PeerStreamer

/* 

    Ringbuffer Implementation for gtvscreen

    Copyright (C) 2000 Marcus Metzler (mocm@metzlerbros.de)

    This program is free software; you can redistribute it and/or modify

    it under the terms of the GNU General Public License as published by

    the Free Software Foundation; either version 2 of the License, or

    (at your option) any later version.

    This program is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of

    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License

    along with this program; if not, write to the Free Software

    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#include "config.h"

#include "ringbuffy.h"

#include <string.h>

int ring_init (ringbuffy *rbuf, int size)

{

        if (size > 0){

                rbuf->size = size;

                if( !(rbuf->buffy = (char *) malloc(sizeof(char)*size)) ){

                        fprintf(stderr,"Not enough memory for ringbuffy\n");

                        return -1;

                }

        } else {

                fprintf(stderr,"Wrong size for ringbuffy\n");

                return -1;

        }

        rbuf->read_pos = 0;        

        rbuf->write_pos = 0;

        return 0;

}

void ring_destroy(ringbuffy *rbuf)

{

        free(rbuf->buffy);

}

int ring_write(ringbuffy *rbuf, char *data, int count)

{

        int diff, free, pos, rest;

        if (count <=0 ) return 0;

               pos  = rbuf->write_pos;

        rest = rbuf->size - pos;

        diff = rbuf->read_pos - pos;

        free = (diff > 0) ? diff-1 : rbuf->size+diff-1;

        if ( free <= 0 ) return FULL_BUFFER;

        if ( free < count ) count = free;

        if (count >= rest){

                memcpy (rbuf->buffy+pos, data, rest);

                if (count - rest)

                        memcpy (rbuf->buffy, data+rest, count - rest);

                rbuf->write_pos = count - rest;

        } else {

                memcpy (rbuf->buffy+pos, data, count);

                rbuf->write_pos += count;

        }

        return count;

}

int ring_peek(ringbuffy *rbuf, char *data, int count, long off)

{

        int diff, free, pos, rest;

        if (count <=0 ) return 0;

        pos  = rbuf->read_pos+off;

        rest = rbuf->size - pos ;

        diff = rbuf->write_pos - pos;

        free = (diff >= 0) ? diff : rbuf->size+diff;

        if ( free <= 0 ) return FULL_BUFFER;

        if ( free < count ) count = free;

        if ( count < rest ){

                memcpy(data, rbuf->buffy+pos, count);

        } else {

                memcpy(data, rbuf->buffy+pos, rest);

                if ( count - rest)

                        memcpy(data+rest, rbuf->buffy, count - rest);

        }

        return count;

}

int ring_read(ringbuffy *rbuf, char *data, int count)

{

        int diff, free, pos, rest;

        if (count <=0 ) return 0;

        pos  = rbuf->read_pos;

        rest = rbuf->size - pos;

        diff = rbuf->write_pos - pos;

        free = (diff >= 0) ? diff : rbuf->size+diff;

        if ( rest <= 0 ) return 0;

        if ( free < count ) count = free;

        if ( count < rest ){

                memcpy(data, rbuf->buffy+pos, count);

                rbuf->read_pos += count;

        } else {

                memcpy(data, rbuf->buffy+pos, rest);

                if ( count - rest)

                        memcpy(data+rest, rbuf->buffy, count - rest);

                rbuf->read_pos = count - rest;

        }

        return count;

}

int ring_write_file(ringbuffy *rbuf, int fd, int count)

{

        int diff, free, pos, rest, rr;

        if (count <=0 ) return 0;

               pos  = rbuf->write_pos;

        rest = rbuf->size - pos;

        diff = rbuf->read_pos - pos;

        free = (diff > 0) ? diff-1 : rbuf->size+diff-1;

        if ( rest <= 0 ) return 0;

        if ( free < count ) count = free;

        if (count >= rest){

                rr = read (fd, rbuf->buffy+pos, rest);

                if (rr == rest && count - rest)

                        rr += read (fd, rbuf->buffy, count - rest);

                if (rr >=0)

                        rbuf->write_pos = (pos + rr) % rbuf->size;

        } else {

                rr = read (fd, rbuf->buffy+pos, count);

                if (rr >=0)

                        rbuf->write_pos += rr;

        }

        return rr;

}

int ring_read_file(ringbuffy *rbuf, int fd, int count)

{

        int diff, free, pos, rest, rr;

        if (count <=0 ) return 0;

        pos  = rbuf->read_pos;

        rest = rbuf->size - pos;

        diff = rbuf->write_pos - pos;

        free = (diff >= 0) ? diff : rbuf->size+diff;

        if ( free <= 0 ) return FULL_BUFFER;

        if ( free < count ) count = free;

        if (count >= rest){

                rr = write (fd, rbuf->buffy+pos, rest);

                if (rr == rest && count - rest)

                        rr += write (fd, rbuf->buffy, count - rest);

                if (rr >=0)

                        rbuf->read_pos = (pos + rr) % rbuf->size;

        } else {

                rr = write (fd, rbuf->buffy+pos, count);

                if (rr >=0)

                        rbuf->read_pos += rr;

        }

        return rr;

}

int ring_rest(ringbuffy *rbuf){

               int diff, free, pos, rest;

        pos  = rbuf->read_pos;

        rest = rbuf->size - pos;

        diff = rbuf->write_pos - pos;

        free = (diff >= 0) ? diff : rbuf->size+diff;

        return free;

}