@ain1084/array-buffer-partitioner/dist/index.js

Partition an ArrayBuffer into multiple TypedArray views efficiently.

/**
 * Creates multiple TypedArray views on a single ArrayBuffer or SharedArrayBuffer.
 * The function takes a constructor (either ArrayBuffer or SharedArrayBuffer) and a configuration object,
 * then allocates the buffer and returns the specified TypedArray views.
 *
 * @typeParam T - A record specifying the TypedArray types and sizes.
 * @param BufferType - The constructor for the buffer, either ArrayBuffer or SharedArrayBuffer.
 * @param config - An object specifying the desired views. Each key represents the name of the view, and the value is a tuple where:
 *  - The first element is the TypedArray class name (e.g., Float32Array, Uint32Array).
 *  - The second element is the number of elements for that view.
 *
 * @returns An object containing the views, with each key corresponding to the provided configuration.
 *
 * @example
 * ```typescript
 * import { createArrayBufferViews } from '@ain1084/array-buffer-partitioner';
 *
 * const views = createArrayBufferViews(ArrayBuffer, {
 *   data: [Float32Array, 1024],
 *   index: [Uint32Array, 1],
 *   flag: [Uint8Array, 1]
 * });
 *
 * console.log(views.data.length); // 1024
 * console.log(views.data.byteOffset); // 0
 * console.log(views.index.length); // 1
 * console.log(views.flag.length); // 1
 * console.log(views.flag.byteOffset); // 4100
 * console.log(views.data.buffer.byteLength); // 4104
 * ```
 */
export function createArrayBufferViews(BufferType, config) {
    const alignTo = (value, alignment) => (value + alignment - 1) & ~(alignment - 1);
    let totalSize = 0;
    for (const [, [type, size]] of Object.entries(config)) {
        const alignment = type.BYTES_PER_ELEMENT;
        totalSize = alignTo(totalSize, alignment) + (alignment * size);
    }
    const buffer = new BufferType(totalSize);
    const result = {};
    let offset = 0;
    for (const key in config) {
        const [type, size] = config[key];
        const alignment = type.BYTES_PER_ELEMENT;
        offset = alignTo(offset, alignment);
        result[key] = new type(buffer, offset, size);
        offset += alignment * size;
    }
    return result;
}
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