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ewah: factor out bitmap growth

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We auto-grow bitmaps when somebody asks to set a bit whose position is
outside of our currently allocated range. Other operations besides
single bit-setting might need to do this, too, so let's pull it into its
own function.

Note that we change the semantics a little: you now ask for the number
of words you'd like to have, not the id of the block you'd like to write
to.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jeff King 2020-12-08 17:03:38 -05:00 committed by Junio C Hamano
parent 2978b00691
commit d574bf43e8
1 changed files with 9 additions and 5 deletions
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14
ewah/bitmap.c
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@ -35,18 +35,22 @@ struct bitmap *bitmap_new(void)
return bitmap_word_alloc(32);
}
void bitmap_set(struct bitmap *self, size_t pos)
static void bitmap_grow(struct bitmap *self, size_t word_alloc)
{
size_t block = EWAH_BLOCK(pos);
if (block >= self->word_alloc) {
if (word_alloc > self->word_alloc) {
size_t old_size = self->word_alloc;
self->word_alloc = block ? block * 2 : 1;
self->word_alloc = word_alloc * 2;
REALLOC_ARRAY(self->words, self->word_alloc);
memset(self->words + old_size, 0x0,
(self->word_alloc - old_size) * sizeof(eword_t));
}
}
void bitmap_set(struct bitmap *self, size_t pos)
{
size_t block = EWAH_BLOCK(pos);
bitmap_grow(self, block + 1);
self->words[block] |= EWAH_MASK(pos);
}