Storage device for storing data while compressing same value input data

A storage device for storing data, while compressing same value of input data, includes an input processing unit, a data storage, a first-in-first-out memory, and an output processing unit. The input processing unit is configured to, upon receiving an input value, determine whether a data value stored in the data storage at an address location corresponding to the input value is valid. If the data value is invalid, the input processing unit stores an initial value at the address location and stores the input value in the first-in-first-out memory. If the data value is valid, the input processing unit performs an arithmetic operation on the data value and stores the operation result in the address location corresponding to the input value. The output processing unit is configured to read and output the input value stored at a head of the first-in-first-out memory, as well as reading and outputting the data value from the address location of the data storage corresponding to the input value, if one or more input values are stored in the first-in-first-out memory and if the data value stored at the address location of the data storage corresponding to the input value is valid, and to update the data value after the output.