CSC656_NOTE/Notes.txt at master · KamiGasai/CSC656_NOTE · GitHub

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MIPS Assembly/Instruction Formats:   https://en.wikibooks.org/wiki/MIPS_Assembly/Instruction_Formats#I_Instructions

R-format:
  e.g.:add $s1, $s2, $s3

opcode	 rs      rt	      rd	    shift(shamt)  	funct
6 bits	5 bits	5 bits	5 bits   	5 bits	      6 bits


I-format:
  e.g.: addi $s1, $s2, 100

J-format:
  e.g.: jump LABEL

----------------------------------------------------------------------------------------------------------------------------------------
ALUSRC：

  The MIPS architecture add instruction adds either two registers, or a register and a 16-bit immediate value that is encoded into the add instruction itself.

  ALUSrc controls a mux that determines whether the second operand to the ALU is a register, or the 16-bit immediate value.

  Reference from:https://tw.answers.yahoo.com/question/index?qid=20121107092830AA9S3Zx


----------------------------------------------------------------------------------------------------------------------------------------

    ALUOp   Action needed by ALU

    00      Addition (for load and store)
    01      Subtraction (for beq)
    10      Determined by funct field (R-type instruction)
    11      Not used

Opcode	ALUOp	operation 	functField    ALUaction 	    ALU cntl
LW	    00	  loadWord	  xxxxxx	         add	          010
SW	    00	  storeWord	  xxxxxx	         add	          010
BEQ	    01	  branchEqual xxxxxx	       subtract 	      110
R-type	10	  add	        100000	         add	          010
R-type	10	  subtract	  100010	       subtract	        110
R-type	10	  AND	        100100	         and	          000
R-type	10	  OR	        100101	          or	          001
R-type	10	  SLT	        101010	    set on less than    111

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More information from Zhihu:

Simple explanation of how 1+1=2 works in computing.

如何通俗的解释计算机是如何实现1+1=2计算的？ - Barbirolli的回答 - 知乎
https://www.zhihu.com/question/29707696/answer/71747103