Palak Handa / startUpJalsa-Backend

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node_modules/to-utf8/index.js 1.48 KB
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f7563de62   Palak Handa   first commit 
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  module.exports = to_utf8
  
  var out = []
    , col = []
    , fcc = String.fromCharCode
    , mask = [0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01]
    , unmask = [
        0x00
      , 0x01
      , 0x02 | 0x01
      , 0x04 | 0x02 | 0x01
      , 0x08 | 0x04 | 0x02 | 0x01
      , 0x10 | 0x08 | 0x04 | 0x02 | 0x01
      , 0x20 | 0x10 | 0x08 | 0x04 | 0x02 | 0x01
      , 0x40 | 0x20 | 0x10 | 0x08 | 0x04 | 0x02 | 0x01
    ]
  
  function to_utf8(bytes, start, end) {
    start = start === undefined ? 0 : start
    end = end === undefined ? bytes.length : end
  
    var idx = 0
      , hi = 0x80
      , collecting = 0
      , pos
      , by
  
    col.length =
    out.length = 0
  
    while(idx < bytes.length) {
      by = bytes[idx]
      if(!collecting && by & hi) {
        pos = find_pad_position(by)
        collecting += pos
        if(pos < 8) {
          col[col.length] = by & unmask[6 - pos]
        }
      } else if(collecting) {
        col[col.length] = by & unmask[6]
        --collecting
        if(!collecting && col.length) {
          out[out.length] = fcc(reduced(col, pos))
          col.length = 0
        }
      } else { 
        out[out.length] = fcc(by)
      }
      ++idx
    }
    if(col.length && !collecting) {
      out[out.length] = fcc(reduced(col, pos))
      col.length = 0
    }
    return out.join('')
  }
  
  function find_pad_position(byt) {
    for(var i = 0; i < 7; ++i) {
      if(!(byt & mask[i])) {
        break
      }
    }
    return i
  }
  
  function reduced(list) {
    var out = 0
    for(var i = 0, len = list.length; i < len; ++i) {
      out |= list[i] << ((len - i - 1) * 6)
    }
    return out
  }