Numeric

Implements an adder-subtractor that operates on bit patterns. You can cascade and pipeline AddSub nodes to achieve higher throughput rates.

1378

Inputs/Outputs

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carry in/inverted borrow in

A Boolean that determines whether this node accounts for an additional least-significant bit (LSB).

True Adds one extra LSB to x + y when sub? is False. Computes x – y normally when sub? is True.
False Subtracts one extra LSB from x – y when sub? is True. Computes x + y normally when sub? is False.

Default value: False

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bypass x

A Boolean that determines whether this node ignores the value you wire to x.

True This node uses a value of 0 instead of the value you wire to x.
False This node uses the value you wire to x.

Use this Boolean to remove x from the expression this node calculates. For example, use this Boolean to return –y instead of x – y.

Default value: False

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sub?

A Boolean that determines whether this node performs subtraction or addition.

Use this Boolean to change the operation of this node programmatically.
TrueThe node calculates x - y.
FalseThe node calculates x + y.

Default value: False

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x

An input to this node.

This input supports scalar values of integer and fixed-point data types.

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y

An input to this node.

This input supports scalar values of integer and fixed-point data types.

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carry out/inverted borrow out

A Boolean that indicates whether the data type of sum cannot represent the result of an unsigned addition operation.

This output is available when you wire unsigned numeric values to x and y.
TrueThe data type of sum cannot represent the result of an unsigned addition operation.
FalseThe data type of sum cannot represent the result of an unsigned subtraction operation.

In this situation, this node wraps the value of sum. If you cascade this node, you can use this output to specify whether a downstream node carries or borrows a value. To specify that a downstream node uses this value, wire carry-out/inverted borrow-out to the carry-in/inverted borrow-in input of the downstream node.

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overflow

A Boolean that indicates if the theoretical computed value of the sum exceeds the valid range of its data type.

This output is available when you wire signed numeric values to x and y.
TrueThis node wraps the value of sum.
FalseThis node does not wrap the value of sum.
Note If you cascade nodes, you must use unsigned versions of the nodes in the intermediate operations. Set the encoding of the final node to the encoding you want for the entire cascaded operation.
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sum

The result this node computes. The result depends on not only the values of x and y but also the values of any Boolean inputs.

This node applies the Wrap overflow mode to sum in the following situations:
  • sub? is True and carry out/inverted borrow out returns False
  • sub? is False and carry out/inverted borrow out returns True