msgpack-javascript/assembly/utf8EncodeUint16Array.ts at master · keybase/msgpack-javascript · GitHub

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import { utf8CountUint16Array } from "./utf8CountUint16Array";

import { storeUint8BE, storeUint16BE, storeUint32BE, loadUint16BE } from "./be";

function storeStringHeader(outputPtr: usize, utf8ByteLength: usize): usize {

let ptr = outputPtr;

if (utf8ByteLength < 32) {

// fixstr

storeUint8BE(ptr++, 0xa0 + (utf8ByteLength as u8));

} else if (utf8ByteLength < 0x100) {

// str 8

storeUint8BE(ptr++, 0xd9);

storeUint8BE(ptr++, utf8ByteLength as u8);

} else if (utf8ByteLength < 0x10000) {

// str 16

storeUint8BE(ptr++, 0xda);

storeUint16BE(ptr, utf8ByteLength as u16);

ptr += sizeof<u16>();

} else if ((utf8ByteLength as u64) < 0x100000000) {

// str 32

storeUint8BE(ptr++, 0xdb);

storeUint32BE(ptr, utf8ByteLength as u32);

ptr += sizeof<u32>();

} else {

throw new Error(`Too long string: ${utf8ByteLength} bytes in UTF-8`);

}

return ptr;

}

// outputPtr: u8*

// inputPtr: u16*

// It adds MessagePack str head bytes to the output

export function utf8EncodeUint16Array(outputPtr: usize, inputPtr: usize, inputLength: usize): usize {

let utf8ByteLength = utf8CountUint16Array(inputPtr, inputLength);

let strHeaderOffset = storeStringHeader(outputPtr, utf8ByteLength);

const u16s = sizeof<u16>();

let inputOffset = inputPtr;

let inputEnd = inputPtr + inputLength * u16s;

let outputOffset = strHeaderOffset;

while (inputOffset < inputEnd) {

let value: u32 = loadUint16BE(inputOffset);

inputOffset += u16s;

if ((value & 0xffffff80) === 0) {

// 1-byte

store<u8>(outputOffset++, value);

continue;

} else if ((value & 0xfffff800) === 0) {

// 2-bytes

store<u8>(outputOffset++, ((value >> 6) & 0x1f) | 0xc0);

} else {

// handle surrogate pair

if (value >= 0xd800 && value <= 0xdbff) {

// high surrogate

if (inputOffset < inputEnd) {

let extra: u32 = loadUint16BE(inputOffset);

if ((extra & 0xfc00) === 0xdc00) {

inputOffset += u16s;

value = ((value & 0x3ff) << 10) + (extra & 0x3ff) + 0x10000;

}

if ((value & 0xffff0000) === 0) {

// 3-byte

store<u8>(outputOffset++, ((value >> 12) & 0x0f) | 0xe0);

store<u8>(outputOffset++, ((value >> 6) & 0x3f) | 0x80);

} else {

// 4-byte

store<u8>(outputOffset++, ((value >> 18) & 0x07) | 0xf0);

store<u8>(outputOffset++, ((value >> 12) & 0x3f) | 0x80);

store<u8>(outputOffset++, ((value >> 6) & 0x3f) | 0x80);

}

store<u8>(outputOffset++, (value & 0x3f) | 0x80);

}

return outputOffset - outputPtr;

}

msgpack-javascript/assembly/utf8EncodeUint16Array.ts at master · keybase/msgpack-javascript · GitHub

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