From 3e4335673367dd0b650d376094cba96e25cfcac8 Mon Sep 17 00:00:00 2001
From: Victor Giers <mail@victorgiers.com>
Date: Mon, 13 Jul 2026 04:41:18 +0200
Subject: [PATCH] Implement structured parsing and typing for pattern events
 (Note, Fader, MIDI, Unknown)

---
 src/lib/parsers.ts | 140 ++++++++++++++++++++++++++++++++++++++++-----
 src/types/types.ts |  58 +++++++++++++++++++
 2 files changed, 183 insertions(+), 15 deletions(-)

diff --git a/src/lib/parsers.ts b/src/lib/parsers.ts
index acbc752..4441d2a 100644
--- a/src/lib/parsers.ts
+++ b/src/lib/parsers.ts
@@ -5,8 +5,11 @@ import {
   Pad,
   PadCode,
   Pattern,
+  PatternEvent,
+  PatternEventKind,
   ProjectSettings,
   Scene,
+  SceneGroupPatternData,
   ScenesSettings,
   Sound,
 } from '../types/types';
@@ -28,10 +31,17 @@ type IntermediateScenes = Record<
   number,
   {
     name: string;
-    groups: Record<string, { bars: number; notes: Record<number, Note[]> }>;
+    groups: Record<string, ParsedPatternData>;
   }
 >;
 
+export type ParsedPatternData = {
+  bars: number;
+  recordCount: number;
+  events: PatternEvent[];
+  notes: Record<number, Note[]>;
+};
+
 const defaultProjectSettings = {
   bpm: 120,
   scale: 0,
@@ -195,32 +205,104 @@ export function collectPads(files: TarFile[], sounds: Sound[]) {
   return result;
 }
 
-function parsePatterns(data: Uint8Array, startOffset: number = 4) {
-  const chunks = chunkArray(data, 8, startOffset);
+export function parsePatternEvents(
+  data: Uint8Array,
+  startOffset: number = 4,
+): ParsedPatternData {
+  const recordCount = data.length >= 4 ? data[2] | (data[3] << 8) : 0;
+  const availableRecordCount = Math.max(0, Math.floor((data.length - startOffset) / 8));
+  const chunks = chunkArray(data, 8, startOffset).slice(
+    0,
+    Math.min(recordCount, availableRecordCount),
+  );
+  const events: PatternEvent[] = [];
   const notes: Record<number, Note[]> = {};
 
   chunks.forEach((chunk) => {
-    // I discovered there could be some weird chunks with pad numbers not multiple of 8
-    // since I don't know what they are, just skip them
-    if (chunk[2] % 8 !== 0) {
+    const kind = chunk[2] & 0x07;
+    const source = chunk[2] >> 3;
+    const position = chunk[0] | (chunk[1] << 8);
+    const flags = chunk[7];
+    const rawData = chunk.slice();
+
+    if (kind === PatternEventKind.Note) {
+      const duration = chunk[5] | (chunk[6] << 8);
+      const noteEvent: PatternEvent = {
+        type: 'note',
+        kind: PatternEventKind.Note,
+        position,
+        source,
+        flags,
+        rawData,
+        pad: source,
+        note: chunk[3],
+        velocity: chunk[4],
+        duration,
+      };
+
+      events.push(noteEvent);
+
+      if (!notes[source]) {
+        notes[source] = [];
+      }
+
+      notes[source].push({
+        note: noteEvent.note,
+        position: noteEvent.position,
+        duration: noteEvent.duration,
+        velocity: noteEvent.velocity,
+      });
       return;
     }
 
-    const pad = chunk[2] / 8;
-    if (!notes[pad]) {
-      notes[pad] = [];
+    if (kind === PatternEventKind.Fader) {
+      const rawValue = chunk[5] | (chunk[6] << 8);
+
+      events.push({
+        type: 'fader',
+        kind: PatternEventKind.Fader,
+        position,
+        source,
+        flags,
+        rawData,
+        parameter: chunk[3],
+        reserved: chunk[4],
+        rawValue,
+        value: rawValue / 32767,
+      });
+      return;
     }
 
-    notes[pad].push({
-      note: chunk[3],
-      position: (chunk[1] << 8) + chunk[0],
-      duration: (chunk[6] << 8) + chunk[5],
-      velocity: chunk[4],
+    const eventData = chunk.slice(3, 7);
+
+    if (kind === PatternEventKind.Midi) {
+      events.push({
+        type: 'midi',
+        kind: PatternEventKind.Midi,
+        position,
+        source,
+        flags,
+        rawData,
+        data: eventData,
+      });
+      return;
+    }
+
+    events.push({
+      type: 'unknown',
+      kind,
+      position,
+      source,
+      flags,
+      rawData,
+      data: eventData,
     });
   });
 
   return {
     bars: data[1],
+    recordCount,
+    events,
     notes,
   };
 }
@@ -248,6 +330,30 @@ function getPatternsForScene(scenesIntermediate: IntermediateScenes, scenePatter
   return patterns;
 }
 
+function getPatternEventsForScene(
+  scenesIntermediate: IntermediateScenes,
+  scenePatternUsage: SceneMeta,
+) {
+  const patternEvents: Partial<Record<Group, SceneGroupPatternData>> = {};
+
+  for (const group of ['a', 'b', 'c', 'd'] as const) {
+    const patternNumber = scenePatternUsage[group];
+    const groupData = scenesIntermediate[patternNumber]?.groups[group];
+
+    if (groupData) {
+      patternEvents[group] = {
+        group,
+        patternNumber,
+        bars: groupData.bars,
+        recordCount: groupData.recordCount,
+        events: groupData.events,
+      };
+    }
+  }
+
+  return patternEvents;
+}
+
 export function collectScenesAndPatterns(files: TarFile[], sku: string) {
   const scenesIntermediateData: IntermediateScenes = {};
   const scenes: Record<string, Scene> = {};
@@ -306,7 +412,7 @@ export function collectScenesAndPatterns(files: TarFile[], sku: string) {
       ...scenesIntermediateData[sceneIndex],
       groups: {
         ...scenesIntermediateData[sceneIndex].groups,
-        [group]: parsePatterns(file.data, sku === SKU_EP40 ? 6 : 4), // EP-40 has 6-byte header
+        [group]: parsePatternEvents(file.data, sku === SKU_EP40 ? 6 : 4), // EP-40 has 6-byte header
       },
     };
   }
@@ -324,6 +430,10 @@ export function collectScenesAndPatterns(files: TarFile[], sku: string) {
     scenes[sceneIndex] = {
       name: sceneData.name,
       patterns,
+      patternEvents: getPatternEventsForScene(
+        scenesIntermediateData,
+        scenePatternUsage[sceneIndex],
+      ),
     };
   });
 
diff --git a/src/types/types.ts b/src/types/types.ts
index a3e2db4..bd80ce4 100644
--- a/src/types/types.ts
+++ b/src/types/types.ts
@@ -74,9 +74,67 @@ export type Pattern = {
   bars: number;
 };
 
+export enum PatternEventKind {
+  Note = 0,
+  Fader = 1,
+  Midi = 2,
+}
+
+export type PatternEventBase = {
+  position: number;
+  source: number;
+  flags: number;
+  rawData: Uint8Array;
+};
+
+export type NotePatternEvent = PatternEventBase & {
+  type: 'note';
+  kind: PatternEventKind.Note;
+  pad: number;
+  note: number;
+  velocity: number;
+  duration: number;
+};
+
+export type FaderAutomationEvent = PatternEventBase & {
+  type: 'fader';
+  kind: PatternEventKind.Fader;
+  parameter: number;
+  reserved: number;
+  rawValue: number;
+  value: number;
+};
+
+export type MidiPatternEvent = PatternEventBase & {
+  type: 'midi';
+  kind: PatternEventKind.Midi;
+  data: Uint8Array;
+};
+
+export type UnknownPatternEvent = PatternEventBase & {
+  type: 'unknown';
+  kind: number;
+  data: Uint8Array;
+};
+
+export type PatternEvent =
+  | NotePatternEvent
+  | FaderAutomationEvent
+  | MidiPatternEvent
+  | UnknownPatternEvent;
+
+export type SceneGroupPatternData = {
+  group: Group;
+  patternNumber: number;
+  bars: number;
+  recordCount: number;
+  events: PatternEvent[];
+};
+
 export type Scene = {
   name: string;
   patterns: Pattern[];
+  patternEvents: Partial<Record<Group, SceneGroupPatternData>>;
 };
 
 export type Note = {