Nevar pievienot vairāk kā 25 tēmas
Tēmai ir jāsākas ar burtu vai ciparu, tā var saturēt domu zīmes ('-') un var būt līdz 35 simboliem gara.
193 rindas
6.5 KiB
193 rindas
6.5 KiB
#! /usr/bin/env python
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import sys
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from optparse import OptionParser
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import random
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import math
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def convert(size):
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length = len(size)
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lastchar = size[length-1]
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if (lastchar == 'k') or (lastchar == 'K'):
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m = 1024
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nsize = int(size[0:length-1]) * m
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elif (lastchar == 'm') or (lastchar == 'M'):
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m = 1024*1024
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nsize = int(size[0:length-1]) * m
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elif (lastchar == 'g') or (lastchar == 'G'):
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m = 1024*1024*1024
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nsize = int(size[0:length-1]) * m
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else:
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nsize = int(size)
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return nsize
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#
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# main program
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#
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parser = OptionParser()
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parser.add_option("-s", "--seed", default=0, help="the random seed",
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action="store", type="int", dest="seed")
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parser.add_option("-A", "--addresses", default="-1",
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help="a set of comma-separated pages to access; -1 means randomly generate",
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action="store", type="string", dest="addresses")
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parser.add_option("-a", "--asize", default="1k",
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help="address space size (e.g., 16, 64k, 32m, 1g)",
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action="store", type="string", dest="asize")
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parser.add_option("-p", "--physmem", default="16k",
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help="physical memory size (e.g., 16, 64k, 32m, 1g)",
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action="store", type="string", dest="psize")
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parser.add_option("-n", "--numaddrs", default=5,
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help="number of virtual addresses to generate",
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action="store", type="int", dest="num")
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parser.add_option("-b", "--b0", default="-1",
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help="value of segment 0 base register",
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action="store", type="string", dest="base0")
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parser.add_option("-l", "--l0", default="-1",
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help="value of segment 0 limit register",
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action="store", type="string", dest="len0")
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parser.add_option("-B", "--b1", default="-1",
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help="value of segment 1 base register",
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action="store", type="string", dest="base1")
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parser.add_option("-L", "--l1", default="-1",
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help="value of segment 1 limit register",
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action="store", type="string", dest="len1")
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parser.add_option("-c", help="compute answers for me",
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action="store_true", default=False, dest="solve")
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(options, args) = parser.parse_args()
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print "ARG seed", options.seed
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print "ARG address space size", options.asize
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print "ARG phys mem size", options.psize
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print ""
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random.seed(options.seed)
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asize = convert(options.asize)
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psize = convert(options.psize)
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addresses = str(options.addresses)
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if psize <= 1:
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print 'Error: must specify a non-zero physical memory size.'
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exit(1)
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if asize == 0:
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print 'Error: must specify a non-zero address-space size.'
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exit(1)
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if psize <= asize:
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print 'Error: physical memory size must be GREATER than address space size (for this simulation)'
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exit(1)
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#
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# need to generate base, bounds for segment registers
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#
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len0 = convert(options.len0)
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len1 = convert(options.len1)
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base0 = convert(options.base0)
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base1 = convert(options.base1)
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if len0 == -1:
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len0 = int(asize/4.0 + (asize/4.0 * random.random()))
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if len1 == -1:
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len1 = int(asize/4.0 + (asize/4.0 * random.random()))
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# now have to find room for them
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if base0 == -1:
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done = 0
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while done == 0:
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base0 = int(psize * random.random())
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if (base0 + len0) < psize:
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done = 1
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# internally, base1 points to the lower address, and base1+len1 the higher address
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# (this differs from what the user would pass in, for example)
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if base1 == -1:
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done = 0
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while done == 0:
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base1 = int(psize * random.random())
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if (base1 + len1) < psize:
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if (base1 > (base0 + len0)) or ((base1 + len1) < base0):
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done = 1
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else:
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base1 = base1 - len1
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if len0 > asize/2.0 or len1 > asize/2.0:
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print 'Error: length register is too large for this address space'
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exit(1)
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print 'Segment register information:'
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print ''
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print ' Segment 0 base (grows positive) : 0x%08x (decimal %d)' % (base0, base0)
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print ' Segment 0 limit : %d' % (len0)
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print ''
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print ' Segment 1 base (grows negative) : 0x%08x (decimal %d)' % (base1+len1, base1+len1)
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print ' Segment 1 limit : %d' % (len1)
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print ''
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nbase1 = base1 + len1
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if (len0 + base0) > (base1) and (base1 > base0):
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print 'Error: segments overlap in physical memory'
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exit(1)
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addrList = []
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if addresses == '-1':
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# need to generate addresses
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for i in range(0, options.num):
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n = int(asize * random.random())
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addrList.append(n)
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else:
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addrList = addresses.split(',')
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#
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# now, need to generate virtual address trace
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#
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print 'Virtual Address Trace'
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i = 0
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for vStr in addrList:
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# vaddr = int(asize * random.random())
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vaddr = int(vStr)
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if vaddr < 0 or vaddr >= asize:
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print 'Error: virtual address %d cannot be generated in an address space of size %d' % (vaddr, asize)
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exit(1)
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if options.solve == False:
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print ' VA %2d: 0x%08x (decimal: %4d) --> PA or segmentation violation?' % (i, vaddr, vaddr)
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else:
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paddr = 0
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if (vaddr >= (asize / 2)):
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# seg 1
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paddr = nbase1 + (vaddr - asize)
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if paddr < base1:
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print ' VA %2d: 0x%08x (decimal: %4d) --> SEGMENTATION VIOLATION (SEG1)' % (i, vaddr, vaddr)
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else:
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print ' VA %2d: 0x%08x (decimal: %4d) --> VALID in SEG1: 0x%08x (decimal: %4d)' % (i, vaddr, vaddr, paddr, paddr)
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else:
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# seg 0
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if (vaddr >= len0):
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print ' VA %2d: 0x%08x (decimal: %4d) --> SEGMENTATION VIOLATION (SEG0)' % (i, vaddr, vaddr)
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else:
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paddr = vaddr + base0
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print ' VA %2d: 0x%08x (decimal: %4d) --> VALID in SEG0: 0x%08x (decimal: %4d)' % (i, vaddr, vaddr, paddr, paddr)
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i += 1
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print ''
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if options.solve == False:
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print 'For each virtual address, either write down the physical address it translates to'
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print 'OR write down that it is an out-of-bounds address (a segmentation violation). For'
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print 'this problem, you should assume a simple address space with two segments: the top'
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print 'bit of the virtual address can thus be used to check whether the virtual address'
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print 'is in segment 0 (topbit=0) or segment 1 (topbit=1). Note that the base/limit pairs'
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print 'given to you grow in different directions, depending on the segment, i.e., segment 0'
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print 'grows in the positive direction, whereas segment 1 in the negative. '
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print ''
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