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    /*
     * Asterisk -- A telephony toolkit for Linux.
     *
     * Flat, binary, ulaw PCM file format.
     * 
     * Copyright (C) 1999, Mark Spencer
     *
     * Mark Spencer <markster@linux-support.net>
     *
     * This program is free software, distributed under the terms of
     * the GNU General Public License
     */
     
    #include <asterisk/channel.h>
    #include <asterisk/file.h>
    #include <asterisk/logger.h>
    #include <asterisk/sched.h>
    #include <asterisk/module.h>
    #include <arpa/inet.h>
    #include <stdlib.h>
    #include <sys/time.h>
    #include <stdio.h>
    #include <unistd.h>
    #include <errno.h>
    #include <string.h>
    #include <pthread.h>
    #include <endian.h>
    
    #define BUF_SIZE 160		/* 160 samples */
    
    struct ast_filestream {
    	void *reserved[AST_RESERVED_POINTERS];
    	/* Believe it or not, we must decode/recode to account for the
    	   weird MS format */
    	/* This is what a filestream means to us */
    	int fd; /* Descriptor */
    	struct ast_channel *owner;
    	struct ast_frame fr;				/* Frame information */
    	char waste[AST_FRIENDLY_OFFSET];	/* Buffer for sending frames, etc */
    	char empty;							/* Empty character */
    	unsigned char buf[BUF_SIZE];				/* Output Buffer */
    	int lasttimeout;
    	struct timeval last;
    	int adj;
    	struct ast_filestream *next;
    };
    
    
    static struct ast_filestream *glist = NULL;
    static pthread_mutex_t pcm_lock = PTHREAD_MUTEX_INITIALIZER;
    static int glistcnt = 0;
    
    static char *name = "pcm";
    static char *desc = "Raw uLaw 8khz Audio support (PCM)";
    static char *exts = "pcm|ulaw|ul|mu";
    
    static struct ast_filestream *pcm_open(int fd)
    {
    	/* We don't have any header to read or anything really, but
    	   if we did, it would go here.  We also might want to check
    	   and be sure it's a valid file.  */
    	struct ast_filestream *tmp;
    	if ((tmp = malloc(sizeof(struct ast_filestream)))) {
    		memset(tmp, 0, sizeof(struct ast_filestream));
    		if (pthread_mutex_lock(&pcm_lock)) {
    			ast_log(LOG_WARNING, "Unable to lock pcm list\n");
    			free(tmp);
    			return NULL;
    		}
    		tmp->next = glist;
    		glist = tmp;
    		tmp->fd = fd;
    		tmp->owner = NULL;
    		tmp->fr.data = tmp->buf;
    		tmp->fr.frametype = AST_FRAME_VOICE;
    		tmp->fr.subclass = AST_FORMAT_ULAW;
    		/* datalen will vary for each frame */
    		tmp->fr.src = name;
    		tmp->fr.mallocd = 0;
    		tmp->lasttimeout = -1;
    		glistcnt++;
    		pthread_mutex_unlock(&pcm_lock);
    		ast_update_use_count();
    	}
    	return tmp;
    }
    
    static struct ast_filestream *pcm_rewrite(int fd, char *comment)
    {
    	/* We don't have any header to read or anything really, but
    	   if we did, it would go here.  We also might want to check
    	   and be sure it's a valid file.  */
    	struct ast_filestream *tmp;
    	if ((tmp = malloc(sizeof(struct ast_filestream)))) {
    		memset(tmp, 0, sizeof(struct ast_filestream));
    		if (pthread_mutex_lock(&pcm_lock)) {
    			ast_log(LOG_WARNING, "Unable to lock pcm list\n");
    			free(tmp);
    			return NULL;
    		}
    		tmp->next = glist;
    		glist = tmp;
    		tmp->fd = fd;
    		tmp->owner = NULL;
    		tmp->lasttimeout = -1;
    		glistcnt++;
    		pthread_mutex_unlock(&pcm_lock);
    		ast_update_use_count();
    	} else
    		ast_log(LOG_WARNING, "Out of memory\n");
    	return tmp;
    }
    
    static struct ast_frame *pcm_read(struct ast_filestream *s)
    {
    	return NULL;
    }
    
    static void pcm_close(struct ast_filestream *s)
    {
    	struct ast_filestream *tmp, *tmpl = NULL;
    	if (pthread_mutex_lock(&pcm_lock)) {
    		ast_log(LOG_WARNING, "Unable to lock pcm list\n");
    		return;
    	}
    	tmp = glist;
    	while(tmp) {
    		if (tmp == s) {
    			if (tmpl)
    				tmpl->next = tmp->next;
    			else
    				glist = tmp->next;
    			break;
    		}
    		tmpl = tmp;
    		tmp = tmp->next;
    	}
    	glistcnt--;
    	if (s->owner) {
    		s->owner->stream = NULL;
    		if (s->owner->streamid > -1)
    			ast_sched_del(s->owner->sched, s->owner->streamid);
    		s->owner->streamid = -1;
    	}
    	pthread_mutex_unlock(&pcm_lock);
    	ast_update_use_count();
    	if (!tmp) 
    		ast_log(LOG_WARNING, "Freeing a filestream we don't seem to own\n");
    	close(s->fd);
    	free(s);
    }
    
    static int ast_read_callback(void *data)
    {
    	int retval = 0;
    	int res;
    	int delay;
    	struct ast_filestream *s = data;
    	struct timeval tv;
    	/* Send a frame from the file to the appropriate channel */
    
    	s->fr.frametype = AST_FRAME_VOICE;
    	s->fr.subclass = AST_FORMAT_ULAW;
    	s->fr.offset = AST_FRIENDLY_OFFSET;
    	s->fr.mallocd = 0;
    	s->fr.data = s->buf;
    	if ((res = read(s->fd, s->buf, BUF_SIZE)) < 1) {
    		if (res)
    			ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
    		s->owner->streamid = -1;
    		return 0;
    	}
    	s->fr.timelen = res / 8;
    	s->fr.datalen = res;
    	delay = s->fr.timelen;
    	/* Lastly, process the frame */
    	if (ast_write(s->owner, &s->fr)) {
    		ast_log(LOG_WARNING, "Failed to write frame\n");
    		s->owner->streamid = -1;
    		return 0;
    	}
    	if (s->last.tv_usec || s->last.tv_usec) {
    		int ms;
    		gettimeofday(&tv, NULL);
    		ms = 1000 * (tv.tv_sec - s->last.tv_sec) + 
    			(tv.tv_usec - s->last.tv_usec) / 1000;
    		s->last.tv_sec = tv.tv_sec;
    		s->last.tv_usec = tv.tv_usec;
    		if ((ms - delay) * (ms - delay) > 4) {
    			/* Compensate if we're more than 2 ms off */
    			s->adj -= (ms - delay);
    		}
    #if 0
    		fprintf(stdout, "Delay is %d, adjustment is %d, last was %d\n", delay, s->adj, ms);
    #endif
    		delay += s->adj;
    		if (delay < 1)
    			delay = 1;
    	} else
    		gettimeofday(&s->last, NULL);
    	if (s->lasttimeout != delay) {
    		/* We'll install the next timeout now. */
    		s->owner->streamid = ast_sched_add(s->owner->sched,
    				delay, ast_read_callback, s); 
    		s->lasttimeout = delay;
    	} else {
    		/* Just come back again at the same time */
    		retval = -1;
    	}
    	return retval;
    }
    
    static int pcm_apply(struct ast_channel *c, struct ast_filestream *s)
    {
    	/* Select our owner for this stream, and get the ball rolling. */
    	s->owner = c;
    	ast_read_callback(s);
    	return 0;
    }
    
    static int pcm_write(struct ast_filestream *fs, struct ast_frame *f)
    {
    	int res;
    	if (f->frametype != AST_FRAME_VOICE) {
    		ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
    		return -1;
    	}
    	if (f->subclass != AST_FORMAT_ULAW) {
    		ast_log(LOG_WARNING, "Asked to write non-ulaw frame (%d)!\n", f->subclass);
    		return -1;
    	}
    	if ((res = write(fs->fd, f->data, f->datalen)) != f->datalen) {
    			ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
    			return -1;
    	}
    	return 0;
    }
    
    static char *pcm_getcomment(struct ast_filestream *s)
    {
    	return NULL;
    }
    
    int load_module()
    {
    	return ast_format_register(name, exts, AST_FORMAT_ULAW,
    								pcm_open,
    								pcm_rewrite,
    								pcm_apply,
    								pcm_write,
    								pcm_read,
    								pcm_close,
    								pcm_getcomment);
    								
    								
    }
    
    int unload_module()
    {
    	struct ast_filestream *tmp, *tmpl;
    	if (pthread_mutex_lock(&pcm_lock)) {
    		ast_log(LOG_WARNING, "Unable to lock pcm list\n");
    		return -1;
    	}
    	tmp = glist;
    	while(tmp) {
    		if (tmp->owner)
    			ast_softhangup(tmp->owner);
    		tmpl = tmp;
    		tmp = tmp->next;
    		free(tmpl);
    	}
    	pthread_mutex_unlock(&pcm_lock);
    	return ast_format_unregister(name);
    }	
    
    int usecount()
    {
    	int res;
    	if (pthread_mutex_lock(&pcm_lock)) {
    		ast_log(LOG_WARNING, "Unable to lock pcm list\n");
    		return -1;
    	}
    	res = glistcnt;
    	pthread_mutex_unlock(&pcm_lock);
    	return res;
    }
    
    char *description()
    {
    	return desc;
    }
    
    
    char *key()
    {
    	return ASTERISK_GPL_KEY;
    }