@bestinslot/nada/dist/src/nada.js

Compression-focused encoding for zero-heavy solidity calldata and bytecode

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.encode = encode;
exports.decode = decode;
exports.decode_with_limit = decode_with_limit;
function encode(input) {
    const output = [];
    let zeroRun = 0;
    for (let i = 0; i <= input.length; i++) {
        const byte = input[i];
        if (byte === 0x00) {
            zeroRun++;
            if (zeroRun === 255) {
                output.push(0xFF, 255); // encode max run
                zeroRun = 0;
            }
        }
        else {
            if (zeroRun > 0) {
                if (zeroRun == 1) {
                    output.push(0x00);
                }
                else if (zeroRun == 2) {
                    output.push(0x00, 0x00);
                }
                else {
                    output.push(0xFF, zeroRun);
                }
                zeroRun = 0;
            }
            if (byte === 0xFF) {
                const next = input[i + 1];
                if (next === 0xFF) {
                    output.push(0xFF, 0x02);
                    i++; // skip the second 0xFF
                }
                else {
                    output.push(0xFF, 0x01);
                }
            }
            else if (byte !== undefined) {
                output.push(byte);
            }
        }
    }
    if (zeroRun > 0) {
        if (zeroRun == 1) {
            output.push(0x00);
        }
        else if (zeroRun == 2) {
            output.push(0x00, 0x00);
        }
        else {
            output.push(0xFF, zeroRun);
        }
        zeroRun = 0;
    }
    return Uint8Array.from(output);
}
function decode(input) {
    return decode_with_limit(input, Number.MAX_SAFE_INTEGER);
}
function decode_with_limit(input, limit) {
    const output = [];
    for (let i = 0; i < input.length; i++) {
        const byte = input[i];
        if (byte === 0xFF) {
            const next = input[++i];
            if (next === 0x00) {
                throw new Error('invalid nada sequence: 0xFF 0x00');
            }
            if (next === undefined) {
                throw new Error('unexpected end of input');
            }
            if (next === 0x01) {
                output.push(0xFF);
            }
            else if (next === 0x02) {
                output.push(0xFF, 0xFF);
            }
            else if (next >= 0x03 && next <= 0xFF) {
                for (let j = 0; j < next; j++) {
                    output.push(0x00);
                }
            }
            else {
                throw new Error(`invalid nada byte: 0x${next.toString(16)}`);
            }
        }
        else {
            output.push(byte);
        }
        if (output.length > limit) {
            throw new Error(`output length exceeded limit: ${limit}`);
        }
    }
    return Uint8Array.from(output);
}
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