struct ewah_bitmap *bitmap_compress(struct bitmap *bitmap)
{
struct ewah_bitmap *ewah = ewah_new();
size_t i, running_empty_words = 0;
eword_t last_word = 0;
for (i = 0; i < bitmap->word_alloc; ++i) {
if (bitmap->words[i] == 0) {
running_empty_words++;
continue;
}
if (last_word != 0) {
ewah_add(ewah, last_word);
}
if (running_empty_words > 0) {
ewah_add_empty_words(ewah, false, running_empty_words);
running_empty_words = 0;
}
last_word = bitmap->words[i];
}
ewah_add(ewah, last_word);
return ewah;
}
void ewah_or(
struct ewah_bitmap *ewah_i,
struct ewah_bitmap *ewah_j,
struct ewah_bitmap *out)
{
struct rlw_iterator rlw_i;
struct rlw_iterator rlw_j;
size_t literals;
rlwit_init(&rlw_i, ewah_i);
rlwit_init(&rlw_j, ewah_j);
while (rlwit_word_size(&rlw_i) > 0 && rlwit_word_size(&rlw_j) > 0) {
while (rlw_i.rlw.running_len > 0 || rlw_j.rlw.running_len > 0) {
struct rlw_iterator *prey, *predator;
if (rlw_i.rlw.running_len < rlw_j.rlw.running_len) {
prey = &rlw_i;
predator = &rlw_j;
} else {
prey = &rlw_j;
predator = &rlw_i;
}
if (predator->rlw.running_bit) {
ewah_add_empty_words(out, 0,
predator->rlw.running_len);
rlwit_discard_first_words(prey,
predator->rlw.running_len);
rlwit_discard_first_words(predator,
predator->rlw.running_len);
} else {
size_t index = rlwit_discharge(prey, out,
predator->rlw.running_len, 0);
ewah_add_empty_words(out, 0,
predator->rlw.running_len - index);
rlwit_discard_first_words(predator,
predator->rlw.running_len);
}
}
literals = min_size(
rlw_i.rlw.literal_words,
rlw_j.rlw.literal_words);
if (literals) {
size_t k;
for (k = 0; k < literals; ++k) {
ewah_add(out,
rlw_i.buffer[rlw_i.literal_word_start + k] |
rlw_j.buffer[rlw_j.literal_word_start + k]
);
}
rlwit_discard_first_words(&rlw_i, literals);
rlwit_discard_first_words(&rlw_j, literals);
}
}
if (rlwit_word_size(&rlw_i) > 0)
rlwit_discharge(&rlw_i, out, ~0, 0);
else
rlwit_discharge(&rlw_j, out, ~0, 0);
out->bit_size = max_size(ewah_i->bit_size, ewah_j->bit_size);
}
