Update README.md

README.md

-# 
+# Building a Simple MIPS Simulator 
 
 ## 개요
 
+이 프로젝트는 MIPS instruction set의 subset의 emulator를 build 하는 것이다.
+
+emulator는 MIPS binary file을 emulation 된 메모리에 로드하고 instruction을 실행한다.
+
+instruction을 실행하면 레지스터와 메모리의 상태가 변경되고 그 변경 된 값을 output으로 보여준다.
 
 ## 사용된 환경 & version
 - Ubuntu 18.04.1 LTS (64bit)
@@ -10,7 +15,7 @@
 
 ## 사용 시 주의사항
 
-**object파일 생성 및 assembler 테스트**
+**object파일 생성 및 simulator 테스트**
 
 ```bash
 make
@@ -23,21 +28,59 @@ make test
 make clean
 ```
 
-**직접 object 파일 생성 및 하나씩 test방법**
-
+**test option**
 ```bash
+./sce212sim [-m addr1:addr2] [-d] [-n num_instr] inputBinary
 ```
 
+- -m : addr1에서 addr2로 메모리 내용을 dump
+- -d : 레지스터 파일 내용을 print. -m 옵션이 활성화 된 경우 메모리 내용도 print.
+- -n : 시뮬레이션 된 instruction 수
 
 ## 기능 설명
 
-### 
+- **States**
+    - The emulator must maintain the system states, which consist of the necessary register set (R0-R31,
+PC) and the memory. The register and memory must be created when the emulation begins.
+
+- **Loading an input binary**
+    - For a given input binary, the loader must identify the text and data section sizes. The text section must
+be loaded to the emulated memory from the address 0x400000. The data section must be loaded to
+the emulated memory from the address 0x10000000. In this project, the simple loader does not create
+the stack region.
+
+- **Initial states**
+    - PC : The initial value of PC is 0x400000.
+    - Registers : All values of register0 to 31 are set to zero.
+    - Memory : You may assume all initial values are zero, except for the loaded text and data sections.
+
+- **Instructio execution**
+    - With the current PC, 4B from the memory is read. The emulator must parse the binary instruction and
+identify what the instruction is and what are the operands. Based on the MIPS ISA, the emulator must
+accurately mimic the execution, which will update either a PC, register, or memory.
+
+- **Supported instruction set**
 
+이미지
 
 
-### 
+### 출력예시
 
-### 
+- If you type the command line as below, the output file should show only PC and register values
+like Figure 1.
+
+```bash
+./sce212sim –n 0 input.o
+```
+
+- If you type the command line as below, the output file should show memory contents of specific
+memory region, PC and register values like Figure 2.
+
+```bash
+./sce212sim –m 0x400000:0x400010 –n 0 input.o
+```
 
+- The functions for printing the memory and register values are provided in the util.c, and
+util.h files.
 
-### 
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+이미지
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