Miroirs/planckforth
1
0
Fork 0
mirror of https://github.com/nineties/planckforth synced 2024-12-26 21:58:42 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions

WIP: bitscan reverse

Browse source
This commit is contained in:
Koichi Nakamura 2021-05-05 23:09:48 +09:00
parent d07e23eb00
commit 4f0380dafa
1 changed files with 27 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

28
lib/bitscan.fs
View file

@ -37,12 +37,29 @@ create bsf-modulo-131-table
cells bsf-modulo-131-table + @
; export
create msb-index-table
create msb-table
-1 , 0 , 1 , 1 , 2 , 2 , 2 , 2 , 3 , 3 , 3 , 3 , 3 , 3 , 3 , 3 ,
4 , 4 , 4 , 4 , 4 , 4 , 4 , 4 , 4 , 4 , 4 , 4 , 4 , 4 , 4 , 4 ,
5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 ,
5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 , 5 ,
6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 ,
6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 ,
6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 ,
6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 , 6 ,
7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 ,
7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 ,
7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 ,
7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 ,
7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 ,
7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 ,
7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 ,
7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 , 7 ,
\ Find the index of the most significant 1 bit
\ If u == 0, returns -1
: bitscan-reverse ( u -- u )
dup 0xff u< if cells msb-table + @ exit then
; export
}private
@ -56,3 +73,12 @@ T{ 5 bitscan-forward -> 0 }T
T{ -1 bitscan-forward -> 0 }T
T{ max-int bitscan-forward -> 0 }T
T{ min-int bitscan-forward -> cell 8 * 1- }T
T{ 0 bitscan-reverse -> -1 }T
T{ 1 bitscan-reverse -> 0 }T
T{ 2 bitscan-reverse -> 1 }T
T{ 3 bitscan-reverse -> 1 }T
T{ 4 bitscan-reverse -> 2 }T
T{ -1 bitscan-reverse -> cell 8 * 1- }T
T{ max-int bitscan-reverse -> cell 8 * 2 - }T
T{ min-int bitscan-reverse -> cell 8 * 1- }T