function y = mu2lin (x, bit)
  
# usage: y = mu2lin (x [, bit])
#
# If x is a vector of audio data with mu-law encoding, mu2lin (x)
# holds the same data with linear encoding.
# The optional argument bit specifies whether the input data is 
# 8 bit (default) or 16 bit.

# Written by AW (Andreas.Weingessel@ci.tuwien.ac.at) on Oct 18, 1994
# Updated by AW (Andreas.Weingessel@ci.tuwien.ac.at) on Oct 27, 1994
# Copyright Department of Probability Theory and Statistics TU Wien

  if (nargin == 1)
    bit = 8;
  elseif (nargin == 2)
    if (bit != 8 && bit != 16)
      error ("mu2lin: bit must be either 8 or 16");
    endif
  else
    usage ("y = mu2lin (x [, bit])");
  endif

  if (! is_vector (x))
    error ("mu2lin: x must be a vector");
  endif
  
  exp_lut = [0; 132; 396; 924; 1980; 4092; 8316; 16764];

  # invert x bitwise
  x = 255 - x;

  # determine sign of y
  sig = (x > 127);

  # determine exponent and fraction of y
  e = fix (x / 16) - 8 .* sig + 1;
  f = rem (x, 16);

  sig = 1 - 2 .* sig;
  y = (pow2 (f, e + 2) + exp_lut (e)) .* sig;

  # convert to 8-bit
  if (bit == 8)
    ld = max (abs (y));
    if (ld < 16384)
      sc = 64 / ld;
    else
      sc = 1 / 256;
    endif
    y = fix (y * sc);
  endif

endfunction