Stratix® V Device Handbook: Volume 1: Device Interfaces and Integration

ID 683665
Date 10/18/2023
Public
Document Table of Contents

3.5.5. Accumulator and Chainout Adder

The Stratix® V variable precision DSP block supports a 64-bit accumulator and a 64-bit adder.

For Stratix® V devices, you can use the 64-bit adder as full adder.

The following signals can dynamically control the function of the accumulator:

  • NEGATE
  • LOADCONST
  • ACCUMULATE
Table 17.   Accumulator Functions and Dynamic Control Signals for 64-Bit Accumulator in Stratix® V Devices
Function Description NEGATE LOADCONST ACCUMULATE
Zeroing Disables the accumulator. 0 0 0
Preload Loads an initial value to the accumulator. Only one bit of the 64-bit preload value can be “1”. It can be used as rounding the DSP result to any position of the 64-bit result. 0 1 0
Accumulation Adds the current result to the previous accumulate result. 0 0 1
Decimation This function takes the current result, converts it into two’s complement, and adds it to the previous result. 1 0 1