You will write a MIPS program that reads a string of up to 1000 characters from user input. The string consists of one or more sub strings separated by comma. S paces or tabs at the beginning or end or around commas are ignored , those spaces or tabs should stay . For each of the substring, if it is a hexadecimal string, i.e. it has only the characters from '0' to '9' and from 'a' to 'f' and from 'A' to 'F' , and it is of no more than 8 characters, the program prints out the corresponding unsigned decimal integer. If the hexadecimal string has more than 8 characters, the program prints out the string of too large . Otherwise, the program prints out the string of NaN . Empty strings before the first comma, between commas or after the last comma are al so considered NaN . The output should be separated by commas in the same way as the input.

The program must have the following 3 subprograms.

Subprogram 1:

It converts a single hexadecimal character to a decimal integer. Registers must be used to pass parameters into the subprogram. Values must be returned via registers.

Subprogram 2:

It converts a single hexadecimal string to a decimal integer. It must call Subprogram 1 to get the decimal value of each of the characters in the string. Registers must be used to pass parameters into the subprogram . Values must be returned via the stack .

Subprogram 3:

It displays an unsigned decimal integer. The stack must be used to pass parameters into the subprogram . No values are returned.

The main program must call Subprogram 2 for conversion and call Subprogram 3 for output.