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//
// This confidential and proprietary software may be used only as
// authorised by a licensing agreement from ARM Limited
// (C) COPYRIGHT 2023 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.
=== Variable Operators
TOSA implements three variable operators for expressing persistent mutable values across multiple TOSA graph invocations.
==== VARIABLE
Defines a new TOSA variable.
This is a persistent mutable value across multiple TOSA graph invocations.
Modifications are expressed using read/write semantics.
include::{generated}/operators/VARIABLE.adoc[]
[source,c++]
----
tensor_t var_tensor = variable_tensor_lookup(uid);
// Invocation for the first time
if (var_tensor == NULL) {
// Allocate the persistent mutable memory for the variable tensor
tensor_t var_tensor = variable_tensor_allocate<var_t>(var_shape, uid);
if (initial_value != NULL) {
REQUIRE(var_t == in_t);
REQUIRE(var_shape == shape);
for_each (index in shape) {
// Copy data from initial_value to var_tensor
in_t value = tensor_read<in_t>(initial_value, shape, index);
tensor_write<in_t>(var_tensor.data, var_shape, index, value);
}
var_tensor.is_written = true;
}
} else { // Variable tensor has already been declared
// It's invalid to declare the second variable with the same uid in a single graph execution,
REQUIRE(!var_tensor.seen);
}
var_tensor.seen = true;
----
==== VARIABLE_WRITE
Assigns a value to the pseudo-buffer resource holding a persistent mutable tensor.
include::{generated}/operators/VARIABLE_WRITE.adoc[]
[source,c++]
----
tensor_t. variable_tensor = variable_tensor_lookup(uid);
// Check this variable tensor has been declared
REQUIRE(variable_tensor);
// The tensor has to be seen before to be written to
// The seen variable is cleared before each graph execution and set in declaration
REQUIRE(variable_tensor.seen);
// Input tensor's shape and variable_tensor's shape have to match
REQUIRE(variable_tensor.shape == shape);
// Input tensor's shape and variable_tensor's type have to match
REQUIRE(variable_tensor.type == in_t);
for_each (index in shape) {
// Write data from the input to the pseudo-buffer resource
in_t value = tensor_read<in_t>(input1, shape, index);
tensor_write<tensor_t>(variable_tensor.data, variable_tensor.shape, index, value);
}
variable_tensor.is_written = true;
----
==== VARIABLE_READ
Reads the value from a pseudo-buffer resource holding a persistent mutable tensor.
include::{generated}/operators/VARIABLE_READ.adoc[]
[source,c++]
----
tensor_t variable_tensor = variable_tensor_lookup(uid);
// Check this variable tensor has been decalred
REQUIRE(variable_tensor != NULL);
// Check this variable tensor has been written
REQUIRE(variable_tensor.is_written);
// Output tensor's shape and variable_tensor's shape have to match
REQUIRE(variable_tensor.shape == shape);
// Output tensor's shape and variable_tensor's type have to match
REQUIRE(variable_tensor.type == out_t);
for_each (index in shape) {
// Read data from pseudo-buffer resource to the output
out_t value = tensor_read<tensor_t>(variable_tensor.data, variable_tensor.shape, index);
tensor_write<out_t>(input1, shape, index, value);
}
----
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