binary_to_decimal

; -*- mode: turing-machine -*-
; http://morphett.info/turing/turing.html
; Converts a number from binary to decimal.
; It does this by successively incrementing the decimal counter and decrementing the binary input until 0 is reached.
; Input: A single number in binary.
;; INITIAL: 1111
;; RATE: .1
0 * * * 1
1 _ _ r 1
1 * * r 1a
1a * * r 1a
1a _ _ l 2   ; found the end of the input
1b _ _ r 1   ; (used later) skip the output, go to end of input
1b * * r 1b
2 1 0 l 3    ; decrement input
2 0 1 l 2    ; decrement & carry
2 _ _ r 20   ; finished. clean up
3 * * l 3    ; find start of output
3 _ _ l 4    ; found end of input
4 0 1 r 1b   ; increment the output
4 1 2 r 1b
4 2 3 r 1b
4 3 4 r 1b
4 4 5 r 1b
4 5 6 r 1b
4 6 7 r 1b
4 7 8 r 1b
4 8 9 r 1b
4 9 0 l 4  ; increment & carry
4 _ 1 r 1b  ; start new column

; clean up
20 _ _ l 21  ; return to end of output
20 * _ r 20  ; erase input
21 _ _ l 21
21 * * l 21a
21a * * l 21a
21a _ _ r halt