ep2s130 Altera Corporation, ep2s130 Datasheet - Page 26

• Manufacturer Part Number: ep2s130
• Description: Stratix Ii Device Family Data Sheet
• Manufacturer: Altera Corporation

Adaptive Logic Modules
Figure 2–13. ALM in Shared Arithmetic Mode
Note to
(1)
2–18
Stratix II Device Handbook, Volume 1
Inputs dataf0 and dataf1 are available for register packing in shared arithmetic mode.
Figure
datae0
datae1
datab
dataa
datad
datac
2–13:
Adder trees can be found in many different applications. For example, the
summation of the partial products in a logic-based multiplier can be
implemented in a tree structure. Another example is a correlator function
that can use a large adder tree to sum filtered data samples in a given time
frame to recover or to de-spread data which was transmitted utilizing
spread spectrum technology.
An example of a three-bit add operation utilizing the shared arithmetic
mode is shown in
partial carry (C[2..0]) is obtained using the LUTs, while the result
(R[2..0]) is computed using the dedicated adders.
4-Input
4-Input
4-Input
4-Input
LUT
LUT
LUT
LUT
shared_arith_out
shared_arith_in
Figure
carry_out
carry_in
2–14. The partial sum (S[2..0]) and the
D
D
reg0
reg1
Q
Q
To general or
To general or
To general or
To general or
local routing
local routing
local routing
local routing
Altera Corporation
May 2007