Chap' 3 Basic Concepts

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Chap. 3 Basic Concepts
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Basic Concepts

• Lexical Conventions
• Data Types
• System Tasks and Compiler Directives
• Summary

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Lexical Conventions - I

• Whitespace
• Blank space (\b)
• Tabs (\t)
• Newlines (\n)
• Comments
• // single line
• / / multiple line
• Operators
• Unary ?!
• Binary ?-?
• Ternary a b ? c d

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Lexical Conventions - II

• Number Specification
• Sized numbers ltsizegtltbase formatgtltnumbergt
• 4b1111
• 12habc
• 16d255
• Unsized numbers
• 23456
• hc3
• o21
• X (unknown) and Z (high impedance)
• 12h13x
• 6hx
• 32bz
• Negative numbers
• -8d3
• Underscore characters and Question marks
• 12b1111_0000_1010 equals to 12b111100001010
• 4b10?? equals to 4b10zz

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Lexical Conventions - III

• String
• Hello Verilog World
• a/b
• Identifiers and Keywords
• reg value
• input clk

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Basic Concepts

• Lexical Conventions
• Data Types
• System Tasks and Compiler Directives
• Summary

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Data Types

• Value set and strength
• Nets
• Registers
• Vectors
• Integer?Real and Time Register Data Types
• Arrays
• Memories
• Parameters
• Strings

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Value Set and Strength
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Nets

• Declare a physical wire
• Keyword wire?wand?wor?tri?trior?trireg
• wire a
• wire b, c
• wire d 1b0

a, b, c are wires (nets).
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Registers

• Storage element for data
• Do not equal to hardware register
• Similar to variables in C

reg reset initial begin reset 1b1
100 reset 1b0 end
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Vectors - I

• wire and register can be defined as vector form
• format
• highlow or lowhigh

wre a wire 70 bus wire 310 busA, busB,
busC reg clock reg 040 virtual_addr
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Vectors - II

• Subset of vector
• Partial bits of vector

busA7 Bus20 Virtual_addr01
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Vectors - III

• Fixed width subset
• ltstarting_bitgtwidth or ltstarting_bitgt-width

reg 2550 data1 reg 0255 data2 reg 70
byte byte data131-8 // data13124 byte
data1248 // data13124 byte
data231-8 // data22431 byte
data2248 // data22431 for (j0 jlt31
jj1) // 70, 158255248 byte
data(j8)8 data1(byteNum8)8 8b0
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Integer, Real, and Time Register Data Types I

• Integer can represent signed number
• Real

integer counter initial counter -1
real dalta initial begin delta 4e10
delta 2.13 end integer i initial i
delta // rounded value of 2.13
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Integer, Real, and Time Register Data Types II

• Time
• Storing simulation time

time save_sim_time initial save_sim_time
time
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Arrays - I

• Type integer, register, time, real, or vector.
• Dimension no limit, but dimension must be
  constant
• Format
• ltarray_namegtltsubscriptgt

integer count07 reg bool310 time
chk_point1100 reg 40 port_id07 integer
matrix400255 reg 630 array_4d
15070702550 wire 70 w_array2
50 wire w_array17050
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Array - II
count5 0 chk_point100 0 port_id3
0 matrix10 33559 araay_4d0000150
0fff port_id 0 // error usage matrix1
0 // error usage
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Memories

• Array of register

reg mem1bit 01023 reg 70 membyte
01023 membyte511
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Parameters

• Define a constant
• Can be re-defined at topper level using
  defparam
• localparam (Verilog 2001 new feature)
• Can not be re-defined by defparam

parameter port_id 5 parameter cache_line_width
256 parameter signed 150 WIDTH
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Strings

• Can be assigned to register

reg 8181 string_value initial
string_value Hello Verilog World
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?3-3 ????
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Basic Concepts

• Lexical Conventions
• Data Types
• System Tasks and Compiler Directives
• Summary

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System Tasks

• Displaying information
• Monitoring information
• Stopping and finishing

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Displaying information - I

• display (p1, p2, p3,, pn)
• Like printf in C
• Format specification list

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Displaying information - II
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Displaying information - III
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Displaying information - IV
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Monitoring Information

• monitor(p1,p2,, pn)
• Monitor signal change and output the change

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Stopping and finishing

• stop stop simulation and enter interactive mode
  to debug
• finish end of simulation

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Compiler Directives

• define
• Define text macro, like define in C
• include
• Include the context of another file, like
  include in C

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Usage of define
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Usage of include
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Basic Concepts

• Lexical Conventions
• Data Types
• System Tasks and Compiler Directives
• Summary

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Summary

• Verilog is similar to C
• Lexical conventions
• Data Types
• Value set, wire, register, vector, integer, real,
  time, array, memory, parameter, string
• System Tasks
• display, monitor, stop, finish
• Compiler Directives
• define and include