41 lines
1.4 KiB
JavaScript
41 lines
1.4 KiB
JavaScript
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/* charCodeAt is the best approach for binary strings */
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function crc32_bstr(bstr) {
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for(var crc = -1, i = 0, L=bstr.length-1; i < L;) {
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crc = (crc >>> 8) ^ table[(crc ^ bstr.charCodeAt(i++)) & 0xFF];
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crc = (crc >>> 8) ^ table[(crc ^ bstr.charCodeAt(i++)) & 0xFF];
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}
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if(i === L) crc = (crc >>> 8) ^ table[(crc ^ bstr.charCodeAt(i++)) & 0xFF];
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return crc ^ -1;
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}
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function crc32_buf(buf) {
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for(var crc = -1, i = 0; i != buf.length; ++i) {
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crc = (crc >>> 8) ^ table[(crc ^ buf[i]) & 0xFF];
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}
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return crc ^ -1;
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}
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/* much much faster to intertwine utf8 and crc */
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function crc32_str(str) {
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for(var crc = -1, i = 0, L=str.length, c, d; i < L;) {
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c = str.charCodeAt(i++);
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if(c < 0x80) {
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crc = (crc >>> 8) ^ table[(crc ^ c) & 0xFF];
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} else if(c < 0x800) {
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crc = (crc >>> 8) ^ table[(crc ^ (192|((c>>6)&31))) & 0xFF];
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crc = (crc >>> 8) ^ table[(crc ^ (128|(c&63))) & 0xFF];
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} else if(c >= 0xD800 && c < 0xE000) {
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c = (c&1023)+64; d = str.charCodeAt(i++) & 1023;
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crc = (crc >>> 8) ^ table[(crc ^ (240|((c>>8)&7))) & 0xFF];
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crc = (crc >>> 8) ^ table[(crc ^ (128|((c>>2)&63))) & 0xFF];
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crc = (crc >>> 8) ^ table[(crc ^ (128|((d>>6)&15)|(c&3))) & 0xFF];
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crc = (crc >>> 8) ^ table[(crc ^ (128|(d&63))) & 0xFF];
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} else {
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crc = (crc >>> 8) ^ table[(crc ^ (224|((c>>12)&15))) & 0xFF];
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crc = (crc >>> 8) ^ table[(crc ^ (128|((c>>6)&63))) & 0xFF];
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crc = (crc >>> 8) ^ table[(crc ^ (128|(c&63))) & 0xFF];
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}
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}
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return crc ^ -1;
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}
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