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[geohash] Modified geohash implementation (based on python-geohash) with no mallocs

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Al
2015-07-04 00:30:35 -04:00
parent f825dcb939
commit 3f07cc6c71
2 changed files with 519 additions and 326 deletions
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src/geohash/geohash.c
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@@ -1,293 +1,514 @@
/*
* geohash.c
* libgeohash
*
* Created by Derek Smith on 10/6/09.
* Copyright (c) 2010, SimpleGeo
* 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 the SimpleGeo 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 HOLDER 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" #include "geohash.h"
#include <stdlib.h> // on Windows, __STDC_IEC_559__ not defined
#include <string.h>
#include <stdio.h>
#define MAX_LAT 90.0 #if defined(_MSC_VER) && (_MSC_VER <= 1500)
#define MIN_LAT -90.0 typedef unsigned __int8 uint8_t;
typedef unsigned __int16 uint16_t;
#define MAX_LONG 180.0 typedef unsigned __int64 uint64_t;
#define MIN_LONG -180.0 #define UINT64_C(C) ((uint64_t) C ## ULL)
#else
#define NORTH 0 #define __STDC_CONSTANT_MACROS 1
#define EAST 1 #include <stdint.h>
#define SOUTH 2 #endif
#define WEST 3
#define LENGTH_OF_DEGREE 111100 // meters
typedef struct IntervalStruct {
double high;
double low;
} Interval;
/* Normal 32 characer map used for geohashing */ static inline uint16_t interleave(uint8_t upper, uint8_t lower) {
static char char_map[32] = "0123456789bcdefghjkmnpqrstuvwxyz"; static const uint16_t map[256] = {
0x0000, 0x0001, 0x0004, 0x0005, 0x0010, 0x0011,
0x0014, 0x0015, 0x0040, 0x0041, 0x0044, 0x0045,
0x0050, 0x0051, 0x0054, 0x0055, 0x0100, 0x0101,
0x0104, 0x0105, 0x0110, 0x0111, 0x0114, 0x0115,
0x0140, 0x0141, 0x0144, 0x0145, 0x0150, 0x0151,
0x0154, 0x0155, 0x0400, 0x0401, 0x0404, 0x0405,
0x0410, 0x0411, 0x0414, 0x0415, 0x0440, 0x0441,
0x0444, 0x0445, 0x0450, 0x0451, 0x0454, 0x0455,
0x0500, 0x0501, 0x0504, 0x0505, 0x0510, 0x0511,
0x0514, 0x0515, 0x0540, 0x0541, 0x0544, 0x0545,
0x0550, 0x0551, 0x0554, 0x0555, 0x1000, 0x1001,
0x1004, 0x1005, 0x1010, 0x1011, 0x1014, 0x1015,
0x1040, 0x1041, 0x1044, 0x1045, 0x1050, 0x1051,
0x1054, 0x1055, 0x1100, 0x1101, 0x1104, 0x1105,
0x1110, 0x1111, 0x1114, 0x1115, 0x1140, 0x1141,
0x1144, 0x1145, 0x1150, 0x1151, 0x1154, 0x1155,
0x1400, 0x1401, 0x1404, 0x1405, 0x1410, 0x1411,
0x1414, 0x1415, 0x1440, 0x1441, 0x1444, 0x1445,
0x1450, 0x1451, 0x1454, 0x1455, 0x1500, 0x1501,
0x1504, 0x1505, 0x1510, 0x1511, 0x1514, 0x1515,
0x1540, 0x1541, 0x1544, 0x1545, 0x1550, 0x1551,
0x1554, 0x1555, 0x4000, 0x4001, 0x4004, 0x4005,
0x4010, 0x4011, 0x4014, 0x4015, 0x4040, 0x4041,
0x4044, 0x4045, 0x4050, 0x4051, 0x4054, 0x4055,
0x4100, 0x4101, 0x4104, 0x4105, 0x4110, 0x4111,
0x4114, 0x4115, 0x4140, 0x4141, 0x4144, 0x4145,
0x4150, 0x4151, 0x4154, 0x4155, 0x4400, 0x4401,
0x4404, 0x4405, 0x4410, 0x4411, 0x4414, 0x4415,
0x4440, 0x4441, 0x4444, 0x4445, 0x4450, 0x4451,
0x4454, 0x4455, 0x4500, 0x4501, 0x4504, 0x4505,
0x4510, 0x4511, 0x4514, 0x4515, 0x4540, 0x4541,
0x4544, 0x4545, 0x4550, 0x4551, 0x4554, 0x4555,
0x5000, 0x5001, 0x5004, 0x5005, 0x5010, 0x5011,
0x5014, 0x5015, 0x5040, 0x5041, 0x5044, 0x5045,
0x5050, 0x5051, 0x5054, 0x5055, 0x5100, 0x5101,
0x5104, 0x5105, 0x5110, 0x5111, 0x5114, 0x5115,
0x5140, 0x5141, 0x5144, 0x5145, 0x5150, 0x5151,
0x5154, 0x5155, 0x5400, 0x5401, 0x5404, 0x5405,
0x5410, 0x5411, 0x5414, 0x5415, 0x5440, 0x5441,
0x5444, 0x5445, 0x5450, 0x5451, 0x5454, 0x5455,
0x5500, 0x5501, 0x5504, 0x5505, 0x5510, 0x5511,
0x5514, 0x5515, 0x5540, 0x5541, 0x5544, 0x5545,
0x5550, 0x5551, 0x5554, 0x5555
};
return (map[upper]<<1)+map[lower];
}
static inline void deinterleave(uint16_t interleaved, uint8_t *upper, uint8_t *lower) {
*upper = *lower = 0;
for (int i=7; i>=0; i--) {
*upper = (*upper<<1) + ((interleaved>>(i*2+1))&0x01);
*lower = (*lower<<1) + ((interleaved>>(i*2))&0x01);
}
}
/**
* map double[-1.0, 1.0) into uint64_t
*/
static inline int double_to_i64(double in, uint64_t *out) {
if (in<-1.0 || 1.0<=in) {
return 0;
}
union {
double d; // assuming IEEE 754-1985 binary64. This might not be true on some CPU (I don't know which).
// formally, we should use unsigned char for type-punning (see C99 ISO/IEC 9899:201x spec 6.2.6)
uint64_t i64;
} x;
x.d = in;
int sign = x.i64 >> 63;
int exp = (x.i64 >> 52) & 0x7FF;
if (exp==0) {
*out = UINT64_C(0x8000000000000000);
return !0;
} else if(exp==0x7FF) {
return 0;
}
x.i64 &= UINT64_C(0x000FFFFFFFFFFFFF);
x.i64 |= UINT64_C(0x0010000000000000);
int shift = exp - 0x3FF + 11;
if (shift > 0) {
x.i64 <<= shift;
} else {
x.i64 >>= -shift;
}
if (sign) {
x.i64 = UINT64_C(0x8000000000000000) - x.i64;
} else {
x.i64 += UINT64_C(0x8000000000000000);
}
*out = x.i64;
return !0;
}
/**
* map uint64_t into double[-1.0, 1.0)
*/
static inline void i64_to_double(uint64_t in, double *out) {
union {
double d; // assuming IEEE 754-1985 binary64. This might not be true on some CPU (I don't know which).
// formally, we should use unsigned char for type-punning (see C99 ISO/IEC 9899:201x spec 6.2.6)
uint64_t i64;
} x;
if (in==UINT64_C(0x8000000000000000)) {
*out = 0.0;
return;
}
int sign = 0;
if (in < UINT64_C(0x8000000000000000)) {
sign = 1; // negative. -1.0 -- 0.0
in = UINT64_C(0x8000000000000000) - in;
} else {
in -= UINT64_C(0x8000000000000000);
}
int i;
for (i=0;i<64;i++) {
if (in>>(63-i)) { break; }
}
if (i>11) {
x.i64 = in<<(i-11);
} else {
x.i64 = in>>(11-i);
}
x.i64 = ((UINT64_C(0x3FF) - i)<<52) + (x.i64 & UINT64_C(0x000FFFFFFFFFFFFF));
if (sign) {
x.i64 |= UINT64_C(0x8000000000000000);
}
*out = x.d;
}
static int interleaved_to_geohashstr(uint16_t *interleaved, size_t length, char *dst, size_t dst_length) {
static const char *map="0123456789bcdefghjkmnpqrstuvwxyz";
unsigned char *w = (unsigned char *)dst;
uint16_t *i = interleaved;
for (unsigned int j = 0; j < dst_length / 16; j++) {
w[ 0] = (unsigned char)( i[0]>>11);
w[ 1] = (unsigned char)( i[0]>>6);
w[ 2] = (unsigned char)( i[0]>>1);
w[ 3] = (unsigned char)((i[1]>>12) + (i[0]<<4));
w[ 4] = (unsigned char)( i[1]>>7);
w[ 5] = (unsigned char)( i[1]>>2);
w[ 6] = (unsigned char)((i[2]>>13) + (i[1]<<3));
w[ 7] = (unsigned char)( i[2]>>8);
w[ 8] = (unsigned char)( i[2]>>3);
w[ 9] = (unsigned char)((i[3]>>14) + (i[2]<<2));
w[10] = (unsigned char)( i[3]>>9);
w[11] = (unsigned char)( i[3]>>4);
w[12] = (unsigned char)((i[4]>>15) + (i[3]<<1));
w[13] = (unsigned char)( i[4]>>10);
w[14] = (unsigned char)( i[4]>>5);
w[15] = (unsigned char)( i[4]);
i += 5;
w += 16;
}
for (unsigned int j=0; j < dst_length % 16; j++) {
if (j == 0) w[ 0] = (unsigned char)( i[0]>>11);
else if (j == 1) w[ 1] = (unsigned char)( i[0]>>6);
else if (j == 2) w[ 2] = (unsigned char)( i[0]>>1);
else if (j == 3) w[ 3] = (unsigned char)((i[1]>>12) + (i[0]<<4));
else if (j == 4) w[ 4] = (unsigned char)( i[1]>>7);
else if (j == 5) w[ 5] = (unsigned char)( i[1]>>2);
else if (j == 6) w[ 6] = (unsigned char)((i[2]>>13) + (i[1]<<3));
else if (j == 7) w[ 7] = (unsigned char)( i[2]>>8);
else if (j == 8) w[ 8] = (unsigned char)( i[2]>>3);
else if (j == 9) w[ 9] = (unsigned char)((i[3]>>14) + (i[2]<<2));
else if (j == 10) w[10] = (unsigned char)( i[3]>>9);
else if (j == 11) w[11] = (unsigned char)( i[3]>>4);
else if (j == 12) w[12] = (unsigned char)((i[4]>>15) + (i[3]<<1));
else if (j == 13) w[13] = (unsigned char)( i[4]>>10);
else if (j == 14) w[14] = (unsigned char)( i[4]>>5);
else if (j == 15) w[15] = (unsigned char)( i[4]);
}
for (unsigned int j = 0; j < dst_length; j++) {
dst[j] = map[dst[j] & 0x1F];
}
return GEOHASH_OK;
}
/* /*
* The follow character maps were created by Dave Troy and used in his Javascript Geohashing latitude must be in [-90.0, 90.0) and longitude must be in [-180.0 180.0)
* library. http://github.com/davetroy/geohash-js */
int geohash_encode(double latitude, double longitude, char *r, size_t capacity) {
uint64_t lat64, lon64;
uint16_t interleaved[9];
if (capacity > 27) {
return GEOHASH_INVALIDARGUMENT;
}
char lr[capacity];
memset(interleaved, 0, sizeof(interleaved));
if (!double_to_i64(latitude/90.0, &lat64) || !double_to_i64(longitude/180.0, &lon64)) {
return GEOHASH_INVALIDARGUMENT;
}
for (int i=0; i<8; i++) {
interleaved[7-i] = interleave((uint8_t)(lon64>>(i*8)), (uint8_t)(lat64>>(i*8)));
}
int ret = GEOHASH_OK;
if ((ret = interleaved_to_geohashstr(interleaved, 8, lr, capacity - 1)) != GEOHASH_OK) {
return ret;
}
lr[capacity - 1] = '\0';
if (0 < capacity) {
memcpy(r, (const char*)lr, capacity-1);
r[capacity - 1] = '\0';
}
return GEOHASH_OK;
}
/**
* handle geohash string decoding operation
*/ */
static char *even_neighbors[] = {"p0r21436x8zb9dcf5h7kjnmqesgutwvy", static int geohashstr_to_interleaved(char *r, size_t length, uint16_t *interleaved, size_t dst_count) {
"bc01fg45238967deuvhjyznpkmstqrwx", static const unsigned char map[128] = {
"14365h7k9dcfesgujnmqp0r2twvyx8zb", '|', '|', '|', '|', '|', '|', '|', '|',
"238967debc01fg45kmstqrwxuvhjyznp" '|', '|', '|', '|', '|', '|', '|', '|',
}; '|', '|', '|', '|', '|', '|', '|', '|',
'|', '|', '|', '|', '|', '|', '|', '|',
'|', '|', '|', '|', '|', '|', '|', '|',
'|', '|', '|', '|', '|', '|', '|', '|',
0, 1, 2, 3, 4, 5, 6, 7,
8, 9, '|', '|', '|', '|', '|', '|',
'|', '|', 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
0x10, '|', 0x11, 0x12, '|', 0x13, 0x14, '|',
0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C,
0x1D, 0x1E, 0x1F, '|', '|', '|', '|', '|',
'|', '|', 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
0x10, '|', 0x11, 0x12, '|', 0x13, 0x14, '|',
0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C,
0x1D, 0x1E, 0x1F, '|', '|', '|', '|', '|',
};
for (unsigned int i=0; i<length; i++) {
if (r[i]==0) {
length = i;
break;
} else if(r[i]<0 || map[(unsigned char)r[i]]=='|') {
return GEOHASH_INVALIDCODE;
}
}
if (dst_count*16 < length*5) {
return GEOHASH_INTERNALERROR;
}
for (unsigned int j=0; j<dst_count; j++) {
interleaved[j]=0;
}
static char *odd_neighbors[] = {"bc01fg45238967deuvhjyznpkmstqrwx", uint16_t *i = interleaved;
"p0r21436x8zb9dcf5h7kjnmqesgutwvy", unsigned char *c = (unsigned char*)r;
"238967debc01fg45kmstqrwxuvhjyznp", for (unsigned int j=0; j<length/16; j++) {
"14365h7k9dcfesgujnmqp0r2twvyx8zb" i[0] = (map[c[ 0]]<<11) + (map[c[ 1]]<< 6) + (map[c[ 2]]<<1) + (map[c[ 3]]>>4);
}; i[1] = (map[c[ 3]]<<12) + (map[c[ 4]]<< 7) + (map[c[ 5]]<<2) + (map[c[ 6]]>>3);
i[2] = (map[c[ 6]]<<13) + (map[c[ 7]]<< 8) + (map[c[ 8]]<<3) + (map[c[ 9]]>>2);
i[3] = (map[c[ 9]]<<14) + (map[c[10]]<< 9) + (map[c[11]]<<4) + (map[c[12]]>>1);
i[4] = (map[c[12]]<<15) + (map[c[13]]<<10) + (map[c[14]]<<5) + (map[c[15]]>>0);
i+=5;
c+=16;
}
for (unsigned int j=0; j<length%16; j++) {
if(j== 0) i[0] = map[c[ 0]]<<11;
if(j== 1) i[0] += map[c[ 1]]<< 6;
if(j== 2) i[0] += map[c[ 2]]<< 1;
if(j== 3) i[0] += map[c[ 3]]>> 4;
if(j== 4) i[1] += map[c[ 4]]<< 7;
if(j== 5) i[1] += map[c[ 5]]<< 2;
if(j== 6) i[1] += map[c[ 6]]>> 3;
if(j== 7) i[2] += map[c[ 7]]<< 8;
if(j== 8) i[2] += map[c[ 8]]<< 3;
if(j== 9) i[2] += map[c[ 9]]>> 2;
if(j==10) i[3] += map[c[10]]<< 9;
if(j==11) i[3] += map[c[11]]<< 4;
if(j==12) i[3] += map[c[12]]>> 1;
if(j==13) i[4] += map[c[13]]<<10;
if(j==14) i[4] += map[c[14]]<< 5;
if(j==15) i[4] += map[c[15]]>> 0;
}
return GEOHASH_OK;
}
static char *even_borders[] = {"prxz", "bcfguvyz", "028b", "0145hjnp"};
static char *odd_borders[] = {"bcfguvyz", "prxz", "0145hjnp", "028b"};
unsigned int index_for_char(char c, char *string) { /*
(latitude, longitude) will be that of south west point.
*/
int geohash_decode(char *r, size_t length, double *latitude, double *longitude) {
uint16_t intr_auto[8];
uint16_t *interleaved = intr_auto;
size_t intr_length = length*5/16+1;
int intr_free = 0;
if (intr_length > 8) {
interleaved = (uint16_t*)malloc(sizeof(uint16_t)*intr_length);
if (!interleaved) {
return GEOHASH_NOMEMORY;
}
intr_free = 1;
} else {
intr_length = 8;
}
int ret = GEOHASH_OK;
if ((ret=geohashstr_to_interleaved(r, length, interleaved, intr_length)) != GEOHASH_OK) {
return ret;
}
uint64_t lat64=0;
uint64_t lon64=0;
for (int i=0; i<8; i++) {
uint8_t upper, lower;
deinterleave(interleaved[i], &upper, &lower);
lon64 = (lon64<<8)+upper;
lat64 = (lat64<<8)+lower;
}
if (intr_free) {
free(interleaved);
}
int index = -1; double t;
int string_amount = strlen(string);
int i;
for(i = 0; i < string_amount; i++) {
if(c == string[i]) { i64_to_double(lat64, &t);
*latitude = t*90.0;
index = i; i64_to_double(lon64, &t);
*longitude = t*180.0;
return GEOHASH_OK;
}
/**
* compare two uint8_t array of variable sized integers.
*/
static int uint8s_cmp(uint8_t *src, uint8_t *dst, size_t length) {
if (length==0) { return 0; }
unsigned int i=0;
for (i=0; i<(length-1)/8; i++) {
if (src[i] != dst[i]) {
return (int)(src[i] - dst[i]);
}
}
uint8_t cell_offset = (8-length%8)%8;
return (int)((src[i]>>cell_offset) - (dst[i]>>cell_offset));
}
/**
* plus minus operations for uint8_t array of variable sized integer.
*/
static int uint8s_plus_minus(uint8_t *src, uint8_t *dst, size_t length, int plus) {
if (length==0) {
return 0;
}
unsigned int cell = (length-1)/8;
for (unsigned int i=0; i<cell; i++) {
dst[cell] = src[cell];
}
uint8_t cell_offset = (8-length%8)%8;
int up = 1;
while (up) {
uint8_t t;
up = 0;
if (plus) {
t = src[cell] + (1<<cell_offset);
if ((src[cell]&0x80) && !(t&0x80)) {
up = 1;
}
} else {
t = src[cell] - (1<<cell_offset);
if (!(src[cell]&0x80) && (t&0x80)) {
up = 1;
}
}
dst[cell] = t;
cell_offset = 0;
if (cell == 0) {
break; break;
} }
cell--;
}
return !0;
}
static int neighbors(uint16_t *interleaved, size_t bitlength, uint16_t *dst, size_t dst_length, size_t *dst_count) {
size_t interleaved_length = 0;
while (interleaved_length*16 < bitlength) {
interleaved_length++;
}
if (dst_length<interleaved_length*8) {
return GEOHASH_INTERNALERROR;
}
uint8_t latlons[interleaved_length*6];
uint8_t *lat_8s = latlons;
uint8_t *lon_8s = latlons + interleaved_length*3;
unsigned int lat_len = bitlength/2;
unsigned int lon_len = bitlength/2+bitlength%2;
for (unsigned int i=0; i<interleaved_length; i++) {
deinterleave(interleaved[i], lon_8s+i, lat_8s+i);
lat_8s[i+interleaved_length*2] = lat_8s[i+interleaved_length] = lat_8s[i];
lon_8s[i+interleaved_length*2] = lon_8s[i+interleaved_length] = lon_8s[i];
} }
return index; uint8_t *lats[3] = {lat_8s, lat_8s+interleaved_length, lat_8s+interleaved_length*2};
} uint8_t *lons[3] = {lon_8s, lon_8s+interleaved_length, lon_8s+interleaved_length*2};
char* get_neighbor(char *hash, int direction) { if (uint8s_plus_minus(lats[0], lats[1], lat_len, 0)) {
if ((lats[1][0]&0x80) && !(lats[0][0]&0x80)) {
int hash_length = strlen(hash); for (unsigned int i=0; i<interleaved_length; i++) {
lats[1][i] = lats[0][i]; // this cause skip
char last_char = hash[hash_length - 1];
int is_odd = hash_length % 2;
char **border = is_odd ? odd_borders : even_borders;
char **neighbor = is_odd ? odd_neighbors : even_neighbors;
char *base = malloc(sizeof(char) * 1);
base[0] = '\0';
strncat(base, hash, hash_length - 1);
if(index_for_char(last_char, border[direction]) != -1)
base = get_neighbor(base, direction);
int neighbor_index = index_for_char(last_char, neighbor[direction]);
last_char = char_map[neighbor_index];
char *last_hash = malloc(sizeof(char) * 2);
last_hash[0] = last_char;
last_hash[1] = '\0';
strcat(base, last_hash);
free(last_hash);
return base;
}
char* geohash_encode(double lat, double lng, int precision) {
if(precision < 1 || precision > 12)
precision = 6;
char* hash = NULL;
if(lat <= 90.0 && lat >= -90.0 && lng <= 180.0 && lng >= -180.0) {
hash = (char*)malloc(sizeof(char) * (precision + 1));
hash[precision] = '\0';
precision *= 5.0;
Interval lat_interval = {MAX_LAT, MIN_LAT};
Interval lng_interval = {MAX_LONG, MIN_LONG};
Interval *interval;
double coord, mid;
int is_even = 1;
unsigned int hashChar = 0;
int i;
for(i = 1; i <= precision; i++) {
if(is_even) {
interval = &lng_interval;
coord = lng;
} else {
interval = &lat_interval;
coord = lat;
} }
mid = (interval->low + interval->high) / 2.0;
hashChar = hashChar << 1;
if(coord > mid) {
interval->low = mid;
hashChar |= 0x01;
} else
interval->high = mid;
if(!(i % 5)) {
hash[(i - 1) / 5] = char_map[hashChar];
hashChar = 0;
}
is_even = !is_even;
}
}
return hash;
}
GeoCoord geohash_decode(char *hash) {
GeoCoord coordinate = {0.0, 0.0, 0.0, 0.0, 0.0, 0.0};
if(hash) {
int char_amount = strlen(hash);
if(char_amount) {
unsigned int char_mapIndex;
Interval lat_interval = {MAX_LAT, MIN_LAT};
Interval lng_interval = {MAX_LONG, MIN_LONG};
Interval *interval;
int is_even = 1;
double delta;
int i, j;
for(i = 0; i < char_amount; i++) {
char_mapIndex = index_for_char(hash[i], (char*)char_map);
if(char_mapIndex < 0)
break;
// Interpret the last 5 bits of the integer
for(j = 0; j < 5; j++) {
interval = is_even ? &lng_interval : &lat_interval;
delta = (interval->high - interval->low) / 2.0;
if((char_mapIndex << j) & 0x0010)
interval->low += delta;
else
interval->high -= delta;
is_even = !is_even;
}
}
coordinate.latitude = lat_interval.high - ((lat_interval.high - lat_interval.low) / 2.0);
coordinate.longitude = lng_interval.high - ((lng_interval.high - lng_interval.low) / 2.0);
coordinate.north = lat_interval.high;
coordinate.east = lng_interval.high;
coordinate.south = lat_interval.low;
coordinate.west = lng_interval.low;
} }
} }
if (uint8s_plus_minus(lats[0], lats[2], lat_len, 1)) {
if (!(lats[2][0]&0x80) && (lats[0][0]&0x80)) {
for (unsigned int i=0; i<interleaved_length; i++) {
lats[2][i] = lats[1][i]; // this cause skip
}
}
}
uint8s_plus_minus(lons[0], lons[1], lon_len, 0);
uint8s_plus_minus(lons[0], lons[2], lon_len, 1);
return coordinate; size_t neighbour_count = 0;
for (unsigned int i=0;i<3;i++) {
if (i>0 && uint8s_cmp(lats[i-1], lats[i], lat_len)==0) {
continue;
}
for (int j=0;j<3;j++) {
if (j>0 && uint8s_cmp(lons[j-1], lons[j], lon_len)==0) {
continue;
}
if (i==0 && j==0) {
continue;
}
for (unsigned int k=0; k<interleaved_length; k++) {
dst[interleaved_length*neighbour_count+k] = interleave(lons[j][k], lats[i][k]);
}
neighbour_count++;
}
}
if (dst_count) {
*dst_count = neighbour_count;
}
return GEOHASH_OK;
} }
int geohash_neighbors(char *hashcode, char *dst, size_t dst_length, int *string_count) {
char** geohash_neighbors(char *hash) { int ret = GEOHASH_OK;
size_t hashcode_length = strlen(hashcode);
char** neighbors = NULL; size_t interleaved_length = 0;
while (interleaved_length*16 < hashcode_length*5) {
if(hash) { interleaved_length++;
// N, NE, E, SE, S, SW, W, NW
neighbors = (char**)malloc(sizeof(char*) * 8);
neighbors[0] = get_neighbor(hash, NORTH);
neighbors[1] = get_neighbor(neighbors[0], EAST);
neighbors[2] = get_neighbor(hash, EAST);
neighbors[3] = get_neighbor(neighbors[2], SOUTH);
neighbors[4] = get_neighbor(hash, SOUTH);
neighbors[5] = get_neighbor(neighbors[4], WEST);
neighbors[6] = get_neighbor(hash, WEST);
neighbors[7] = get_neighbor(neighbors[6], NORTH);
} }
return neighbors; uint16_t interleaved[interleaved_length * 9];
}
if ((ret=geohashstr_to_interleaved(hashcode, hashcode_length, interleaved, interleaved_length)) != GEOHASH_OK) {
GeoBoxDimension geohash_dimensions_for_precision(int precision) { return ret;
}
GeoBoxDimension dimensions = {0.0, 0.0};
size_t dst_count = 0;
if(precision > 0) { uint16_t *intr_dst = interleaved + interleaved_length;
if ((ret = neighbors(interleaved, hashcode_length*5, intr_dst, interleaved_length*8, &dst_count) != GEOHASH_OK)) {
int lat_times_to_cut = precision * 5 / 2; return ret;
int lng_times_to_cut = precision * 5 / 2 + (precision % 2 ? 1 : 0); }
double width = 360.0; size_t blen = hashcode_length;
double height = 180.0;
char buffer[blen];
int i; memset(buffer, 0, blen);
for(i = 0; i < lat_times_to_cut; i++)
height /= 2.0; size_t t = hashcode_length + 1;
for (unsigned int i=0; i<dst_count; i++) {
for(i = 0; i < lng_times_to_cut; i++) if ((ret = interleaved_to_geohashstr(intr_dst+i*interleaved_length, interleaved_length, buffer, blen)) != GEOHASH_OK) {
width /= 2.0; return ret;
}
dimensions.width = width; buffer[hashcode_length] = '\0';
dimensions.height = height; memcpy(dst+i*t, buffer, t);
}
}
if (string_count) {
return dimensions; *string_count = dst_count;
}
return GEOHASH_OK;
} }

108
src/geohash/geohash.h
View File

@@ -1,77 +1,49 @@
/* /*** MIT License
* geohash.h Permission is hereby granted, free of charge, to any person obtaining a copy
* libgeohash of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* Created by Derek Smith on 10/6/09. to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* Copyright (c) 2010, SimpleGeo copies of the Software, and to permit persons to whom the Software is
* All rights reserved. furnished to do so, subject to the following conditions:
*
* 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 The above copyright notice and this permission notice shall be included in
* of conditions and the following disclaimer. Redistributions in binary form must all copies or substantial portions of the Software.
* 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 the SimpleGeo 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 HOLDER 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.
*/
// Metric in meters THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
typedef struct GeoBoxDimensionStruct { IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/
double height; #ifndef GEOHASH_H
double width; #define GEOHASH_H
} GeoBoxDimension; #include <stdio.h>
#include <string.h>
#include <stdlib.h>
typedef struct GeoCoordStruct { #ifdef __cplusplus
extern "C" {
#endif
double latitude; enum {
double longitude; GEOHASH_OK,
GEOHASH_NOTSUPPORTED,
GEOHASH_INVALIDCODE,
GEOHASH_INVALIDARGUMENT,
GEOHASH_INTERNALERROR,
GEOHASH_NOMEMORY
};
double north; int geohash_encode(double latitude, double longitude, char* r, size_t capacity);
double east; int geohash_decode(char* r, size_t length, double *latitude, double *longitude);
double south; int geohash_neighbors(char *hashcode, char* dst, size_t dst_length, int *string_count);
double west;
GeoBoxDimension dimension; #ifdef __cplusplus
}
#endif
} GeoCoord; #endif
/*
* Creates a the hash at the specified precision. If precision is set to 0.
* or less than it defaults to 12.
*/
extern char* geohash_encode(double lat, double lng, int precision);
/*
* Returns the latitude and longitude used to create the hash along with
* the bounding box for the encoded coordinate.
*/
extern GeoCoord geohash_decode(char* hash);
/*
* Return an array of geohashes that represent the neighbors of the passed
* in value. The neighbors are indexed as followed:
*
* N, NE, E, SE, S, SW, W, NW
* 0, 1, 2, 3, 4, 5, 6, 7
*/
extern char** geohash_neighbors(char* hash);
/*
* Returns the width and height of a precision value.
*/
extern GeoBoxDimension geohash_dimensions_for_precision(int precision);