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math.bitwise: some cleanup of zero handling.

db4
John Benediktsson 2012-08-31 15:58:54 -07:00
parent 18a087cb2a
commit b39547a866
1 changed files with 7 additions and 6 deletions
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13
basis/math/bitwise/bitwise.factor
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@ -10,18 +10,19 @@ IN: math.bitwise
! utilities
: clear-bit ( x n -- y ) 2^ bitnot bitand ; inline
: set-bit ( x n -- y ) 2^ bitor ; inline
: bit-clear? ( x n -- ? ) 2^ bitand 0 = ; inline
: bit-clear? ( x n -- ? ) 2^ bitand zero? ; inline
: unmask ( x n -- ? ) bitnot bitand ; inline
: unmask? ( x n -- ? ) unmask 0 > ; inline
: unmask? ( x n -- ? ) unmask zero? not ; inline
: mask ( x n -- ? ) bitand ; inline
: mask? ( x n -- ? ) mask 0 > ; inline
: mask? ( x n -- ? ) mask zero? not ; inline
: wrap ( m n -- m' ) 1 - bitand ; inline
: on-bits ( m -- n ) 2^ 1 - ; inline
: bits ( m n -- m' ) on-bits mask ; inline
: mask-bit ( m n -- m' ) 2^ mask ; inline
: toggle-bit ( m n -- m' ) 2^ bitxor ; inline
: >signed ( x n -- y )
[ bits ] keep 2dup neg 1 + shift 1 = [ 2^ - ] [ drop ] if ;
[ bits ] keep 2dup neg 1 + shift
1 number= [ 2^ - ] [ drop ] if ;
: >odd ( m -- n ) 0 set-bit ; foldable
: >even ( m -- n ) 0 clear-bit ; foldable
: next-even ( m -- n ) >even 2 + ; foldable
@ -109,9 +110,9 @@ M: fixnum (bit-count)
fixnum-bit-count { fixnum } declare ; inline
M: bignum (bit-count)
dup 0 = [ drop 0 ] [
[ 0 ] [
[ byte-bit-count ] [ -8 shift (bit-count) ] bi +
] if ;
] if-zero ;
: byte-array-bit-count ( byte-array -- n )
0 [ byte-bit-count + ] reduce ; inline