random.c,v

lpc10-15为美军2400bps语音压缩标准的C语音源代码。

head	1.2;
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1.2
date	96.08.20.20.41.32;	author jaf;	state Exp;
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next	1.1;

1.1
date	96.08.19.22.30.49;	author jaf;	state Exp;
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desc
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1.2
log
@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().
@
text
@/*

$Log: random.c,v $
 * Revision 1.1  1996/08/19  22:30:49  jaf
 * Initial revision
 *

*/

#ifdef P_R_O_T_O_T_Y_P_E_S
extern integer random_(struct lpc10_decoder_state *st);
#endif

/*  -- translated by f2c (version 19951025).
   You must link the resulting object file with the libraries:
	-lf2c -lm   (in that order)
*/

#include "f2c.h"

/* ********************************************************************** */

/* 	RANDOM Version 49 */

/* $Log: random.c,v $
 * 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_ */

@


1.1
log
@Initial revision
@
text
@d3 4
a6 1
$Log$
d11 1
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extern integer random_(void);
d25 4
a28 1
/* $Log: random.f,v $ */
d53 1
a53 1
integer random_(void)
d57 3
a59 3
    static integer j = 2;
    static integer k = 5;
    static shortint y[5] = { -21161,-8478,30892,-10216,16950 };
d68 10
a77 5
    y[k - 1] += y[j - 1];
    ret_val = y[k - 1];
    --k;
    if (k <= 0) {
	k = 5;
d79 3
a81 3
    --j;
    if (j <= 0) {
	j = 5;
@