Filter Design Toolbox

setbits

Set all data format property values for quantized filters and quantized FFTs

Syntax

• setbits(Hq,format)
  

setbits(F,fmt)

Description

When Hq is a floating-point quantized filter, setbits(Hq,format) sets all data format properties for the quantized filter Hq to the values specified by format. In this case, format is a two-element vector of integers whose entries are described as follows:

• The first entry in format sets the word length in bits.
• The second entry in format sets the exponent length in bits.

When Hq is a fixed-point quantized filter, setbits(Hq,format) sets the properties CoefficientFormat, InputFormat, and OutputFormat to the value specified by format, whereas the property values SumFormat and ProductFormat are specified by 2*format. In this case, format is a two-element vector of integers whose entries are described as follows:

• The first entry in format sets the word length in bits.
• The second entry in format sets the fraction length (the number of bits after the radix point).

Note    When 2*format exceeds the maximum values for the SumFormat and ProductFormat properties, their maximum values are used instead.

setbits(F,fmt) sets all data format property values for quantized FFT F.

When F is a fixed-point quantized FFT, fmt = [w, f] where w is the word length and f is the fraction length. The twiddle, input, and output formats are set to [w, f]. The sum and product formats are set to [2w, 2f].

When F is a floating-point quantized FFT, fmt = [w, e] where w is the word length and e is the exponent length. All formats are set to [w, e].

If the specified formats exceed the maximum allowed, they are set to the maximum.

Examples

Create a quantized filter with default data format property values. Set the CoefficientFormat, InputFormat, and OutputFormat property values for a 24-bit word length, and a 23-bit fraction length, while setting the SumFormat and ProductFormat property values to a 48-bit word length and a 46-bit fraction length.

• Hq = qfilt;
  setbits(Hq,[24 23])
  
  get(Hq)
  
  Quantized Direct form II transposed filter                     
  Numerator                                                             
       QuantizedCoefficients{1}    ReferenceCoefficients{1}             
  + (1)      0.9999998807907105  1.000000000000000000                   
    (2)      0.5000000000000000  0.500000000000000000                   
  Denominator                                                           
       QuantizedCoefficients{2}    ReferenceCoefficients{2}             
  + (1)      0.9999998807907105  1.000000000000000000                   
    (2)      0.7000000476837158  0.699999999999999960                   
    (3)      0.8899999856948853  0.890000000000000010                   
                                                                        
     FilterStructure = df2t                                             
         ScaleValues = [1]                                              
    NumberOfSections = 1                                                
    StatesPerSection = [2]                                              
   CoefficientFormat = quantizer('fixed', 'round', 'saturate', [24  23])
         InputFormat = quantizer('fixed', 'floor', 'saturate', [24  23])
        OutputFormat = quantizer('fixed', 'floor', 'saturate', [24  23])
  MultiplicandFormat = quantizer('fixed', 'floor', 'saturate', [24  23])
       ProductFormat = quantizer('fixed', 'floor', 'saturate', [48  46])
           SumFormat = quantizer('fixed', 'floor', 'saturate', [48  46])
  

See Also
get, qfilt, set

set

sos