.adoc[]

include::type_conversion.adoc[]

include::data_nodes.adoc[]

include::custom.adoc[]

include::control_flow.adoc[]
