module.exports = function bufferIndexOf(buff, search, offset, encoding){
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if (!Buffer.isBuffer(buff)) {
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throw TypeError('buffer is not a buffer');
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}
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// allow optional offset when providing an encoding
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if (encoding === undefined && typeof offset === 'string') {
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encoding = offset;
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offset = undefined;
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}
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if (typeof search === 'string') {
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search = new Buffer(search, encoding || 'utf8');
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} else if (typeof search === 'number' && !isNaN(search)) {
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search = new Buffer([search])
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} else if (!Buffer.isBuffer(search)) {
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throw TypeError('search is not a bufferable object');
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}
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if (search.length === 0) {
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return -1;
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}
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if (offset === undefined || (typeof offset === 'number' && isNaN(offset))) {
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offset = 0;
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} else if (typeof offset !== 'number') {
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throw TypeError('offset is not a number');
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}
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if (offset < 0) {
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offset = buff.length + offset
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}
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if (offset < 0) {
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offset = 0;
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}
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var m = 0;
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var s = -1;
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for (var i = offset; i < buff.length ; ++i) {
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if(buff[i] != search[m]){
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s = -1;
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// <-- go back
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// match abc to aabc
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// 'aabc'
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// 'aab'
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// ^ no match
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// a'abc'
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// ^ set index here now and look at these again.
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// 'abc' yay!
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i -= m-1
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m = 0;
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}
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if(buff[i] == search[m]) {
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if(s == -1) {
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s = i;
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}
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++m;
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if(m == search.length) {
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break;
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}
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}
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}
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if (s > -1 && buff.length - s < search.length) {
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return -1;
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}
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return s;
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}
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