EP2S15 datasheet(22/238 Pages) ALTERA

22 / 238 page

2–14

Altera Corporation

Stratix II Device Handbook, Volume 1

May 2007

Adaptive Logic Modules

Figure 2–10. Template for Supported Seven-Input Functions in Extended LUT Mode

Note to Figure 2–10:

(1)

If the seven-input function is unregistered, the unused eighth input is available for register packing. The second

Arithmetic Mode

The arithmetic mode is ideal for implementing adders, counters,

accumulators, wide parity functions, and comparators. An ALM in

arithmetic mode uses two sets of two four-input LUTs along with two

dedicated full adders. The dedicated adders allow the LUTs to be

available to perform pre-adder logic; therefore, each adder can add the

output of two four-input functions. The four LUTs share the dataa and

datab

inputs. As shown in Figure 2–11, the carry-in signal feeds to

adder0

, and the carry-out from adder0 feeds to carry-in of adder1. The

carry-out from adder1 drives to adder0 of the next ALM in the LAB.

ALMs in arithmetic mode can drive out registered and/or unregistered

versions of the adder outputs.

datae0

combout0

5-Input

LUT

5-Input

LUT

datac

dataa

datab

datad

dataf0

datae1

dataf1

To general or

local routing

To general or

local routing

reg0

This input is available

for register packing.

(1)

EP2S15 Datasheet(PDF) 22 Page - Altera Corporation

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