Xilinx Synthesis Technology User Guide

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XST User Guide Blocks The following table lists the results of evaluating expressions using the more frequently used operators supported by XST. Note The (===) and (!==) are special comparison operators useful in simulations to check if a variable is assigned a value of (x) or (z). They are treated as (==) or (!=) in synthesis. Table 7-2 Results of Evaluating Expressions a b a==b a===b a!=b a!==b a&b a&&b a|b a||b a^b 0 0 1 1 0 0 0 0 0 0 0 0 1 0 0 1 1 0 0 1 1 1 0 x x 0 x 1 0 0 x x x 0 z x 0 x 1 0 0 x x x 1 0 0 0 1 1 0 0 1 1 1 1 1 1 1 0 0 1 1 1 1 0 1 x x 0 x 1 x x 1 1 x 1 z x 0 x 1 x x 1 1 x x 0 x 0 x 1 0 0 x x x x 1 x 0 x 1 x x 1 1 x x x x 1 x 0 x x x x x x z x 0 x 1 x x x x x z 0 x 0 x 1 0 0 x x x z 1 x 0 x 1 x x 1 1 x z x x 0 x 1 x x x x x z z x 1 x 0 x x x x x Block statements are used to group statements together. XST only supports sequential blocks. Within these blocks, the statements are executed in the order listed. Parallel blocks are not supported by XST. Block statements are designated by begin and end keywords, and are discussed within examples later in this chapter. 7-8 Xilinx Development System
Modules Verilog Language Support In Verilog a design component is represented by a module. The connections between components are specified within module instantiation statements. Such a statement specifies an instance of a module. Each module instantiation statement must be given a name (instance name). In addition to the name, a module instantiation statement contains an association list that specifies which actual nets or ports are associated with which local ports (formals) of the module declaration. All procedural statements occur in blocks that are defined inside modules. There are two kinds of procedural blocks: the initial block and the always block. Within each block, Verilog uses a begin and end to enclose the statements. Since initial blocks are ignored during synthesis, only always blocks are discussed. Always blocks usually take the following format: always begin statement …... end where each statement is a procedural assignment line terminated by a semicolon. Module Declaration In the module declaration, the I/O ports of the circuit are declared. Each port has a name and a mode (in, out, and inout) as shown in the example below. module EXAMPLE (A, B, C, D, E); input A, B, C; output D; inout E; wire D, E; ... assign E = oe ? A : 1’bz; assign D = B & E; ... endmodule XST User Guide 7-9
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Xilinx Synthesis Technology (XST) U
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About This Manual Manual Contents T
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Resource Description/URL About This
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Conventions Typographical This manu
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Contents About This Manual Conventi
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Contents 8-bit Shift-Left Register
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Contents Dividers .................
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Contents Verilog Flow: ............
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Contents Sequential Process with a
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Introduction Architecture Support X
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Introduction 4. Set the desired Syn
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Figure 1-1 View Synthesis Report In
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HDL Coding Techniques This chapter
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HDL Coding Techniques The following
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Table 2-1 VHDL and Verilog Examples
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Signed/Unsigned Support Registers H
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Flip-flop with Positive-Edge Clock
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VHDL Code HDL Coding Techniques Fol
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IO Pins Description CE Clock Enable
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Log File HDL Coding Techniques The
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HDL Coding Techniques Verilog Code
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HDL Coding Techniques 4-bit Latch w
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Tristates Log File HDL Coding Techn
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Counters HDL Coding Techniques XST
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HDL Coding Techniques 4-bit Unsigne
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HDL Coding Techniques entity counte
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Verilog Code HDL Coding Techniques
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HDL Coding Techniques 4-bit Unsigne
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Accumulators HDL Coding Techniques
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HDL Coding Techniques • shift mod
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HDL Coding Techniques 8-bit Shift-L
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Dynamic Shift Register module shift
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library IEEE; use IEEE.std_logic_11
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neither Full nor Parallel module no
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Related Constraints Related constra
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HDL Coding Techniques entity mux is
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Decoders Log File HDL Coding Techni
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VHDL (One-Cold) Following is the VH
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VHDL Following is the VHDL code. li
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Priority Encoders Log File HDL Codi
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Verilog Logical Shifters HDL Coding
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Example 1 HDL Coding Techniques The
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Verilog Arithmetic Operations Follo
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Unsigned 8-bit Adder HDL Coding Tec
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HDL Coding Techniques Verilog Follo
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Simple Signed 8-bit Adder HDL Codin
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Unsigned 8-bit Adder/Subtractor HDL
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Comparators (=, /=,=) HDL Coding Te
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HDL Coding Techniques this, XST can
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Dividers HDL Coding Techniques VHDL
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B C A OPER +/- RES OPER X8984 HDL C
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HDL Coding Techniques • RAM descr
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HDL Coding Techniques entity raminf
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HDL Coding Techniques VHDL The foll
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HDL Coding Techniques Verilog The f
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HDL Coding Techniques VHDL The foll
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VHDL Following is the VHDL code for
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HDL Coding Techniques Single-Port R
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Verilog HDL Coding Techniques Follo
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HDL Coding Techniques Single-Port R
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Verilog Following is the Verilog co
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VHDL HDL Coding Techniques Followin
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Dual-Port RAM with Asynchronous Rea
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HDL Coding Techniques Dual-Port RAM
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HDL Coding Techniques architecture
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HDL Coding Techniques Dual-Port RAM
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VHDL Following is the VHDL code for
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Inputs Next State Function RESET CL
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FSM with 1 Process HDL Coding Techn
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Inputs FSM with 2 Processes HDL Cod
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process2 : process (state, x1) begi
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State Registers HDL Coding Techniqu
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Compact HDL Coding Techniques Compa
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Black Box Support Log File HDL Codi
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FPGA Optimization Introduction This
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Macro Generation • Number of Cloc
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Multiplexers FPGA Optimization For
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RAMs FPGA Optimization Two types of
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Flip-Flop Retiming FPGA Optimizatio
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FPGA Optimization INCREMENTAL_SYNTH
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FPGA Optimization Note In the curre
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FPGA Optimization generated NGC fil
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FPGA Optimization The problem most
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Log File Analysis FPGA Optimization
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FPGA Optimization • Tristates Thi
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FPGA Optimization NOTE: THESE TIMIN
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FPGA Optimization The start point a
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FPGA Optimization If the box_type a
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Instantiation of MUXF5 FPGA Optimiz
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Specifying INITs and RLOCs in HDL C
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FPGA Optimization for registers onl
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PCI Flow FPGA Optimization To succe
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CPLD Optimization This chapter cont
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Implementation Details for Macro Ge
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CPLD Optimization • Final results
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CPLD Optimization The CPLD fitter m
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Design Constraints Chapter 5 This c
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Synthesis Options Design Constraint
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Design Constraints Figure 5-4 Synth
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• Mux Extraction • Mux Style
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Design Constraints For FPGA device
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XST Constraint File (XCF) Design Co
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Design Constraints Timing Constrain
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Design Constraints • Add IO Buffe
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Design Constraints the components c
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HDL Constraints Design Constraints
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FPGA Constraints (non-timing) Desig
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Design Constraints • Number of Cl
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Design Constraints This constraint
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Timing Constraints Design Constrain
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Design Constraints See the “CLOCK
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Design Constraints The following ti
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Design Constraints • TIMEGRP TIME
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Design Constraints See the “INPAD
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Constraint Name clock_buffer bufgdl
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Constraint Name move_last- _stage m
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Constraint Name xor_collapse yes, n
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Constraint Name synthesis/ synopsis
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Design Constraints The following ta
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*Also Supported in XCF format. Impl
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Design Constraints The binary equiv
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Table 5-5 Third Party Constraints N
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Table 5-5 Third Party Constraints N
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Constraints Precedence Design Const
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VHDL Language Support Chapter 6 Thi
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VHDL Language Support 'W' means wea
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Command Line Mode You can improve t
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Command Line Mode Sometimes, XST is
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XST Shell Command Line Mode To use
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Case 2 Command Line Mode Each desig
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Log File Analysis Introduction This
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Quiet Mode Timing Report Log File A
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RAM Style : Auto ROM Extraction : y
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Synthesizing Unit . Related source
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# Counters : 2 # 4-bit up counter :
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Log File Analysis Data Path: sixty_
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CPLD Log File Log File Analysis The
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Analyzing Entity (Architecture ).
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Log File Analysis =================
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XST Naming Conventions This appendi
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