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-rw-r--r--examples/redis-unstable/src/geohash.c299
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diff --git a/examples/redis-unstable/src/geohash.c b/examples/redis-unstable/src/geohash.c
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-/*
- * Copyright (c) 2013-2014, yinqiwen <yinqiwen@gmail.com>
- * Copyright (c) 2014, Matt Stancliff <matt@genges.com>.
- * Copyright (c) 2015-current, Redis Ltd.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- * * Redistributions of source code must retain the above copyright notice,
- * this list of conditions and the following disclaimer.
- * * Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * * Neither the name of Redis nor the names of its contributors may be used
- * to endorse or promote products derived from this software without
- * specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
- * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
- * THE POSSIBILITY OF SUCH DAMAGE.
- */
-#include "geohash.h"
-
-/**
- * Hashing works like this:
- * Divide the world into 4 buckets. Label each one as such:
- * -----------------
- * | | |
- * | | |
- * | 0,1 | 1,1 |
- * -----------------
- * | | |
- * | | |
- * | 0,0 | 1,0 |
- * -----------------
- */
-
-/* Interleave lower bits of x and y, so the bits of x
- * are in the even positions and bits from y in the odd;
- * x and y must initially be less than 2**32 (4294967296).
- * From: https://graphics.stanford.edu/~seander/bithacks.html#InterleaveBMN
- */
-static inline uint64_t interleave64(uint32_t xlo, uint32_t ylo) {
- static const uint64_t B[] = {0x5555555555555555ULL, 0x3333333333333333ULL,
- 0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
- 0x0000FFFF0000FFFFULL};
- static const unsigned int S[] = {1, 2, 4, 8, 16};
-
- uint64_t x = xlo;
- uint64_t y = ylo;
-
- x = (x | (x << S[4])) & B[4];
- y = (y | (y << S[4])) & B[4];
-
- x = (x | (x << S[3])) & B[3];
- y = (y | (y << S[3])) & B[3];
-
- x = (x | (x << S[2])) & B[2];
- y = (y | (y << S[2])) & B[2];
-
- x = (x | (x << S[1])) & B[1];
- y = (y | (y << S[1])) & B[1];
-
- x = (x | (x << S[0])) & B[0];
- y = (y | (y << S[0])) & B[0];
-
- return x | (y << 1);
-}
-
-/* reverse the interleave process
- * derived from http://stackoverflow.com/questions/4909263
- */
-static inline uint64_t deinterleave64(uint64_t interleaved) {
- static const uint64_t B[] = {0x5555555555555555ULL, 0x3333333333333333ULL,
- 0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
- 0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL};
- static const unsigned int S[] = {0, 1, 2, 4, 8, 16};
-
- uint64_t x = interleaved;
- uint64_t y = interleaved >> 1;
-
- x = (x | (x >> S[0])) & B[0];
- y = (y | (y >> S[0])) & B[0];
-
- x = (x | (x >> S[1])) & B[1];
- y = (y | (y >> S[1])) & B[1];
-
- x = (x | (x >> S[2])) & B[2];
- y = (y | (y >> S[2])) & B[2];
-
- x = (x | (x >> S[3])) & B[3];
- y = (y | (y >> S[3])) & B[3];
-
- x = (x | (x >> S[4])) & B[4];
- y = (y | (y >> S[4])) & B[4];
-
- x = (x | (x >> S[5])) & B[5];
- y = (y | (y >> S[5])) & B[5];
-
- return x | (y << 32);
-}
-
-void geohashGetCoordRange(GeoHashRange *long_range, GeoHashRange *lat_range) {
- /* These are constraints from EPSG:900913 / EPSG:3785 / OSGEO:41001 */
- /* We can't geocode at the north/south pole. */
- long_range->max = GEO_LONG_MAX;
- long_range->min = GEO_LONG_MIN;
- lat_range->max = GEO_LAT_MAX;
- lat_range->min = GEO_LAT_MIN;
-}
-
-int geohashEncode(const GeoHashRange *long_range, const GeoHashRange *lat_range,
- double longitude, double latitude, uint8_t step,
- GeoHashBits *hash) {
- /* Check basic arguments sanity. */
- if (hash == NULL || step > 32 || step == 0 ||
- RANGEPISZERO(lat_range) || RANGEPISZERO(long_range)) return 0;
-
- /* Return an error when trying to index outside the supported
- * constraints. */
- if (longitude > GEO_LONG_MAX || longitude < GEO_LONG_MIN ||
- latitude > GEO_LAT_MAX || latitude < GEO_LAT_MIN) return 0;
-
- hash->bits = 0;
- hash->step = step;
-
- if (latitude < lat_range->min || latitude > lat_range->max ||
- longitude < long_range->min || longitude > long_range->max) {
- return 0;
- }
-
- double lat_offset =
- (latitude - lat_range->min) / (lat_range->max - lat_range->min);
- double long_offset =
- (longitude - long_range->min) / (long_range->max - long_range->min);
-
- /* convert to fixed point based on the step size */
- lat_offset *= (1ULL << step);
- long_offset *= (1ULL << step);
- hash->bits = interleave64(lat_offset, long_offset);
- return 1;
-}
-
-int geohashEncodeType(double longitude, double latitude, uint8_t step, GeoHashBits *hash) {
- GeoHashRange r[2] = {{0}};
- geohashGetCoordRange(&r[0], &r[1]);
- return geohashEncode(&r[0], &r[1], longitude, latitude, step, hash);
-}
-
-int geohashEncodeWGS84(double longitude, double latitude, uint8_t step,
- GeoHashBits *hash) {
- return geohashEncodeType(longitude, latitude, step, hash);
-}
-
-int geohashDecode(const GeoHashRange long_range, const GeoHashRange lat_range,
- const GeoHashBits hash, GeoHashArea *area) {
- if (HASHISZERO(hash) || NULL == area || RANGEISZERO(lat_range) ||
- RANGEISZERO(long_range)) {
- return 0;
- }
-
- area->hash = hash;
- uint8_t step = hash.step;
- uint64_t hash_sep = deinterleave64(hash.bits); /* hash = [LAT][LONG] */
-
- double lat_scale = lat_range.max - lat_range.min;
- double long_scale = long_range.max - long_range.min;
-
- uint32_t ilato = hash_sep; /* get lat part of deinterleaved hash */
- uint32_t ilono = hash_sep >> 32; /* shift over to get long part of hash */
-
- /* divide by 2**step.
- * Then, for 0-1 coordinate, multiply times scale and add
- to the min to get the absolute coordinate. */
- area->latitude.min =
- lat_range.min + (ilato * 1.0 / (1ull << step)) * lat_scale;
- area->latitude.max =
- lat_range.min + ((ilato + 1) * 1.0 / (1ull << step)) * lat_scale;
- area->longitude.min =
- long_range.min + (ilono * 1.0 / (1ull << step)) * long_scale;
- area->longitude.max =
- long_range.min + ((ilono + 1) * 1.0 / (1ull << step)) * long_scale;
-
- return 1;
-}
-
-int geohashDecodeType(const GeoHashBits hash, GeoHashArea *area) {
- GeoHashRange r[2] = {{0}};
- geohashGetCoordRange(&r[0], &r[1]);
- return geohashDecode(r[0], r[1], hash, area);
-}
-
-int geohashDecodeWGS84(const GeoHashBits hash, GeoHashArea *area) {
- return geohashDecodeType(hash, area);
-}
-
-int geohashDecodeAreaToLongLat(const GeoHashArea *area, double *xy) {
- if (!xy) return 0;
- xy[0] = (area->longitude.min + area->longitude.max) / 2;
- if (xy[0] > GEO_LONG_MAX) xy[0] = GEO_LONG_MAX;
- if (xy[0] < GEO_LONG_MIN) xy[0] = GEO_LONG_MIN;
- xy[1] = (area->latitude.min + area->latitude.max) / 2;
- if (xy[1] > GEO_LAT_MAX) xy[1] = GEO_LAT_MAX;
- if (xy[1] < GEO_LAT_MIN) xy[1] = GEO_LAT_MIN;
- return 1;
-}
-
-int geohashDecodeToLongLatType(const GeoHashBits hash, double *xy) {
- GeoHashArea area = {{0}};
- if (!xy || !geohashDecodeType(hash, &area))
- return 0;
- return geohashDecodeAreaToLongLat(&area, xy);
-}
-
-int geohashDecodeToLongLatWGS84(const GeoHashBits hash, double *xy) {
- return geohashDecodeToLongLatType(hash, xy);
-}
-
-static void geohash_move_x(GeoHashBits *hash, int8_t d) {
- if (d == 0)
- return;
-
- uint64_t x = hash->bits & 0xaaaaaaaaaaaaaaaaULL;
- uint64_t y = hash->bits & 0x5555555555555555ULL;
-
- uint64_t zz = 0x5555555555555555ULL >> (64 - hash->step * 2);
-
- if (d > 0) {
- x = x + (zz + 1);
- } else {
- x = x | zz;
- x = x - (zz + 1);
- }
-
- x &= (0xaaaaaaaaaaaaaaaaULL >> (64 - hash->step * 2));
- hash->bits = (x | y);
-}
-
-static void geohash_move_y(GeoHashBits *hash, int8_t d) {
- if (d == 0)
- return;
-
- uint64_t x = hash->bits & 0xaaaaaaaaaaaaaaaaULL;
- uint64_t y = hash->bits & 0x5555555555555555ULL;
-
- uint64_t zz = 0xaaaaaaaaaaaaaaaaULL >> (64 - hash->step * 2);
- if (d > 0) {
- y = y + (zz + 1);
- } else {
- y = y | zz;
- y = y - (zz + 1);
- }
- y &= (0x5555555555555555ULL >> (64 - hash->step * 2));
- hash->bits = (x | y);
-}
-
-void geohashNeighbors(const GeoHashBits *hash, GeoHashNeighbors *neighbors) {
- neighbors->east = *hash;
- neighbors->west = *hash;
- neighbors->north = *hash;
- neighbors->south = *hash;
- neighbors->south_east = *hash;
- neighbors->south_west = *hash;
- neighbors->north_east = *hash;
- neighbors->north_west = *hash;
-
- geohash_move_x(&neighbors->east, 1);
- geohash_move_y(&neighbors->east, 0);
-
- geohash_move_x(&neighbors->west, -1);
- geohash_move_y(&neighbors->west, 0);
-
- geohash_move_x(&neighbors->south, 0);
- geohash_move_y(&neighbors->south, -1);
-
- geohash_move_x(&neighbors->north, 0);
- geohash_move_y(&neighbors->north, 1);
-
- geohash_move_x(&neighbors->north_west, -1);
- geohash_move_y(&neighbors->north_west, 1);
-
- geohash_move_x(&neighbors->north_east, 1);
- geohash_move_y(&neighbors->north_east, 1);
-
- geohash_move_x(&neighbors->south_east, 1);
- geohash_move_y(&neighbors->south_east, -1);
-
- geohash_move_x(&neighbors->south_west, -1);
- geohash_move_y(&neighbors->south_west, -1);
-}
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