Jacket
#import "Bit_Array";
A fixed-length sequence of bits packed into words.
seen := make_bit_array(100);
defer deinit(*seen);
seen[42] = true;
assert(seen[42] && !seen[43]);Sets up array to hold count bits, all cleared, replacing whatever it was. Allocates the words with the array's allocator, taking context.allocator if it has none.
bits: Bit_Array;
init_bit_array(*bits, 16);
assert(bits.count == 16 && !bits[3]);
deinit(*bits);A new Bit_Array of count cleared bits. The caller owns the storage and releases it with deinit.
bits := make_bit_array(200);
assert(bits.count == 200 && !bits[199]);
deinit(*bits);Frees the words and leaves the array empty (count is zero). It can be set up again with init_bit_array.
bits := make_bit_array(8);
deinit(*bits);
assert(bits.count == 0);Sets bit i; bits[i] reads it back.
bits := make_bit_array(8);
set_bit(*bits, 3);
assert(bits[3] && !bits[2]);Clears bit i. An index outside 0..count-1 fails an assert.
bits := make_bit_array(4);
set_bit(*bits, 1);
clear_bit(*bits, 1);
assert(!bits[1]);
deinit(*bits);Flips bit i. An index outside 0..count-1 fails an assert.
bits := make_bit_array(4);
toggle_bit(*bits, 2);
assert(bits[2]);
toggle_bit(*bits, 2);
assert(!bits[2]);
deinit(*bits);Sets bit i when value is true and clears it otherwise; this is what bits[i] = value does.
bits := make_bit_array(4);
set_bit_to(*bits, 1, true);
assert(bits[1]);
set_bit_to(*bits, 1, false);
assert(!bits[1]);
deinit(*bits);Clears every bit, including the padding bits of the last word.
bits := make_bit_array(70);
set_all_bits(*bits);
clear_all_bits(*bits);
for bits assert(!it);
deinit(*bits);Sets every bit, including the padding bits of the last word, so slots holds all ones.
bits := make_bit_array(5);
set_all_bits(*bits);
for bits assert(it);
deinit(*bits);Flips every bit, including the padding bits of the last word.
bits := make_bit_array(3);
bits[0] = true;
toggle_all_bits(*bits);
assert(!bits[0] && bits[1] && bits[2]);
deinit(*bits);Lets a Bit_Array be used in a for loop over all its bits, in order: it is the bit and it_index its position.
bits := make_bit_array(4);
bits[2] = true;
for bits if it assert(it_index == 2);
deinit(*bits);A loop body for visiting just the set bits, used as for: only_set bits; it is true and it_index the position.
bits := make_bit_array(8);
bits[1] = true;
bits[6] = true;
positions: [..] int;
for: only_set bits array_add(*positions, it_index);
assert(positions.count == 2 && positions[1] == 6);
array_free(positions);
deinit(*bits);Like only_set, but visits the cleared bits.
bits := make_bit_array(4);
bits[0] = true;
cleared := 0;
for: only_unset bits cleared += 1;
assert(cleared == 3);
deinit(*bits);A fixed-length sequence of bits packed into 64-bit words; count is the number of bits.
bits := make_bit_array(10);
set_bit(*bits, 2);
bits[5] = true;
toggle_bit(*bits, 2);
assert(!bits[2] && bits[5]);
set := 0;
for bits if it set += 1; // `it` is the bit, `it_index` its position
assert(set == 1);
deinit(*bits);