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Module

std/webgpu/row_padding.ts

Deno standard library
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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
/** Return value for {@linkcode getRowPadding}. */export interface Padding { /** The number of bytes per row without padding calculated. */ unpadded: number; /** The number of bytes per row with padding calculated. */ padded: number;}
/** Buffer-Texture copies must have [`bytes_per_row`] aligned to this number. */export const COPY_BYTES_PER_ROW_ALIGNMENT = 256;
/** Number of bytes per pixel. */export const BYTES_PER_PIXEL = 4;
/** * Calculates the number of bytes including necessary padding when passing a {@linkcode GPUImageCopyBuffer}. * * Ref: https://en.wikipedia.org/wiki/Data_structure_alignment#Computing_padding * * @example * ```ts * import { getRowPadding } from "https://deno.land/std@$STD_VERSION/webgpu/row_padding.ts"; * * getRowPadding(2); // { unpadded: 8, padded: 256 } * ``` */export function getRowPadding(width: number): Padding { // It is a WebGPU requirement that // GPUImageCopyBuffer.layout.bytesPerRow % COPY_BYTES_PER_ROW_ALIGNMENT == 0 // So we calculate paddedBytesPerRow by rounding unpaddedBytesPerRow // up to the next multiple of COPY_BYTES_PER_ROW_ALIGNMENT.
const unpaddedBytesPerRow = width * BYTES_PER_PIXEL; const paddedBytesPerRowPadding = (COPY_BYTES_PER_ROW_ALIGNMENT - (unpaddedBytesPerRow % COPY_BYTES_PER_ROW_ALIGNMENT)) % COPY_BYTES_PER_ROW_ALIGNMENT; const paddedBytesPerRow = unpaddedBytesPerRow + paddedBytesPerRowPadding;
return { unpadded: unpaddedBytesPerRow, padded: paddedBytesPerRow, };}
/** * Creates a new buffer while removing any unnecessary empty bytes. * Useful for when wanting to save an image as a specific format. * * @example * ```ts * import { resliceBufferWithPadding } from "https://deno.land/std@$STD_VERSION/webgpu/row_padding.ts"; * * const input = new Uint8Array([0, 255, 0, 255, 120, 120, 120]); * resliceBufferWithPadding(input, 1, 1); // Uint8Array(4) [ 0, 255, 0, 255 ] * ``` */export function resliceBufferWithPadding( buffer: Uint8Array, width: number, height: number,): Uint8Array { const { padded, unpadded } = getRowPadding(width); const outputBuffer = new Uint8Array(unpadded * height);
for (let i = 0; i < height; i++) { const slice = buffer .slice(i * padded, (i + 1) * padded) .slice(0, unpadded);
outputBuffer.set(slice, i * unpadded); }
return outputBuffer;}