6.6.11 Bit Vectors ¶

Bit vectors are zero-origin, one-dimensional arrays of booleans. They are displayed as a sequence of 0s and 1s prefixed by #*, e.g.,

(make-bitvector 8 #f) ⇒
#*00000000

Bit vectors are the special case of one dimensional bit arrays, and can thus be used with the array procedures, See Arrays.

Scheme Procedure: bitvector? obj ¶

Return #t when obj is a bitvector, else return #f.

Scheme Procedure: make-bitvector len [fill] ¶

Create a new bitvector of length len and optionally initialize all elements to fill.

Scheme Procedure: bitvector bit … ¶

Create a new bitvector with the arguments as elements.

Scheme Procedure: bitvector-length vec ¶

Return the length of the bitvector vec.

Scheme Procedure: bitvector-bit-set? vec idx ¶

Scheme Procedure: bitvector-bit-clear? vec idx ¶

Return #t if the bit at index idx of the bitvector vec is set (for bitvector-bit-set?) or clear (for bitvector-bit-clear?).

Scheme Procedure: bitvector-set-bit! vec idx ¶

Scheme Procedure: bitvector-clear-bit! vec idx ¶

Set (for bitvector-set-bit!) or clear (for bitvector-clear-bit!) the bit at index idx of the bitvector vec.

Scheme Procedure: bitvector-set-all-bits! vec ¶

Scheme Procedure: bitvector-clear-all-bits! vec ¶

Scheme Procedure: bitvector-flip-all-bits! vec ¶

Set, clear, or flip all bits of vec.

Scheme Procedure: list->bitvector list ¶

C Function: scm_list_to_bitvector (list) ¶

Return a new bitvector initialized with the elements of list.

Scheme Procedure: bitvector->list vec ¶

C Function: scm_bitvector_to_list (vec) ¶

Return a new list initialized with the elements of the bitvector vec.

Scheme Procedure: bitvector-copy bitvector [start [end]] ¶

C Function: scm_bitvector_copy (bitvector, start, end) ¶

Returns a freshly allocated bitvector containing the elements of bitvector in the range [start ... end). start defaults to 0 and end defaults to the length of bitvector.

Scheme Procedure: bitvector-count bitvector ¶

Return a count of how many entries in bitvector are set.

(bitvector-count #*000111000)  ⇒ 3

Scheme Procedure: bitvector-count-bits bitvector bits ¶

Return a count of how many entries in bitvector are set, with the bitvector bits selecting the entries to consider. bitvector must be at least as long as bits.

For example,

(bitvector-count-bits #*01110111 #*11001101) ⇒ 3

Scheme Procedure: bitvector-position bitvector bool start ¶

C Function: scm_bitvector_position (bitvector, bool, start) ¶

Return the index of the first occurrence of bool in bitvector, starting from start. If there is no bool entry between start and the end of bitvector, then return #f. For example,

(bitvector-position #*000101 #t 0)  ⇒ 3
(bitvector-position #*0001111 #f 3) ⇒ #f

Scheme Procedure: bitvector-set-bits! bitvector bits ¶

Set entries of bitvector to #t, with bits selecting the bits to set. The return value is unspecified. bitvector must be at least as long as bits.

(define bv (bitvector-copy #*11000010))
(bitvector-set-bits! bv #*10010001)
bv
⇒ #*11010011

Scheme Procedure: bitvector-clear-bits! bitvector bits ¶

Set entries of bitvector to #f, with bits selecting the bits to clear. The return value is unspecified. bitvector must be at least as long as bits.

(define bv (bitvector-copy #*11000010))
(bitvector-clear-bits! bv #*10010001)
bv
⇒ #*01000010

C Function: int scm_is_bitvector (SCM obj) ¶

C Function: SCM scm_c_make_bitvector (size_t len, SCM fill) ¶

C Function: int scm_bitvector_bit_is_set (SCM vec, size_t idx) ¶

C Function: int scm_bitvector_bit_is_clear (SCM vec, size_t idx) ¶

C Function: void scm_c_bitvector_set_bit_x (SCM vec, size_t idx) ¶

C Function: void scm_c_bitvector_clear_bit_x (SCM vec, size_t idx) ¶

C Function: void scm_c_bitvector_set_bits_x (SCM vec, SCM bits) ¶

C Function: void scm_c_bitvector_clear_bits_x (SCM vec, SCM bits) ¶

C Function: void scm_c_bitvector_set_all_bits_x (SCM vec) ¶

C Function: void scm_c_bitvector_clear_all_bits_x (SCM vec) ¶

C Function: void scm_c_bitvector_flip_all_bits_x (SCM vec) ¶

C Function: size_t scm_c_bitvector_length (SCM bitvector) ¶

C Function: size_t scm_c_bitvector_count (SCM bitvector) ¶

C Function: size_t scm_c_bitvector_count_bits (SCM bitvector, SCM bits) ¶

C API for the corresponding Scheme bitvector interfaces.

C Function: const scm_t_uint32 * scm_bitvector_elements (SCM vec, scm_t_array_handle *handle, size_t *offp, size_t *lenp, ssize_t *incp) ¶

Like scm_vector_elements (see Vector Accessing from C), but for bitvectors. The variable pointed to by offp is set to the value returned by scm_array_handle_bit_elements_offset. See scm_array_handle_bit_elements for how to use the returned pointer and the offset.

C Function: scm_t_uint32 * scm_bitvector_writable_elements (SCM vec, scm_t_array_handle *handle, size_t *offp, size_t *lenp, ssize_t *incp) ¶

Like scm_bitvector_elements, but the pointer is good for reading and writing.