UVVM Data Stack

The UVVM Data Stack is a memory buffer that can be used to hold one or more stacks. Each stack will be allocated a chosen size and ID number. This allows a selectable number of stacks to operate individually and be independently accessed.

The difference between the FIFO (First-In-First-Out) and the stack is that the stack follows the LIFO (Last-In-First-Out) principle. This means that the last element added to the stack is the first one to be removed.

Functional Parameters

Name	Type	Description
buffer_idx	natural	The index of the stack that shall be initialized. The maximum number of stacks is defined by C_NUMBER_OF_DATA_BUFFERS in adaptations_pkg.
buffer_size_in_bits	natural	The size of the stack. The maximum stack size is defined by C_TOTAL_NUMBER_OF_BITS_IN_DATA_BUFFER in adaptations_pkg
entry_size_in_bits	natural	The size of the returned std_logic_vector
data	std_logic_vector	The data that shall be pushed to the stack
void	t_void	Unused, empty input parameter

Methods

• All stack functions and procedures are defined in data_stack_pkg.vhd

• All parameters in brackets are optional.

uvvm_stack_init()

This UVVM stack call will allocate space in the stack buffer. If no buffer_idx is given, the call will return a buffer index for use when addressing the stack. Note that 0 will be returned on error. If a buffer_idx is given, the stack is initialized with this index.

uvvm_stack_init([buffer_idx], buffer_size_in_bits)

-- Examples:
uvvm_stack_init(C_BUFFER_IDX_1, C_BUFFER_SIZE-1); -- initialize buffer with index C_BUFFER_IDX_1
v_stack_idx := uvvm_stack_init(C_BUFFER_SIZE-1);

uvvm_stack_push()

This procedure pushes data into a stack with index buffer_idx. The size of the data is unconstrained, meaning that it can be any size. Pushing data with a size that is larger than the stack size results in wrapping, i.e., that when reaching the end that data remaining will overwrite the data that was first written.

uvvm_stack_push(buffer_idx, data)

-- Examples:
uvvm_stack_push(C_BUFFER_IDX_1, v_rx_data);

uvvm_stack_pop()

This function returns the data from the stack and removes the returned data from the stack. Note that buffer_idx is the index of the stack that shall be read, and that entry_size_in_bits is the size of the returned data as SLV. Attempting to get data from an empty stack is allowed but triggers a TB_WARNING and returns garbage data. Attempting to get a larger value than the stack size is allowed but triggers a TB_WARNING.

std_logic_vector := uvvm_stack_pop(buffer_idx, entry_size_in_bits)

-- Examples:
v_rx_data := uvvm_stack_pop(C_BUFFER_IDX_1, C_ENTRY_SIZE-1);

uvvm_stack_flush()

This procedure empties the stack given by buffer_idx.

uvvm_stack_flush(buffer_idx)

-- Examples:
uvvm_stack_flush(C_BUFFER_IDX_1);

uvvm_stack_peek()

This function returns the data from the stack without removing it. Note that apart from not removing the data, this function will behave in the same way as the uvvm_stack_pop() function.

std_logic_vector := uvvm_stack_peek(buffer_idx, entry_size_in_bits)

-- Examples:
v_rx_data := uvvm_stack_peek(C_BUFFER_IDX_1, C_ENTRY_SIZE-1);

uvvm_stack_get_count()

This function returns a natural indicating the number of elements currently occupying the stack given by buffer_idx.

natural := uvvm_stack_get_count(buffer_idx)

-- Examples:
v_num_elements := uvvm_stack_get_count(C_BUFFER_IDX);

uvvm_stack_get_max_count()

This function returns a natural indicating the maximum number of elements that can occupy the stack given by buffer_idx.

natural := uvvm_stack_get_max_count(buffer_idx)

-- Examples:
v_max_elements := uvvm_stack_get_max_count(C_BUFFER_IDX);

uvvm_stack_is_full()

This function returns a boolean indicating if the stack is full or not.

boolean := uvvm_stack_is_full(buffer_idx)

-- Examples:
v_stack_is_full := uvvm_stack_is_full(C_BUFFER_IDX);

uvvm_stack_deallocate()

This function de-allocates the stack buffer, all the stack pointers are reset.

uvvm_stack_deallocate(VOID)

-- Examples:
uvvm_stack_deallocate(VOID);

Note

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