1 files changed, 148 insertions, 0 deletions

diff --git a/apps/metadata/ay.c b/apps/metadata/ay.c
new file mode 100644
index 0000000000..8b737a7eba
--- /dev/null
+++ b/apps/metadata/ay.c
@@ -0,0 +1,148 @@
+#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;
+}
+
+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);
+}