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Beam interpreter in Pyhton
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#!/usr/bin/python | |
import sys | |
if(len(sys.argv) < 5): | |
print 'Usage: ./beam.py path <debug> <debugpoints> <memsize>' | |
print ' debug: on or off' | |
print ' debugpoints: ;-seperated list of coordinates (e.g. 0,9;0,2)' | |
print ' (use -1,-1 for none)' | |
print ' memsize: how many memory cells' | |
sys.exit(-3) | |
debug = False | |
cycles = 0 | |
bps = sys.argv[3].split(';') | |
bps = map(lambda a: a.split(','),bps) | |
bps = map(lambda ds: (int(ds[0]),int(ds[1])),bps) | |
memsize = int(sys.argv[4]) | |
if(sys.argv[2] == 'on'): | |
debug = True | |
elif(sys.argv[2] == 'off'): | |
debug = False | |
else: | |
print 'Unknown option: ' + sys.argv[2] | |
sys.exit(-2) | |
fpath = sys.argv[1] | |
fhandle = open(fpath, 'r') | |
fcontents = fhandle.read() | |
lines = fcontents.splitlines() | |
chars = map(list,lines) | |
x = 0 | |
y = 0 | |
h = len(lines) | |
xd = 1 | |
yd = 0 | |
beam = 0 | |
store = 0 | |
memory = [0] * memsize | |
while True: | |
cycles += 1 | |
if y < 0 or y >= h: | |
sys.stderr.write("y out of bounds: " + str(x) + "," + str(y) + "\n") | |
sys.exit(-1) | |
w = len(lines[y]) | |
if x < 0 or x >= w: | |
sys.stderr.write("x out of bounds: " + str(x) + "," + str(y) + "\n") | |
sys.exit(-2) | |
if((x,y) in bps): | |
print '== DEBUGPOINT ==' | |
print 'Beam := %d, Store := %d' % (beam, store) | |
print 'Cycles := %d' % (cycles) | |
print 'C := %s' % (lines[y][x]) | |
print ' ** MEMORY **' | |
print memory | |
c = lines[y][x] | |
if(debug): print '%d,%d: %s ; %d,%d' % (x,y,c,beam,store) | |
if(c == 'H'): | |
break | |
elif(c == '>'): | |
xd = 1; yd = 0 | |
elif(c == '<'): | |
xd = -1; yd = 0 | |
elif(c == '^'): | |
yd = -1; xd = 0 | |
elif(c == 'v'): | |
yd = 1; xd = 0 | |
elif(c == '+'): | |
beam += 1 | |
if(beam >= 256): beam = 0 | |
elif(c == '-'): | |
beam -= 1 | |
if(beam < 0): beam = 255 | |
elif(c == '@'): | |
sys.stdout.write(chr(beam)) | |
elif(c == ':'): | |
sys.stdout.write(str(beam)) | |
elif(c == '/'): | |
if(xd == -1): | |
yd = 1; xd = 0; | |
elif(yd == -1): | |
xd = 1; yd = 0; | |
elif(xd == 1): | |
yd = -1; xd = 0; | |
elif(yd == 1): | |
xd = -1; yd = 0; | |
elif(c == '\\'): | |
if(xd == 1): | |
yd = 1; xd = 0; | |
elif(yd == -1): | |
xd = -1; yd = 0; | |
elif(yd == 1): | |
xd = 1; yd = 0; | |
elif(xd == -1): | |
yd = -1; xd = 0 | |
elif(c == '!'): | |
if(beam != 0): | |
xd *= -1 | |
yd *= -1 | |
elif(c == '?'): | |
if(beam == 0): | |
xd *= -1 | |
yd *= -1 | |
elif(c == '|'): | |
if(yd == 0): | |
xd *= -1; yd = 0 | |
elif(c == '_'): | |
if(xd == 0): | |
yd *= -1; xd = 0 | |
elif(c == 'S'): | |
store = beam | |
elif(c == 'L'): | |
beam = store | |
beam %= 256 | |
elif(c == 's'): | |
memory[beam] = store % 256 | |
elif(c == 'g'): | |
store = memory[beam] | |
elif(c == 'P'): | |
memory[store] = beam | |
elif(c == 'p'): | |
beam = memory[store] | |
elif(c == 'u'): | |
if(beam != store): | |
yd = -1; xd = 0; | |
elif(c == 'n'): | |
if(beam != store): | |
yd = 1; xd = 0; | |
elif(c == '`'): | |
store -= 1 | |
if(store < 0): store = 255 | |
elif(c == '\''): | |
store += 1 | |
elif(c == ')'): | |
if(store != 0): xd = -1; yd = 0; | |
elif(c == '('): | |
if(store != 0): xd = 1; yd = 0; | |
elif(c == 'r'): | |
s = sys.stdin.read(1) | |
if(len(s) != 0): | |
beam = ord(s) | |
else: | |
beam = 0 | |
x += xd | |
y += yd | |
print "" | |
print "" | |
print "Took %d cycles." % (cycles) |
Author
FMNSSun
commented
Oct 24, 2015
$ echo -n "hi there" | ./beam.py revstdin.beam off "12,4" 18
ereht ih
== DEBUGPOINT ==
Beam := 0, Store := 0
Cycles := 715
C := H
** MEMORY **
[0, 104, 0, 105, 0, 32, 0, 116, 0, 104, 0, 101, 0, 114, 0, 101, 0, 0]
Took 715 cycles.
Hi, with the store decrementer the value is set to 255 if less than 0, but there is no reciprocal rule on the incrementer.
The store
is an arbitrarily large positive integer as by the Beam specification.
However, line
if(beam < 0): beam = 256
should be beam = 255
. I'll fix it.
fixed
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