Post by eddavis2 on Sept 17, 2022 17:17:09 GMT -6
I recently created an interpreter for Tiny Basic in RCBasic. See below.
It supports just enough features to be able to play a Tiny Basic version of Star Trek.
Tiny Star Trek is farther below.
It supports 26 integer variables, a..z.
It supports a single integer array, denoted by @, e.g., @(8 * x + y + 62) = 4
It supports single line "if", "goto", "gosub/return", "for/next", along with "print", and a few others.
It has a trace mode.
It has an interactive mode - for instance, one can type:
for i = 1 to 10: print i: next i: print "done"
Tiny Star Trek
It supports just enough features to be able to play a Tiny Basic version of Star Trek.
Tiny Star Trek is farther below.
It supports 26 integer variables, a..z.
It supports a single integer array, denoted by @, e.g., @(8 * x + y + 62) = 4
It supports single line "if", "goto", "gosub/return", "for/next", along with "print", and a few others.
It has a trace mode.
It has an interactive mode - for instance, one can type:
for i = 1 to 10: print i: next i: print "done"
const c_maxlines = 7000
const c_maxvars = 26
const c_at_max = 500
const c_g_stack = 100
dim pgm$[c_maxlines + 1] ' program stored here
dim vars[c_maxvars + 1]
dim gstackln[c_g_stack] ' gosub line stack
dim gstacktp[c_g_stack] ' gosub textp stack
dim gsp
dim atarry[c_at_max] ' the @ array
dim forvar[c_maxvars + 1]
dim forlimit[c_maxvars + 1]
dim forline[c_maxvars + 1]
dim forpos[c_maxvars + 1]
dim tok$, toktype$ ' current token, and it's type
dim thelin$, thech$ ' current program line, current character
dim curline, textp ' position in current line
dim num ' last number read by scanner
dim errors
dim tracing
dim timestart
function space$(n)
dim s$
s$ = ""
while n > 0
s$ = s$ + " "
n = n - 1
wend
return s$
end function
sub getch()
' Any more text on this line?
if textp > len(thelin) then
thech$ = "": return
end if
thech$ = mid(thelin, textp - 1, 1)
textp = textp + 1
end sub
sub skiptoeol()
tok$ = "": toktype$ = ""
textp = len(thelin$) + 1
end sub
' leave the " as the beginning of the string, so it won't get confused with other tokens
' especially in the print routines
sub readstr()
tok$ = thech$: toktype$ = "string"
getch()
do
if thech$ = "" then
print "String not terminated": errors = true: return
end if
if asc(thech$) = 34 then ' a double quote
exit do
end if
tok$ = tok$ + thech$
getch()
loop
getch()
end sub
sub readint()
tok$ = "": toktype$ = "number"
while thech$ <> ""
if asc(thech$) >= asc("0") and asc(thech$) <= asc("9") then
tok$ = tok$ + thech$
getch()
else
exit while
end if
wend
num = val(tok$)
end sub
sub readident()
tok$ = "": toktype$ = "ident"
while thech$ <> ""
if (asc(thech$) >= asc("a") and asc(thech$) <= asc("z")) or (asc(thech$) >= asc("A") and asc(thech$) <= asc("Z")) then
tok$ = tok$ + lcase(thech$)
getch()
else
exit while
end if
wend
end sub
sub nexttok()
tok$ = "": toktype$ = ""
do
if thech$ = "" then
return
end if
if asc(thech$) > asc(" ") then
exit do
end if
getch()
loop
if (asc(thech$) >= asc("a") and asc(thech$) <= asc("z")) or (asc(thech$) >= asc("A") and asc(thech$) <= asc("Z")) then
readident()
if tok$ = "rem" then
skiptoeol()
end if
elseif asc(thech$) >= asc("0") and asc(thech$) <= asc("9") then
readint()
elseif asc(thech$) = 34 then ' double quote
readstr()
elseif asc(thech$) = asc("'") then
skiptoeol()
else
p = instr("#()*+,-/:;<=>?@\\^", thech$)
if p >= 0 and p < 17 then
toktype$ = "punct"
tok$ = thech$
getch
if tok$ = "<" or tok$ = ">" then
if thech$ = "=" or thech$ = ">" then
tok$ = tok$ + thech$
getch
end if
end if
return
else
toktype$ = ""
print "("; curline; ") "; "What?"; thech$; " : "; thelin: errors = true
getch
return
end if
end if
end sub
sub initlex2()
thelin$ = pgm$[curline]
thech$ = " "
nexttok()
end sub
sub initlex(n)
curline = n
textp = 1
initlex2()
end sub
sub validlinenum()
if num <= 0 or num > c_maxlines then
print "Line number out of range": errors = true
end if
end sub
function getvarindex()
if toktype$ <> "ident" then
print "Not a variable:"; tok$:
errors = true:
return
end if
return asc(left(tok$, 1)) - asc("a")
end function
sub clearvars()
dim i
for i = 1 to c_maxvars
vars[i] = 0
next
gsp = 0
end sub
function expect(s$)
if tok$ = s$ then
nexttok()
return true
end if
print "Expecting: "; s$; " but found: "; tok$: errors = true
return false
end function
function accept(s$)
if tok$ = s$ then
nexttok()
return true
end if
return false
end function
function expression(minprec)
dim n
' handle numeric operands - numbers and unary operators
if toktype$ = "number" then: n = num: nexttok()
elseif tok$ = "(" then
nexttok(): n = expression(0)
expect(")")
elseif tok$ = "not" then: nexttok(): n = not expression(3)
elseif tok$ = "abs" then:
nexttok()
expect("(")
n = abs(expression(0))
expect(")")
elseif tok$ = "asc" then:
nexttok():
expect("("):
n = asc(mid(tok$, 1, 1)):
nexttok():
expect(")")
elseif tok$ = "rnd" or tok$ = "irnd" then:
nexttok():
expect("(")
n = rand(expression(0)):
if n = 0 then
n = n + 1
end if
expect(")")
elseif tok$ = "sgn" then:
nexttok():
expect("(")
n = sign(expression(0))
expect(")")
elseif toktype$ = "ident" then: n = vars[getvarindex()]: nexttok()
elseif tok$ = "@" then:
nexttok():
expect("(")
n = atarry[expression(0)]
expect(")")
elseif tok$ = "-" then: nexttok(): n = -expression(7)
elseif tok$ = "+" then: nexttok(): n = expression(7)
else: print "syntax error: expecting an operand, found: "; tok$: errors = true: return
end if
do ' while binary operator and precedence of tok$ >= minprec
if minprec <= 1 and tok$ = "or" then: nexttok(): n = n or expression(2)
elseif minprec <= 2 and tok$ = "and" then: nexttok(): n = n and expression(3)
elseif minprec <= 4 and tok$ = "=" then: nexttok(): n = n = expression(5)
elseif minprec <= 4 and tok$ = "<" then: nexttok(): n = n < expression(5)
elseif minprec <= 4 and tok$ = ">" then: nexttok(): n = n > expression(5)
elseif minprec <= 4 and tok$ = "<>" then: nexttok(): n = n <> expression(5)
elseif minprec <= 4 and tok$ = "<=" then: nexttok(): n = n <= expression(5)
elseif minprec <= 4 and tok$ = ">=" then: nexttok(): n = n >= expression(5)
elseif minprec <= 5 and tok$ = "+" then: nexttok(): n = n + expression(6)
elseif minprec <= 5 and tok$ = "-" then: nexttok(): n = n - expression(6)
elseif minprec <= 6 and tok$ = "*" then: nexttok(): n = n * expression(7)
elseif minprec <= 6 and (tok$ = "/" or tok$ = "\\") then: nexttok(): n = int(n / expression(7))
elseif minprec <= 6 and tok$ = "mod" then: nexttok(): n = n mod expression(7)
elseif minprec <= 8 and tok$ = "^" then: nexttok(): n = n ^ expression(9)
else: exit do
end if
loop
return n
end function
function getfilename$(action$)
dim filename$
if toktype$ = "string" then
filename$ = right$(tok$, length(tok$) - 1)
else
filename$ = input$(action$)
end if
if filename$ <> "" then
if instr(filename$, ".") > length(filename$) then
filename$ = filename$ + ".bas"
end if
end if
return filename$
end function
sub runstmt()
timestart = timer
clearvars()
initlex(1)
end sub
sub returnstmt() ' return from a subroutine
curline = gstackln[gsp]
textp = gstacktp[gsp]
gsp = gsp - 1
initlex2()
end sub
' "print" [[#num "," ] expr { "," [#num ","] expr }] [","] {":" stmt} eol
' expr can also be a literal string
sub printstmt()
dim printnl, printwidth, n
dim junk$
printnl = true
while tok$ <> ":" and tok$ <> "" and tok$ <> "else"
printnl = true
printwidth = 0
if accept("#") then
if num <= 0 then
print "Expecting a print width, found:"; tok$:
return
end if
printwidth = num
nexttok()
if not accept(",") then
print "Print: Expecting a ',', found:"; tok$:
return
end if
end if
if toktype$ = "string" then
junk = right$(tok$, length(tok$) - 1)
nexttok()
else
n = expression(0)
junk = ltrim(str(n))
end if
printwidth = printwidth - len(junk)
if printwidth <= 0 then
print junk;
else
print space$(printwidth); junk;
end if
if accept(",") or accept(";") then
printnl = false
else
exit while
end if
wend
if printnl then
print ""
end if
end sub
sub nextstmt()
dim forndx
' tok$ needs to have the variable
forndx = getvarindex()
forvar[forndx] = forvar[forndx] + 1
vars[forndx] = forvar[forndx]
if forvar[forndx] <= forlimit[forndx] then
curline = forline[forndx]
textp = forpos[forndx]
'print "nextstmt tok$>"; tok$; " textp>"; textp; " >"; mid(thelin$, textp)
initlex2()
else
nexttok() ' skip the ident for now
end if
end sub
sub newstmt()
dim i
clearvars()
for i = 1 to c_maxlines
pgm$[i] = ""
next
end sub
sub loadstmt()
dim f, n, filename$
newstmt()
filename$ = getfilename("Load: ")
if filename$ = "" then
return
end if
if not fileopen(f, filename$, TEXT_INPUT) then
print "Could not open: "; filename$
return
end if
n = 0
while not eof(f)
pgm$[0] = readline$(f)
initlex(0)
if toktype$ = "number" and num > 0 and num <= c_maxlines then
n = num
else
n = n + 1: textp = 1
end if
pgm$[n] = right$(pgm$[0], length(pgm$[0]) - textp + 1)
wend
fileclose(f)
curline = 0
end sub
sub liststmt()
dim i
for i = 1 to c_maxlines
if pgm$[i] <> "" then
print i; " "; pgm$[i]
end if
next
print ""
end sub
sub inputstmt() ' "input" [string ","] var
dim thevar, st$, prompt$
prompt$ = "? "
if toktype$ = "string" then
prompt$ = right(tok$, length(tok$) - 1)
nexttok()
expect(",")
end if
thevar = getvarindex(): nexttok()
st$ = input$(prompt$)
if st$ = "" then
st$ = "0"
end if
if asc(left(st$, 1)) >= asc("0") and asc(left(st$, 1)) <= asc("9") then
vars[thevar] = val(st$)
else
vars[thevar] = asc(st$)
end if
end sub
sub gotostmt()
num = expression(0)
validlinenum()
initlex(num)
end sub
sub gosubstmt() ' for gosub: save the line and column
gsp = gsp + 1
gstackln[gsp] = curline
gstacktp[gsp] = textp
gotostmt()
end sub
sub ifstmt()
if expression(0) = 0 then
skiptoeol()
return
end if
accept("then")
if toktype$ = "number" then
gotostmt()
end if
end sub
sub arrassn() ' array assignment: @(expr) = expr
dim n, atndx
expect("(")
atndx = expression(0)
expect(")")
expect("=")
n = expression(0)
atarry[atndx] = n
if tracing then
print "*** @("; atndx; ") = "; n
end if
end sub
sub assign()
dim thevar
thevar = getvarindex(): nexttok()
expect("=")
vars[thevar] = expression(0)
if tracing then
print "*** "; chr(thevar + asc("a")); " = "; vars[thevar]
end if
end sub
sub forstmt() ' for i = expr to expr
dim thevar, n, forndx
thevar = getvarindex()
assign()
' vars(thevar) has the value; thevar has the number value of the variable in 0..25
forndx = thevar
forvar[forndx] = vars[thevar]
expect("to")
n = expression(0)
forlimit[forndx] = n
' need to store iter, limit, line, and col
forline[forndx] = curline
if tok$ = "" then
forpos[forndx] = textp
else
forpos[forndx] = textp - 2
end if
end sub
sub help()
print "┌────────────────────── Tiny Basic Help (FreeBasic)───────────────────┐"
print "│ bye, clear, end, help, list, load, new, run, save, stop │█"
print "│ goto <expr> │█"
print "│ gosub <expr> ... return │█"
print "│ if <expr> then <statement> │█"
print "│ input [prompt,] <var> │█"
print "│ <var>=<expr> │█"
print "│ print <expr|string>[,<expr|string>][;] │█"
print "│ rem <anystring> │█"
print "│ Operators: + - * / < <= > >= <> = │█"
print "│ Integer variables a..z, and array @(expr) │█"
print "│ Functions: rnd(expr) │█"
print "└─────────────────────────────────────────────────────────────────────┘█"
print " ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀"
end sub
sub showtime(running)
if running then
print "Took : " + str(timer - timestart) + " seconds"
end if
end sub
sub docmd()
dim running
do
if tracing and left(tok$, 1) <> ":" then
print curline; tok$; thech$; mid(thelin$, textp, length(thelin$) - textp)
end if
select case tok$
case "bye", "quit" : nexttok(): end
case "end", "stop" : nexttok(): return
case "clear" : nexttok(): clearvars(): return
case "help" : nexttok(): help(): return
case "list" : nexttok(): liststmt(): return
case "load" : nexttok(): loadstmt(): return
case "new" : nexttok(): newstmt(): return
case "run" : nexttok(): runstmt(): running = true
' case "save" : nexttok(): savestmt(): return
case "tron" : nexttok(): tracing = true
case "troff" : nexttok(): tracing = false
case "cls" : nexttok():
case "for" : nexttok(): forstmt()
case "gosub" : nexttok(): gosubstmt()
case "goto" : nexttok(): gotostmt()
case "if" : nexttok(): ifstmt()
case "input" : nexttok(): inputstmt()
case "next" : nexttok(): nextstmt()
case "print", "?" : nexttok(): printstmt()
case "return" : nexttok(): returnstmt()
case "@" : nexttok(): arrassn()
case ":" : nexttok() ' just continue
case "" : ' handled below
default
if tok$ = "let" then
nexttok()
end if
if toktype$ = "ident" then
assign()
else
print "Unknown token "; tok$; " at line "; curline: errors = true
end if
end select
if errors then
return
end if
if curline > c_maxlines then
showtime(running): return
end if
while tok$ = ""
if curline = 0 or curline >= c_maxlines then
showtime(running): return
end if
initlex(curline + 1)
wend
loop
end sub
newstmt()
do
errors = false
pgm$[0] = input$("rcb>: ")
if ltrim(pgm$[0]) <> "" then
initlex(0)
if toktype$ = "number" then
validlinenum()
pgm$[num] = right$(pgm$[0], length(pgm$[0]) - textp + 1)
else
docmd
end if
end if
loop
Tiny Star Trek
1 ' StarTrek for TinyBasic
5 y = 2999: input "Do you want a difficult game? (y or n):", a
10 print "Stardate 3200: your mission is ";: if a = asc("y") then y = 999
15 k = 0: b = 0: d = 30: for i = 0 to 63: j = abs(rnd(99) < 5): b = b + j
20 m = rnd(y): m = abs((m < 209) + (m < 99) + (m < 49) + (m < 24) + (m < 9) + (m < 2)): k = k + m
25 @(i) = -100 * m - 10 * j - rnd(8): next i: if (b < 2) + (k < 4) goto 15
30 print "to destroy ",#1,k," Klingons in 30 stardates."
35 print "there are ",#1,b," starbases.": gosub 160: c = 0: h = k
40 u = rnd(8): v = rnd(8): x = rnd(8): y = rnd(8)
45 for i = 71 to 152: @(i) = 0: next i: @(8 * x + y + 62) = 4: m = abs(@(8 * u + v - 9)): n = m / 100
50 i = 1: if n then for j = 1 to n: gosub 165: @(j + 134) = 300: @(j + 140) = s: @(j + 146) = t: next j
55 gosub 175: m = m - 100 * n: i = 2: if m / 10 gosub 165
60 m = m - m / 10 * 10: i = 3: if m then for j = 1 to m: gosub 165: next j
65 gosub 145: gosub 325: if k goto 95
70 print : print "Mission accomplished.": if d < 3 then print "Boy, you barely made it."
75 if d > 5 then print "Good work...": if d > 9 then print "Fantastic!": if d > 13 then print "Unbelievable!"
80 d = 30 - d: i = h * 100 / d * 10: print #1,h," Klingons in ",d," stardates. (",i,")"
85 j = 100 * abs(c = 0) - 5 * c: print #1,c," casualties incurred. (",j,")"
90 print "your score:",i + j: goto 110
95 if d < 0 then print "It's too late, the Federation has been conquered.": goto 110
100 if e >= 0 goto 120
105 print "Enterprise destroyed": if h - k > 9 then print "But you were a good man"
110 y = 987: print : input "Another game? (y or n):", a: if a = asc("y") goto 5
115 print "Good bye.": end
120 input "Captain:", a
122 if a = asc("g") then goto 180 'Galaxy map
123 if a = asc("l") then goto 200 'LR. sensor
121 if a = asc("s") then goto 220 'SR. sensor
124 if a = asc("p") then goto 260 'Phaser
125 if a = asc("r") then goto 420 'Report
126 if a = asc("w") then goto 465 'Warp engine
127 if a = asc("t") then goto 555 'Torpedo
128 if a = asc("q") then goto 110 'Quit
130 print "r=Report s=SR. Sensor l=LR. Sensor"
135 print "g=Galaxy Map p=Phaser t=Torpedo"
140 print "w=Warp Engine q=Quit ***Please use one of these commands***": goto 120
145 for i = x - abs(x > 1) to x + abs(x < 8): for j = y - abs(y > 1) to y + abs(y < 8)
150 if @(8 * i + j + 62) <> 2 then next j: next i: o = 0: return
155 if o = 0 then print "Sulu: 'Captain, we are docked at starbase."
160 e = 4000: f = 10: o = 1: for i = 64 to 70: @(i) = 0: next i: return
165 s = rnd(8): t = rnd(8): a = 8 * s + t + 62: if @(a) goto 165
170 @(a) = i: return
175 print "Enterprise in q-",#1,u,v," s-",x,y: return
180 gosub 175: j = 2: gosub 375: if i goto 120
185 print " of galaxy map": for i = 0 to 7: print : print #1,i + 1,":",: for j = 0 to 7: m = @(8 * i + j)
190 print #4,abs(m > 0) * m,: next j: print : next i: print " ",: for i = 0 to 7: print " ..",: next i: print
195 print " ",: for i = 1 to 8: print #4,i,: next i: print : print : goto 120
200 gosub 175: j = 3: gosub 375: if i goto 120
205 print : for i = u - 1 to u + 1: for j = v - 1 to v + 1: m = 8 * i + j - 9: a = 0
210 if (i > 0) * (i < 9) * (j > 0) * (j < 9) then a = abs(@(m)): @(m) = a
215 print #4,a,: next j: print : next i: goto 120
220 gosub 175: j = 1: gosub 375: if i goto 120
225 m = 8 * u + v - 9: @(m) = abs(@(m))
230 print : for i = 1 to 8: print #1,i,: for j = 1 to 8: m = @(8 * i + j + 62): if m = 0 then print " .",
235 if m = 1 then print " K",
240 if m = 2 then print " B",
245 if m = 3 then print " *",
250 if m = 4 then print " E",
255 next j: print : next i: print " ",: for i = 1 to 8: print #2,i,: next i: print : goto 120
260 j = 4: gosub 375: if i goto 120
265 input " energized. units to fire:", a: if a < 1 goto 120
270 if a > e then print "Spock: 'we have only ",#1,e," units.'": goto 120
275 e = e - a: if n < 1 then print "phaser fired at empty space.": goto 65
280 a = a / n: for m = 135 to 140: if @(m) = 0 goto 290
285 gosub 295: print #3,s," units hit ",: gosub 305
290 next m: goto 65
295 if a > 1090 then print "...overloaded..": j = 4: @(67) = 1: a = 9: gosub 375
300 i = @(m + 6) - x: j= @(m + 12) - y: s = a * 30 / (30 + i * i + j * j) + 1: return
305 print "Klingon at s-",#1,@(m + 6),@(m + 12),: @(m) = @(m) - s
310 if @(m) > 0 then print " **damaged**": return
315 @(m) = 0: i = 8 * u + v - 9: j = @(i) / abs(@(i)): @(i) = @(i) - 100 * j: k = k - 1
320 i = 8 * @(m + 6) + @(m + 12) + 62: @(i) = 0: n = n - 1: print " ***destroyed***": return
325 if n = 0 return
330 print "Klingon attack": if o then print "starbase print tects Enterprise": return
335 t = 0: for m = 135 to 140: if @(m) = 0 goto 350
340 a = (@(m) + rnd(@(m))) / 2: gosub 295: t = t + s: i = @(m + 6): j = @(m + 12)
345 print #3,s," units hit from Klingon at s-",#1,i,j
350 next m: e = e - t: if e <= 0 then print "*** bang ***": return
355 print #1,e," units of energy left.": if rnd(e / 4) > t return
360 if @(70) = 0 then @(70) = rnd(t / 50 + 1): j = 7: goto 375
365 j = rnd(6): @(j + 63) = rnd(t / 99 + 1)+@(j + 63): i = rnd(8) + 1: c = c + i
370 print "Mc coy: 'sickbay to bridge, we suffered",#2,i," casualties."
375 i = @(j + 63): if j = 1 then print "short range sensor",
380 if j = 2 then print "Computer display",
385 if j = 3 then print "Long range sensor",
390 if j = 4 then print "Phaser",
395 if j = 5 then print "Warp engine",
400 if j = 6 then print "Photon torpedo tubes",
405 if j = 7 then print "Shield",
410 if i = 0 then return
415 print " damaged, ",#1,i," stardates estimated for repair": return
420 print "status report:": print "stardate",#10,3230 - d: print "time left",#7,d
425 print "condition ",: if o then print "docked": goto 445
430 if n then print "red": goto 445
435 if e < 999 then print "yellow": goto 445
440 print "green"
445 print "position q-",#1,u,v," s-",x,y: print "energy",#12,e
450 print "torpedoes",#7,f: print "Klingons left",#3,k: print "starbases",#6,b
455 for j = 1 to 7: if @(j + 63) gosub 375
460 next j: goto 120
465 j = 5: gosub 375: if i = 0 then print
470 input "sector distance:", w: if w < 1 goto 120
475 if i * (w > 2) then print "Chekov: 'we can try 2 at most, sir.'": goto 470
480 if w > 91 then w = 91: print "Spock: 'are you sure, Captain?'"
485 if e < w * w / 2 then print "Scotty: 'sir, we do not have the energy.'": goto 120
490 gosub 615: if r = 0 goto 120
495 d = d - 1: e = e - w * w / 2: @(8 * x + y + 62) = 0
500 for m = 64 to 70: @(m) = (@(m) - 1) * abs(@(m) > 0): next m
505 p = 45 * x + 22: g = 45 * y + 22: w = 45 * w: for m = 1 to 8: w = w - r: if w < -22 goto 525
510 p = p + s: g = g + t: i = p / 45: j = g / 45: if (i < 1) + (i > 8) + (j < 1) + (j > 8) goto 530
515 if @(8 * i + j + 62) = 0 then x = i: y = j: next m
520 print "**Emergency stop**": print "Spock: 'to err is human.'"
525 @(8 * x + y + 62) = 4: gosub 175: goto 65
530 p = u * 72 + p / 5 + w / 5 * s / r - 9: u = p / 72: g = v * 72 + g / 5 + w / 5 * t / r - 9: v = g / 72
535 if rnd(9) < 2 then print "***Space storm***": t = 100: gosub 360
540 if (u > 0) * (u < 9) * (v > 0) * (v < 9) then x = (p + 9 - 72 * u) / 9: y = (g + 9 - 72 * v) / 9: goto 45
545 print "**You wandered outside the galaxy**"
550 print "On board computer takes over, and saved your life": goto 40
555 j = 6: gosub 375: if i goto 120
560 if f = 0 then print " empty": goto 120
565 print " loaded": gosub 615: if r = 0 goto 120
570 print "torpedo track ",: f = f - 1: p = 45 * x + 22: g = 45 * y + 22: for m = 1 to 8
575 p = p + s: g = g + t: i = p / 45: j = g / 45: if (i < 1) + (i > 8) + (j < 1) + (j > 8) goto 585
580 l = 8 * i + j + 62: w = 8 * u + v - 9: r = @(w) / abs(@(w)): print #1,i,j," ",: goto 585 + 5 * @(l)
585 next m: print "...missed": goto 65
590 s = rnd(99) + 280: for m = 135 to 140: if (@(m + 6) = i) * (@(m + 12) = j) gosub 305
592 next m: goto 65
595 b = b - 1: @(l) = 0: @(w) = @(w) - 10 * r: print "starbase destroyed"
597 print "Spock: 'I often find human behaviour fascinating.'": goto 65
600 print "hit a star": if rnd(9) < 3 then print "torpedo absorbed": goto 65
605 @(l) = 0: @(w) = @(w) - r: if rnd(9) < 6 then print "star destroyed": goto 65
610 t = 300: print "it novas ***radiation alarm***": gosub 360: goto 65
615 input "course (0-360):", i: if (i > 360) + (i < 0) then r = 0: return
620 s = (i + 45) / 90: i = i - s * 90: r = (45 + i * i) / 110 + 45: goto 625 + 5 * abs(s < 4) * s
625 s = -45: t = i: return
630 s = i: t = 45: return
635 s = 45: t = -i: return
640 s = -i: t = -45: return
