All Addresses Great and Small

There are no alignment requirements for the three instructions: lb, lbu, and sb. Any byte in memory that is acceptable for program data can be used. This is fortunate since character strings are usually stored in successive bytes.

Byte load and store instructions are often used for input and output with media that must be used on many types of systems. Often the data written to magnetic tape by one government agency is used by other agencies using different computers. To make the data transportable, the format of the data is described byte by byte. The format must be followed, regardless of the inherent byte order of the computers writing or reading the data.

QUESTION 4:

A particular data tape requires big-endian integers. Data is assembled in memory in a buffer before it is written out to the tape. The I/O buffer for the tape starts at address 0x10000000. Complete the following instructions so that the integer in register $9 is stored in the four bytes starting at address 0x10000000. Put the most significant byte (the "big end") at the starting address.

lui  $8,0x1000       # $8 is base register

sb   $9,($8)    # least significant byte

srl  $9,$9,     # move next byte to low order

sb   $9,($8)    # bits 8-15 

srl  $9,$9,     # move next byte to low order

sb   $9,($8)    # bits 16-23 

srl  $9,$9,     # move next byte to low order

sb   $9,($8)    # most significant byte

Answer:

All Addresses Great and Small

QUESTION 4: