emms package

1 files changed, 95 insertions, 0 deletions

diff --git a/elisp/emms-info-spc.el b/elisp/emms-info-spc.el
new file mode 100644
index 0000000..fd092a5
--- /dev/null
+++ b/elisp/emms-info-spc.el
@@ -0,0 +1,95 @@
+;;; emms-info-spc.el --- Native Emacs Lisp info method for EMMS -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2023  Free Software Foundation, Inc.
+
+;; Author: Warren Wilkinson <[email protected]>
+
+;; This file is part of EMMS.
+
+;; EMMS 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 3, or (at your option)
+;; any later version.
+
+;; EMMS 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 EMMS; see the file COPYING. If not, write to the Free
+;; Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+;; MA 02110-1301, USA.
+
+;;; Commentary:
+
+;; This file provides a native emms-info-method for SPC files. (well,
+;; actually the id666 tag embedded inside them). "Native" means a pure
+;; Emacs Lisp implementation instead of one relying on external tools
+;; or libraries.
+
+;;; Code:
+
+(require 'bindat)
+
+(defconst emms-info-spc--id666-magic-array
+  [#x53 #x4e #x45 #x53 #x2d #x53 #x50#x43 #x37 #x30 #x30 #x20 #x53 #x6f #x75 #x6e #x64 #x20 #x46 #x69 #x6c #x65 #x20 #x44 #x61 #x74 #x61 #x20 #x76 #x30 #x2e #x33 #x30]
+  "id666 header magic pattern `SNES-SPC700 Sound File Data v0.30'")
+
+(defconst emms-info-spc--id666-header-bindat-spec
+  '((file-identifier vec 33)
+    (eval (unless (equal last emms-info-spc--id666-magic-array)
+            (error "id666 framing mismatch: expected `%s', got `%s'"
+                   emms-info-spc--id666-magic-array
+                   last)))
+    (unused u16)
+    (has-id666 u8)
+    (revision u8)
+    (pc-reg u16)
+    (a-reg u8)
+    (x-reg u8)
+    (y-reg u8)
+    (psw-reg u8)
+    (sp-reg u8)
+    (res-reg u16)
+    (song-title strz 32)
+    (game-title strz 32)
+    (dumper strz 16)
+    (comment strz 32)
+    (date strz 11)
+    (fadeout vec 3)
+    (fadeout-length vec 5)
+    (artist strz 32))
+  "id666 header specification.
+
+Sources:
+
+- URL `https://ocremix.org/info/SPC_Format_Specification'
+- URL `https://picard-docs.musicbrainz.org/en/appendices/tag_mapping.html'")
+
+(defun emms-info-spc--decode-id666-header (filename)
+  "Read and decode id666 header from FILENAME."
+  (with-temp-buffer
+    (set-buffer-multibyte nil)
+    (insert-file-contents-literally filename nil 0 210)
+    (bindat-unpack emms-info-spc--id666-header-bindat-spec
+                   (buffer-string))))
+
+(defun emms-info-spc--decode-id666 (filename)
+  "Read and decode id666 metadata from FILENAME.
+Return metadata in a list of (FIELD . VALUE) cons cells, or nil
+in case of errors or if there were no known fields in FILENAME."
+  (condition-case nil
+      (let ((header (emms-info-spc--decode-id666-header filename)))
+	(when (= 26 (bindat-get-field header 'has-id666))
+	  (list
+	   (cons 'info-title (bindat-get-field header 'song-title))
+	   (cons 'info-album (bindat-get-field header 'game-title))
+	   (cons 'info-artist (bindat-get-field header 'artist))
+	   (cons 'info-composer (bindat-get-field header 'artist))
+	   (cons 'info-note (bindat-get-field header 'comment)))))
+    (error nil)))
+
+(provide 'emms-info-spc)
+
+;;; emms-info-spc.el ends here