From 284f0ced684f2d42c30eba70a600a347f9793343 Mon Sep 17 00:00:00 2001
From: tildearrow <me@tildearrow.org>
Date: Tue, 23 Apr 2024 14:43:38 -0500
Subject: [PATCH] fix .mod import and update doc

---
 doc/3-pattern/effects.md   | 19 +++++++++++++++++--
 src/engine/fileOps/mod.cpp |  2 +-
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/doc/3-pattern/effects.md b/doc/3-pattern/effects.md
index dca26d21b..8fe6e6ef4 100644
--- a/doc/3-pattern/effects.md
+++ b/doc/3-pattern/effects.md
@@ -93,10 +93,25 @@ not all chips support these effects.
 - `FCxx`: **Note release.** releases current note after `xx` ticks. this releases macros and triggers key off in FM/hardware envelope chips.
 - `E7xx`: **Macro release.** releases macros after `xx` ticks. this does not trigger key off.
 
+## sample offset
+
+these effects make the current playing sample on the channel jump to a specific position.
+only some chips support this effect.
+
+sample offset is a 24-bit (3 byte) number.
+
+- `90xx`: **Set sample offset (first byte).**
+- `91xx`: **Set sample offset (second byte).**
+- `92xx`: **Set sample offset (third byte).**
+
+you may use these effects simultaneously in a row.
+
+if you do not set a byte, its last value will be used.
+
+in previous versions of Furnace a `9xxx` effect existed which set the sample position to `$xxx00` (`xxx` was effectively multiplied by 256). this maps to `920x 91xx` in current Furnace.
+
 ## other
 
-- `9xxx`: **Set sample position.** jumps current sample to position `xxx * 0x100`.
-  - not all chips support this effect.
 - `EBxx`: **Set LEGACY sample mode bank.** selects sample bank. used only for compatibility.
   - does not apply on Amiga.
 - `EExx`: **Send external command.**
diff --git a/src/engine/fileOps/mod.cpp b/src/engine/fileOps/mod.cpp
index 02cecc9fd..9aa72e444 100644
--- a/src/engine/fileOps/mod.cpp
+++ b/src/engine/fileOps/mod.cpp
@@ -322,7 +322,7 @@ bool DivEngine::loadMod(unsigned char* file, size_t len) {
               setEffectState[3]=fxVal;
               break;
             case 9: // set offset
-              writeFxCol(0x90,fxVal);
+              writeFxCol(0x91,fxVal);
               break;
             case 10: // vol slide
               effectState[4]=fxVal;