CS 2734 Computer Organization II

In this laboratory you will be writing code to break an input MIPS instruction into its component parts.

• Create a new directory for this assignment.

• Use the following function prototype as a starting point:

  /* mipsInstrReg.h: Instruction Register Simulator header file */
  void InstrReg(unsigned int IRinstr, unsigned int *op,
     unsigned int *rs, unsigned int *rt, unsigned int *rd,
     unsigned int *sh, unsigned int *ft,
     unsigned int *ai, unsigned int *ta);
  /* InstrReg: Simulate Instruction Register (break instruction into fields)
   * Input: 
   *   IRinstr: input 32-bit instruction
   * Outputs:
   *   op: op code,     bits 26-31
   *   rs: read reg #1, bits 21-25
   *   rt: read reg #2, bits 16-20
   *   rd: write reg,   bits 11-15
   *   sh: shamt,       bits 6-10
   *   ft: funct,       bits 0-5
   *   ai: addr/immed,  bits 0-15
   *   ta: target addr, bits 0-25
   */
  void dumpInstrReg(void);
  

• We discussed a strategy for doing this assignment in class: Use a mask and a C bitwise "and" operation to pick off the bits of the field, and then right shift them to the zeroth bit position. (Alternatively, as we discussed in class, you can use two shifts.)

• Note that there is overlap between the fields, that is, some bits contribute to several different fields, which might or might not be needed, depending on the particular instruction.

• Write a testInstrReg.c program to test the program. It might read and process a 32-bit instruction (a 32-bit hex number should be input). The output should be the various fields of the instruction, as unsigned ints.

• The answer form in the disassembly part of Lab 7 shows various machine instructions broken into their component parts, as a first step toward converting them to assembly language. We will be doing this first step, but then will be simulating the actions of the MIPS computer on these components.

• You should check off the function with the lab TA. You must hand the source code to the TA before he starts checking off the project.