Updated README

README.md

@@ -1,3 +1,139 @@
 # SIC-XE Assembler
 
-Course project for System Software. 
+### C++ implementation of an SIC-XE Assembler.
+
+#### The implementation currently supports: 
+
+<input type="checkbox" disabled checked /> Format 1 instructions
+
+<input type="checkbox" disabled checked /> Format 2 instructions
+
+<input type="checkbox" disabled checked /> Format 3 instructions
+
+<input type="checkbox" disabled checked /> Format 4 instructions
+
+<input type="checkbox" disabled checked /> Base Directive
+
+<input type="checkbox" disabled checked /> Program Relocation
+
+<input type="checkbox" disabled checked /> Literals
+
+<input type="checkbox" disabled checked /> LTORG directive
+
+<input type="checkbox" disabled checked /> EQU directive
+
+<input type="checkbox" disabled checked /> ORG directive
+
+<input type="checkbox" disabled checked /> Expressions
+
+<input type="checkbox" disabled checked /> Program Blocks
+
+## HOW TO RUN
+
+To run the assembler, simply run ``` ./Run.sh ``` from your terminal after cloning the repository. The assembler will ask for the path to your file. If the program is not erroneous, it will generate the corresponding ``` HEADER RECORD ``` in the Output directory. 
+
+Here is an example of execution of a correct program : 
+
+<img src="./utils/correct_execution.png" alt="Correct Execution">
+
+
+The implementation has a testing framwork and build workflow integrated into it. In case something needs to be modified, we can ensure it does not break other functions by running the tests. So if you find something that should be changed according to you, or perhaps you see an optimisation, do the required changes and add a test for it in the ``` tests ``` directory. I am currently using ``` gtest ``` for the testing. It involves comparing the headers as expected and generated by the assembler. Something like : 
+
+```cpp
+TEST({TEST_NAME}, CompareFiles) {
+    string filePath1 = "{GENERATED HEADER FILE PATH}";
+    string filePath2 = "{EXPECTED HEADER FILE PATH}";
+    ASSERT_TRUE(compareFiles(filePath1, filePath2));
+}
+```
+
+To ensure that your changes pass the CI/CD pipeline for Formatting, run ``` ./format.sh ``` which will run ``` cmake-format -i ``` over the files mentioned in the script. In case you add another file, include the file in the script. 
+
+In case you get the following error : 
+
+```rs
+Invalid opcode: {Your_Opcode}
+```
+
+It simply means that the Opcode is not included in the opcode.info file. To add it, simply follow the below format : 
+
+```rs
+MNEMONIC |  FORMAT   | OPCODE 
+{Name}   | {1,2,3/4} | {Code}
+```
+
+To ensure the correct execution of the assembler, Please write statements like 
+
+```rs
+ADDR    X , A
+ADD     TABLE2, X
+EQU     BUFEND - BUFFER
+```
+
+as 
+
+```rs
+ADDR    X,A
+ADD     TABLE2,X
+EQU     BUFEND-BUFFER
+```
+
+Notice the spacing between the statements after the Opcode MNEMONIC. 
+
+## DESIGN
+
+To Explain the design of the assembler, I will take the following code as reference : 
+
+```rs
+COPY    START   0
+FIRST   STL     RETADR
+CLOOP   JSUB    RDREC
+        LDA     LENGTH
+        COMP    #0
+        JEQ     ENDFIL
+        JSUB    WRREC
+        J       CLOOP
+ENDFIL  LDA     =C'EOF'
+        STA     BUFFER
+        LDA     #3
+        STA     LENGTH
+        JSUB    WRREC
+        J       @RETADR
+        USE     CDATA
+RETADR  RESW    1
+LENGTH  RESW    1
+        USE     CBLKS
+BUFFER  RESB    4096
+BUFEND  EQU     *
+MAXLEN  EQU     BUFEND-BUFFER
+        USE
+RDREC   CLEAR   X
+        CLEAR   A
+        CLEAR   S
+        +LDT    #MAXLEN
+RLOOP   TD      INPUT
+        JEQ     RLOOP
+        RD      INPUT
+        COMPR   A,S
+        JEQ     EXIT
+        STCH    BUFFER,X
+        TIXR    T
+        JLT     RLOOP
+EXIT    STX     LENGTH
+        RSUB
+        USE     CDATA
+INPUT   BYTE    X'F1'
+        USE
+WRREC   CLEAR   X
+        LDT     LENGTH
+WLOOP   TD      =X'05'
+        JEQ     WLOOP
+        LDCH    BUFFER,X
+        WD      =X'05'
+        TIXR    T
+        JLT     WLOOP
+        RSUB
+        USE     CDATA
+        LTORG
+        END     FIRST
+```