📅 最后修改于: 2023-12-03 14:58:28.053000 🧑 作者: Mango
This problem is about implementing a simple version of a compiler that translates a program in a programming language called "TINY" into an equivalent program in assembly language.
The TINY programming language has the following types of statements:
Assignment statement: x := expr, where x is a variable and expr is an arithmetic or logical expression.
Conditional statement: if cond then stmt1 else stmt2, where cond is a Boolean expression, stmt1 is a statement to execute if cond is true, and stmt2 is a statement to execute if cond is false.
Loop statement: while cond do stmt, where cond is a Boolean expression and stmt is a statement to execute repeatedly as long as cond is true.
Read statement: read x to read an integer value into variable x.
Write statement: write expr to write the value of expr to the output.
The TINY instruction set has the following instructions:
ADD x,y: Add the contents of memory location x and memory location y and store the result in x.
SUB x,y: Subtract the contents of memory location y from the contents of memory location x and store the result in x.
MULT x,y: Multiply the contents of memory location x by the contents of memory location y and store the result in x.
DIV x,y: Divide the contents of memory location x by the contents of memory location y and store the result in x.
LOAD x: Load the contents of memory location x into the accumulator.
STORE x: Store the contents of the accumulator into memory location x.
READ x: Read an integer value from input and store it in memory location x.
WRITE x: Write the contents of memory location x to the output.
BRANCH x: Unconditional jump to the instruction at memory location x.
BRANCHNEG x: Jump to the instruction at memory location x if the contents of the accumulator are negative.
BRANCHZERO x: Jump to the instruction at memory location x if the contents of the accumulator are zero.
HALT: Terminate the program.
Here is an example program in the TINY programming language:
read x
read y
if x < y then
write y
else
write x
Here is the equivalent program in assembly language:
READ X
READ Y
SUB X,Y
BRANCHNEG ELSE
WRITE Y
BRANCH ENDIF
ELSE: WRITE X
ENDIF: HALT
To implement this conversion from TINY to assembly language, you could write a parser that translates each TINY statement into an equivalent sequence of assembly instructions. You could use a stack data structure to keep track of the state of the program, such as the nested structure of if-else blocks or while loops.
Here is a Python implementation of a TINY to assembly language converter:
from typing import List, Tuple
def tiny_to_assembly(tiny_program: str) -> str:
"""Convert a TINY program to an equivalent program in assembly language."""
assembly_program = ""
tokens = tiny_program.split()
i = 0
while i < len(tokens):
if tokens[i] == "read":
assembly_program += f"READ {tokens[i+1]}\n"
i += 2
elif tokens[i] == "write":
assembly_program += f"WRITE {tokens[i+1]}\n"
i += 2
elif tokens[i] == "if":
cond_tokens = []
j = i + 1
while tokens[j] != "then":
cond_tokens.append(tokens[j])
j += 1
then_tokens = []
j += 1
while tokens[j] != "else":
then_tokens.append(tokens[j])
j += 1
else_tokens = []
j += 1
while tokens[j] != "endif":
else_tokens.append(tokens[j])
j += 1
else_tokens.append("HALT")
true_label = f"L{i}"
false_label = f"L{j}"
assembly_program += f"{compile_conditional(cond_tokens, true_label, false_label)}\n"
assembly_program += f"{true_label}:\n"
assembly_program += f"{compile_sequence(then_tokens)}\n"
assembly_program += f"BRANCH {false_label}\n"
assembly_program += f"{false_label}:\n"
assembly_program += f"{compile_sequence(else_tokens)}\n"
i = j + 1
elif tokens[i] == "while":
cond_tokens = []
j = i + 1
while tokens[j] != "do":
cond_tokens.append(tokens[j])
j += 1
body_tokens = []
j += 1
while tokens[j] != "endwhile":
body_tokens.append(tokens[j])
j += 1
body_tokens.append(f"BRANCH {i}")
true_label = f"L{i}"
false_label = f"L{j+1}"
assembly_program += f"{true_label}:\n"
assembly_program += f"{compile_conditional(cond_tokens, false_label, true_label)}\n"
assembly_program += f"{false_label}:\n"
assembly_program += f"{compile_sequence(body_tokens)}\n"
i = j + 1
else: # assignment statement
assembly_program += f"LOAD {tokens[i+2]}\n"
if tokens[i+3] == "+":
assembly_program += f"ADD {tokens[i+4]},{tokens[i+2]}\n"
elif tokens[i+3] == "-":
assembly_program += f"SUB {tokens[i+4]},{tokens[i+2]}\n"
elif tokens[i+3] == "*":
assembly_program += f"MULT {tokens[i+4]},{tokens[i+2]}\n"
else: # division
assembly_program += f"DIV {tokens[i+4]},{tokens[i+2]}\n"
assembly_program += f"STORE {tokens[i]}\n"
i += 5 # skip over the whole assignment statement
assembly_program += "HALT\n"
return assembly_program
def compile_conditional(tokens: List[str], true_label: str, false_label: str) -> str:
"""Compile a conditional statement to assembly language."""
op = tokens[1]
if op == "<":
return f"SUB {tokens[0]},{tokens[2]}\nBRANCHNEG {true_label}\nBRANCH {false_label}"
elif op == ">":
return f"SUB {tokens[2]},{tokens[0]}\nBRANCHNEG {true_label}\nBRANCH {false_label}"
else: # equality
return f"SUB {tokens[0]},{tokens[2]}\nBRANCHZERO {true_label}\nBRANCH {false_label}"
def compile_sequence(tokens: List[str]) -> str:
"""Compile a sequence of statements to assembly language."""
assembly = ""
for i, token in enumerate(tokens):
if token == ";":
continue
if token == "read" or token == "write":
assembly += f"{tiny_to_assembly(f'{token} {tokens[i+1]}')}"
elif token == "if":
j = i + 1
while tokens[j] != "endif":
j += 1
j += 1
assembly += f"{tiny_to_assembly(' '.join(tokens[i:j]))}"
i = j
elif token == "while":
j = i + 1
while tokens[j] != "endwhile":
j += 1
j += 1
assembly += f"{tiny_to_assembly(' '.join(tokens[i:j]))}"
i = j
else: # assignment statement
assembly += f"LOAD {tokens[i+2]}\n"
if tokens[i+3] == "+":
assembly += f"ADD {tokens[i+4]},{tokens[i+2]}\n"
elif tokens[i+3] == "-":
assembly += f"SUB {tokens[i+4]},{tokens[i+2]}\n"
elif tokens[i+3] == "*":
assembly += f"MULT {tokens[i+4]},{tokens[i+2]}\n"
else: # division
assembly += f"DIV {tokens[i+4]},{tokens[i+2]}\n"
assembly += f"STORE {tokens[i]}\n"
i += 5 # skip over the whole assignment statement
return assembly
This implementation uses recursion to handle nested if-else blocks and while loops. The compile_sequence function is used to compile a sequence of statements, and it calls the tiny_to_assembly function recursively as needed to handle all types of statements.
Implementing a compiler is a complex task that requires knowledge of programming language syntax and semantics, as well as skills in parsing and code generation. The TINY programming language and instruction set provide a simple yet powerful framework for demonstrating these concepts and for practicing programming skills.