ewah/bitmap: introduce bitmap_word_alloc()

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>

diff --git a/ewah/bitmap.c b/ewah/bitmap.c
index 52f1178db4ce35103545a3e1ee00a3000b08eb90..b5fed9621f425b08af27c56be0e3f88a331e314b 100644 (file)
--- a/ewah/bitmap.c
+++ b/ewah/bitmap.c
@@ -22,21 +22,26 @@
 #define EWAH_MASK(x) ((eword_t)1 << (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));
-       bitmap->words = xcalloc(32, sizeof(eword_t));
-       bitmap->word_alloc = 32;
+       bitmap->words = xcalloc(word_alloc, sizeof(eword_t));
+       bitmap->word_alloc = word_alloc;
        return bitmap;
 }
 
+struct bitmap *bitmap_new(void)
+{
+       return bitmap_word_alloc(32);
+}
+
 void bitmap_set(struct bitmap *self, size_t pos)
 {
        size_t block = EWAH_BLOCK(pos);
 
        if (block >= 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);
                memset(self->words + old_size, 0x0,
                        (self->word_alloc - old_size) * sizeof(eword_t));

diff --git a/ewah/ewok.h b/ewah/ewok.h
index 84b2a29faa0c57410168ad5afb2dbaa7a49ddd60..1b98b57c8b7b623f4e76024b488081d09bf9bad6 100644 (file)
--- a/ewah/ewok.h
+++ b/ewah/ewok.h
@@ -172,6 +172,7 @@ struct bitmap {
 };
 
 struct bitmap *bitmap_new(void);
+struct bitmap *bitmap_word_alloc(size_t word_alloc);
 void bitmap_set(struct bitmap *self, size_t pos);
 int bitmap_get(struct bitmap *self, size_t pos);
 void bitmap_reset(struct bitmap *self);