![]() Verilog expands filling the specified by working from right-to-left Spaces are allowed between the size, radix and value.Radix and hex digits (a,b,c,d,e,f) are case insensitive.In a radix of binary, octal, decimal, or hexadecimal.Sized or unsized numbers (Unsized size is 32 bits).Verilog HDL allows integer numbers to be specified as The underscore character (_) is legal anywhere in a number except as the first character, where it is ignored. When used in a number, the question mark (?) character is the Verilog alternative for the z character. Negative numbers are represented in 2's complement form. You can specify constant numbers in decimal, hexadecimal, octal, or binary format. So if you really want to use a identifier to start with a numeric value then use a escape character as shown below.ġ3 14 endmodule You could download file escape_id.v here Verilog does not allow to identifier to start with a numeric character. Terminate escaped identifiers with white space, otherwise characters that should follow the identifier are considered as part of it.Escaped identifier is terminated by white space (Characters such as commas, parentheses, and semicolons become part of the escaped identifier unless preceded by a white space).Entire identifier is escaped by the back slash.Escaped identifiers begin with the back slash ( \ ).Escaped identifiers provide a means of including any of the printable ASCII characters in an identifier (the decimal values 33 through 126, or 21 through 7E in hexadecimal). Verilog HDL allows any character to be used in an identifier by escaping the identifier. Identifiers can be up to 1024 characters long.Identifiers may contain alphabetic characters, numeric characters, the underscore, and the dollar sign ( a-z A-Z 0-9 _ $ ).Identifiers must begin with an alphabetic character or the underscore character ( a-z A-Z _ ).Identifiers are names used to give an object, such as a register or a function or a module, a name so that it can be referenced from other places in a description. NOTE : Never use Verilog keywords as unique names, even if the case is different. You could download file unique_names.v here Lower case letters are unique from upper case letters.Multi line comments begin with the token /* and end with the token */Ģ4 25 endmodule You could download file comment.v here.Single line comments begin with the token // and end with a carriage return.There are two forms to introduce comments. However, blanks and tabs are significant in strings.ģ wire a,b,ci,sum,co endmodule You could download file bad_code.v hereġ7 18 endmodule You could download file good_code.v here ![]() These characters are ignored except when they serve to separate other tokens. White space can contain the characters for blanks, tabs, newlines, and form feeds. Verilog HDL is a case-sensitive language. Thus, the number 2345.The basic lexical conventions used by Verilog HDL are similar to those in the C programming language.Meanwhile, the digit 6 after the decimal point is in the tenths (1/10, which is 10 -1) and 7 is in the hundredths (1/100, which is 10 -2) position.2 is in the position of thousands (10 3).3 is in the position of hundreds (10 2). ![]() The digit 5 is in the position of ones (10 0, which equals 1),. ![]() The Hindu-Arabic numeral system gives positions to the digits in a number and this method works by using powers of the base 10 digits are raised to the n th power, in accordance with their position.įor instance, take the number 2345.67 in the decimal system: The difficulty of representing very large numbers in the decimal system was overcome by the Hindu–Arabic numeral system. Therefore, it has 10 symbols: The numbers from 0 to 9 namely 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.Īs one of the oldest known numeral systems, the decimal numeral system has been used by many ancient civilizations. It uses the number 10 as its base (radix). The decimal numeral system is the most commonly used and the standard system in daily life.
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