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-rw-r--r--lib/rbcodec/metadata/vgm.c195
1 files changed, 195 insertions, 0 deletions
diff --git a/lib/rbcodec/metadata/vgm.c b/lib/rbcodec/metadata/vgm.c
new file mode 100644
index 0000000000..9ea95b3939
--- /dev/null
+++ b/lib/rbcodec/metadata/vgm.c
@@ -0,0 +1,195 @@
+#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"
+
+/* Ripped off from Game_Music_Emu 0.5.2. http://www.slack.net/~ant/ */
+
+typedef unsigned char byte;
+
+enum { header_size = 0x40 };
+enum { max_field = 64 };
+
+struct header_t
+{
+ char tag [4];
+ byte data_size [4];
+ byte version [4];
+ byte psg_rate [4];
+ byte ym2413_rate [4];
+ byte gd3_offset [4];
+ byte track_duration [4];
+ byte loop_offset [4];
+ byte loop_duration [4];
+ byte frame_rate [4];
+ byte noise_feedback [2];
+ byte noise_width;
+ byte unused1;
+ byte ym2612_rate [4];
+ byte ym2151_rate [4];
+ byte data_offset [4];
+ byte unused2 [8];
+};
+
+static byte const* skip_gd3_str( byte const* in, byte const* end )
+{
+ while ( end - in >= 2 )
+ {
+ in += 2;
+ if ( !(in [-2] | in [-1]) )
+ break;
+ }
+ return in;
+}
+
+static byte const* get_gd3_str( byte const* in, byte const* end, char* field )
+{
+ byte const* mid = skip_gd3_str( in, end );
+ int len = (mid - in) / 2 - 1;
+ if ( field && len > 0 )
+ {
+ len = len < (int) max_field ? len : (int) max_field;
+
+ field [len] = 0;
+ /* Conver to utf8 */
+ utf16LEdecode( in, field, len );
+
+ /* Copy string back to id3v2buf */
+ strcpy( (char*) in, field );
+ }
+ return mid;
+}
+
+static byte const* get_gd3_pair( byte const* in, byte const* end, char* field )
+{
+ return skip_gd3_str( get_gd3_str( in, end, field ), end );
+}
+
+static void parse_gd3( byte const* in, byte const* end, struct mp3entry* id3 )
+{
+ char* p = id3->path;
+ id3->title = (char *) in;
+ in = get_gd3_pair( in, end, p ); /* Song */
+
+ id3->album = (char *) in;
+ in = get_gd3_pair( in, end, p ); /* Game */
+
+ in = get_gd3_pair( in, end, NULL ); /* System */
+
+ id3->artist = (char *) in;
+ in = get_gd3_pair( in, end, p ); /* Author */
+
+#if MEMORYSIZE > 2
+ in = get_gd3_str ( in, end, NULL ); /* Copyright */
+ in = get_gd3_pair( in, end, NULL ); /* Dumper */
+
+ id3->comment = (char *) in;
+ in = get_gd3_str ( in, end, p ); /* Comment */
+#endif
+}
+
+int const gd3_header_size = 12;
+
+static long check_gd3_header( byte* h, long remain )
+{
+ if ( remain < gd3_header_size ) return 0;
+ if ( memcmp( h, "Gd3 ", 4 ) ) return 0;
+ if ( get_long_le( h + 4 ) >= 0x200 ) return 0;
+
+ long gd3_size = get_long_le( h + 8 );
+ if ( gd3_size > remain - gd3_header_size )
+ gd3_size = remain - gd3_header_size;
+
+ return gd3_size;
+}
+
+static void get_vgm_length( struct header_t* h, struct mp3entry* id3 )
+{
+ long length = get_long_le( h->track_duration ) * 10 / 441;
+ if ( length > 0 )
+ {
+ long loop_length = 0, intro_length = 0;
+ long loop = get_long_le( h->loop_duration );
+ if ( loop > 0 && get_long_le( h->loop_offset ) )
+ {
+ loop_length = loop * 10 / 441;
+ intro_length = length - loop_length;
+ }
+ else
+ {
+ intro_length = length; /* make it clear that track is no longer than length */
+ loop_length = 0;
+ }
+
+ id3->length = intro_length + 2 * loop_length; /* intro + 2 loops */
+ return;
+ }
+
+ id3->length = 150 * 1000; /* 2.5 minutes */
+}
+
+bool get_vgm_metadata(int fd, struct mp3entry* id3)
+{
+ /* Use the id3v2 part of the id3 structure as a temporary buffer */
+ unsigned char* buf = (unsigned char *)id3->id3v2buf;
+ int read_bytes;
+
+ memset(buf, 0, ID3V2_BUF_SIZE);
+ if ((lseek(fd, 0, SEEK_SET) < 0)
+ || ((read_bytes = read(fd, buf, header_size)) < header_size))
+ {
+ return false;
+ }
+
+ id3->vbr = false;
+ id3->filesize = filesize(fd);
+
+ id3->bitrate = 706;
+ id3->frequency = 44100;
+
+ /* If file is gzipped, will get metadata later */
+ if (memcmp(buf, "Vgm ", 4))
+ {
+ /* We must set a default song length here because
+ the codec can't do it anymore */
+ id3->length = 150 * 1000; /* 2.5 minutes */
+ return true;
+ }
+
+ /* Get song length from header */
+ struct header_t* header = (struct header_t*) buf;
+ get_vgm_length( header, id3 );
+
+ long gd3_offset = get_long_le( header->gd3_offset ) - 0x2C;
+
+ /* No gd3 tag found */
+ if ( gd3_offset < 0 )
+ return true;
+
+ /* Seek to gd3 offset and read as
+ many bytes posible */
+ gd3_offset = id3->filesize - (header_size + gd3_offset);
+ if ((lseek(fd, -gd3_offset, SEEK_END) < 0)
+ || ((read_bytes = read(fd, buf, ID3V2_BUF_SIZE)) <= 0))
+ return true;
+
+ byte* gd3 = buf;
+ long gd3_size = check_gd3_header( gd3, read_bytes );
+
+ /* GD3 tag is zero */
+ if ( gd3_size == 0 )
+ return true;
+
+ /* Finally, parse gd3 tag */
+ if ( gd3 )
+ parse_gd3( gd3 + gd3_header_size, gd3 + read_bytes, id3 );
+
+ return true;
+}