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/*
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 "ringbuffy.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;
}
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