js-crc32/crc32.mjs

/*! crc32.js (C) 2014-present SheetJS -- http://sheetjs.com */
/* vim: set ts=2: */
var CRC32 = {};
CRC32.version = '1.2.3';
/*::
type CRC32Type = number;
type ABuf = Array<number> | Buffer | Uint8Array;
type CRC32TableType = Array<number> | Int32Array;
*/
/*global Int32Array */
function signed_crc_table()/*:CRC32TableType*/ {
	var c = 0, table/*:Array<number>*/ = new Array(256);

	for(var n =0; n != 256; ++n){
		c = n;
		c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
		c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
		c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
		c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
		c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
		c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
		c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
		c = ((c&1) ? (-306674912 ^ (c >>> 1)) : (c >>> 1));
		table[n] = c;
	}

	return typeof Int32Array !== 'undefined' ? new Int32Array(table) : table;
}

var T0 = signed_crc_table();
function slice_by_16_tables(T) {
	var c = 0, v = 0, n = 0, table/*:Array<number>*/ = typeof Int32Array !== 'undefined' ? new Int32Array(4096) : new Array(4096) ;

	for(n = 0; n != 256; ++n) table[n] = T[n];
	for(n = 0; n != 256; ++n) {
		v = T[n];
		for(c = 256 + n; c < 4096; c += 256) v = table[c] = (v >>> 8) ^ T[v & 0xFF];
	}
	var out = [];
	for(n = 1; n != 16; ++n) out[n - 1] = typeof Int32Array !== 'undefined' ? table.subarray(n * 256, n * 256 + 256) : table.slice(n * 256, n * 256 + 256);
	return out;
}
var TT = slice_by_16_tables(T0);
var T1 = TT[0],  T2 = TT[1],  T3 = TT[2],  T4 = TT[3],  T5 = TT[4];
var T6 = TT[5],  T7 = TT[6],  T8 = TT[7],  T9 = TT[8],  Ta = TT[9];
var Tb = TT[10], Tc = TT[11], Td = TT[12], Te = TT[13], Tf = TT[14];
function crc32_bstr(bstr/*:string*/, seed/*:?CRC32Type*/)/*:CRC32Type*/ {
	var C = seed/*:: ? 0 : 0 */ ^ -1;
	for(var i = 0, L = bstr.length; i < L;) C = (C>>>8) ^ T0[(C^bstr.charCodeAt(i++))&0xFF];
	return ~C;
}

function crc32_buf(B/*:ABuf*/, seed/*:?CRC32Type*/)/*:CRC32Type*/ {
	var C = seed/*:: ? 0 : 0 */ ^ -1, L = B.length - 15, i = 0;
	for(; i < L;) C =
		Tf[B[i++] ^ (C & 255)] ^
		Te[B[i++] ^ ((C >> 8) & 255)] ^
		Td[B[i++] ^ ((C >> 16) & 255)] ^
		Tc[B[i++] ^ (C >>> 24)] ^
		Tb[B[i++]] ^ Ta[B[i++]] ^ T9[B[i++]] ^ T8[B[i++]] ^
		T7[B[i++]] ^ T6[B[i++]] ^ T5[B[i++]] ^ T4[B[i++]] ^
		T3[B[i++]] ^ T2[B[i++]] ^ T1[B[i++]] ^ T0[B[i++]];
	L += 15;
	while(i < L) C = (C>>>8) ^ T0[(C^B[i++])&0xFF];
	return ~C;
}

function crc32_str(str/*:string*/, seed/*:?CRC32Type*/)/*:CRC32Type*/ {
	var C = seed/*:: ? 0 : 0 */ ^ -1;
	for(var i = 0, L = str.length, c = 0, d = 0; i < L;) {
		c = str.charCodeAt(i++);
		if(c < 0x80) {
			C = (C>>>8) ^ T0[(C^c)&0xFF];
		} else if(c < 0x800) {
			C = (C>>>8) ^ T0[(C ^ (192|((c>>6)&31)))&0xFF];
			C = (C>>>8) ^ T0[(C ^ (128|(c&63)))&0xFF];
		} else if(c >= 0xD800 && c < 0xE000) {
			c = (c&1023)+64; d = str.charCodeAt(i++)&1023;
			C = (C>>>8) ^ T0[(C ^ (240|((c>>8)&7)))&0xFF];
			C = (C>>>8) ^ T0[(C ^ (128|((c>>2)&63)))&0xFF];
			C = (C>>>8) ^ T0[(C ^ (128|((d>>6)&15)|((c&3)<<4)))&0xFF];
			C = (C>>>8) ^ T0[(C ^ (128|(d&63)))&0xFF];
		} else {
			C = (C>>>8) ^ T0[(C ^ (224|((c>>12)&15)))&0xFF];
			C = (C>>>8) ^ T0[(C ^ (128|((c>>6)&63)))&0xFF];
			C = (C>>>8) ^ T0[(C ^ (128|(c&63)))&0xFF];
		}
	}
	return ~C;
}
export const version = CRC32.version;
export const table = T0;
export const bstr = crc32_bstr;
export const buf = crc32_buf;
export const str = crc32_str;