added SimpleBuffer to wrap DataView and node's Buffer

src/mol-io/common/simple-buffer.ts

+/**
+ * Copyright (c) 2019 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ *
+ * @author Alexander Rose <alexander.rose@weirdbyte.de>
+ */
+
+export interface SimpleBuffer extends Uint8Array {
+    readInt8: (offset: number) => number
+    readUInt8: (offset: number) => number
+
+    writeInt8: (value: number, offset: number) => void
+    writeUInt8: (value: number, offset: number) => void
+
+    readInt16LE: (offset: number) => number
+    readInt32LE: (offset: number) => number
+    readUInt16LE: (offset: number) => number
+    readUInt32LE: (offset: number) => number
+    readFloatLE: (offset: number) => number
+    readDoubleLE: (offset: number) => number
+
+    writeInt16LE: (value: number, offset: number) => void
+    writeInt32LE: (value: number, offset: number) => void
+    writeUInt16LE: (value: number, offset: number) => void
+    writeUInt32LE: (value: number, offset: number) => void
+    writeFloatLE: (value: number, offset: number) => void
+    writeDoubleLE: (value: number, offset: number) => void
+
+    readInt16BE: (offset: number) => number
+    readInt32BE: (offset: number) => number
+    readUInt16BE: (offset: number) => number
+    readUInt32BE: (offset: number) => number
+    readFloatBE: (offset: number) => number
+    readDoubleBE: (offset: number) => number
+
+    writeInt16BE: (value: number, offset: number) => void
+    writeInt32BE: (value: number, offset: number) => void
+    writeUInt16BE: (value: number, offset: number) => void
+    writeUInt32BE: (value: number, offset: number) => void
+    writeFloatBE: (value: number, offset: number) => void
+    writeDoubleBE: (value: number, offset: number) => void
+}
+
+export namespace SimpleBuffer {
+    export function fromUint8Array(array: Uint8Array): SimpleBuffer {
+        const dv = new DataView(array.buffer)
+        return Object.assign(array.subarray(0), {
+            readInt8: (offset: number) => dv.getInt8(offset),
+            readUInt8: (offset: number) => dv.getUint8(offset),
+            writeInt8: (value: number, offset: number) => dv.setInt8(offset, value),
+            writeUInt8: (value: number, offset: number) => dv.setUint8(offset, value),
+
+            readInt16LE: (offset: number) => dv.getInt16(offset, true),
+            readInt32LE: (offset: number) => dv.getInt32(offset, true),
+            readUInt16LE: (offset: number) => dv.getUint16(offset, true),
+            readUInt32LE: (offset: number) => dv.getUint32(offset, true),
+            readFloatLE: (offset: number) => dv.getFloat32(offset, true),
+            readDoubleLE: (offset: number) => dv.getFloat64(offset, true),
+
+            writeInt16LE: (value: number, offset: number) => dv.setInt16(offset, value, true),
+            writeInt32LE: (value: number, offset: number) => dv.setInt32(offset, value, true),
+            writeUInt16LE: (value: number, offset: number) => dv.setUint16(offset, value, true),
+            writeUInt32LE: (value: number, offset: number) => dv.setUint32(offset, value, true),
+            writeFloatLE: (value: number, offset: number) => dv.setFloat32(offset, value, true),
+            writeDoubleLE: (value: number, offset: number) => dv.setFloat64(offset, value, true),
+
+            readInt16BE: (offset: number) => dv.getInt16(offset, false),
+            readInt32BE: (offset: number) => dv.getInt32(offset, false),
+            readUInt16BE: (offset: number) => dv.getUint16(offset, false),
+            readUInt32BE: (offset: number) => dv.getUint32(offset, false),
+            readFloatBE: (offset: number) => dv.getFloat32(offset, false),
+            readDoubleBE: (offset: number) => dv.getFloat64(offset, false),
+
+            writeInt16BE: (value: number, offset: number) => dv.setInt16(offset, value, false),
+            writeInt32BE: (value: number, offset: number) => dv.setInt32(offset, value, false),
+            writeUInt16BE: (value: number, offset: number) => dv.setUint16(offset, value, false),
+            writeUInt32BE: (value: number, offset: number) => dv.setUint32(offset, value, false),
+            writeFloatBE: (value: number, offset: number) => dv.setFloat32(offset, value, false),
+            writeDoubleBE: (value: number, offset: number) => dv.setFloat64(offset, value, false),
+        })
+    }
+
+    export function fromBuffer(buffer: Buffer): SimpleBuffer {
+        return buffer
+    }
+
+    /** source and target can't be the same */
+    export function flipByteOrder(source: SimpleBuffer, target: Uint8Array, byteCount: number, elementByteSize: number, offset: number) {
+        for (let i = 0, n = byteCount; i < n; i += elementByteSize) {
+            for (let j = 0; j < elementByteSize; j++) {
+                target[offset + i + elementByteSize - j - 1] = source[offset + i + j];
+            }
+        }
+    }
+}
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