revised-readvarint.go

func ReadVarIntToUint(r io.Reader) (uint64, error) {
    var (
        varbs []byte
        ba    [1]byte
        u     uint64
        n     int
        err   error
    )

    varbs = make([]byte, 0, 10)

    /* ---[ read in all varint bytes ]--- */
    for {
        n, err = r.Read(ba[:])
        if err != nil {
            return 0, oerror.NewTrace(err)
        }
        if n != 1 {
            return 0, oerror.IncorrectNetworkRead{Expected: 1, Actual: n}
        }
        varbs = append(varbs, ba[0])
        if IsFinalVarIntByte(ba[0]) {
            varbs = append(varbs, byte(0x0))
            break
        }
    }

    /* ---[ decode ]--- */

    var right, left uint

    finalbs := make([]byte, 8)

    idx := 0
    for i := 0; i < len(varbs)-1 && idx < 8; i++ {
        right = uint(i) % 8
        left = 7 - right
        if i == 7 {
            continue
        }
        vbcurr := varbs[i]
        vbnext := varbs[i+1]

        x := vbcurr & byte(0x7f)
        y := x >> right
        z := vbnext << left
        finalbs[idx] = y | z
        idx++
    }

    u = binary.LittleEndian.Uint64(finalbs)
    return u, nil
}