bin2int.m

FS1016源代码

% MATLAB SIMULATION OF NSA FS-1016 CELP v3.2
% COPYRIGHT (C) 1995-99 ANDREAS SPANIAS AND TED PAINTER
%
% This Copyright applies only to this particular MATLAB implementation
% of the FS-1016 CELP coder.  The MATLAB software is intended only for educational
% purposes.  No other use is intended or authorized.  This is not a public
% domain program and distribution to individuals or networks is strictly
% prohibited.  Be aware that use of the standard in any form is goverened
% by rules of the US DoD.  Therefore patents and royalties may apply to
% authors, companies, or committees associated with this standard, FS-1016.  For
% questions regarding the MATLAB implementation please contact Andreas
% Spanias [phone].  For questions on rules,
% royalties, or patents associated with the standard, please contact the DoD.
%
% ALL DERIVATIVE WORKS MUST INCLUDE THIS COPYRIGHT NOTICE.
%
% ******************************************************************
% BIN2INT
%
% DEVELOPED TO SUPPORT BITWISE OPERATIONS WHEN PORTING C TO MATLAB
% 3-30-94
%
% REVISED TO SUPPORT n-BIT INTEGERS
% 6-17-94
%
% ******************************************************************
%
% DESCRIPTION
%
% Obtain MATLAB scalar variable (integer) from a n-bit,
% 2's Compliment binary representation, as provided by int2bin().
% Input is an n-bit bit vector, output is a scalar integer.
%
% DESIGN NOTES
%
% Compute weighted sum of powers of two.  Incorporate n-bit offset
% for negative values, assuming 2's Compliment input format.
%
% VARIABLES
%
% INPUTS
%   v        -   n-bit, 2's Compliment bit vector, MSB first
%
% OUTPUTS
%   i        -   Scalar integer output
%
% INTERNALS
%   n        -   Vector length (bits)
%   offset   -   Correction factor for negative input words
%
% ******************************************************************
function i = bin2int( v )

% DETERMINE VECTOR LENGTH
n = length(v);

% TEST FOR NEGATIVE INPUT VECTOR
if v(1) == 1
     offset = 2^n;
else
     offset = 0;
end

% COMPUTE WEIGHTED SUM, ADJUST FOR SIGN
i = sum( v .* (2 .^ (n-1:-1:0)) ) - offset;