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

ID 683213
Date 10/18/2023
Document Table of Contents

3.5.6. Accumulator and Chainout Adder

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

For Arria® V GX, GT, SX, and ST devices, the accumulator and chainout adder features are not supported in two independent 18 x 19 modes and three independent 9 x 9 modes.

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

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

Table 21.   Accumulator Functions and Dynamic Control Signals This table lists the dynamic signals settings and description for each function. In this table, X denotes a "don't care" value.
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 X 1
Decimation This function takes the current result, converts it into two’s complement, and adds it to the previous result. 1 X 1