merge(third_party/git): Merge squashed git subtree at v2.23.0 r/373

Merge commit '1b593e1ea4d2af0f6444d9a7788d5d99abd6fde5' as 'third_party/git'

1 files changed, 191 insertions, 0 deletions

diff --git a/third_party/git/ewah/ewok.h b/third_party/git/ewah/ewok.h
new file mode 100644
index 000000000000..84b2a29faa0c
--- /dev/null
+++ b/third_party/git/ewah/ewok.h
@@ -0,0 +1,191 @@
+/**
+ * Copyright 2013, GitHub, Inc
+ * Copyright 2009-2013, Daniel Lemire, Cliff Moon,
+ *	David McIntosh, Robert Becho, Google Inc. and Veronika Zenz
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __EWOK_BITMAP_H__
+#define __EWOK_BITMAP_H__
+
+struct strbuf;
+typedef uint64_t eword_t;
+#define BITS_IN_EWORD (sizeof(eword_t) * 8)
+
+/**
+ * Do not use __builtin_popcountll. The GCC implementation
+ * is notoriously slow on all platforms.
+ *
+ * See: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36041
+ */
+static inline uint32_t ewah_bit_popcount64(uint64_t x)
+{
+	x = (x & 0x5555555555555555ULL) + ((x >>  1) & 0x5555555555555555ULL);
+	x = (x & 0x3333333333333333ULL) + ((x >>  2) & 0x3333333333333333ULL);
+	x = (x & 0x0F0F0F0F0F0F0F0FULL) + ((x >>  4) & 0x0F0F0F0F0F0F0F0FULL);
+	return (x * 0x0101010101010101ULL) >> 56;
+}
+
+/* __builtin_ctzll was not available until 3.4.0 */
+#if defined(__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3  && __GNUC_MINOR > 3))
+#define ewah_bit_ctz64(x) __builtin_ctzll(x)
+#else
+static inline int ewah_bit_ctz64(uint64_t x)
+{
+	int n = 0;
+	if ((x & 0xffffffff) == 0) { x >>= 32; n += 32; }
+	if ((x &     0xffff) == 0) { x >>= 16; n += 16; }
+	if ((x &       0xff) == 0) { x >>=  8; n +=  8; }
+	if ((x &        0xf) == 0) { x >>=  4; n +=  4; }
+	if ((x &        0x3) == 0) { x >>=  2; n +=  2; }
+	if ((x &        0x1) == 0) { x >>=  1; n +=  1; }
+	return n + !x;
+}
+#endif
+
+struct ewah_bitmap {
+	eword_t *buffer;
+	size_t buffer_size;
+	size_t alloc_size;
+	size_t bit_size;
+	eword_t *rlw;
+};
+
+typedef void (*ewah_callback)(size_t pos, void *);
+
+struct ewah_bitmap *ewah_pool_new(void);
+void ewah_pool_free(struct ewah_bitmap *self);
+
+/**
+ * Allocate a new EWAH Compressed bitmap
+ */
+struct ewah_bitmap *ewah_new(void);
+
+/**
+ * Free all the memory of the bitmap
+ */
+void ewah_free(struct ewah_bitmap *self);
+
+int ewah_serialize_to(struct ewah_bitmap *self,
+		      int (*write_fun)(void *out, const void *buf, size_t len),
+		      void *out);
+int ewah_serialize_strbuf(struct ewah_bitmap *self, struct strbuf *);
+
+ssize_t ewah_read_mmap(struct ewah_bitmap *self, const void *map, size_t len);
+
+uint32_t ewah_checksum(struct ewah_bitmap *self);
+
+/**
+ * Call the given callback with the position of every single bit
+ * that has been set on the bitmap.
+ *
+ * This is an efficient operation that does not fully decompress
+ * the bitmap.
+ */
+void ewah_each_bit(struct ewah_bitmap *self, ewah_callback callback, void *payload);
+
+/**
+ * Set a given bit on the bitmap.
+ *
+ * The bit at position `pos` will be set to true. Because of the
+ * way that the bitmap is compressed, a set bit cannot be unset
+ * later on.
+ *
+ * Furthermore, since the bitmap uses streaming compression, bits
+ * can only set incrementally.
+ *
+ * E.g.
+ *		ewah_set(bitmap, 1); // ok
+ *		ewah_set(bitmap, 76); // ok
+ *		ewah_set(bitmap, 77); // ok
+ *		ewah_set(bitmap, 8712800127); // ok
+ *		ewah_set(bitmap, 25); // failed, assert raised
+ */
+void ewah_set(struct ewah_bitmap *self, size_t i);
+
+struct ewah_iterator {
+	const eword_t *buffer;
+	size_t buffer_size;
+
+	size_t pointer;
+	eword_t compressed, literals;
+	eword_t rl, lw;
+	int b;
+};
+
+/**
+ * Initialize a new iterator to run through the bitmap in uncompressed form.
+ *
+ * The iterator can be stack allocated. The underlying bitmap must not be freed
+ * before the iteration is over.
+ *
+ * E.g.
+ *
+ *		struct ewah_bitmap *bitmap = ewah_new();
+ *		struct ewah_iterator it;
+ *
+ *		ewah_iterator_init(&it, bitmap);
+ */
+void ewah_iterator_init(struct ewah_iterator *it, struct ewah_bitmap *parent);
+
+/**
+ * Yield every single word in the bitmap in uncompressed form. This is:
+ * yield single words (32-64 bits) where each bit represents an actual
+ * bit from the bitmap.
+ *
+ * Return: true if a word was yield, false if there are no words left
+ */
+int ewah_iterator_next(eword_t *next, struct ewah_iterator *it);
+
+void ewah_xor(
+	struct ewah_bitmap *ewah_i,
+	struct ewah_bitmap *ewah_j,
+	struct ewah_bitmap *out);
+
+/**
+ * Direct word access
+ */
+size_t ewah_add_empty_words(struct ewah_bitmap *self, int v, size_t number);
+void ewah_add_dirty_words(
+	struct ewah_bitmap *self, const eword_t *buffer, size_t number, int negate);
+size_t ewah_add(struct ewah_bitmap *self, eword_t word);
+
+
+/**
+ * Uncompressed, old-school bitmap that can be efficiently compressed
+ * into an `ewah_bitmap`.
+ */
+struct bitmap {
+	eword_t *words;
+	size_t word_alloc;
+};
+
+struct bitmap *bitmap_new(void);
+void bitmap_set(struct bitmap *self, size_t pos);
+int bitmap_get(struct bitmap *self, size_t pos);
+void bitmap_reset(struct bitmap *self);
+void bitmap_free(struct bitmap *self);
+int bitmap_equals(struct bitmap *self, struct bitmap *other);
+int bitmap_is_subset(struct bitmap *self, struct bitmap *super);
+
+struct ewah_bitmap * bitmap_to_ewah(struct bitmap *bitmap);
+struct bitmap *ewah_to_bitmap(struct ewah_bitmap *ewah);
+
+void bitmap_and_not(struct bitmap *self, struct bitmap *other);
+void bitmap_or_ewah(struct bitmap *self, struct ewah_bitmap *other);
+void bitmap_or(struct bitmap *self, const struct bitmap *other);
+
+size_t bitmap_popcount(struct bitmap *self);
+
+#endif