Functional Categories

This section categorizes, by function, the logic elements that are described in detail in the “Design Elements” sections. Each category is briefly described. Tables under each category identify all the available elements for the function and indicate which libraries include the element.

Elements are listed in alphanumeric order under each category. There are a number of standard TTL 7400-type functions in the different libraries. All 7400-type functions start with a “X74” prefix and are listed after all other elements. The numeric sequence following the “X74” prefix uses ascending numbers, for example, X74_42 precedes X74_138.

A check mark () in the column under the library name means that the element applies to the devices that use that library. (Refer to the “Applicable Architectures” section of the “Xilinx Unified Libraries” chapter for information on the specific device families that use each library.) A blank column means that the element does not apply.

The categories are as follows.

• Arithmetic Functions
  
  
• Buffers
  
  
• Comparators
  
  
• Counters
  
  
• Data Registers
  
  
• Decoders
  
  
• Edge Decoders
  
  
• Encoders
  
  
• Flip-Flops
  
  
• General
  
  
• Input/Output Flip-Flops
  
  
• Input/Output Functions
  
  
• Input Latches
  
  
• Latches
  
  
• Logic Primitives
  
  
• Map Elements
  
  
• Memory Elements
  
  
• Multiplexers
  
  
• Shift Registers
  
  
• Shifters
  
  

NOTE

When converting your design between FPGA families, use elements that have equivalent functions in each of the architectural families (libraries) to minimize re-designing.

Arithmetic Functions

There are three types of arithmetic functions: accumulators (ACC), adders (ADD), and adder/subtracters (ADSU). With an ADSU, either unsigned binary or twos-complement operations cause an overflow. If the result crosses the overflow boundary, an overflow is generated. Similarly, when the result crosses the carry-out boundary, a carry-out is generated. The following figure shows the ADSU carry-out and overflow boundaries.

Figure 2.1 ADSU Carry-Out and Overflow Boundaries

		1-Bit Loadable Cascadable Accumulator with Carry-In, Carry-Out, and Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-, 8-, 16-Bit Loadable Cascadable Accumulators with Carry-In, Carry-Out, and Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		1-Bit Full Adder with Carry-In and Carry-Out
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-, 8-, 16-Bit Cascadable Full Adders with Carry-In, Carry-Out, and Overflow
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		1-Bit Cascadable Adder/Subtracter with Carry-In, Carry-Out
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-, 8-, 16-Bit Cascadable Adders/Subtracters with Carry-In, Carry-Out and Overflow
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		9-Bit Odd/Even Parity Generator/Checker
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-Bit Full Adder with Carry-In and Carry-Out
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

Buffers

The buffers in this section route high fan-out signals, 3-state signals, and clocks inside a PLD device. The “Input/Output Functions” section later in this chapter covers off-chip interface buffers.

		Alternate Clock Buffer
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		General-Purpose Buffer
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		General-Purpose Buffers
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Fast Connect Buffer
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Internal 3-State Buffers with Active High Enable
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex
				*
* not supported for XC9500XL devices

		Global Fast Clock Buffer
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Global Clock Buffer
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Clock Delay Locked Loop Buffer
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Global Low Early Clock Buffer
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Global Low Skew Clock Buffer
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Primary Global Buffer for Driving Clocks or Longlines (Four per PLD Device)
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Secondary Global Buffer for Driving Clocks or Longlines (Four per PLD Device)
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Global Set/Reset Input Buffer
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Global Three-State Input Buffer
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Open-Drain Buffer
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Internal 3-State Buffers with Active-Low Enable
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex
				*
* not supported for XC9500XL devices

		Global Clock Buffer
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

Comparators

There are two types of comparators, identity (COMP) and magnitude (COMPM).

		2-, 4-, 8-, 16-Bit Identity Comparators
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		2-, 4-, 8-, 16-Bit Magnitude Comparators
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		8-, 16-Bit Magnitude Comparators
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-Bit Expandable Magnitude Comparator
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		8-Bit Identity Comparator with Active-Low Enable
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		8-Bit Identity Comparator with Active-Low Enable and Output
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

Counters

There are six types of counters with various synchronous and asynchronous inputs. The name of the counter defines the modulo or bit size, the counter type, and which control functions are included. The counter naming convention is shown in the following figure.

Figure 2.2 Counter Naming Convention

A carry-lookahead design accommodates large counters without extra gating. On TTL 7400-type counters with trickle clock enable (ENT), parallel clock enable (ENP), and ripple carry-out (RCO), both the ENT and ENP inputs must be High to count. ENT is propagated forward to enable RCO, which produces a High output with the approximate duration of the QA output. The following figure illustrates a carry-lookahead design.

Figure 2.3 Carry-Lookahead Design

The RCO output of the first stage of the ripple carry is connected to the ENP input of the second stage and all subsequent stages. The RCO output of the second stage and all subsequent stages is connected to the ENT input of the next stage. The ENT of the second stage is always enabled/tied to VCC. CE is always connected to the ENT input of the first stage. This cascading method allows the first stage of the ripple carry to be built as a prescaler. In other words, the first stage is built to count very fast.

		2-, 4-, 8-, 16-Bit Cascadable Binary Counters with Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		2-, 4-, 8-, 16-Bit Loadable Cascadable Binary Counters with Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		2-, 4-, 8-, 16-Bit Loadable Cascadable Bidirectional Binary Counters with Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		2-, 4-, 8-, 16-Bit Cascadable Binary Counters with Clock Enable and Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		2-, 4-, 8-, 16-Bit Loadable Cascadable Binary Counters with Clock Enable and Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		2-, 4-, 8-, 16-Bit Loadable Cascadable Bidirectional Binary Counters with Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		2-, 4-, 8-, 16-Bit Loadable Cascadable Bidirectional Binary Counters with Clock Enable and Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		8-, 16-Bit Cascadable Binary Counters with Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		8-, 16-Bit Loadable Cascadable Binary Counters with Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		8-, 16-Bit Loadable Cascadable Bidirectional Binary Counters with Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		8-, 16-Bit Cascadable Binary Counters with Clock Enable and Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-Bit Cascadable BCD Counter with Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-Bit Loadable Cascadable BCD Counter with Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-Bit Cascadable BCD Counter with Clock Enable and Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-Bit Loadable Cascadable BCD Counter with Clock Enable and Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-, 5-, 8-Bit Johnson Counters with Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-, 5-, 8-Bit Johnson Counters with Clock Enable and Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		8-, 16-Bit Negative-Edge Binary Ripple Counters with Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-Bit BCD Counter with Parallel and Trickle Enables, Active-Low Load Enable, and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-Bit Binary Counter with Parallel and Trickle Enables, Active-Low Load Enable, and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-Bit BCD Counter with Parallel and Trickle Enables, Active-Low Load Enable, and Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-Bit Binary Counter with Parallel and Trickle Enables, Active-Low Load Enable, and Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-Bit BCD Bidirectional Counter with Parallel and Trickle Clock Enables and Active-Low Load Enable
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-Bit BCD/Bi-Quinary Ripple Counter with Negative-Edge Clocks and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

Data Registers

There are three TTL 7400-type data registers designed to function exactly as the TTL elements for which they are named.

		6-Bit Data Register with Active-Low Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		8-Bit Data Register with Active-Low Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		8-Bit Data Register with Active-Low Clock Enable
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

Decoders

Decoder names, shown in the following figure, indicate the number of inputs and outputs and if an enable is available. Decoders with an enable can be used as multiplexers. This group includes some standard TTL 7400-type decoders whose names have an “X74” prefix.

Figure 2.4 Decoder Naming Convention

		2- to 4-Line Decoder/Demultiplexer with Enable
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		3- to 8-Line Decoder/Demultiplexer with Enable
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4- to 16-Line Decoder/Demultiplexer with Enable
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-, 8-, 16-Bit Active Low Decoders
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4- to 10-Line BCD-to-Decimal Decoder with Active-Low Outputs
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		3- to 8-Line Decoder/Demultiplexer with Active-Low Outputs and Three Enables
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		2- to 4-Line Decoder/Demultiplexer with Active-Low Outputs and Active-Low Enable
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4- to 16-Line Decoder/Demultiplexer with Two Enables and Active-Low Outputs
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

Edge Decoders

Edge decoders are open-drain wired-AND gates that are available in different bit sizes.

		4-, 8-, 16-Bit Active-Low Decoders
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		32- and 64-Bit Active-Low Decoders
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

Encoders

There are two priority encoders (ENCPR) that function like the TTL 7400-type elements they are named after. There is a 10- to 4-line BCD encoder and an 8- to 3-line binary encoder.

		10- to 4-Line Priority Encoder with Active-Low Inputs and Outputs
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		8- to 3-Line Cascadable Priority Encoder with Active-Low Inputs and Outputs
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

Flip-Flops

There are three types of flip-flops (D, J-K, toggle) with various synchronous and asynchronous inputs. Some are available with inverted clock inputs and/or the ability to set in response to global set/reset rather than reset. The naming convention shown in the following figure provides a description for each flip-flop. D-type flip-flops are available in multiples of up to 16 in one macro.

Figure 2.5 Flip-Flop Naming Convention

		D Flip-Flop
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Negative-Edge Clock
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Multiple D Flip-Flops
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-, 8-, 16-Bit Data Registers with Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		4-, 8-, 16-Bit Data Registers with Clock Enable and Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Negative-Edge Clock and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Negative-Edge Clock, Clock Enable, and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Asynchronous Preset and Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Negative-Edge Clock and Asynchronous Preset and Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Clock Enable and Asynchronous Preset and Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Negative-Edge Clock, Clock Enable, and Asynchronous Preset and Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Clock Enable
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Negative-Edge Clock and Clock Enable
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Asynchronous Preset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Negative-Edge Clock and Asynchronous Preset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Clock Enable and Asynchronous Preset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Negative-Edge Clock, Clock Enable, and Asynchronous Preset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Negative-Edge Clock and Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Clock Enable and Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Negative-Clock Edge, Clock Enable, and Synchronous Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Synchronous Reset and Synchronous Set
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Negative-Clock Edge and Synchronous Reset and Set
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Synchronous Reset and Set and Clock Enable
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Negative-Clock Edge, Synchronous Reset and Set, and Clock Enable
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Synchronous Set
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Negative-Edge Clock and Synchronous Set
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Clock Enable and Synchronous Set
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Negative-Edge Clock, Clock Enable, and Synchronous Set
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Synchronous Set and Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		D Flip-Flop with Synchronous Set and Reset and Clock Enable
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		J-K Flip-Flop with Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		J-K Flip-Flop with Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		J-K Flip-Flop with Asynchronous Clear and Preset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		J-K Flip-Flop with Asynchronous Clear and Preset and Clock Enable
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		J-K Flip-Flop with Asynchronous Preset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		J-K Flip-Flop with Clock Enable and Asynchronous Preset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		J-K Flip-Flop with Clock Enable and Synchronous Reset and Set
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		J-K Flip-Flop with Clock Enable and Synchronous Set and Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Toggle Flip-Flop with Toggle Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Toggle Flip-Flop with Toggle and Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Toggle/Loadable Flip-Flop with Toggle and Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Toggle/Loadable Flip-Flop with Toggle and Clock Enable and Asynchronous Clear
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Toggle Flip-Flop with Toggle Enable and Asynchronous Clear and Preset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Toggle Flip-Flop with Toggle and Clock Enable and Asynchronous Clear and Preset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Loadable Toggle Flip-Flop with Toggle and Clock Enable and Asynchronous Clear and Preset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Toggle Flip-Flop with Toggle Enable and Asynchronous Preset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Toggle Flip-Flop with Toggle and Clock Enable and Asynchronous Preset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Toggle/Loadable Flip-Flop with Toggle and Clock Enable and Asynchronous Preset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Toggle Flip-Flop with Toggle and Clock Enable and Synchronous Reset and Set
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Toggle/Loadable Flip-Flop with Toggle and Clock Enable and Synchronous Reset and Set
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Toggle Flip-Flop with Toggle and Clock Enable and Synchronous Set and Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Toggle/Loadable Flip-Flop with Toggle and Clock Enable and Synchronous Set and Reset
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

General

General elements include FPGA configuration functions, oscillators, boundary scan logic, and other functions not classified in other sections.

		Boundary Scan Logic Control Circuit
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Virtex Boundary Scan Logic Control Circuit
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Bypass Oscillator
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Virtex Register State Capture for Bitstream Readback
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Internal Multiple-Frequency Clock Divider
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		CLB Configuration Symbol
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Clock Delay Locked Loop
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		High Frequency Clock Delay Locked Loop
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Repository for Schematic-Level (Global) Attributes
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Initialization Stage for Carry Chain
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex

		Ground-Connection Signal Tag
XC3000	XC4000E	XC4000X	XC5200	XC9000	Spartan	SpartanXL	Virtex