Xilinx Synthesis Technology User Guide

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XST User Guide not Full but Parallel module notfull (sel, i1, i2, i3, o1); input [1:0] sel; input [1:0] i1, i2, i3; output [1:0] o1; reg [1:0] o1; always @(sel or i1 or i2 or i3) begin case (sel) 2'b00: o1 = i1; 2'b01: o1 = i2; 2'b10: o1 = i3; endcase end endmodule 2-74 Xilinx Development System
neither Full nor Parallel module notfull_notparallel (sel1, sel2, i1, i2, o1); input [1:0] sel1, sel2; input [1:0] i1, i2; output [1:0] o1; reg [1:0] o1; always @(sel1 or sel2) begin case (2'b00) sel1: o1 = i1; sel2: o1 = i2; endcase end endmodule HDL Coding Techniques XST automatically determines the characteristics of the Case statements and generates logic using multiplexers, priority encoders and latches that best implement the exact behavior of the Case statement. This characterization of the Case statements can be guided or modified by using the Case Implementation Style parameter. Please refer to the “Design Constraints” chapter for more details. Accepted values for this parameter are default, full, parallel and full-parallel. • If the default is used, XST will implement the exact behavior of the Case statements. • If full is used, XST will consider that Case statements are complete and will avoid latch creation. • If parallel is used, XST will consider that the branches cannot occur in parallel and will not use a priority encoder. • If full-parallel is used, XST will consider that Case statements are complete and that the branches cannot occur in parallel, therefore saving latches and priority encoders. XST User Guide 2-75
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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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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 57 and 58: VHDL Code HDL Coding Techniques Fol
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
Page 67 and 68: Verilog Code HDL Coding Techniques
Page 69 and 70: HDL Coding Techniques 4-bit Unsigne
Page 73 and 74: Accumulators HDL Coding Techniques
Page 77 and 78: HDL Coding Techniques • shift mod
Page 79 and 80: Log File HDL Coding Techniques The
Page 83 and 84: HDL Coding Techniques 8-bit Shift-L
Page 93 and 94: Dynamic Shift Register module shift
Page 95 and 96: library IEEE; use IEEE.std_logic_11
Page 97: HDL Coding Techniques The following
Page 101 and 102: Related Constraints Related constra
Page 103 and 104: HDL Coding Techniques entity mux is
Page 107 and 108: Decoders Log File HDL Coding Techni
Page 109 and 110: VHDL (One-Cold) Following is the VH
Page 111 and 112: VHDL Following is the VHDL code. li
Page 115 and 116: Priority Encoders Log File HDL Codi
Page 117 and 118: Verilog Logical Shifters HDL Coding
Page 119 and 120: Example 1 HDL Coding Techniques The
Page 123 and 124: Verilog Arithmetic Operations Follo
Page 125 and 126: Unsigned 8-bit Adder HDL Coding Tec
Page 127 and 128: HDL Coding Techniques Verilog Follo
Page 131 and 132: Simple Signed 8-bit Adder HDL Codin
Page 133 and 134: Unsigned 8-bit Adder/Subtractor HDL
Page 135 and 136: Comparators (=, /=,=) HDL Coding Te
Page 137 and 138: HDL Coding Techniques this, XST can
Page 139 and 140: Dividers HDL Coding Techniques VHDL
Page 143 and 144: B C A OPER +/- RES OPER X8984 HDL C
Page 145 and 146: HDL Coding Techniques • RAM descr
Page 147 and 148: 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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VHDL Following is the VHDL code. li
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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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