Xilinx Synthesis Technology User Guide

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XST User Guide ROMs For Block RAM XST uses: • RAMB4_Sn primitives for Single-Port Synchronous Block RAM • RAMB4_Sn_Sn primitives for Dual-Port Synchronous Block RAM In order to have a better control of the implementation of the inferred RAM, XST offers a way to control RAM inference, and to select the generation of Distributed RAM or Block RAMs (if possible). The attribute RAM_STYLE specifies that an inferred RAM be generated using: • Block RAM if the value is block. • Distributed RAM if the value is distributed. You can apply the RAM_STYLE attribute either to a signal that defines the RAM or the instance name of the RAM. This attribute can also be global. If the RAM resources are limited, XST can generate additional RAMs using registers. To do this use the attribute RAM_EXTRACT with the value set to no. In Virtex-II and Virtex-II Pro, a ROM can be inferred when all assigned contexts in a Case or If...else statement are constants. Macro inference will only consider ROMs of at least 16 words with no width restriction. For example, the following HDL equation can be implemented with a ROM of 16 words of 4 bits. data = if address = 0000 then 0010 if address = 0001 then 1100 if address = 0010 then 1011 ... if address = 1111 then 0001 3-8 Xilinx Development System
Flip-Flop Retiming FPGA Optimization A ROM can also be inferred from an array composed entirely of constants, as in the following HDL example. type ROM_TYPE is array(15 downto 0)of std_logic_vector(3 downto 0); constant ROM : rom_type := ("0010", "1100", "1011", ..., "0001"); ... data
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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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Page 175 and 176: VHDL HDL Coding Techniques Followin
Page 177 and 178: HDL Coding Techniques Dual-Port RAM
Page 179 and 180: Verilog HDL Coding Techniques Follo
Page 181 and 182: HDL Coding Techniques architecture
Page 183 and 184: HDL Coding Techniques Dual-Port RAM
Page 195 and 196: VHDL Following is the VHDL code for
Page 197 and 198: Inputs Next State Function RESET CL
Page 199 and 200: FSM with 1 Process HDL Coding Techn
Page 201 and 202: Inputs FSM with 2 Processes HDL Cod
Page 205 and 206: process2 : process (state, x1) begi
Page 207 and 208: State Registers HDL Coding Techniqu
Page 209 and 210: Compact HDL Coding Techniques Compa
Page 211 and 212: Black Box Support Log File HDL Codi
Page 215 and 216: FPGA Optimization Introduction This
Page 217 and 218: Macro Generation • Number of Cloc
Page 219 and 220: Multiplexers FPGA Optimization For
Page 221: RAMs FPGA Optimization Two types of
Page 225 and 226: FPGA Optimization INCREMENTAL_SYNTH
Page 227 and 228: FPGA Optimization Note In the curre
Page 229 and 230: FPGA Optimization generated NGC fil
Page 231 and 232: FPGA Optimization The problem most
Page 233 and 234: Log File Analysis FPGA Optimization
Page 235 and 236: FPGA Optimization • Tristates Thi
Page 237 and 238: FPGA Optimization NOTE: THESE TIMIN
Page 239 and 240: FPGA Optimization The start point a
Page 241 and 242: FPGA Optimization If the box_type a
Page 243 and 244: Instantiation of MUXF5 FPGA Optimiz
Page 247 and 248: Specifying INITs and RLOCs in HDL C
Page 249 and 250: FPGA Optimization for registers onl
Page 251 and 252: PCI Flow FPGA Optimization To succe
Page 253 and 254: CPLD Optimization This chapter cont
Page 255 and 256: Implementation Details for Macro Ge
Page 257 and 258: CPLD Optimization • Final results
Page 259 and 260: CPLD Optimization The CPLD fitter m
Page 261 and 262: Design Constraints Chapter 5 This c
Page 263 and 264: Synthesis Options Design Constraint
Page 265 and 266: Design Constraints Figure 5-4 Synth
Page 267 and 268: • Mux Extraction • Mux Style
Page 269 and 270: Design Constraints For FPGA device
Page 271 and 272: 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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