twoscomplement.m

Digital Signal Processing with MATLAB是Proakis於DSP的經點著作 內涵此書的source code

function y = TwosComplement(x,b)
%
% y = TwosComplement(x,b)
% ---------------
% Decimal equivalent of 
%  Sign-Magnitude format integer to b-bit One's-Complement format conversion
%
%    x: integer between -2^(b-1) <= x <  2^(b-1) (sign-magnitude)
%    y: integer between        0 <= y <= 2^b-1   (2's-complement)

if any((x < -2^(b-1) | (x >= 2^(b-1)))) 
    error('Numbers must satisfy -2^(b-1) <= x <  2^(b-1)')
end

s = sign(x);  % sign of x (-1 if x<0, 0 if x=0, 1 if x>0)
sb = (s < 0); % sign-bit  (0 if x>=0, 1 if x<0));

y = (1-sb).*x + sb.*(2^b+x);
%y = (1-sb).*x + sb.*(bitcmp(abs(x),b)+1);
%y = dec2bin(y,b);