78 lines
2.0 KiB
C
78 lines
2.0 KiB
C
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/*
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$Id: cddb.c,v 1.1 2005/03/06 11:21:52 rocky Exp $
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Copyright (C) 2005 Rocky Bernstein <rocky@panix.com>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <cdio/cdio.h>
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#include <cdio/util.h>
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#include "cddb.h"
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/* Return the number of seconds (discarding frame portion) of an MSF */
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static inline unsigned int
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msf_seconds(msf_t *p_msf)
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{
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return
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cdio_from_bcd8(p_msf->m)*CDIO_CD_SECS_PER_MIN + cdio_from_bcd8(p_msf->s);
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}
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/*!
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Returns the sum of the decimal digits in a number. Eg. 1955 = 20
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*/
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static int
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cddb_dec_digit_sum(int n)
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{
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int ret=0;
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for (;;) {
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ret += n%10;
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n = n/10;
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if (!n) return ret;
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}
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}
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/*!
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Compute the CDDB disk ID for an Audio disk. This is a funny checksum
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consisting of the concatenation of 3 things:
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the sum of the decimal digits of sizes of all tracks,
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the total length of the disk, and
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the number of tracks.
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*/
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unsigned long
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cddb_discid(CdIo_t *p_cdio, track_t i_tracks)
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{
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int i,t,n=0;
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msf_t start_msf;
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msf_t msf;
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for (i = 1; i <= i_tracks; i++) {
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cdio_get_track_msf(p_cdio, i, &msf);
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n += cddb_dec_digit_sum(msf_seconds(&msf));
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}
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cdio_get_track_msf(p_cdio, 1, &start_msf);
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cdio_get_track_msf(p_cdio, CDIO_CDROM_LEADOUT_TRACK, &msf);
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t = msf_seconds(&msf) - msf_seconds(&start_msf);
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return ((n % 0xff) << 24 | t << 8 | i_tracks);
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}
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