68 lines
1.4 KiB
Forth
68 lines
1.4 KiB
Forth
Words to encode floating point numbers into two cells.
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~~~
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:st (-) dump-stack nl f:dump-stack ;
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:f:sign (-n|f:a-)
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f:dup .0 f:eq? [ #0 f:drop ] if;
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.0 f:gt? [ #1 ] [ #-1 ] choose ;
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~~~
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~~~
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:f:encode.w (|f:n-n) f:dup f:sign f:abs f:sqrt n:to-float f:* ;
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:f:decode.w (|f:n-n) f:dup f:sign f:square n:to-float f:* ;
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~~~
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```
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.-12345.6789 f:encode.w st
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f:decode.w st
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```
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~~~
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{{
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:f:-shift9 .1.e9 f:* ;
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:f:shift9 .1.e-9 f:* ;
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---reveal---
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:f:split (-|f:n-fi)_absFrac.-shift9_signedInt
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f:dup f:sign (s|f:_n
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f:abs f:dup f:floor f:swap f:over (s|f:_abs.int_abs_abs.int
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f:- f:-shift9 (s|f:_abs.int_abs.frac.-shift9
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f:swap n:to-float f:* (_|f:_abs.frac.-shift9_signedInt
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;
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:f:join (-|f:fi-n)
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f:dup f:sign f:abs (s|f:_abs.frac.-shift9_abs.int
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f:swap f:shift9 f:+ n:to-float f:* (_|f:_n
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;
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}}
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~~~
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```
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.-123456789.0987654321 f:split st
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f:join st
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```
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~~~
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:f:to-w (-fi|f:n-)_frac_sInt
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f:encode.w f:split f:to-number f:to-number swap ;
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:w:to-f (fi-|f:-n)
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swap n:to-float n:to-float (_|f:_abs.frac_signedInt
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f:join f:decode.w ;
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~~~
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```
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.-123456789.0987654321 f:to-w st
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w:to-f st
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```
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~~~
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:f:var (s-|f:n-) f:to-w rot d:create , , ; immediate
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:f:fetch (a-|f:-n) fetch-next [ fetch ] dip w:to-f ;
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:f:store (a-|f:n-) f:to-w rot store-next store ;
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~~~
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```
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.-123456789.0987654321 'FVar f:var
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&FVar f:fetch st
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.-9876543210.123456789 &FVar f:store
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&FVar f:fetch st
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```
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