pack-bitmap: extract `read_bitmap()` function

The pack-bitmap machinery uses the `read_bitmap_1()` function to read a
bitmap from within the mmap'd region corresponding to the .bitmap file.
As as side-effect of calling this function, `read_bitmap_1()` increments
the `index->map_pos` variable to reflect the number of bytes read.

Extract the core of this routine to a separate function (that operates
over a `const unsigned char *`, a `size_t` and a `size_t *` pointer)
instead of a `struct bitmap_index *` pointer.

This function (called `read_bitmap()`) is part of the pack-bitmap.h API
so that it can be used within the upcoming portion of the implementation
in pseduo-merge.ch.

Rewrite the existing function, `read_bitmap_1()`, in terms of its more
generic counterpart.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/pack-bitmap.c b/pack-bitmap.c
index 35c5ef9d3cd15ed34ecc3e77aee0d0f8eba766a5..3519edb896b06c6632422a92ed5ac7b8fd4fce91 100644 (file)
--- a/pack-bitmap.c
+++ b/pack-bitmap.c
@@ -129,17 +129,13 @@ static struct ewah_bitmap *lookup_stored_bitmap(struct stored_bitmap *st)
        return composed;
 }
 
-/*
- * Read a bitmap from the current read position on the mmaped
- * index, and increase the read position accordingly
- */
-static struct ewah_bitmap *read_bitmap_1(struct bitmap_index *index)
+struct ewah_bitmap *read_bitmap(const unsigned char *map,
+                               size_t map_size, size_t *map_pos)
 {
        struct ewah_bitmap *b = ewah_pool_new();
 
-       ssize_t bitmap_size = ewah_read_mmap(b,
-               index->map + index->map_pos,
-               index->map_size - index->map_pos);
+       ssize_t bitmap_size = ewah_read_mmap(b, map + *map_pos,
+                                            map_size - *map_pos);
 
        if (bitmap_size < 0) {
                error(_("failed to load bitmap index (corrupted?)"));
@@ -147,10 +143,20 @@ static struct ewah_bitmap *read_bitmap_1(struct bitmap_index *index)
                return NULL;
        }
 
-       index->map_pos += bitmap_size;
+       *map_pos += bitmap_size;
+
        return b;
 }
 
+/*
+ * Read a bitmap from the current read position on the mmaped
+ * index, and increase the read position accordingly
+ */
+static struct ewah_bitmap *read_bitmap_1(struct bitmap_index *index)
+{
+       return read_bitmap(index->map, index->map_size, &index->map_pos);
+}
+
 static uint32_t bitmap_num_objects(struct bitmap_index *index)
 {
        if (index->midx)

diff --git a/pack-bitmap.h b/pack-bitmap.h
index db9ae554fa8ee6d57ef7d3572b11e877460030a4..21aabf805ea2dd1be27232defa3b0fc1ac82c6a2 100644 (file)
--- a/pack-bitmap.h
+++ b/pack-bitmap.h
@@ -160,4 +160,6 @@ int bitmap_is_preferred_refname(struct repository *r, const char *refname);
 
 int verify_bitmap_files(struct repository *r);
 
+struct ewah_bitmap *read_bitmap(const unsigned char *map,
+                               size_t map_size, size_t *map_pos);
 #endif