Register Ordering, Data01 Addr02 Atod03 Dtoa04

Register Ordering

ACLB (Virtex/-E/-II/-II PRO or Spartan-II/IIE slice) has two flip-flops, so two register bits can be mapped into one CLB. For PAR (Place And Route) to place a register in the most effective way, you want as many pairs of contiguous bits as possible to be mapped together into the same CLBs (for example, bit 0 and bit 1 together in one CLB, bit 2 and bit 3 in another).

MAP pairs register bits (performing register ordering) if it recognizes that a series of flip- flops comprise a register. When you create your design, you can name register bits so they are mapped using register ordering.

Note: MAP does not perform register ordering on any flip-flops which have BLKNM, LOC, or RLOC properties attached to them. The BLKNM, LOC, and RLOC properties define how blocks are to be mapped, and these properties override register ordering.

To be recognized as a candidate for register ordering, the flip-flops must have the following characteristics:

•The flip-flops must share a common clock signal and common control signals (for example, Reset and Clock Enable).

•The flip-flop output signals must all be named according to this convention.

•Output signal names must begin with a common root containing at least one alphabetic character.

The names must end with numeric characters or with numeric characters surrounded by parentheses “( )”, angle brackets “< >”, or square brackets “[ ]”.

For example, acceptable output signal names for register ordering are as follows:

data1	addr(04)	bus<1>
data2	addr(08)	bus<2>
data3	addr(12)	bus<3>
data4	addr(16)	bus<4>

If a series of flip-flops is recognized as a candidate for register ordering, they are paired in CLBs in sequential numerical order. For example, in the first set of names shown above, data1 and data2, are paired in one CLB, while data3 and data4 are paired in another.

In the example below, no register ordering is performed, since the root names for the signals are not identical

data01

addr02

atod03

dtoa04

When it finds a signal with this type of name, MAP ignores the underscore and the numeric characters when it considers the signal for register ordering. For example, if signals are named data00_1 and data01_2, MAP considers them as data00 and data01 for purposes of register ordering. These two signals are mapped to the same CLB.

MAP does not change signal names when it checks for underscores—it only ignores the underscore and the number when it checks to see if the signal is a candidate for register ordering.

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8.2i specifications

Xilinx 8.2i is a significant version of the Xilinx ISE (Integrated Software Environment) that emerged in the early 2000s, marking an important milestone in the world of FPGA (Field-Programmable Gate Array) development. This version introduced a slew of advanced features, technologies, and characteristics that made it an indispensable tool for engineers and developers in designing, simulating, and implementing digital circuits.

One of the standout features of Xilinx 8.2i is its enhanced design entry capabilities. This version supports multiple design entry methods, including schematic entry, VHDL, and Verilog HDL, giving engineers the flexibility to choose their preferred approach. The integrated environment provides user-friendly graphical interfaces, making it accessible for both novice and experienced users.

Xilinx 8.2i's synthesis tools have been improved to enable more efficient design compilation and optimization. The new algorithms used in this version facilitate faster synthesis times while reducing power consumption and improving performance. Furthermore, it features support for advanced FPGA architectures, which allows for the implementation of more complex designs with greater efficiency.

The implementation tools in Xilinx 8.2i include advanced place and route capabilities, utilizing state-of-the-art algorithms for optimized resource usage. These tools enable designers to make better use of FPGA resources, ensuring that designs fit within the constraints of the target device while maximizing performance.

Another key characteristic of Xilinx 8.2i is its extensive support for various Xilinx devices such as the Spartan, Virtex, and CoolRunner series. This compatibility ensures that developers can leverage the powerful features of these FPGA families, including high-speed transceivers and DSP slices.

Xilinx 8.2i also places a strong emphasis on simulation and verification. The version integrates with various simulation tools, allowing for thorough testing of the designs before implementation. This reduces the risk of errors and ensures that the final product meets specifications.

In addition, this version includes support for design constraints, enabling engineers to specify timing, area, and other critical design parameters. By accommodating constraints, Xilinx 8.2i helps in achieving reliable and efficient designs tailored to project needs.

In summary, Xilinx 8.2i is a robust software development tool that enhances the design process for FPGAs. Its comprehensive features, including multiple design entry options, advanced synthesis and implementation tools, extensive device support, and strong simulation capabilities, make it a valuable resource for engineers and developers striving for innovation in digital design.

Xilinx 8.2i manual Register Ordering, Data01 Addr02 Atod03 Dtoa04

Models: 8.2i