Computer Science – 5.2 Language Translators | e-Consult
5.2 Language Translators (1 questions)
An assembler would translate the given assembly code into a sequence of machine code instructions. The process involves several stages:
1. Symbol Table Creation: The assembler creates a symbol table to store information about the labels used in the code (e.g., 'data'). The symbol table maps these labels to their corresponding memory addresses.
2. Instruction Decoding: The assembler parses each assembly instruction and identifies its operation (e.g., MOV, ADD, STORE) and its operands (e.g., R1, R2, R3, data). Each instruction is associated with a specific opcode.
3. Opcode and Operand Conversion: The assembler converts the mnemonic instructions and operands into their corresponding machine code opcodes and binary representations of the operands. For example:
- MOV R1, 10: This instruction would be translated into a machine code instruction that specifies the opcode for the MOV instruction and the binary representation of register R1 and the immediate value 10.
- ADD R3, R1, R2: This instruction would be translated into a machine code instruction that specifies the opcode for the ADD instruction and the binary representations of registers R3, R1, and R2.
- STORE data, R3: This instruction would be translated into a machine code instruction that specifies the opcode for the STORE instruction and the memory address of the 'data' label and the binary representation of register R3.
4. Address Calculation: The assembler calculates the memory addresses for the operands. For example, the assembler needs to determine the memory address of the 'data' label. This address is then included in the machine code instruction.
5. Machine Code Generation: The assembler combines the opcodes and operand representations to generate the final machine code instructions. These instructions are typically stored in an object file.
Data Structures Involved:
| Symbol Table: A data structure (e.g., a hash table or a linked list) that stores the mapping between labels and their corresponding memory addresses. |
| Instruction Table: A table that stores the opcodes for each assembly instruction. |
| Accumulator: A register used to store information during the assembly process (e.g., to keep track of the current line number or the current memory address). |