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AR# 22258

XST and LogiCORE Turbo Product Code Encoder and Decoder (TPC) - How can I get the TPC to compile using XST, without incurring MAP Pack ERROR:Pack:679?

Description

How can I get the TPC to compile using XST, without incurring MAP Pack ERROR:Pack:679?

******************************************************************************

ERROR:Pack:679 - Unable to obey design constraints (MACRONAME=hset, RLOC=X0Y0)

which require the combination of the following symbols into a single SLICE

component:

LUT symbol "U_tpc_fifo/U0/U00" (Output Signal = U_tpc_fifo/U0/_n0001)

LUT symbol "U_tpc_fifo/U0/U01" (Output Signal = U_tpc_fifo/U0/z0<1>)

MUXCY symbol "U_tpc_fifo/U0/U10" (Output Signal = U_tpc_fifo/U0/c0<1>)

MUXCY symbol "U_tpc_fifo/U0/U11" (Output Signal = U_tpc_fifo/U0/c0<2>)

XORCY symbol "U_tpc_fifo/U0/U20" (Output Signal = U_tpc_fifo/U0/_n0006)

XORCY symbol "U_tpc_fifo/U0/U21" (Output Signal = U_tpc_fifo/U0/d0<1>)

FLOP symbol "U_tpc_fifo/U0/U30" (Output Signal = U_tpc_fifo/write_addr<0>)

FLOP symbol "U_tpc_fifo/U0/U31" (Output Signal = U_tpc_fifo/write_addr<1>)

Signal `U_tpc_fifo/U0/c0<1>' has a NOMERGE parameter. Please correct the

design constraints accordingly.

******************************************************************************

Solution

XST has a problem with the way the "syn_keep" is used for the carry chains in the "up_counter.vhd" and "down_counter.vhd".

To work around this issue, comment out the following lines:

- attribute syn_keep of c0 : signal is true;

- Line 91 in up_counter.vhd

- Line 91 in down_counter.vhd

- attribute BEL of U0 : label is bel_lut(i mod 2);

- attribute BEL of U2 : label is bel_xor(i mod 2);

- Lines 89 and 90 in subtract.vhd

For a detailed list of LogiCORE Turbo Product Code (TPC) Decoder Release Notes and Known Issues, see (Xilinx Answer 30178).

For a detailed list of LogiCORE Turbo Product Code (TPC) Encoder Release Notes and Known Issues, see (Xilinx Answer 30179).

AR# 22258
Date Created 09/04/2007
Last Updated 12/15/2012
Status Active
Type General Article