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ewah/bitmap: introduce bitmap_word_alloc()

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In a following commit we will need to allocate a variable
number of bitmap words, instead of always 32, so let's add
bitmap_word_alloc() for this purpose.

Note that we have to adjust the block growth in bitmap_set(),
since a caller could now use an initial size of "0" (we don't
plan to do that, but it doesn't hurt to be defensive).

Helped-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jeff King 2019-12-18 12:25:38 +01:00 committed by Junio C Hamano
parent 56d9cbe68b
commit 14fbd26044
2 changed files with 10 additions and 4 deletions
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13
ewah/bitmap.c
View File

@ -22,21 +22,26 @@
#define EWAH_MASK(x) ((eword_t)1 << (x % BITS_IN_EWORD)) #define EWAH_MASK(x) ((eword_t)1 << (x % BITS_IN_EWORD))
#define EWAH_BLOCK(x) (x / BITS_IN_EWORD) #define EWAH_BLOCK(x) (x / BITS_IN_EWORD)
struct bitmap *bitmap_new(void) struct bitmap *bitmap_word_alloc(size_t word_alloc)
{ {
struct bitmap *bitmap = xmalloc(sizeof(struct bitmap)); struct bitmap *bitmap = xmalloc(sizeof(struct bitmap));
bitmap->words = xcalloc(32, sizeof(eword_t)); bitmap->words = xcalloc(word_alloc, sizeof(eword_t));
bitmap->word_alloc = 32; bitmap->word_alloc = word_alloc;
return bitmap; return bitmap;
} }
struct bitmap *bitmap_new(void)
{
return bitmap_word_alloc(32);
}
void bitmap_set(struct bitmap *self, size_t pos) void bitmap_set(struct bitmap *self, size_t pos)
{ {
size_t block = EWAH_BLOCK(pos); size_t block = EWAH_BLOCK(pos);
if (block >= self->word_alloc) { if (block >= self->word_alloc) {
size_t old_size = self->word_alloc; size_t old_size = self->word_alloc;
self->word_alloc = block * 2; self->word_alloc = block ? block * 2 : 1;
REALLOC_ARRAY(self->words, self->word_alloc); REALLOC_ARRAY(self->words, self->word_alloc);
memset(self->words + old_size, 0x0, memset(self->words + old_size, 0x0,
(self->word_alloc - old_size) * sizeof(eword_t)); (self->word_alloc - old_size) * sizeof(eword_t));

1
ewah/ewok.h
View File

@ -172,6 +172,7 @@ struct bitmap {
}; };
struct bitmap *bitmap_new(void); struct bitmap *bitmap_new(void);
struct bitmap *bitmap_word_alloc(size_t word_alloc);
void bitmap_set(struct bitmap *self, size_t pos); void bitmap_set(struct bitmap *self, size_t pos);
int bitmap_get(struct bitmap *self, size_t pos); int bitmap_get(struct bitmap *self, size_t pos);
void bitmap_reset(struct bitmap *self); void bitmap_reset(struct bitmap *self);