Jaco Greeff
80db504a3b
* WIP * ... and more * yet more... * and examples (more-or-less) fixed * Only problematic promisify left... * Last batch * rm config header * Update * Use Record * Bumps
35 lines
1.2 KiB
TypeScript
35 lines
1.2 KiB
TypeScript
// Copyright 2017-2019 @polkadot/trie-codec authors & contributors
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// This software may be modified and distributed under the terms
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// of the Apache-2.0 license. See the LICENSE file for details.
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import { assert, u8aConcat } from '@polkadot/util';
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import { EXTENSION_NODE_BIG, EXTENSION_NODE_OFFSET, LEAF_NODE_BIG, LEAF_NODE_OFFSET } from '../constants';
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import fromNibbles from './fromNibbles';
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const MAX_FUSE_LENGTH = 255 + 126;
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export default function fuseNibbles (nibbles: Uint8Array, isLeaf: boolean): Uint8Array {
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assert(nibbles.length < MAX_FUSE_LENGTH, `Input to fuseNibbles too large, found ${nibbles.length} >= ${MAX_FUSE_LENGTH}`);
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const [firstByteSmall, bigThreshold] = isLeaf
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? [LEAF_NODE_OFFSET, LEAF_NODE_BIG - LEAF_NODE_OFFSET]
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: [EXTENSION_NODE_OFFSET, EXTENSION_NODE_BIG - EXTENSION_NODE_OFFSET];
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const result: Uint8Array[] = [
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Uint8Array.from([firstByteSmall + Math.min(nibbles.length, bigThreshold)])
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];
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const oddFlag = nibbles.length % 2;
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if (nibbles.length >= bigThreshold) {
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result.push(Uint8Array.from([nibbles.length - bigThreshold]));
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}
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if (oddFlag === 1) {
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result.push(nibbles.subarray(0, 1));
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}
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result.push(fromNibbles(nibbles.subarray(oddFlag)));
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return u8aConcat(...result);
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}
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