Logical - 2020.2 English

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

Document ID
Release Date
2020.2 English

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

The Xilinx Logical block performs bitwise logical operations on fixed-point numbers. Operands are zero padded and sign extended as necessary to make binary point positions coincide; then the logical operation is performed and the result is delivered at the output port.

In hardware this block is implemented as synthesizable VHDL. If you build a tree of logical gates, this synthesizable implementation is best as it facilitates logic collapsing in synthesis and mapping.

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:
Logical function
Specifies one of the following bitwise logical operators: AND, NAND, OR, NOR, XOR, XNOR.
Number of inputs
Specifies the number of inputs (1 - 1024).
Logical Reduction Operation
When the number of inputs is specified as 1, a unary logical reduction operation performs a bit-wise operation on the single operand to produce a single bit result. The first step of the operation applies the logical operator between the least significant bit of the operand and the next most significant bit. The second and subsequent steps apply the operator between the one-bit result of the prior step and the next bit of the operand using the same logical operator. The logical reduction operator implements the same functionality as that of the logical reduction operation in HDLs. The output of the logical reduction operation is always Boolean.
Output Type tab
Parameters specific to the Output Type tab are as follows.
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.