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diff --git a/src/geohash.h b/src/geohash.h
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+/*
+ * Copyright (c) 2013-2014, yinqiwen <yinqiwen@gmail.com>
+ * Copyright (c) 2014, Matt Stancliff <matt@genges.com>.
+ * Copyright (c) 2015, Salvatore Sanfilippo <antirez@gmail.com>.
+ * 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.
+ */
+
+#ifndef GEOHASH_H_
+#define GEOHASH_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+#define HASHISZERO(r) (!(r).bits && !(r).step)
+#define RANGEISZERO(r) (!(r).max && !(r).min)
+#define RANGEPISZERO(r) (r == NULL || RANGEISZERO(*r))
+
+#define GEO_STEP_MAX 26 /* 26*2 = 52 bits. */
+
+/* Limits from EPSG:900913 / EPSG:3785 / OSGEO:41001 */
+#define GEO_LAT_MIN -85.05112878
+#define GEO_LAT_MAX 85.05112878
+#define GEO_LONG_MIN -180
+#define GEO_LONG_MAX 180
+
+typedef enum {
+    GEOHASH_NORTH = 0,
+    GEOHASH_EAST,
+    GEOHASH_WEST,
+    GEOHASH_SOUTH,
+    GEOHASH_SOUTH_WEST,
+    GEOHASH_SOUTH_EAST,
+    GEOHASH_NORT_WEST,
+    GEOHASH_NORT_EAST
+} GeoDirection;
+
+typedef struct {
+    uint64_t bits;
+    uint8_t step;
+} GeoHashBits;
+
+typedef struct {
+    double min;
+    double max;
+} GeoHashRange;
+
+typedef struct {
+    GeoHashBits hash;
+    GeoHashRange longitude;
+    GeoHashRange latitude;
+} GeoHashArea;
+
+typedef struct {
+    GeoHashBits north;
+    GeoHashBits east;
+    GeoHashBits west;
+    GeoHashBits south;
+    GeoHashBits north_east;
+    GeoHashBits south_east;
+    GeoHashBits north_west;
+    GeoHashBits south_west;
+} GeoHashNeighbors;
+
+#define CIRCULAR_TYPE 1
+#define RECTANGLE_TYPE 2
+typedef struct {
+    int type; /* search type */
+    double xy[2]; /* search center point, xy[0]: lon, xy[1]: lat */
+    double conversion; /* km: 1000 */
+    double bounds[4]; /* bounds[0]: min_lon, bounds[1]: min_lat
+                       * bounds[2]: max_lon, bounds[3]: max_lat */
+    union {
+        /* CIRCULAR_TYPE */
+        double radius;
+        /* RECTANGLE_TYPE */
+        struct {
+            double height;
+            double width;
+        } r;
+    } t;
+} GeoShape;
+
+/*
+ * 0:success
+ * -1:failed
+ */
+void geohashGetCoordRange(GeoHashRange *long_range, GeoHashRange *lat_range);
+int geohashEncode(const GeoHashRange *long_range, const GeoHashRange *lat_range,
+                  double longitude, double latitude, uint8_t step,
+                  GeoHashBits *hash);
+int geohashEncodeType(double longitude, double latitude,
+                      uint8_t step, GeoHashBits *hash);
+int geohashEncodeWGS84(double longitude, double latitude, uint8_t step,
+                       GeoHashBits *hash);
+int geohashDecode(const GeoHashRange long_range, const GeoHashRange lat_range,
+                  const GeoHashBits hash, GeoHashArea *area);
+int geohashDecodeType(const GeoHashBits hash, GeoHashArea *area);
+int geohashDecodeWGS84(const GeoHashBits hash, GeoHashArea *area);
+int geohashDecodeAreaToLongLat(const GeoHashArea *area, double *xy);
+int geohashDecodeToLongLatType(const GeoHashBits hash, double *xy);
+int geohashDecodeToLongLatWGS84(const GeoHashBits hash, double *xy);
+void geohashNeighbors(const GeoHashBits *hash, GeoHashNeighbors *neighbors);
+
+#if defined(__cplusplus)
+}
+#endif
+#endif /* GEOHASH_H_ */