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Assembler Architecture.md

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  To Do
 Assembler Design
  Program Files
   MOT table reader
  Pass 1 Files
   Assembly File Reader
   LC Processing
   Symbol Table Generation
    Protected Words
  Pass 2 Files
  Error Checking
   Whole ASM program error correction
   Single line Error correction
 Assembly Language reference
   Statements
   Mnemonics Types
    AD
    IS
    DL
    Fields of MOT Table / Attributes of Mnemonics
   Symbol / Label
    Two Types of Symbol
    Symbols Uses Type
   Operand Types
    [Label](#label)
    Register
    Constant
    Literal

To Do

  • Make working v1.0

  • execute subroutine from MOT file instead of program files

  • To pass support argument pass for main program (asm = sample.asm and ltorgmode = False)

  • LTORG support

    • Support Ltorg mode by changing a Variable

  • Check path return by os.path module when run inside module

  • comment can be at the end of line with statements Statemnt #comment123

  • Implement warning library instead of print statement

  • START and END must be only used once

    • START must be first

    • END must be last

  • Uppercase ? How to deal with case?

    • Mnemonics , Protected Values must be UPPER case .

    • code can't be similar to them in any case

  • To implement operands checker for each Mnemonics

    • Implement Protected Symbols(LT LE ET GE GT for jump). Mnemonics are already protected as

    • Operand1 and Operand2 in binary (112) = 3 op1 present (102) both absent(002) = 0

  • Separate leftover LC Processing from assembly file reader

  • Learn Hyperlinking within markdown file

Assembler Design

  1. It is 2 pass Assembler

Program Files

MOT table reader

  1. it reads mot table - which is in file format TSV (tab separated values)

  2. provides functions

    1. For getting other values from given Mnemonics

    2. Checking if Mnemonics is valid or not

    3. Return dict with all attributes of given Mnemonics

      def get_Mnemonics_attribute(mnemonic :str , attribute = 'Size'):
def isMnemonics(mnemonic: str):
def return_given_mnemonics_dict(mnemonic :str):

Pass 1 Files

Assembly File Reader

  1. It reads Assembly (asm) file .

  2. True 1 pass reader

    1. It reads by iterator so each line is only read once thought out whole program

  3. Supports Comments

    1. Comment line start with "#" .

    2. there can be white space before "#"

    3. removes comment part of line , if it contains both statement and comment
      Statement #comment

  4. Supports Empty Line

  5. Splits the Statement into Label , Mnemonics , Operand1 and Operand2 fields

  6. Error Checks Each line

  7. Error checks some overall Structure

LC Processing

  1. Supports START and START 200 like commands

  2. Supports ORG commands

  3. Deals with DC and DS Statement

Symbol Table Generation

Protected Words

  1. All Mnemonics

  2. For Branch condition [LE , LT , ET , GT , GE]

  3. Registers Name [AREG, BREG, CREG, DREG]

Pass 2 Files

Error Checking

Whole ASM program error correction

  1. START must be first command and only used once

  2. END must be last command and only used once

  3. Label

    • Todo

  4. Symbol

Single line Error correction

  1. List line No of the command with error, in Exception reporting

Assembly Language reference

Statements

Standard Statements - Label: Menmonics Operand1, Operand2

or [Label[:] ]Menmonics[ Operand1[, Operand2]] where [] fields are Optional

Mnemonics Types

AD

  1. START

  2. ORG

  3. LTORG

  4. END

IS
  1. Branch
    1. JUMP [Branch_condiction] , Symbol(Address) or JUMP Symbol(Address)
  2. Arithmetic

    1. ADD Operand1 , Operand2

    2. SUB Operand1 , Operand2

    3. MUL Operand1 , Operand2

    4. DIV Operand1 , Operand2

    5. INC Operand1

    6. DEC Operand1

  3. Moving
    1. MOVER Register , [Operand2]
DL
Fields of MOT Table / Attributes of Mnemonics

  1. Mnemonics

  2. Opcode

  3. Size

  4. Type

  5. DS_routine ?

Symbol / Label

Two Types of Symbol

  1. Address Symbols

  2. Variable Symbols

Symbols Uses Type

  1. Declaration

  2. Usage(Mnemonics Opcode Table)

Operand Types

Operand 1 Operand 2
Label(Address or Data) or Register label(Address or Data) or register or constant or Literal
May change Does not Change
Label
Register
  1. AREG, BREG, CREG, DREG
Constant
  1. +ve Whole Number
Literal

  1. Used in only older system which need LTORG support

  2. in form of ='<constant>' eg. ='5'