retroforth/interfaces/io_floatingpoint.forth
crc a3d8f559bb fix issue with floating point encoding example (was using an older approach, not the one in the latest draft)
FossilOrigin-Name: 89fb77d0d8c0de1e3c0829f71995324b2b50ef6618a971f3b9b603e078ed0cb3
2018-11-25 00:38:45 +00:00

132 lines
3.8 KiB
Forth

~~~
{{
'io:FloatingPoint var
:identify
@io:FloatingPoint n:zero? [
#2 io:scan-for dup n:negative?
[ drop 'IO_DEVICE_TYPE_0002_NOT_FOUND s:put nl ]
[ !io:FloatingPoint ] choose ] if ;
---reveal---
:io:float-operation identify @io:FloatingPoint io:invoke ;
}}
~~~
# Floating Point
~~~
:n:to-float (n-_f:-n) #0 io:float-operation ;
:s:to-float (s-_f:-n) #1 io:float-operation ;
:f:to-number (f:a-__-n) #2 io:float-operation ;
:f:to-string (f:n-__-s) s:empty dup #3 io:float-operation ;
:f:+ (f:ab-c) #4 io:float-operation ;
:f:- (f:ab-c) #5 io:float-operation ;
:f:* (f:ab-c) #6 io:float-operation ;
:f:/ (f:ab-c) #7 io:float-operation ;
:f:floor (f:ab-c) #8 io:float-operation ;
:f:ceiling (f:f-f) #9 io:float-operation ;
:f:sqrt (f:f-f) #10 io:float-operation ;
:f:eq? (f:ab-c) #11 io:float-operation ;
:f:-eq? (f:ab-c) #12 io:float-operation ;
:f:lt? (f:ab-c) #13 io:float-operation ;
:f:gt? (f:ab-c) #14 io:float-operation ;
:f:depth (-n) #15 io:float-operation ;
:f:dup (f:a-aa) #16 io:float-operation ;
:f:drop (f:a-) #17 io:float-operation ;
:f:swap (f:ab-ba) #18 io:float-operation ;
:f:log (f:ab-c) #19 io:float-operation ;
:f:power (f:ab-c) #20 io:float-operation ;
:f:sin (f:f-f) #21 io:float-operation ;
:f:cos (f:f-f) #22 io:float-operation ;
:f:tan (f:f-f) #23 io:float-operation ;
:f:asin (f:f-f) #24 io:float-operation ;
:f:acos (f:f-f) #25 io:float-operation ;
:f:atan (f:f-f) #26 io:float-operation ;
:f:square (f:n-m) f:dup f:* ;
:f:over (f:ab-aba) f:to-string f:dup s:to-float f:swap ;
:f:tuck (f:ab-bab) f:swap f:over ;
:f:positive? (-f__f:a-) #0 n:to-float f:gt? ;
:f:negative? (-f__f:a-) #0 n:to-float f:lt? ;
:f:negate (f:a-b) #-1 n:to-float f:* ;
:f:abs (f:a-b) f:dup f:negative? [ f:negate ] if ;
:prefix:. (s-__f:-a)
compiling? [ s:keep ] [ s:temp ] choose &s:to-float class:word ; immediate
:f:put (f:a-) f:to-string s:put ;
:f:PI (f:-F) .3.141592 ;
:f:E (f:-F) .2.718281 ;
:f:NAN (f:-n) .0 .0 f:/ ;
:f:INF (f:-n) .1.0 .0 f:/ ;
:f:-INF (f:-n) .-1.0 .0 f:/ ;
:f:nan? (f:n-,-f) f:dup f:-eq? ;
:f:inf? (f:n-,-f) f:INF f:eq? ;
:f:-inf? (f:n-,-f) f:-INF f:eq? ;
:f:round (-|f:a-b)
f:dup f:negative?
[ .0.5 f:- f:ceiling ]
[ .0.5 f:+ f:floor ] choose ;
~~~
---------------------------------------------------------------
# Float
## Description
This implements a means of encoding floating point values into signed integer cells. The technique is described in the paper titled "Encoding floating point numbers to shorter integers" by Kiyoshi Yoneda and Charles Childers.
This will extend the `f:` vocabulary and adds a new `u:` vocabulary.
## Code & Commentary
Define some constants. The range is slightly reduced from the standard integer range as the smallest value is used for NaN.
~~~
n:MAX n:dec 'u:MAX const
n:MAX n:dec n:negate 'u:MIN const
n:MIN 'u:NAN const
n:MAX 'u:INF const
n:MAX n:negate 'u:-INF const
~~~
~~~
:u:n? (u-f)
u:MIN n:inc u:MAX n:dec n:between? ;
:u:max? (u-f) u:MAX eq? ;
:u:min? (u-f) u:MIN eq? ;
:u:zero? (u-f) n:zero? ;
:u:nan? (u-f) u:NAN eq? ;
:u:inf? (u-f) u:INF eq? ;
:u:-inf? (u-f) u:-INF eq? ;
:u:clip (u-u) u:MIN u:MAX n:limit ;
~~~
~~~
{{
:s .10.0e-4 ;
:f:encode .0.5 f:power s .-1.0 f:power f:* ;
:f:decode f:square s f:square f:* ;
---reveal---
:f:to-u (-u|f:a-)
f:dup f:encode f:round f:to-number u:clip
f:dup f:nan? [ drop u:NAN ] if
f:dup f:inf? [ drop u:INF ] if
f:dup f:-inf? [ drop u:-INF ] if
f:drop ;
:u:to-f (u-|f:-b)
n:to-float f:decode ;
:u:to-f (u-|f:-b)
dup n:to-float f:decode
dup u:nan? [ f:drop f:NAN ] if
dup u:inf? [ f:drop f:INF ] if
dup u:-inf? [ f:drop f:-INF ] if
drop ;
}}
~~~
~~~
:f:store (a-|f:n-) [ f:to-u ] dip store ;
:f:fetch (a-|f:-n) fetch u:to-f ;
~~~