Intel® Agilex™ Variable Precision DSP Blocks User Guide

ID 683037
Date 11/17/2022

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Document Table of Contents Multiply-Add or Multiply-Subtract Mode

This mode performs floating-point multiplication followed by floating-point addition or floating-point subtraction. The chainin parameter allows you to enable a multiple-chain mode.

Table 22.  Equations Applied to Multiply-Add or Multiply-Subtract Mode
Chainin Parameter Multiply-Add Mode Multiply-Subtract Mode
Disable fp32_result = (fp32_mult_a*fp32_mult_b) + fp32_adder_a fp32_result = (fp32_mult_a*fp32_mult_b) - fp32_adder_a
Enable fp32_result = (fp32_mult_a*fp32_mult_b) + fp32_chainin fp32_result = (fp32_mult_a*fp32_mult_b) - fp32_chainin
The floating-point multiply-adder or multiply-subtract mode supports the following exception flags:
  • fp32_mult_invalid
  • fp32_mult_inexact
  • fp32_mult_overflow
  • fp32_mult_underflow
  • fp32_adder_invalid
  • fp32_adder_inexact
  • fp32_adder_overflow
  • fp32_adder_underflow
Figure 39. Multiply-Add or Multiply-Subtract Mode for Intel® Agilex™ Devices