Read file data of root directory entries

src/floppy/disk.ts

@@ -46,6 +46,8 @@ export interface IStandardDirEntry {
   attributes: IAttributes
   size: number
   firstCluster: number
+  clusterChain: number[]
+  data: ArrayBuffer
 }
 
 export interface ILongFileNameDirEntry {
@@ -84,7 +86,45 @@ export class FloppyDisk {
           new DataView(this._buffer, this.rootDirOffset, this.rootDirSize),
         )
       }
+
+      if (this._rootDirEntries === null) {
+        return null
       }
+
+      for (const entry of this._rootDirEntries) {
+        if (entry.type === 'standard-entry' && (entry.size > 0 || entry.attributes.directory)) {
+          entry.clusterChain = this.clusterChain(entry.firstCluster)
+
+          const dataSize = entry.clusterChain.length * this.bytesPerCluster
+          if (dataSize === 0) {
+            continue
+          }
+
+          const data = new Uint8Array(dataSize)
+          for (let i = 0; i < entry.clusterChain.length; i++) {
+            const offset = (entry.clusterChain[i] - 2) * this.bytesPerCluster
+            const view = new Uint8Array(
+              this._buffer,
+              this.dataOffset + offset,
+              this.bytesPerCluster,
+            )
+            data.set(view, i * this.bytesPerCluster)
+          }
+          console.log(
+            entry.name.trim() + (entry.extension.trim() ? '.' + entry.extension.trim() : ''),
+          )
+          entry.data = data.slice(0, entry.size > 0 ? entry.size : data.byteLength)
+          if (
+            !entry.attributes.directory &&
+            (['BAT', 'TXT', 'BAS'].includes(entry.extension) || entry.name.trim() === 'LICENSE')
+          ) {
+            const decoder = new TextDecoder()
+            console.log(decoder.decode(entry.data))
+          }
+        }
+      }
+    }
+
     return this._rootDirEntries
   }
 
@@ -116,6 +156,14 @@ export class FloppyDisk {
     return this.bootSectorInfo?.biosParameterBlock?.bytesPerSector ?? 0
   }
 
+  get sectorsPerCluster() {
+    return this.bootSectorInfo?.biosParameterBlock?.sectorsPerCluster ?? 0
+  }
+
+  get bytesPerCluster() {
+    return this.bytesPerSector * this.sectorsPerCluster
+  }
+
   get rootDirSectors() {
     if (this.bytesPerSector === 0) {
       return 0
@@ -143,6 +191,34 @@ export class FloppyDisk {
   get rootDirSize() {
     return this.rootDirSectors * this.bytesPerSector
   }
+
+  nextCluster(current: number): number {
+    const tableOffset = Math.floor(current + current / 2)
+    const tableSector = Math.floor(this.reservedSectorCount + tableOffset / this.bytesPerSector)
+    const entityOffset = tableOffset % this.bytesPerSector
+
+    const table = new DataView(
+      this._buffer,
+      tableSector * this.bytesPerSector,
+      2 * this.bytesPerSector,
+    )
+
+    const value = table.getUint16(entityOffset, true)
+
+    return current & 1 ? value >> 4 : value & 0x0fff
+  }
+
+  clusterChain(start: number): number[] {
+    const chain = [start]
+
+    let next = this.nextCluster(start)
+    while (next > 1 && next < 0xff7) {
+      chain.push(next)
+      next = this.nextCluster(next)
+    }
+
+    return chain
+  }
 }
 
 function decodeBootSector(data: DataView): IBootSectorInfo | null {
@@ -262,6 +338,8 @@ function decodeDirectoryEntry(data: DataView): DirEntry | null {
       extension,
       attributes,
       firstCluster,
+      clusterChain: [],
+      data: new ArrayBuffer(0),
       size,
     }
   }