rollin.bas

'Roll a die or more, DND style syntax.
declare function roll( byref s as string ) as uinteger

#define ALGO_CRYPTO 5
#define ALGO_QBASIC 4
#define ALGO_MERSEN 3
#define ALGO_FAST   2
#define ALGO_CRAND  1

'Main

var algo = valint(environ("RALGO"))
if algo = 0 then algo = 5
if algo > 5 then algo = 5

if command() = "--test" then
    print "Don't trust random numbers?"
    print "Here is a distribution breakdown of 100,000 random d20 rolls."
    print "*note the results are divided by 10 for display"
    print "Algorithm in use: (see help to decode) " & algo
    print
    randomize timer, algo
    dim dist(1 to 20) as integer
    for n as integer = 0 to 99999 : dist( roll("d20") ) += 1 : next
    for n as integer = 1 to 20 : print using "### "; dist(n)\10; : next
    print
    for n as integer = 1 to 20 : print using " ## "; n; : next
    print

elseif command() <> "" andalso command() <> "--help" then
    randomize timer, algo
    for n as integer = 1 to __FB_ARGC__ -1
        print command(n) & ": " & roll(command(n))
    next

else
    print "Simulate a dice roll using standard DND format."
    print "This die roller is Open Source under the STFUOIWCU License."
    print
    print "Usage:"
    print "rollin {option} die (repeated die may be seperated by spaces)"
    print
    print "Options:"
    print "--test - run a distribution test of the pRNG."
    print "--help - print this help message."
    print
    print "Environment Variables Recognized:"
    print "RALGO - Set the pRNG used to generate the dice rolls."
    print "        Is a nummber between 1 and 5 with 5 being the default."
    print "        Algorithms:"
    print "        1 - C rand() function"
    print "        2 - 'fast' function"
    print "        3 - Mersenne Twister, reasonably good"
    print "        4 - the QBASIC rnd function"
    print "        5 - Windows/Linux crypto grade pRNG"
    print
    print "Die Specification Format: {x}d[n]{+z}"
    print "where optional x is the number of die in this roll"
    print "the letter d is required"
    print "n is the number of faces on the die, a standard die is 6"
    print "+z is an optional bonus (preceded by a +) to be applied"
    print "    after all rolls."
    print
    print "Example dice rolls:"
    print "2d6 - Roll 2 standard dice, result will be"
    print "      at least 2 and at a maximum 12."
    print "3d12+4 - Roll 3x 12 sided dice, result will be"
    print "         at least 7 (3+4) and at most 40 (36+4)."
    print
    print "Example usage:"
    print "rollin 2d6+1 1d20+5 d100+2 d20"
    print "2d6+1: " & roll("2d6+1")
    print "1d20+5: " & roll("1d20+5")
    print "d100+2: " & roll("d100+2")
    print "d20: " & roll("d20")
end if

function roll( byref s as string ) as uinteger
    var d = instr(s,"d")
    var plus = instr(s,"+")
    var ret = 0u
    var rep = 0u
    if d = 1 then
        rep = 1
    else
        rep = valint(mid(s,1,d-1))
    end if
    var die = valint(mid(s,d+1,plus-d-1))
    var bonus = valint(mid(s,plus+1))
    for n as integer = 1 to rep
        ret += int(rnd(1)*die)+1
    next
    return ret + bonus

end function