Bitwise Operations

primitive: logand n1 n2

Returns the integer which is the bit-wise AND of the two integer arguments.

Example:

(number->string (logand #b1100 #b1010) 2)
   => "1000"

primitive: logior n1 n2

Returns the integer which is the bit-wise OR of the two integer arguments.

Example:

(number->string (logior #b1100 #b1010) 2)
   => "1110"

primitive: logxor n1 n2

Returns the integer which is the bit-wise XOR of the two integer arguments.

Example:

(number->string (logxor #b1100 #b1010) 2)
   => "110"

primitive: lognot n

Returns the integer which is the 2s-complement of the integer argument.

Example:

(number->string (lognot #b10000000) 2)
   => "-10000001"
(number->string (lognot #b0) 2)
   => "-1"

primitive: logtest j k

(logtest j k) == (not (zero? (logand j k)))

(logtest #b0100 #b1011) => #f
(logtest #b0100 #b0111) => #t

primitive: logbit? index j

(logbit? index j) == (logtest (integer-expt 2 index) j)

(logbit? 0 #b1101) => #t
(logbit? 1 #b1101) => #f
(logbit? 2 #b1101) => #t
(logbit? 3 #b1101) => #t
(logbit? 4 #b1101) => #f

primitive: ash int count

Returns an integer equivalent to (inexact->exact (floor (* int (expt 2 count)))).

Example:

(number->string (ash #b1 3) 2)
   => "1000"
(number->string (ash #b1010 -1) 2)
   => "101"

primitive: logcount n

Returns the number of bits in integer n. If integer is positive, the 1-bits in its binary representation are counted. If negative, the 0-bits in its two's-complement binary representation are counted. If 0, 0 is returned.

Example:

(logcount #b10101010)
   => 4
(logcount 0)
   => 0
(logcount -2)
   => 1

primitive: integer-length n

Returns the number of bits neccessary to represent n.

Example:

(integer-length #b10101010)
   => 8
(integer-length 0)
   => 0
(integer-length #b1111)
   => 4

primitive: integer-expt n k

Returns n raised to the non-negative integer exponent k.

Example:

(integer-expt 2 5)
   => 32
(integer-expt -3 3)
   => -27

primitive: bit-extract n start end

Returns the integer composed of the start (inclusive) through end (exclusive) bits of n. The startth bit becomes the 0-th bit in the result.

Example:

(number->string (bit-extract #b1101101010 0 4) 2)
   => "1010"
(number->string (bit-extract #b1101101010 4 9) 2)
   => "10110"

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