ref: 5add94edece948a9ac9fae9e9203744d6758df5c
dir: /lpc10/random.c/
/*
* Revision 1.2 1996/08/20 20:41:32 jaf
* Removed all static local variables that were SAVE'd in the Fortran
* code, and put them in struct lpc10_decoder_state that is passed as an
* argument.
*
* Removed init function, since all initialization is now done in
* init_lpc10_decoder_state().
*
* Revision 1.1 1996/08/19 22:30:49 jaf
* Initial revision
*
*/
/* -- translated by f2c (version 19951025).
You must link the resulting object file with the libraries:
-lf2c -lm (in that order)
*/
#include "f2c.h"
extern integer random_(struct lpc10_decoder_state *st);
/* ********************************************************************** */
/* RANDOM Version 49 */
/*
* Revision 1.2 1996/08/20 20:41:32 jaf
* Removed all static local variables that were SAVE'd in the Fortran
* code, and put them in struct lpc10_decoder_state that is passed as an
* argument.
*
* Removed init function, since all initialization is now done in
* init_lpc10_decoder_state().
*
* Revision 1.1 1996/08/19 22:30:49 jaf
* Initial revision
* */
/* Revision 1.3 1996/03/20 16:13:54 jaf */
/* Rearranged comments a little bit, and added comments explaining that */
/* even though there is local state here, there is no need to create an */
/* ENTRY for reinitializing it. */
/* Revision 1.2 1996/03/14 22:25:29 jaf */
/* Just rearranged the comments and local variable declarations a bit. */
/* Revision 1.1 1996/02/07 14:49:01 jaf */
/* Initial revision */
/* ********************************************************************* */
/* Pseudo random number generator based on Knuth, Vol 2, p. 27. */
/* Function Return: */
/* RANDOM - Integer variable, uniformly distributed over -32768 to 32767 */
/* This subroutine maintains local state from one call to the next. */
/* In the context of the LPC10 coder, there is no reason to reinitialize */
/* this local state when switching between audio streams, because its */
/* results are only used to generate noise for unvoiced frames. */
integer random_(struct lpc10_decoder_state *st)
{
/* Initialized data */
integer *j;
integer *k;
shortint *y;
/* System generated locals */
integer ret_val;
/* Parameters/constants */
/* Local state */
/* The following is a 16 bit 2's complement addition, */
/* with overflow checking disabled */
j = &(st->j);
k = &(st->k);
y = &(st->y[0]);
y[*k - 1] += y[*j - 1];
ret_val = y[*k - 1];
--(*k);
if (*k <= 0) {
*k = 5;
}
--(*j);
if (*j <= 0) {
*j = 5;
}
return ret_val;
} /* random_ */