basinterp.py

来自「M5,一个功能强大的多处理器系统模拟器.很多针对处理器架构,性能的研究都使用它作」· Python 代码 · 共 441 行 · 第 1/2 页

# This file provides the runtime support for running a basic program
# Assumes the program has been parsed using basparse.py

import sys
import math
import random

class BasicInterpreter:

    # Initialize the interpreter. prog is a dictionary
    # containing (line,statement) mappings
    def __init__(self,prog):
         self.prog = prog

         self.functions = {           # Built-in function table
             'SIN' : lambda z: math.sin(self.eval(z)),
             'COS' : lambda z: math.cos(self.eval(z)),
             'TAN' : lambda z: math.tan(self.eval(z)),
             'ATN' : lambda z: math.atan(self.eval(z)),
             'EXP' : lambda z: math.exp(self.eval(z)),
             'ABS' : lambda z: abs(self.eval(z)),
             'LOG' : lambda z: math.log(self.eval(z)),
             'SQR' : lambda z: math.sqrt(self.eval(z)),
             'INT' : lambda z: int(self.eval(z)),
             'RND' : lambda z: random.random()
         }

    # Collect all data statements
    def collect_data(self):
         self.data = []
         for lineno in self.stat:
              if self.prog[lineno][0] == 'DATA':
                  self.data = self.data + self.prog[lineno][1]
         self.dc = 0                  # Initialize the data counter

    # Check for end statements
    def check_end(self):
         has_end = 0
         for lineno in self.stat:
             if self.prog[lineno][0] == 'END' and not has_end:
                  has_end = lineno
         if not has_end:
             print "NO END INSTRUCTION"
             self.error = 1
         if has_end != lineno:
             print "END IS NOT LAST"
             self.error = 1

    # Check loops
    def check_loops(self):
         for pc in range(len(self.stat)):
             lineno = self.stat[pc]
             if self.prog[lineno][0] == 'FOR':
                  forinst = self.prog[lineno]
                  loopvar = forinst[1]
                  for i in range(pc+1,len(self.stat)):
                       if self.prog[self.stat[i]][0] == 'NEXT':
                            nextvar = self.prog[self.stat[i]][1]
                            if nextvar != loopvar: continue
                            self.loopend[pc] = i
                            break
                  else:
                       print "FOR WITHOUT NEXT AT LINE" % self.stat[pc]
                       self.error = 1

    # Evaluate an expression
    def eval(self,expr):
        etype = expr[0]
        if etype == 'NUM': return expr[1]
        elif etype == 'GROUP': return self.eval(expr[1])
        elif etype == 'UNARY':
             if expr[1] == '-': return -self.eval(expr[2])
        elif etype == 'BINOP':
             if expr[1] == '+': return self.eval(expr[2])+self.eval(expr[3])
             elif expr[1] == '-': return self.eval(expr[2])-self.eval(expr[3])
             elif expr[1] == '*': return self.eval(expr[2])*self.eval(expr[3])
             elif expr[1] == '/': return float(self.eval(expr[2]))/self.eval(expr[3])
             elif expr[1] == '^': return abs(self.eval(expr[2]))**self.eval(expr[3])
        elif etype == 'VAR':
             var,dim1,dim2 = expr[1]
             if not dim1 and not dim2:
                  if self.vars.has_key(var):
                       return self.vars[var]
                  else:
                       print "UNDEFINED VARIABLE", var, "AT LINE", self.stat[self.pc]
                       raise RuntimeError
             # May be a list lookup or a function evaluation
             if dim1 and not dim2:
                if self.functions.has_key(var):
                      # A function
                      return self.functions[var](dim1)
                else:
                      # A list evaluation
                      if self.lists.has_key(var):
                            dim1val = self.eval(dim1)
                            if dim1val < 1 or dim1val > len(self.lists[var]):
                                 print "LIST INDEX OUT OF BOUNDS AT LINE", self.stat[self.pc]
                                 raise RuntimeError
                            return self.lists[var][dim1val-1]
             if dim1 and dim2:
                 if self.tables.has_key(var):
                      dim1val = self.eval(dim1)
                      dim2val = self.eval(dim2)
                      if dim1val < 1 or dim1val > len(self.tables[var]) or dim2val < 1 or dim2val > len(self.tables[var][0]):
                           print "TABLE INDEX OUT OUT BOUNDS AT LINE", self.stat[self.pc]
                           raise RuntimeError
                      return self.tables[var][dim1val-1][dim2val-1]
             print "UNDEFINED VARIABLE", var, "AT LINE", self.stat[self.pc]
             raise RuntimeError

    # Evaluate a relational expression
    def releval(self,expr):
         etype = expr[1]
         lhs   = self.eval(expr[2])
         rhs   = self.eval(expr[3])
         if etype == '<':
             if lhs < rhs: return 1
             else: return 0

         elif etype == '<=':
             if lhs <= rhs: return 1
             else: return 0

         elif etype == '>':
             if lhs > rhs: return 1
             else: return 0

         elif etype == '>=':
             if lhs >= rhs: return 1
             else: return 0

         elif etype == '=':
             if lhs == rhs: return 1
             else: return 0

         elif etype == '<>':
             if lhs != rhs: return 1
             else: return 0

    # Assignment
    def assign(self,target,value):
        var, dim1, dim2 = target
        if not dim1 and not dim2:
            self.vars[var] = self.eval(value)
        elif dim1 and not dim2:
            # List assignment
            dim1val = self.eval(dim1)
            if not self.lists.has_key(var):
                 self.lists[var] = [0]*10

            if dim1val > len(self.lists[var]):
                 print "DIMENSION TOO LARGE AT LINE", self.stat[self.pc]
                 raise RuntimeError
            self.lists[var][dim1val-1] = self.eval(value)
        elif dim1 and dim2:
            dim1val = self.eval(dim1)
            dim2val = self.eval(dim2)
            if not self.tables.has_key(var):
                 temp = [0]*10
                 v = []
                 for i in range(10): v.append(temp[:])
                 self.tables[var] = v
            # Variable already exists
            if dim1val > len(self.tables[var]) or dim2val > len(self.tables[var][0]):
                 print "DIMENSION TOO LARGE AT LINE", self.stat[self.pc]
                 raise RuntimeError
            self.tables[var][dim1val-1][dim2val-1] = self.eval(value)

    # Change the current line number
    def goto(self,linenum):
         if not self.prog.has_key(linenum):
              print "UNDEFINED LINE NUMBER %d AT LINE %d" % (linenum, self.stat[self.pc])
              raise RuntimeError
         self.pc = self.stat.index(linenum)

    # Run it
    def run(self):
        self.vars   = { }            # All variables
        self.lists  = { }            # List variables
        self.tables = { }            # Tables
        self.loops  = [ ]            # Currently active loops
        self.loopend= { }            # Mapping saying where loops end
        self.gosub  = None           # Gosub return point (if any)
        self.error  = 0              # Indicates program error

        self.stat = self.prog.keys()      # Ordered list of all line numbers
        self.stat.sort()
        self.pc = 0                  # Current program counter

        # Processing prior to running

        self.collect_data()          # Collect all of the data statements
        self.check_end()
        self.check_loops()

        if self.error: raise RuntimeError

        while 1:
            line  = self.stat[self.pc]
            instr = self.prog[line]

            op = instr[0]

            # END and STOP statements
            if op == 'END' or op == 'STOP':
                 break           # We're done

            # GOTO statement
            elif op == 'GOTO':
                 newline = instr[1]
                 self.goto(newline)
                 continue

            # PRINT statement
            elif op == 'PRINT':
                 plist = instr[1]
                 out = ""
                 for label,val in plist:
                     if out:
                          out += ' '*(15 - (len(out) % 15))
                     out += label