56 lines
1.3 KiB
Forth
56 lines
1.3 KiB
Forth
This is a vocabulary for working with double cell numeric
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values. By using two cells we can achieve a greater range
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than the standard 32-bit cells. This probably will not work
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correctly on a Retro with 64-bit cells unless you make some
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small changes (see the `dn:div` in particular).
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~~~
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'~res var
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:dn:h@ (D-n) fetch ;
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:dn:l@ (D-n) n:inc fetch ;
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:dn:h! (nD-) store ;
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:dn:l! (nD-) n:inc store ;
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:dn:new (-D) here #0 dup comma comma ;
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:dn:lows (DD-nn) [ dn:l@ ] bi@ ;
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:dn:highs (DD-nn) [ dn:h@ ] bi@ ;
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:dn:make (nn-D) here [ swap comma comma ] dip ;
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:dn:put fetch-next n:put sp fetch n:put nl ;
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:dn:add (DD-D)
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dn:new !~res
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dup-pair dn:lows n:add @~res dn:l!
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over @~res dn:lows gt? n:abs [ dn:highs n:add ] dip n:add
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@~res dn:h!
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@~res ;
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:dn:sub (DD-D)
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dn:new !~res
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dup-pair dn:lows n:sub @~res dn:l!
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over @~res dn:lows lt? n:abs [ dn:highs n:sub ] dip n:sub
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@~res dn:h!
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@~res ;
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:dn:mul (DD-D)
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dn:new !~res
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dup-pair dn:lows n:mul @~res dn:l!
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@~res dn:l@ n:negative? n:abs
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[ dup-pair
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[ dn:h@ ] [ dn:l@ ] bi* n:mul
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[ [ dn:l@ ] [ dn:h@ ] bi* n:mul ] dip n:add
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] dip n:add
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@~res dn:h!
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@~res ;
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:dn:div (DD-D)
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dn:new !~res
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dup-pair dn:lows n:div @~res dn:l!
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dup-pair
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[ dn:h@ ] [ dn:l@ ] bi* n:div #-1 shift
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[ [ dn:l@ ] [ dn:h@ ] bi* n:mod #31 shift ] dip n:add
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@~res dn:h!
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@~res ;
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~~~
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