Expression - 2020.2 English

Vivado Design Suite Reference Guide: Model-Based DSP Design Using System Generator (UG958)

Document ID
UG958
Release Date
2020-11-18
Version
2020.2 English

This block is listed in the following Xilinx® Blockset libraries: Basic Elements, Control Logic, Math, and Index.

The Xilinx Expression block performs a bitwise logical expression.

The expression is specified with operators described in the table below. The number of input ports is inferred from the expression. The input port labels are identified from the expression, and the block is subsequently labeled accordingly. For example, the expression: ~((a1 | a2) & (b1 ^ b2)) results in the following block with 4 input ports labeled 'a1', 'a2', 'b1', and 'b2'.

The expression is parsed and an equivalent statement is written in VHDL (or Verilog). Shown below, in decreasing order of precedence, are the operators that can be used in the Expression block.

Operator Symbol
Precedence ()
NOT ~
AND &
OR |
XOR ^

Block Parameters

The block parameters dialog box can be invoked by double-clicking the icon in your Simulink® model.

Basic tab
Parameters specific to the Basic tab are as follows.
Expression
Bitwise logical expression.
Align Binary Point
Specifies that the block must align binary points automatically. If not selected, all inputs must have the same binary point position.

Other parameters used by this block are explained in the topic Common Options in Block Parameter Dialog Boxes.