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AR# 32987 11.1 MAP, Virtex-6/ Virtex-5/ Spartan-6 - What options are available that allow two SRL16s to be combined into one LUT Complex?

Description

I would like MAP to combine two SRL16s into a single LUT Complex. How can this be done?

Solution


For manual control of SRL16 LUT sharing, two SRL16s can be constrained to the same LUT Complex by assigning each the same LUTNM property as follows :

INST "SRL16E_0" lutnm = group_1;
INST "SRL16E_1" lutnm = group_1;

Automatic LUT sharing for SRL16s is being introduced in ISE version 11.2. The following describes the behavior of the three affected device families:

Virtex-6
Default is "AUTO", other values are "AREA" and "OFF"
The value can be changed with the following variable:
setenv XIL_MAP_SRL_COMPRESSION AREA (Linux)
SET XIL_MAP_SRL_COMPRESSION=AREA (Windows)

Spartan-6
Default is "AREA", other values are "AUTO" and "OFF"
The value can be changed with the following variable:
setenv XIL_MAP_SRL_COMPRESSION AUTO (Linux)
SET XIL_MAP_SRL_COMPRESSION=AUTO (Windows)

Virtex-5
Default is off. When turned on, this feature is equivalent to AREA mode.
The feature can be turned on with the following variable:
setenv XIL_MAP_SRL_COMPRESSION 1 (Linux)
SET XIL_MAP_SRL_COMPRESSION AUTO=1 (Windows)
NOTE: Unset the variable to turn this feature off for Virtex-5. Do not use "0" as any value is considered to be "on".

Linked Answer Records

Associated Answer Records

Answer Number Answer Title Version Found Version Resolved
37213 Virtex-6 FPGA Design Assistant - Troubleshoot common fabric problems N/A N/A

Actions

AR# 32987
Date Created 06/18/2009
Last Updated 12/15/2012
Status Active
Type General Article
Devices
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