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Inside Multimedia 1995 August
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IMM0895.ISO01.iso
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os2
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track061
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automato.c
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1992-10-30
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/* automaton.c */
/* modified by David Nichols for OS/2 PM MOD player */
/* $Author: espie $
* $Id: automaton.c,v 2.5 1991/11/20 20:46:35 espie Exp espie $
* $Revision: 2.5 $
* $Log: automaton.c,v $
* Revision 2.5 1991/11/20 20:46:35 espie
* Minor correction.
*
* Revision 2.4 1991/11/19 16:07:19 espie
* Added comments, moved minor stuff around.
*
* Revision 2.3 1991/11/18 01:23:30 espie
* Added two level of fault tolerancy.
*
* Revision 2.2 1991/11/18 01:12:31 espie
* Minor changes.
*
* Revision 2.1 1991/11/17 23:07:58 espie
* Coming from str32.
*
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "defs.h"
/* updates the pattern to play in the automaton.
* Checks that the pattern actually exists.
*/
void set_pattern (struct automaton *a)
{
static int p;
if (a->pattern_num >= a->info->length)
{
error = UNRECOVERABLE;
return;
}
/* there is a level of indirection in the format,
* i.e., patterns can be repeated.
*/
p = a->info->patnumber[a->pattern_num];
if (p >= a->info->maxpat)
{
error = UNRECOVERABLE;
return;
}
a->pattern = a->info->pblocks + p;
}
/* initialize all the fields of the automaton necessary
* to play a given song.
*/
void init_automaton (struct automaton *a, struct song *song)
{
a->info = song->info;
a->pattern_num = 0; /* first pattern */
a->note_num = 0; /* first note in pattern */
a->counter = 0; /* counter for the effect tempo */
a->speed = NORMAL_SPEED; /* this is the default effect tempo */
a->finespeed = NORMAL_FINESPEED;
/* this is the fine speed (100%) */
a->do_stuff = DO_NOTHING;
/* some effects affect the automaton,
* we keep them here.
*/
error = NONE; /* Maybe we should not reset errors at
* this point.
*/
set_pattern (a);
}
/* Gets to the next pattern, and displays stuff */
void advance_pattern (struct automaton *a)
{
if (++a->pattern_num >= a->info->length)
{
a->pattern_num = 0;
error = ENDED;
}
set_pattern (a);
a->note_num = 0;
}
/* process all the stuff which we need to advance in the song,
* including set_speed, set_skip and set_fastskip.
*/
void next_tick (struct automaton *a)
{
if (a->do_stuff & SET_SPEED && a->new_speed)
{
/* there are three classes of speed changes:
* 0 does nothing.
* <32 is the effect speed (resets the fine speed).
* >=32 changes the finespeed, so this is 32% to 255%
*/
if (a->new_speed >= 32)
a->finespeed = a->new_speed;
else
{
a->speed = a->new_speed;
a->finespeed = 100;
}
}
if (++a->counter >= a->speed)
{
a->counter = 0;
if (a->do_stuff & SET_FASTSKIP)
{
a->pattern_num = a->new_pattern;
set_pattern (a);
a->note_num = 0;
}
else if (a->do_stuff & SET_SKIP)
{
advance_pattern (a);
a->note_num = a->new_note;
}
else
{
if (++a->note_num >= BLOCK_LENGTH)
advance_pattern (a);
}
a->do_stuff = DO_NOTHING;
}
}