Altera Integer Arithmetic IP Manuale Utente Scaricare il pdf (Pagina 83)

A multiplier-accumulator accepts a pair of inputs, multiplies the two inputs together, and feeds their

result into an accumulator to be added to or subtracted from its previous registered result. This function is

expressed in the following equation.

Where N is the number of cycles of data that has been entered into the accumulator.

Features

The ALTMULT_ACCUM megafunction offers the following features:

• Generates a multiplier-accumulator

• Supports data widths of 1–256 bits

• Supports signed and unsigned data representation format

• Supports pipelining with configurable output latency

• Provides a choice of implementation in dedicated DSP block circuitry or logic elements (LEs)

Note:

When building multipliers larger than the natively supported size there may/will be a perform‐

ance impact resulting from the cascading of the DSP blocks.

• Provides an option to dynamically switch between add and subtract operations in the accumulator

• Provides an option to dynamically switch between signed and unsigned data support

• Provides an option to set up data shift register chains

• Supports hardware saturation and rounding (for Stratix III and Stratix IV devices only)

• Supports optional asynchronous clear and clock enable input ports

• Supports systolic delay register mode (for Arria V, Cyclone V, and Stratix V devices only)

• Supports pre-adder with 8 coefficients per multiplier (for Arria V, Cyclone V, and Stratix V devices

only)

• Supports pre-load constant to complement accumulator feedback (for Arria V, Cyclone V, and Stratix

V devices only)

Refer to the following megafunctions in this user guide for other multiplier implementations:

• Multiplier-Adder Megafunction (ALTMULT_ADD)

• Memory-based Constant Coefficient Multiplier (ALTMEMMULT (Memory-based Constant

Coefficient Multiplier))

• Multiplier Megafunction (LPM_MULT (Multiplier))

Resource Utilization and Performance

The following table provides resource utilization and performance information for the

ALTMULT_ACCUM megafunction.

8-2

Features

UG-01063

2014.12.19

Altera Corporation

ALTMULT_ACCUM (Multiply-Accumulate)

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Altera Integer Arithmetic IP Manuale Utente Pagina 83