Xilinx Synthesis Technology User Guide

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XST User Guide XCF Syntax and Utilization ......................................................5-11 Timing Constraints vs. Non-timing Constraints ...................5-13 Limitations ...........................................................................5-13 Old XST Constraint Syntax ...........................................................5-14 General Constraints ......................................................................5-14 HDL Constraints ............................................................................5-19 FPGA Constraints (non-timing) .....................................................5-21 CPLD Constraints (non-timing) .....................................................5-25 Timing Constraints ........................................................................5-27 Global Timing Constraints Support ..........................................5-29 Domain Definitions ..............................................................5-30 XCF Timing Constraint Support ...............................................5-30 Old Timing Constraint Support .................................................5-33 Constraints Summary ....................................................................5-36 Implementation Constraints ..........................................................5-47 Handling by XST ......................................................................5-47 Examples .................................................................................5-48 Example 1 ...........................................................................5-48 Example 2 ...........................................................................5-49 Example 3 ...........................................................................5-49 Third Party Constraints .................................................................5-50 Constraints Precedence ................................................................5-55 Chapter 6 VHDL Language Support Introduction ...................................................................................6-2 Data Types in VHDL .....................................................................6-2 Overloaded Data Types ...........................................................6-4 Multi-dimensional Array Types .................................................6-5 Record Types ................................................................................6-7 Objects in VHDL ............................................................................6-7 Operators ......................................................................................6-8 Entity and Architecture Descriptions .............................................6-8 Entity Declaration .....................................................................6-9 Architecture Declaration ...........................................................6-9 Component Instantiation ..........................................................6-10 Recursive Component Instantiation ....................................6-12 Component Configuration ........................................................6-14 Generic Parameter Declaration ...............................................6-14 Combinatorial Circuits ...................................................................6-15 Concurrent Signal Assignments ...............................................6-15 Simple Signal Assignment .......................................................6-16 Selected Signal Assignment ....................................................6-16 Conditional Signal Assignment ................................................6-17 Generate Statement .................................................................6-18 Combinatorial Process .............................................................6-19 If...Else Statement ....................................................................6-22 Case Statement .......................................................................6-24 For...Loop Statement ...............................................................6-25 Sequential Circuits ........................................................................6-26 xvi Xilinx Development System
Contents Sequential Process with a Sensitivity List ................................6-26 Sequential Process without a Sensitivity List ...........................6-27 Examples of Register and Counter Descriptions .....................6-27 Multiple Wait Statements Descriptions ....................................6-31 Functions and Procedures ............................................................6-33 Packages ......................................................................................6-36 STANDARD Package ..............................................................6-37 IEEE Packages ........................................................................6-38 Synopsys Packages .................................................................6-39 VHDL Language Support ..............................................................6-40 VHDL Reserved Words .................................................................6-47 Chapter 7 Verilog Language Support Introduction ...................................................................................7-2 Behavioral Verilog Features ..........................................................7-3 Variable Declaration .................................................................7-3 Arrays .................................................................................7-3 Multi-dimensional Arrays ....................................................7-3 Data Types ...............................................................................7-4 Legal Statements .....................................................................7-5 Expressions .............................................................................7-5 Blocks ......................................................................................7-8 Modules ...................................................................................7-9 Module Declaration ..................................................................7-9 Verilog Assignments ................................................................7-10 Continuous Assignments .........................................................7-10 Procedural Assignments ..........................................................7-11 Combinatorial Always Blocks ..............................................7-11 If...Else Statement ..............................................................7-12 Case Statement ..................................................................7-12 For and Repeat Loops ........................................................7-13 While Loops .......................................................................7-15 Sequential Always Blocks ...................................................7-16 Assign and Deassign Statements .......................................7-18 Assignment Extension Past 32 Bits ....................................7-22 Tasks and Functions ...........................................................7-22 Blocking Versus Non-Blocking Procedural Assignments ....7-25 Constants, Macros, Include Files and Comments ...................7-26 Constants ............................................................................7-26 Macros ................................................................................7-26 Include Files ........................................................................7-27 Comments ..........................................................................7-27 Structural Verilog Features ...........................................................7-28 Parameters ....................................................................................7-31 Verilog Limitations in XST .............................................................7-32 Case Sensitivity .......................................................................7-32 Blocking and Nonblocking Assignments ..................................7-33 Integer Handling .......................................................................7-34 Verilog Meta Comments ................................................................7-35 XST User Guide xvii
Page 1 and 2: Xilinx Synthesis Technology (XST) U
Page 3 and 4: About This Manual Manual Contents T
Page 5 and 6: Resource Description/URL About This
Page 7 and 8: Conventions Typographical This manu
Page 9 and 10: Contents About This Manual Conventi
Page 11 and 12: Contents 8-bit Shift-Left Register
Page 13 and 14: Contents Dividers .................
Page 15: Contents Verilog Flow: ............
Page 19 and 20: Introduction Architecture Support X
Page 21 and 22: Introduction 4. Set the desired Syn
Page 23 and 24: Figure 1-1 View Synthesis Report In
Page 25 and 26: HDL Coding Techniques This chapter
Page 27 and 28: HDL Coding Techniques The following
Page 31 and 32: Table 2-1 VHDL and Verilog Examples
Page 37 and 38: Signed/Unsigned Support Registers H
Page 39 and 40: Flip-flop with Positive-Edge Clock
Page 43 and 44: VHDL Code HDL Coding Techniques Fol
Page 47 and 48: IO Pins Description CE Clock Enable
Page 49 and 50: Log File HDL Coding Techniques The
Page 51 and 52: HDL Coding Techniques Verilog Code
Page 53 and 54: HDL Coding Techniques 4-bit Latch w
Page 55 and 56: Tristates Log File HDL Coding Techn
Page 59 and 60: Counters HDL Coding Techniques XST
Page 63 and 64: HDL Coding Techniques 4-bit Unsigne
Page 65 and 66: 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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VHDL Code HDL Coding Techniques Fol
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Accumulators HDL Coding Techniques
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HDL Coding Techniques • shift mod
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Log File HDL Coding Techniques The
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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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HDL Coding Techniques The following
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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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Log File HDL Coding Techniques The
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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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VHDL Language Support compiled in t
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Record Types Objects in VHDL MATRIX
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Entity Declaration VHDL Language Su
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VHDL Language Support Example 6-2 g
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VHDL Language Support Example 6-3 4
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egin Y 13), port map (X,Y,C1); C2
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VHDL Language Support Example 6-5 M
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VHDL Language Support Example 6-8 N
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Example 6-10 Combinatorial Process
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VHDL Language Support Example 6-12
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For...Loop Statement VHDL Language
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Sequential Process without a Sensit
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egin if RST = '1' then DO
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Multiple Wait Statements Descriptio
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Functions and Procedures VHDL Langu
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VHDL Language Support Example 6-24
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STANDARD Package VHDL Language Supp
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VHDL Language Support Note Function
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Packages Enumeration Types Integer
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Table 6-4 Objects VHDL Language Sup
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Wait Statement Loop Statement Table
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VHDL Reserved Words The following t
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Verilog Language Support Chapter 7
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Behavioral Verilog Features Verilog
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Verilog Language Support Example 7-
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Table 7-1 Expressions Bitwise Negat
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Modules Verilog Language Support In
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Procedural Assignments Verilog Lang
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Verilog Language Support Casez trea
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While Loops Verilog Language Suppor
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Verilog Language Support Example 7-
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Verilog Language Support The main l
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Verilog Language Support • You ca
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Example 7-9 Function Declaration an
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Blocking Versus Non-Blocking Proced
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Include Files Verilog Language Supp
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Verilog Language Support Each insta
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Parameters Verilog Language Support
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Verilog Language Support • Design
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Verilog Meta Comments Verilog Langu
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Table 7-4 Data Types Registers Vect
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Table 7-8 Design Hierarchy Module d
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Verilog Reserved Keywords Verilog L
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Command Line Mode Introduction Chap
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Command Line Mode • Script File
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Command Line Mode • Second column
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Table 8-4 HDL Options (VHDL and Ver
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Command Line Mode Table 8-6 Target
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Command Line Mode • To get a list
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Elaborate Command Time Command Comm
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♦ smallcntr.vhd Command Line Mode
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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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