mirror of
https://github.com/KevinMidboe/linguist.git
synced 2025-10-29 09:40:21 +00:00
80 lines
2.9 KiB
Forth
80 lines
2.9 KiB
Forth
\ KataDiversion in Forth
|
|
|
|
\ -- utils
|
|
|
|
\ empty the stack
|
|
: EMPTY
|
|
DEPTH 0 <> IF BEGIN
|
|
DROP DEPTH 0 =
|
|
UNTIL
|
|
THEN ;
|
|
|
|
\ power
|
|
: ** ( n1 n2 -- n1_pow_n2 ) 1 SWAP ?DUP IF 0 DO OVER * LOOP THEN NIP ;
|
|
|
|
\ compute the highest power of 2 below N.
|
|
\ e.g. : 31 -> 16, 4 -> 4
|
|
: MAXPOW2 ( n -- log2_n ) DUP 1 < IF 1 ABORT" Maxpow2 need a positive value."
|
|
ELSE DUP 1 = IF 1
|
|
ELSE
|
|
1 >R
|
|
BEGIN ( n |R: i=1)
|
|
DUP DUP I - 2 *
|
|
( n n 2*[n-i])
|
|
R> 2 * >R ( … |R: i*2)
|
|
> ( n n>2*[n-i] )
|
|
UNTIL
|
|
R> 2 /
|
|
THEN
|
|
THEN NIP ;
|
|
|
|
\ -- kata
|
|
|
|
\ test if the given N has two adjacent 1 bits
|
|
\ e.g. : 11 -> 1011 -> -1
|
|
\ 9 -> 1001 -> 0
|
|
: ?NOT-TWO-ADJACENT-1-BITS ( n -- bool )
|
|
\ the word uses the following algorithm :
|
|
\ (stack|return stack)
|
|
\ ( A N | X ) A: 0, X: N LOG2
|
|
\ loop: if N-X > 0 then A++ else A=0 ; X /= 2
|
|
\ return 0 if A=2
|
|
\ if X=1 end loop and return -1
|
|
0 SWAP DUP DUP 0 <> IF
|
|
MAXPOW2 >R
|
|
BEGIN
|
|
DUP I - 0 >= IF
|
|
SWAP DUP 1 = IF 1+ SWAP
|
|
ELSE DROP 1 SWAP I -
|
|
THEN
|
|
ELSE NIP 0 SWAP
|
|
THEN
|
|
OVER
|
|
2 =
|
|
I 1 = OR
|
|
R> 2 / >R
|
|
UNTIL
|
|
R> 2DROP
|
|
2 <>
|
|
ELSE 2DROP INVERT
|
|
THEN ;
|
|
|
|
\ return the maximum number which can be made with N (given number) bits
|
|
: MAX-NB ( n -- m ) DUP 1 < IF DROP 0 ( 0 )
|
|
ELSE
|
|
DUP IF DUP 2 SWAP ** NIP 1 - ( 2**n - 1 )
|
|
THEN
|
|
THEN ;
|
|
|
|
|
|
\ return the number of numbers which can be made with N (given number) bits
|
|
\ or less, and which have not two adjacent 1 bits.
|
|
\ see http://www.codekata.com/2007/01/code_kata_fifte.html
|
|
: HOW-MANY-NB-NOT-TWO-ADJACENT-1-BITS ( n -- m )
|
|
DUP 1 < IF DUP 0
|
|
ELSE
|
|
0 SWAP
|
|
MAX-NB 1 + 0 DO I ?NOT-TWO-ADJACENT-1-BITS - LOOP
|
|
THEN ;
|
|
|