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#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <inttypes.h>
#include "system.h"
#include "metadata.h"
#include "metadata_common.h"
#include "metadata_parsers.h"
#include "rbunicode.h"
/* Taken from blargg's Game_Music_Emu library */
typedef unsigned char byte;
/* AY file header */
enum { header_size = 0x14 };
struct header_t
{
byte tag[8];
byte vers;
byte player;
byte unused[2];
byte author[2];
byte comment[2];
byte max_track;
byte first_track;
byte track_info[2];
};
struct file_t {
struct header_t const* header;
byte const* tracks;
byte const* end; /* end of file data */
};
static int get_be16( const void *a )
{
return get_short_be( (void*) a );
}
/* Given pointer to 2-byte offset of data, returns pointer to data, or NULL if
* offset is 0 or there is less than min_size bytes of data available. */
static byte const* get_data( struct file_t const* file, byte const ptr [], int min_size )
{
int offset = (int16_t) get_be16( ptr );
int pos = ptr - (byte const*) file->header;
int size = file->end - (byte const*) file->header;
int limit = size - min_size;
if ( limit < 0 || !offset || (unsigned) (pos + offset) > (unsigned) limit )
return NULL;
return ptr + offset;
}
static const char *parse_header( byte const in [], int size, struct file_t* out )
{
if ( size < header_size )
return "wrong file type";
out->header = (struct header_t const*) in;
out->end = in + size;
struct header_t const* h = (struct header_t const*) in;
if ( memcmp( h->tag, "ZXAYEMUL", 8 ) )
return "wrong file type";
out->tracks = get_data( out, h->track_info, (h->max_track + 1) * 4 );
if ( !out->tracks )
return "missing track data";
return 0;
}
static void copy_ay_fields( struct file_t const* file, struct mp3entry* id3, int track )
{
int track_count = file->header->max_track + 1;
/* calculate track length based on number of subtracks */
if (track_count > 1) {
id3->length = file->header->max_track * 1000;
} else {
byte const* track_info = get_data( file, file->tracks + track * 4 + 2, 6 );
if (track_info)
id3->length = get_be16( track_info + 4 ) * (1000 / 50); /* frames to msec */
else id3->length = 120 * 1000;
}
if ( id3->length <= 0 )
id3->length = 120 * 1000; /* 2 minutes */
/* If meta info was found in the m3u skip next step */
if (id3->title && id3->title[0]) return;
/* If file has more than one track will
use file name as title */
char * tmp;
if (track_count <= 1) {
tmp = (char *) get_data( file, file->tracks + track * 4, 1 );
if ( tmp ) id3->title = tmp;
}
/* Author */
tmp = (char *) get_data( file, file->header->author, 1 );
if (tmp) id3->artist = tmp;
/* Comment */
tmp = (char *) get_data( file, file->header->comment, 1 );
if (tmp) id3->comment = tmp;
}
static bool parse_ay_header(int fd, struct mp3entry *id3)
{
/* Use the trackname part of the id3 structure as a temporary buffer */
unsigned char* buf = (unsigned char *)id3->id3v2buf;
struct file_t file;
int read_bytes;
lseek(fd, 0, SEEK_SET);
if ((read_bytes = read(fd, buf, ID3V2_BUF_SIZE)) < header_size)
return false;
buf [ID3V2_BUF_SIZE] = '\0';
if ( parse_header( buf, read_bytes, &file ) )
return false;
copy_ay_fields( &file, id3, 0 );
return true;
}
bool get_ay_metadata(int fd, struct mp3entry* id3)
{
char ay_type[8];
if ((lseek(fd, 0, SEEK_SET) < 0) ||
read(fd, ay_type, 8) < 8)
return false;
id3->vbr = false;
id3->filesize = filesize(fd);
id3->bitrate = 706;
id3->frequency = 44100;
/* Make sure this is a ZX Ay file */
if (memcmp( ay_type, "ZXAYEMUL", 8 ) != 0)
return false;
return parse_ay_header(fd, id3);
}
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