AF_comp_u(3)							 AF_comp_u(3)



NAME
  AF_comp_u, AF_comp_a - linear	to ULAW	and ALAW compression tables

SYNTAX
  #include <AF/AFUtils.h>

  extern unsigned char AF_comp_u[];

  extern unsigned char AF_comp_a[];

DESCRIPTION
  AF_comp_u and	AF_comp_a are precomputed tables you can link with your
  application.	Each is	indexed	by the low 14 bits of a	linear twos-
  complement value in the range	between	-8192 and +8191.  AF_comp_u contains
  the corresponding U255 law encoding while AF_comp_a contains the
  corresponding	ALAW encoding.

EXAMPLES
  Typical usage	is:

  unsigned char	ulaw;
  int input;
  /* first limit the signal to the proper range	*/
  if (input > 8191) input = 8191;
  else if (input < -8181) input	= -8191;
  /* then translate */
  ulaw = AF_comp_u[ input & 0x3fff ];

DIAGNOSTICS
  If you index the table with an out-of-range linear value you may cause a
  protection fault and crash your application.

SEE ALSO
  AF_exp_u(3), AF_exp_a(3), AF_cvt_u2s(3), AF_cvt_a2s(3), AF_cvt_u2f(3),
  AF_cvt_a2f(3)
  AF(1)

BUGS
  If you encounter a reproducible bug, please submit a problem report to
  (af-bugs@crl.dec.com).

COPYRIGHT
  Copyright 1990-1994, Digital Equipment Corporation.
  See AF(1) for	a full statement of rights and permissions.

AUTHORS
  Tom Levergood	and Larry Stewart, Digital Cambridge Research Lab