VHDL numbering conventions

The first of two VHDL number styles is:

[ - ] [ radix # ] value [ # ]


  

  

    
 
Element
    
 
Description
  
  

    
 
- 
    
 
indicates a negative number; optional
  
  

    
 
radix 
    
 
can be any base in the range 2 through 16 (2, 8, 10, or 16); by default, numbers are assumed to be decimal; optional
  
  

    
 
value
    
 
specifies the numeric value, expressed in the specified radix; required
  
  

    
 
# 
    
 
is a delimiter between the radix and the value; the first # sign is required if a radix is used, the second is always optional
  





 

Note: A `-' can also be used to designate a "don't care" element when you search for a signal in the List or Wave window. If you want the `-' to be read as a "don't care" element, rather than a negative sign, be sure to enclose the number in double quotes. For instance, you would type "-0110--" as opposed to -0110--. If you don't include the double quotes, ModelSim will read the `-' as a negative sign.

Examples

16#FFca23#
2#11111110
-23749 

The second VHDL number style is:

base "value"


  

  

    
 
Element
    
 
Description
  
  

    
 
base
    
 
specifies the base; binary: B, octal: O, hex: X; required
  
  

    
 
value
    
 
specifies digits in the appropriate base with optional underscore separators; default is decimal; required
  





 

Examples

B"11111110"
X"FFca23" 

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