int2bin.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 at  [phone].  For questions on rules,
% royalties, or patents associated with the standard, please contact the DoD.
%
% ALL DERIVATIVE WORKS MUST INCLUDE THIS COPYRIGHT NOTICE.
%
% ******************************************************************
% INT2BIN
%
% DEVELOPED TO SUPPORT BITWISE OPERATIONS WHEN PORTING C TO MATLAB
% 3-30-94
%
% REVISED TO SUPPORT n-BIT INTEGERS INSTEAD OF 8-BIT
% 6-17-94
%
% REVISED TO HANDLE VECTORS OF INPUT VALUES IN a. ALL OUTPUT BINARY
% WORDS WILL BE OF LENGTH n BITS.
% 8-2-94
%
% ******************************************************************
%
% DESCRIPTION
%
% Obtain n-bit, 2's Compliment binary representation for an integer
% MATLAB variable. Input is an integer, output is a vector of n bits.
%
% DESIGN NOTES
%
% Use modulo division in place of bit mask, which would have been
% available in C.  Encode negative values in 2's Compliment, as
% is done with most C compilers.
%
% SEE ALSO:  BIN2INT
%
% VARIABLES
%
% INPUTS
%   a        -   Input integer(s) (Actually double float in MATLAB)
%   n        -   Number of bits desired
%
% OUTPUTS
%   bv       -   n-bit, 2's Compliment bit vector(s), MSB first
%
% ******************************************************************

function bv = int2bin( a, n )

for i = 1:length(a)
    % CONVERT USING MODULO DIVISION FOR BITMASK
    % MASK HIGH BITS, THEN SUBTRACT REMAINING BITS
    % CONVERT NEGATIVE VALUES TO 2'S COMP
    if a(i) >= 0
        bv(i,:) = sign(rem(a(i),2.^(n:-1:1))-rem(a(i),2.^((n-1):-1:0)));
    else
        a(i) = a(i) + 1;
        bv(i,:) = ~sign(rem(a(i),2.^(n:-1:1))-rem(a(i),2.^((n-1):-1:0)));
    end
end