/**
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
#include "git-compat-util.h"
#include "ewok.h"

#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 = xmalloc(sizeof(struct bitmap));
        bitmap->words = xcalloc(32, sizeof(eword_t));
        bitmap->word_alloc = 32;
        return bitmap;
}

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->words = xrealloc(self->words,
                                      self->word_alloc * sizeof(eword_t));

                memset(self->words + old_size, 0x0,
                        (self->word_alloc - old_size) * sizeof(eword_t));
        }

        self->words[block] |= EWAH_MASK(pos);
}

void bitmap_clear(struct bitmap *self, size_t pos)
{
        size_t block = EWAH_BLOCK(pos);

        if (block < self->word_alloc)
                self->words[block] &= ~EWAH_MASK(pos);
}

int bitmap_get(struct bitmap *self, size_t pos)
{
        size_t block = EWAH_BLOCK(pos);
        return block < self->word_alloc &&
                (self->words[block] & EWAH_MASK(pos)) != 0;
}

struct ewah_bitmap *bitmap_to_ewah(struct bitmap *bitmap)
{
        struct ewah_bitmap *ewah = ewah_new();
        size_t i, running_empty_words = 0;
        eword_t last_word = 0;

        for (i = 0; i < bitmap->word_alloc; ++i) {
                if (bitmap->words[i] == 0) {
                        running_empty_words++;
                        continue;
                }

                if (last_word != 0)
                        ewah_add(ewah, last_word);

                if (running_empty_words > 0) {
                        ewah_add_empty_words(ewah, 0, running_empty_words);
                        running_empty_words = 0;
                }

                last_word = bitmap->words[i];
        }

        ewah_add(ewah, last_word);
        return ewah;
}

struct bitmap *ewah_to_bitmap(struct ewah_bitmap *ewah)
{
        struct bitmap *bitmap = bitmap_new();
        struct ewah_iterator it;
        eword_t blowup;
        size_t i = 0;

        ewah_iterator_init(&it, ewah);

        while (ewah_iterator_next(&blowup, &it)) {
                if (i >= bitmap->word_alloc) {
                        bitmap->word_alloc *= 1.5;
                        bitmap->words = xrealloc(
                                bitmap->words, bitmap->word_alloc * sizeof(eword_t));
                }

                bitmap->words[i++] = blowup;
        }

        bitmap->word_alloc = i;
        return bitmap;
}

void bitmap_and_not(struct bitmap *self, struct bitmap *other)
{
        const size_t count = (self->word_alloc < other->word_alloc) ?
                self->word_alloc : other->word_alloc;

        size_t i;

        for (i = 0; i < count; ++i)
                self->words[i] &= ~other->words[i];
}

void bitmap_or_ewah(struct bitmap *self, struct ewah_bitmap *other)
{
        size_t original_size = self->word_alloc;
        size_t other_final = (other->bit_size / BITS_IN_EWORD) + 1;
        size_t i = 0;
        struct ewah_iterator it;
        eword_t word;

        if (self->word_alloc < other_final) {
                self->word_alloc = other_final;
                self->words = xrealloc(self->words,
                        self->word_alloc * sizeof(eword_t));
                memset(self->words + original_size, 0x0,
                        (self->word_alloc - original_size) * sizeof(eword_t));
        }

        ewah_iterator_init(&it, other);

        while (ewah_iterator_next(&word, &it))
                self->words[i++] |= word;
}

void bitmap_each_bit(struct bitmap *self, ewah_callback callback, void *data)
{
        size_t pos = 0, i;

        for (i = 0; i < self->word_alloc; ++i) {
                eword_t word = self->words[i];
                uint32_t offset;

                if (word == (eword_t)~0) {
                        for (offset = 0; offset < BITS_IN_EWORD; ++offset)
                                callback(pos++, data);
                } else {
                        for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
                                if ((word >> offset) == 0)
                                        break;

                                offset += ewah_bit_ctz64(word >> offset);
                                callback(pos + offset, data);
                        }
                        pos += BITS_IN_EWORD;
                }
        }
}

size_t bitmap_popcount(struct bitmap *self)
{
        size_t i, count = 0;

        for (i = 0; i < self->word_alloc; ++i)
                count += ewah_bit_popcount64(self->words[i]);

        return count;
}

int bitmap_equals(struct bitmap *self, struct bitmap *other)
{
        struct bitmap *big, *small;
        size_t i;

        if (self->word_alloc < other->word_alloc) {
                small = self;
                big = other;
        } else {
                small = other;
                big = self;
        }

        for (i = 0; i < small->word_alloc; ++i) {
                if (small->words[i] != big->words[i])
                        return 0;
        }

        for (; i < big->word_alloc; ++i) {
                if (big->words[i] != 0)
                        return 0;
        }

        return 1;
}

void bitmap_reset(struct bitmap *bitmap)
{
        memset(bitmap->words, 0x0, bitmap->word_alloc * sizeof(eword_t));
}

void bitmap_free(struct bitmap *bitmap)
{
        if (bitmap == NULL)
                return;

        free(bitmap->words);
        free(bitmap);
}