collects/data/bit-vector.rkt

3          (for-syntax "private/count-bits-in-fixnum.rkt")
11          "private/count-bits-in-fixnum.rkt")
13 (define bits-in-a-word 8)
14 (define bits-in-a-word-log2 3)
17   (- (expt 2 bits-in-a-word) 1))
20   (arithmetic-shift n (- bits-in-a-word-log2)))
22   (bitwise-and n (sub1 bits-in-a-word)))
25   (define-values (q r) (quotient/remainder size bits-in-a-word))
29     (bytes-set! words q (- (expt 2 r) 1)))
34          (lambda init-bits
35            (list->bit-vector init-bits))])
60      (define bit  (bitwise-bit-set? word bi))
77 (define (bit-vector-set! bv n b)
83      (define bit  (bitwise-bit-set? word bi))
86        (bytes-set! words wi new-word))]))
126 (define (list->bit-vector init-bits)
127   (define len (length init-bits))
130         [b (in-list init-bits)])
131     (bit-vector-set! bv i b))
138       (string-set! s i (if (unsafe-bit-vector-ref bv i) #\1 #\0)))
145         (bit-vector-set! bv i #t)))
151   bit-vector? bit-vector-length bit-vector-ref bit-vector-set! make-bit-vector
152   unsafe-bit-vector-ref bit-vector-set! bit-vector-length
164   ; size      is the number of bits in bitvector
171     (let-values ([(q r) (quotient/remainder size bits-in-a-word)])
173                    ;; make sure "unreachable" bits are unset
175         (error 'bit-vector "bit vector data contains wrong number of bits")))
179                           bit-vector-set!
180                           #f ;; set
203                    ;; These use all bits, therefore simple eq?.
207                    ;; Check the used bits of the last byte.
208                    (let ([used-bits (min 8 (remainder nx 256))])
211                                              used-bits)
214                                              used-bits)))))))))
228   (-> any/c any)]
234   (->* (bit-vector? exact-nonnegative-integer?) (any/c) any)]
235  [bit-vector-set!
236   (-> bit-vector? exact-nonnegative-integer? boolean? any)]
238   (-> bit-vector? any)]
240   (-> bit-vector? any)]