From 6266e3e5577bc7c11d300a873c150b6a7900376a Mon Sep 17 00:00:00 2001
From: Javier Degirolmo
Date: Mon, 27 Aug 2012 07:58:24 -0300
Subject: Fuck it, we're doing it live

---
 doc/eif.txt | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 doc/eif.txt

(limited to 'doc/eif.txt')

diff --git a/doc/eif.txt b/doc/eif.txt
new file mode 100644
index 0000000..3d1f27d
--- /dev/null
+++ b/doc/eif.txt
@@ -0,0 +1,27 @@
+=============================================================================
+
+OVERVIEW
+
+    EIF stands for "Echo Instrument Format" and it's the format in which FM
+    instruments are stored.
+
+FORMAT
+
+    EIF instruments are essentially raw dumps of the YM2612 registers. They
+    consist of 29 bytes, where each byte belongs to a different YM2612
+    register. The registers are stored in the following order (assuming the
+    first FM channel):
+    
+        $B4                     -- Algorithm and feedback
+        $30, $34, $38, $3C      -- Multiplier and detune
+        $40, $44, $48, $4C      -- Total level
+        $50, $54, $58, $5C      -- Attack rate
+        $60, $64, $68, $6C      -- Decay rate
+        $70, $74, $78, $7C      -- Sustain rate
+        $80, $84, $88, $8C      -- Release rate and sustain level
+        $90, $94, $98, $9C      -- SSG-EG
+    
+    Some bits are unused and ignored by the YM2612. In an EIF instrument,
+    they *must* be 0, since Echo will rely on this for optimization purposes.
+
+=============================================================================
-- 
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