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35 lines
1.0 KiB
Lua
35 lines
1.0 KiB
Lua
%import c64utils
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%zeropage basicsafe
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; This example computes the first 20 values of the Fibonacci sequence.
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; It uses the feature that variables that don't have an initialization value,
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; will retain their previous value over multiple invocations of the program or subroutine.
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; This is extremely handy for the Fibonacci sequence because it is defined
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; in terms of 'the next value is the sum of the previous two values'
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~ main {
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sub start() {
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c64scr.print("fibonacci sequence\n")
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fib_setup()
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for ubyte i in 0 to 20 {
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c64scr.print_uw(fib_next())
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c64.CHROUT('\n')
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}
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}
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sub fib_setup() {
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; (re)start the sequence
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main.fib_next.prev=0
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main.fib_next.current=1
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}
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sub fib_next() -> uword {
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uword prev ; no init value so will retain previous value
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uword current ; no init value so will retain previous value
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uword new = current + prev
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prev = current
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current = new
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return prev
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}
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}
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