h3_baseCells.c

/*
 * Copyright 2016-2020 Uber Technologies, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/** @file baseCells.c
 * @brief   Base cell related lookup tables and access functions.
 */

#include "h3_baseCells.h"

#include "h3_h3Index.h"

/** @struct BaseCellRotation
 *  @brief base cell at a given ijk and required rotations into its system
 */
typedef struct {
    int baseCell;  ///< base cell number
    int ccwRot60;  ///< number of ccw 60 degree rotations relative to current
                   /// face
} BaseCellRotation;

/** @brief Neighboring base cell ID in each IJK direction.
 *
 * For each base cell, for each direction, the neighboring base
 * cell ID is given. 127 indicates there is no neighbor in that direction.
 */
const int baseCellNeighbors[NUM_BASE_CELLS][7] = {
    {0, 1, 5, 2, 4, 3, 8},                          // base cell 0
    {1, 7, 6, 9, 0, 3, 2},                          // base cell 1
    {2, 6, 10, 11, 0, 1, 5},                        // base cell 2
    {3, 13, 1, 7, 4, 12, 0},                        // base cell 3
    {4, INVALID_BASE_CELL, 15, 8, 3, 0, 12},        // base cell 4 (pentagon)
    {5, 2, 18, 10, 8, 0, 16},                       // base cell 5
    {6, 14, 11, 17, 1, 9, 2},                       // base cell 6
    {7, 21, 9, 19, 3, 13, 1},                       // base cell 7
    {8, 5, 22, 16, 4, 0, 15},                       // base cell 8
    {9, 19, 14, 20, 1, 7, 6},                       // base cell 9
    {10, 11, 24, 23, 5, 2, 18},                     // base cell 10
    {11, 17, 23, 25, 2, 6, 10},                     // base cell 11
    {12, 28, 13, 26, 4, 15, 3},                     // base cell 12
    {13, 26, 21, 29, 3, 12, 7},                     // base cell 13
    {14, INVALID_BASE_CELL, 17, 27, 9, 20, 6},      // base cell 14 (pentagon)
    {15, 22, 28, 31, 4, 8, 12},                     // base cell 15
    {16, 18, 33, 30, 8, 5, 22},                     // base cell 16
    {17, 11, 14, 6, 35, 25, 27},                    // base cell 17
    {18, 24, 30, 32, 5, 10, 16},                    // base cell 18
    {19, 34, 20, 36, 7, 21, 9},                     // base cell 19
    {20, 14, 19, 9, 40, 27, 36},                    // base cell 20
    {21, 38, 19, 34, 13, 29, 7},                    // base cell 21
    {22, 16, 41, 33, 15, 8, 31},                    // base cell 22
    {23, 24, 11, 10, 39, 37, 25},                   // base cell 23
    {24, INVALID_BASE_CELL, 32, 37, 10, 23, 18},    // base cell 24 (pentagon)
    {25, 23, 17, 11, 45, 39, 35},                   // base cell 25
    {26, 42, 29, 43, 12, 28, 13},                   // base cell 26
    {27, 40, 35, 46, 14, 20, 17},                   // base cell 27
    {28, 31, 42, 44, 12, 15, 26},                   // base cell 28
    {29, 43, 38, 47, 13, 26, 21},                   // base cell 29
    {30, 32, 48, 50, 16, 18, 33},                   // base cell 30
    {31, 41, 44, 53, 15, 22, 28},                   // base cell 31
    {32, 30, 24, 18, 52, 50, 37},                   // base cell 32
    {33, 30, 49, 48, 22, 16, 41},                   // base cell 33
    {34, 19, 38, 21, 54, 36, 51},                   // base cell 34
    {35, 46, 45, 56, 17, 27, 25},                   // base cell 35
    {36, 20, 34, 19, 55, 40, 54},                   // base cell 36
    {37, 39, 52, 57, 24, 23, 32},                   // base cell 37
    {38, INVALID_BASE_CELL, 34, 51, 29, 47, 21},    // base cell 38 (pentagon)
    {39, 37, 25, 23, 59, 57, 45},                   // base cell 39
    {40, 27, 36, 20, 60, 46, 55},                   // base cell 40
    {41, 49, 53, 61, 22, 33, 31},                   // base cell 41
    {42, 58, 43, 62, 28, 44, 26},                   // base cell 42
    {43, 62, 47, 64, 26, 42, 29},                   // base cell 43
    {44, 53, 58, 65, 28, 31, 42},                   // base cell 44
    {45, 39, 35, 25, 63, 59, 56},                   // base cell 45
    {46, 60, 56, 68, 27, 40, 35},                   // base cell 46
    {47, 38, 43, 29, 69, 51, 64},                   // base cell 47
    {48, 49, 30, 33, 67, 66, 50},                   // base cell 48
    {49, INVALID_BASE_CELL, 61, 66, 33, 48, 41},    // base cell 49 (pentagon)
    {50, 48, 32, 30, 70, 67, 52},                   // base cell 50
    {51, 69, 54, 71, 38, 47, 34},                   // base cell 51
    {52, 57, 70, 74, 32, 37, 50},                   // base cell 52
    {53, 61, 65, 75, 31, 41, 44},                   // base cell 53
    {54, 71, 55, 73, 34, 51, 36},                   // base cell 54
    {55, 40, 54, 36, 72, 60, 73},                   // base cell 55
    {56, 68, 63, 77, 35, 46, 45},                   // base cell 56
    {57, 59, 74, 78, 37, 39, 52},                   // base cell 57
    {58, INVALID_BASE_CELL, 62, 76, 44, 65, 42},    // base cell 58 (pentagon)
    {59, 63, 78, 79, 39, 45, 57},                   // base cell 59
    {60, 72, 68, 80, 40, 55, 46},                   // base cell 60
    {61, 53, 49, 41, 81, 75, 66},                   // base cell 61
    {62, 43, 58, 42, 82, 64, 76},                   // base cell 62
    {63, INVALID_BASE_CELL, 56, 45, 79, 59, 77},    // base cell 63 (pentagon)
    {64, 47, 62, 43, 84, 69, 82},                   // base cell 64
    {65, 58, 53, 44, 86, 76, 75},                   // base cell 65
    {66, 67, 81, 85, 49, 48, 61},                   // base cell 66
    {67, 66, 50, 48, 87, 85, 70},                   // base cell 67
    {68, 56, 60, 46, 90, 77, 80},                   // base cell 68
    {69, 51, 64, 47, 89, 71, 84},                   // base cell 69
    {70, 67, 52, 50, 83, 87, 74},                   // base cell 70
    {71, 89, 73, 91, 51, 69, 54},                   // base cell 71
    {72, INVALID_BASE_CELL, 73, 55, 80, 60, 88},    // base cell 72 (pentagon)
    {73, 91, 72, 88, 54, 71, 55},                   // base cell 73
    {74, 78, 83, 92, 52, 57, 70},                   // base cell 74
    {75, 65, 61, 53, 94, 86, 81},                   // base cell 75
    {76, 86, 82, 96, 58, 65, 62},                   // base cell 76
    {77, 63, 68, 56, 93, 79, 90},                   // base cell 77
    {78, 74, 59, 57, 95, 92, 79},                   // base cell 78
    {79, 78, 63, 59, 93, 95, 77},                   // base cell 79
    {80, 68, 72, 60, 99, 90, 88},                   // base cell 80
    {81, 85, 94, 101, 61, 66, 75},                  // base cell 81
    {82, 96, 84, 98, 62, 76, 64},                   // base cell 82
    {83, INVALID_BASE_CELL, 74, 70, 100, 87, 92},   // base cell 83 (pentagon)
    {84, 69, 82, 64, 97, 89, 98},                   // base cell 84
    {85, 87, 101, 102, 66, 67, 81},                 // base cell 85
    {86, 76, 75, 65, 104, 96, 94},                  // base cell 86
    {87, 83, 102, 100, 67, 70, 85},                 // base cell 87
    {88, 72, 91, 73, 99, 80, 105},                  // base cell 88
    {89, 97, 91, 103, 69, 84, 71},                  // base cell 89
    {90, 77, 80, 68, 106, 93, 99},                  // base cell 90
    {91, 73, 89, 71, 105, 88, 103},                 // base cell 91
    {92, 83, 78, 74, 108, 100, 95},                 // base cell 92
    {93, 79, 90, 77, 109, 95, 106},                 // base cell 93
    {94, 86, 81, 75, 107, 104, 101},                // base cell 94
    {95, 92, 79, 78, 109, 108, 93},                 // base cell 95
    {96, 104, 98, 110, 76, 86, 82},                 // base cell 96
    {97, INVALID_BASE_CELL, 98, 84, 103, 89, 111},  // base cell 97 (pentagon)
    {98, 110, 97, 111, 82, 96, 84},                 // base cell 98
    {99, 80, 105, 88, 106, 90, 113},                // base cell 99
    {100, 102, 83, 87, 108, 114, 92},               // base cell 100
    {101, 102, 107, 112, 81, 85, 94},               // base cell 101
    {102, 101, 87, 85, 114, 112, 100},              // base cell 102
    {103, 91, 97, 89, 116, 105, 111},               // base cell 103
    {104, 107, 110, 115, 86, 94, 96},               // base cell 104
    {105, 88, 103, 91, 113, 99, 116},               // base cell 105
    {106, 93, 99, 90, 117, 109, 113},               // base cell 106
    {107, INVALID_BASE_CELL, 101, 94, 115, 104,
     112},                                // base cell 107 (pentagon)
    {108, 100, 95, 92, 118, 114, 109},    // base cell 108
    {109, 108, 93, 95, 117, 118, 106},    // base cell 109
    {110, 98, 104, 96, 119, 111, 115},    // base cell 110
    {111, 97, 110, 98, 116, 103, 119},    // base cell 111
    {112, 107, 102, 101, 120, 115, 114},  // base cell 112
    {113, 99, 116, 105, 117, 106, 121},   // base cell 113
    {114, 112, 100, 102, 118, 120, 108},  // base cell 114
    {115, 110, 107, 104, 120, 119, 112},  // base cell 115
    {116, 103, 119, 111, 113, 105, 121},  // base cell 116
    {117, INVALID_BASE_CELL, 109, 118, 113, 121,
     106},                                // base cell 117 (pentagon)
    {118, 120, 108, 114, 117, 121, 109},  // base cell 118
    {119, 111, 115, 110, 121, 116, 120},  // base cell 119
    {120, 115, 114, 112, 121, 119, 118},  // base cell 120
    {121, 116, 120, 119, 117, 113, 118},  // base cell 121
};

/** @brief Neighboring base cell rotations in each IJK direction.
 *
 * For each base cell, for each direction, the number of 60 degree
 * CCW rotations to the coordinate system of the neighbor is given.
 * -1 indicates there is no neighbor in that direction.
 */
const int baseCellNeighbor60CCWRots[NUM_BASE_CELLS][7] = {
    {0, 5, 0, 0, 1, 5, 1},   // base cell 0
    {0, 0, 1, 0, 1, 0, 1},   // base cell 1
    {0, 0, 0, 0, 0, 5, 0},   // base cell 2
    {0, 5, 0, 0, 2, 5, 1},   // base cell 3
    {0, -1, 1, 0, 3, 4, 2},  // base cell 4 (pentagon)
    {0, 0, 1, 0, 1, 0, 1},   // base cell 5
    {0, 0, 0, 3, 5, 5, 0},   // base cell 6
    {0, 0, 0, 0, 0, 5, 0},   // base cell 7
    {0, 5, 0, 0, 0, 5, 1},   // base cell 8
    {0, 0, 1, 3, 0, 0, 1},   // base cell 9
    {0, 0, 1, 3, 0, 0, 1},   // base cell 10
    {0, 3, 3, 3, 0, 0, 0},   // base cell 11
    {0, 5, 0, 0, 3, 5, 1},   // base cell 12
    {0, 0, 1, 0, 1, 0, 1},   // base cell 13
    {0, -1, 3, 0, 5, 2, 0},  // base cell 14 (pentagon)
    {0, 5, 0, 0, 4, 5, 1},   // base cell 15
    {0, 0, 0, 0, 0, 5, 0},   // base cell 16
    {0, 3, 3, 3, 3, 0, 3},   // base cell 17
    {0, 0, 0, 3, 5, 5, 0},   // base cell 18
    {0, 3, 3, 3, 0, 0, 0},   // base cell 19
    {0, 3, 3, 3, 0, 3, 0},   // base cell 20
    {0, 0, 0, 3, 5, 5, 0},   // base cell 21
    {0, 0, 1, 0, 1, 0, 1},   // base cell 22
    {0, 3, 3, 3, 0, 3, 0},   // base cell 23
    {0, -1, 3, 0, 5, 2, 0},  // base cell 24 (pentagon)
    {0, 0, 0, 3, 0, 0, 3},   // base cell 25
    {0, 0, 0, 0, 0, 5, 0},   // base cell 26
    {0, 3, 0, 0, 0, 3, 3},   // base cell 27
    {0, 0, 1, 0, 1, 0, 1},   // base cell 28
    {0, 0, 1, 3, 0, 0, 1},   // base cell 29
    {0, 3, 3, 3, 0, 0, 0},   // base cell 30
    {0, 0, 0, 0, 0, 5, 0},   // base cell 31
    {0, 3, 3, 3, 3, 0, 3},   // base cell 32
    {0, 0, 1, 3, 0, 0, 1},   // base cell 33
    {0, 3, 3, 3, 3, 0, 3},   // base cell 34
    {0, 0, 3, 0, 3, 0, 3},   // base cell 35
    {0, 0, 0, 3, 0, 0, 3},   // base cell 36
    {0, 3, 0, 0, 0, 3, 3},   // base cell 37
    {0, -1, 3, 0, 5, 2, 0},  // base cell 38 (pentagon)
    {0, 3, 0, 0, 3, 3, 0},   // base cell 39
    {0, 3, 0, 0, 3, 3, 0},   // base cell 40
    {0, 0, 0, 3, 5, 5, 0},   // base cell 41
    {0, 0, 0, 3, 5, 5, 0},   // base cell 42
    {0, 3, 3, 3, 0, 0, 0},   // base cell 43
    {0, 0, 1, 3, 0, 0, 1},   // base cell 44
    {0, 0, 3, 0, 0, 3, 3},   // base cell 45
    {0, 0, 0, 3, 0, 3, 0},   // base cell 46
    {0, 3, 3, 3, 0, 3, 0},   // base cell 47
    {0, 3, 3, 3, 0, 3, 0},   // base cell 48
    {0, -1, 3, 0, 5, 2, 0},  // base cell 49 (pentagon)
    {0, 0, 0, 3, 0, 0, 3},   // base cell 50
    {0, 3, 0, 0, 0, 3, 3},   // base cell 51
    {0, 0, 3, 0, 3, 0, 3},   // base cell 52
    {0, 3, 3, 3, 0, 0, 0},   // base cell 53
    {0, 0, 3, 0, 3, 0, 3},   // base cell 54
    {0, 0, 3, 0, 0, 3, 3},   // base cell 55
    {0, 3, 3, 3, 0, 0, 3},   // base cell 56
    {0, 0, 0, 3, 0, 3, 0},   // base cell 57
    {0, -1, 3, 0, 5, 2, 0},  // base cell 58 (pentagon)
    {0, 3, 3, 3, 3, 3, 0},   // base cell 59
    {0, 3, 3, 3, 3, 3, 0},   // base cell 60
    {0, 3, 3, 3, 3, 0, 3},   // base cell 61
    {0, 3, 3, 3, 3, 0, 3},   // base cell 62
    {0, -1, 3, 0, 5, 2, 0},  // base cell 63 (pentagon)
    {0, 0, 0, 3, 0, 0, 3},   // base cell 64
    {0, 3, 3, 3, 0, 3, 0},   // base cell 65
    {0, 3, 0, 0, 0, 3, 3},   // base cell 66
    {0, 3, 0, 0, 3, 3, 0},   // base cell 67
    {0, 3, 3, 3, 0, 0, 0},   // base cell 68
    {0, 3, 0, 0, 3, 3, 0},   // base cell 69
    {0, 0, 3, 0, 0, 3, 3},   // base cell 70
    {0, 0, 0, 3, 0, 3, 0},   // base cell 71
    {0, -1, 3, 0, 5, 2, 0},  // base cell 72 (pentagon)
    {0, 3, 3, 3, 0, 0, 3},   // base cell 73
    {0, 3, 3, 3, 0, 0, 3},   // base cell 74
    {0, 0, 0, 3, 0, 0, 3},   // base cell 75
    {0, 3, 0, 0, 0, 3, 3},   // base cell 76
    {0, 0, 0, 3, 0, 5, 0},   // base cell 77
    {0, 3, 3, 3, 0, 0, 0},   // base cell 78
    {0, 0, 1, 3, 1, 0, 1},   // base cell 79
    {0, 0, 1, 3, 1, 0, 1},   // base cell 80
    {0, 0, 3, 0, 3, 0, 3},   // base cell 81
    {0, 0, 3, 0, 3, 0, 3},   // base cell 82
    {0, -1, 3, 0, 5, 2, 0},  // base cell 83 (pentagon)
    {0, 0, 3, 0, 0, 3, 3},   // base cell 84
    {0, 0, 0, 3, 0, 3, 0},   // base cell 85
    {0, 3, 0, 0, 3, 3, 0},   // base cell 86
    {0, 3, 3, 3, 3, 3, 0},   // base cell 87
    {0, 0, 0, 3, 0, 5, 0},   // base cell 88
    {0, 3, 3, 3, 3, 3, 0},   // base cell 89
    {0, 0, 0, 0, 0, 0, 1},   // base cell 90
    {0, 3, 3, 3, 0, 0, 0},   // base cell 91
    {0, 0, 0, 3, 0, 5, 0},   // base cell 92
    {0, 5, 0, 0, 5, 5, 0},   // base cell 93
    {0, 0, 3, 0, 0, 3, 3},   // base cell 94
    {0, 0, 0, 0, 0, 0, 1},   // base cell 95
    {0, 0, 0, 3, 0, 3, 0},   // base cell 96
    {0, -1, 3, 0, 5, 2, 0},  // base cell 97 (pentagon)
    {0, 3, 3, 3, 0, 0, 3},   // base cell 98
    {0, 5, 0, 0, 5, 5, 0},   // base cell 99
    {0, 0, 1, 3, 1, 0, 1},   // base cell 100
    {0, 3, 3, 3, 0, 0, 3},   // base cell 101
    {0, 3, 3, 3, 0, 0, 0},   // base cell 102
    {0, 0, 1, 3, 1, 0, 1},   // base cell 103
    {0, 3, 3, 3, 3, 3, 0},   // base cell 104
    {0, 0, 0, 0, 0, 0, 1},   // base cell 105
    {0, 0, 1, 0, 3, 5, 1},   // base cell 106
    {0, -1, 3, 0, 5, 2, 0},  // base cell 107 (pentagon)
    {0, 5, 0, 0, 5, 5, 0},   // base cell 108
    {0, 0, 1, 0, 4, 5, 1},   // base cell 109
    {0, 3, 3, 3, 0, 0, 0},   // base cell 110
    {0, 0, 0, 3, 0, 5, 0},   // base cell 111
    {0, 0, 0, 3, 0, 5, 0},   // base cell 112
    {0, 0, 1, 0, 2, 5, 1},   // base cell 113
    {0, 0, 0, 0, 0, 0, 1},   // base cell 114
    {0, 0, 1, 3, 1, 0, 1},   // base cell 115
    {0, 5, 0, 0, 5, 5, 0},   // base cell 116
    {0, -1, 1, 0, 3, 4, 2},  // base cell 117 (pentagon)
    {0, 0, 1, 0, 0, 5, 1},   // base cell 118
    {0, 0, 0, 0, 0, 0, 1},   // base cell 119
    {0, 5, 0, 0, 5, 5, 0},   // base cell 120
    {0, 0, 1, 0, 1, 5, 1},   // base cell 121
};

/** @brief Resolution 0 base cell lookup table for each face.
 *
 * Given the face number and a resolution 0 ijk+ coordinate in that face's
 * face-centered ijk coordinate system, gives the base cell located at that
 * coordinate and the number of 60 ccw rotations to rotate into that base
 * cell's orientation.
 *
 * Valid lookup coordinates are from (0, 0, 0) to (2, 2, 2).
 *
 * This table can be accessed using the functions `_faceIjkToBaseCell` and
 * `_faceIjkToBaseCellCCWrot60`
 */
static const BaseCellRotation faceIjkBaseCells[NUM_ICOSA_FACES][3][3][3] = {
    {// face 0
     {
         // i 0
         {{16, 0}, {18, 0}, {24, 0}},  // j 0
         {{33, 0}, {30, 0}, {32, 3}},  // j 1
         {{49, 1}, {48, 3}, {50, 3}}   // j 2
     },
     {
         // i 1
         {{8, 0}, {5, 5}, {10, 5}},    // j 0
         {{22, 0}, {16, 0}, {18, 0}},  // j 1
         {{41, 1}, {33, 0}, {30, 0}}   // j 2
     },
     {
         // i 2
         {{4, 0}, {0, 5}, {2, 5}},    // j 0
         {{15, 1}, {8, 0}, {5, 5}},   // j 1
         {{31, 1}, {22, 0}, {16, 0}}  // j 2
     }},
    {// face 1
     {
         // i 0
         {{2, 0}, {6, 0}, {14, 0}},    // j 0
         {{10, 0}, {11, 0}, {17, 3}},  // j 1
         {{24, 1}, {23, 3}, {25, 3}}   // j 2
     },
     {
         // i 1
         {{0, 0}, {1, 5}, {9, 5}},    // j 0
         {{5, 0}, {2, 0}, {6, 0}},    // j 1
         {{18, 1}, {10, 0}, {11, 0}}  // j 2
     },
     {
         // i 2
         {{4, 1}, {3, 5}, {7, 5}},  // j 0
         {{8, 1}, {0, 0}, {1, 5}},  // j 1
         {{16, 1}, {5, 0}, {2, 0}}  // j 2
     }},
    {// face 2
     {
         // i 0
         {{7, 0}, {21, 0}, {38, 0}},  // j 0
         {{9, 0}, {19, 0}, {34, 3}},  // j 1
         {{14, 1}, {20, 3}, {36, 3}}  // j 2
     },
     {
         // i 1
         {{3, 0}, {13, 5}, {29, 5}},  // j 0
         {{1, 0}, {7, 0}, {21, 0}},   // j 1
         {{6, 1}, {9, 0}, {19, 0}}    // j 2
     },
     {
         // i 2
         {{4, 2}, {12, 5}, {26, 5}},  // j 0
         {{0, 1}, {3, 0}, {13, 5}},   // j 1
         {{2, 1}, {1, 0}, {7, 0}}     // j 2
     }},
    {// face 3
     {
         // i 0
         {{26, 0}, {42, 0}, {58, 0}},  // j 0
         {{29, 0}, {43, 0}, {62, 3}},  // j 1
         {{38, 1}, {47, 3}, {64, 3}}   // j 2
     },
     {
         // i 1
         {{12, 0}, {28, 5}, {44, 5}},  // j 0
         {{13, 0}, {26, 0}, {42, 0}},  // j 1
         {{21, 1}, {29, 0}, {43, 0}}   // j 2
     },
     {
         // i 2
         {{4, 3}, {15, 5}, {31, 5}},  // j 0
         {{3, 1}, {12, 0}, {28, 5}},  // j 1
         {{7, 1}, {13, 0}, {26, 0}}   // j 2
     }},
    {// face 4
     {
         // i 0
         {{31, 0}, {41, 0}, {49, 0}},  // j 0
         {{44, 0}, {53, 0}, {61, 3}},  // j 1
         {{58, 1}, {65, 3}, {75, 3}}   // j 2
     },
     {
         // i 1
         {{15, 0}, {22, 5}, {33, 5}},  // j 0
         {{28, 0}, {31, 0}, {41, 0}},  // j 1
         {{42, 1}, {44, 0}, {53, 0}}   // j 2
     },
     {
         // i 2
         {{4, 4}, {8, 5}, {16, 5}},    // j 0
         {{12, 1}, {15, 0}, {22, 5}},  // j 1
         {{26, 1}, {28, 0}, {31, 0}}   // j 2
     }},
    {// face 5
     {
         // i 0
         {{50, 0}, {48, 0}, {49, 3}},  // j 0
         {{32, 0}, {30, 3}, {33, 3}},  // j 1
         {{24, 3}, {18, 3}, {16, 3}}   // j 2
     },
     {
         // i 1
         {{70, 0}, {67, 0}, {66, 3}},  // j 0
         {{52, 3}, {50, 0}, {48, 0}},  // j 1
         {{37, 3}, {32, 0}, {30, 3}}   // j 2
     },
     {
         // i 2
         {{83, 0}, {87, 3}, {85, 3}},  // j 0
         {{74, 3}, {70, 0}, {67, 0}},  // j 1
         {{57, 1}, {52, 3}, {50, 0}}   // j 2
     }},
    {// face 6
     {
         // i 0
         {{25, 0}, {23, 0}, {24, 3}},  // j 0
         {{17, 0}, {11, 3}, {10, 3}},  // j 1
         {{14, 3}, {6, 3}, {2, 3}}     // j 2
     },
     {
         // i 1
         {{45, 0}, {39, 0}, {37, 3}},  // j 0
         {{35, 3}, {25, 0}, {23, 0}},  // j 1
         {{27, 3}, {17, 0}, {11, 3}}   // j 2
     },
     {
         // i 2
         {{63, 0}, {59, 3}, {57, 3}},  // j 0
         {{56, 3}, {45, 0}, {39, 0}},  // j 1
         {{46, 3}, {35, 3}, {25, 0}}   // j 2
     }},
    {// face 7
     {
         // i 0
         {{36, 0}, {20, 0}, {14, 3}},  // j 0
         {{34, 0}, {19, 3}, {9, 3}},   // j 1
         {{38, 3}, {21, 3}, {7, 3}}    // j 2
     },
     {
         // i 1
         {{55, 0}, {40, 0}, {27, 3}},  // j 0
         {{54, 3}, {36, 0}, {20, 0}},  // j 1
         {{51, 3}, {34, 0}, {19, 3}}   // j 2
     },
     {
         // i 2
         {{72, 0}, {60, 3}, {46, 3}},  // j 0
         {{73, 3}, {55, 0}, {40, 0}},  // j 1
         {{71, 3}, {54, 3}, {36, 0}}   // j 2
     }},
    {// face 8
     {
         // i 0
         {{64, 0}, {47, 0}, {38, 3}},  // j 0
         {{62, 0}, {43, 3}, {29, 3}},  // j 1
         {{58, 3}, {42, 3}, {26, 3}}   // j 2
     },
     {
         // i 1
         {{84, 0}, {69, 0}, {51, 3}},  // j 0
         {{82, 3}, {64, 0}, {47, 0}},  // j 1
         {{76, 3}, {62, 0}, {43, 3}}   // j 2
     },
     {
         // i 2
         {{97, 0}, {89, 3}, {71, 3}},  // j 0
         {{98, 3}, {84, 0}, {69, 0}},  // j 1
         {{96, 3}, {82, 3}, {64, 0}}   // j 2
     }},
    {// face 9
     {
         // i 0
         {{75, 0}, {65, 0}, {58, 3}},  // j 0
         {{61, 0}, {53, 3}, {44, 3}},  // j 1
         {{49, 3}, {41, 3}, {31, 3}}   // j 2
     },
     {
         // i 1
         {{94, 0}, {86, 0}, {76, 3}},  // j 0
         {{81, 3}, {75, 0}, {65, 0}},  // j 1
         {{66, 3}, {61, 0}, {53, 3}}   // j 2
     },
     {
         // i 2
         {{107, 0}, {104, 3}, {96, 3}},  // j 0
         {{101, 3}, {94, 0}, {86, 0}},   // j 1
         {{85, 3}, {81, 3}, {75, 0}}     // j 2
     }},
    {// face 10
     {
         // i 0
         {{57, 0}, {59, 0}, {63, 3}},  // j 0
         {{74, 0}, {78, 3}, {79, 3}},  // j 1
         {{83, 3}, {92, 3}, {95, 3}}   // j 2
     },
     {
         // i 1
         {{37, 0}, {39, 3}, {45, 3}},  // j 0
         {{52, 0}, {57, 0}, {59, 0}},  // j 1
         {{70, 3}, {74, 0}, {78, 3}}   // j 2
     },
     {
         // i 2
         {{24, 0}, {23, 3}, {25, 3}},  // j 0
         {{32, 3}, {37, 0}, {39, 3}},  // j 1
         {{50, 3}, {52, 0}, {57, 0}}   // j 2
     }},
    {// face 11
     {
         // i 0
         {{46, 0}, {60, 0}, {72, 3}},  // j 0
         {{56, 0}, {68, 3}, {80, 3}},  // j 1
         {{63, 3}, {77, 3}, {90, 3}}   // j 2
     },
     {
         // i 1
         {{27, 0}, {40, 3}, {55, 3}},  // j 0
         {{35, 0}, {46, 0}, {60, 0}},  // j 1
         {{45, 3}, {56, 0}, {68, 3}}   // j 2
     },
     {
         // i 2
         {{14, 0}, {20, 3}, {36, 3}},  // j 0
         {{17, 3}, {27, 0}, {40, 3}},  // j 1
         {{25, 3}, {35, 0}, {46, 0}}   // j 2
     }},
    {// face 12
     {
         // i 0
         {{71, 0}, {89, 0}, {97, 3}},   // j 0
         {{73, 0}, {91, 3}, {103, 3}},  // j 1
         {{72, 3}, {88, 3}, {105, 3}}   // j 2
     },
     {
         // i 1
         {{51, 0}, {69, 3}, {84, 3}},  // j 0
         {{54, 0}, {71, 0}, {89, 0}},  // j 1
         {{55, 3}, {73, 0}, {91, 3}}   // j 2
     },
     {
         // i 2
         {{38, 0}, {47, 3}, {64, 3}},  // j 0
         {{34, 3}, {51, 0}, {69, 3}},  // j 1
         {{36, 3}, {54, 0}, {71, 0}}   // j 2
     }},
    {// face 13
     {
         // i 0
         {{96, 0}, {104, 0}, {107, 3}},  // j 0
         {{98, 0}, {110, 3}, {115, 3}},  // j 1
         {{97, 3}, {111, 3}, {119, 3}}   // j 2
     },
     {
         // i 1
         {{76, 0}, {86, 3}, {94, 3}},   // j 0
         {{82, 0}, {96, 0}, {104, 0}},  // j 1
         {{84, 3}, {98, 0}, {110, 3}}   // j 2
     },
     {
         // i 2
         {{58, 0}, {65, 3}, {75, 3}},  // j 0
         {{62, 3}, {76, 0}, {86, 3}},  // j 1
         {{64, 3}, {82, 0}, {96, 0}}   // j 2
     }},
    {// face 14
     {
         // i 0
         {{85, 0}, {87, 0}, {83, 3}},     // j 0
         {{101, 0}, {102, 3}, {100, 3}},  // j 1
         {{107, 3}, {112, 3}, {114, 3}}   // j 2
     },
     {
         // i 1
         {{66, 0}, {67, 3}, {70, 3}},   // j 0
         {{81, 0}, {85, 0}, {87, 0}},   // j 1
         {{94, 3}, {101, 0}, {102, 3}}  // j 2
     },
     {
         // i 2
         {{49, 0}, {48, 3}, {50, 3}},  // j 0
         {{61, 3}, {66, 0}, {67, 3}},  // j 1
         {{75, 3}, {81, 0}, {85, 0}}   // j 2
     }},
    {// face 15
     {
         // i 0
         {{95, 0}, {92, 0}, {83, 0}},  // j 0
         {{79, 0}, {78, 0}, {74, 3}},  // j 1
         {{63, 1}, {59, 3}, {57, 3}}   // j 2
     },
     {
         // i 1
         {{109, 0}, {108, 0}, {100, 5}},  // j 0
         {{93, 1}, {95, 0}, {92, 0}},     // j 1
         {{77, 1}, {79, 0}, {78, 0}}      // j 2
     },
     {
         // i 2
         {{117, 4}, {118, 5}, {114, 5}},  // j 0
         {{106, 1}, {109, 0}, {108, 0}},  // j 1
         {{90, 1}, {93, 1}, {95, 0}}      // j 2
     }},
    {// face 16
     {
         // i 0
         {{90, 0}, {77, 0}, {63, 0}},  // j 0
         {{80, 0}, {68, 0}, {56, 3}},  // j 1
         {{72, 1}, {60, 3}, {46, 3}}   // j 2
     },
     {
         // i 1
         {{106, 0}, {93, 0}, {79, 5}},  // j 0
         {{99, 1}, {90, 0}, {77, 0}},   // j 1
         {{88, 1}, {80, 0}, {68, 0}}    // j 2
     },
     {
         // i 2
         {{117, 3}, {109, 5}, {95, 5}},  // j 0
         {{113, 1}, {106, 0}, {93, 0}},  // j 1
         {{105, 1}, {99, 1}, {90, 0}}    // j 2
     }},
    {// face 17
     {
         // i 0
         {{105, 0}, {88, 0}, {72, 0}},  // j 0
         {{103, 0}, {91, 0}, {73, 3}},  // j 1
         {{97, 1}, {89, 3}, {71, 3}}    // j 2
     },
     {
         // i 1
         {{113, 0}, {99, 0}, {80, 5}},   // j 0
         {{116, 1}, {105, 0}, {88, 0}},  // j 1
         {{111, 1}, {103, 0}, {91, 0}}   // j 2
     },
     {
         // i 2
         {{117, 2}, {106, 5}, {90, 5}},  // j 0
         {{121, 1}, {113, 0}, {99, 0}},  // j 1
         {{119, 1}, {116, 1}, {105, 0}}  // j 2
     }},
    {// face 18
     {
         // i 0
         {{119, 0}, {111, 0}, {97, 0}},  // j 0
         {{115, 0}, {110, 0}, {98, 3}},  // j 1
         {{107, 1}, {104, 3}, {96, 3}}   // j 2
     },
     {
         // i 1
         {{121, 0}, {116, 0}, {103, 5}},  // j 0
         {{120, 1}, {119, 0}, {111, 0}},  // j 1
         {{112, 1}, {115, 0}, {110, 0}}   // j 2
     },
     {
         // i 2
         {{117, 1}, {113, 5}, {105, 5}},  // j 0
         {{118, 1}, {121, 0}, {116, 0}},  // j 1
         {{114, 1}, {120, 1}, {119, 0}}   // j 2
     }},
    {// face 19
     {
         // i 0
         {{114, 0}, {112, 0}, {107, 0}},  // j 0
         {{100, 0}, {102, 0}, {101, 3}},  // j 1
         {{83, 1}, {87, 3}, {85, 3}}      // j 2
     },
     {
         // i 1
         {{118, 0}, {120, 0}, {115, 5}},  // j 0
         {{108, 1}, {114, 0}, {112, 0}},  // j 1
         {{92, 1}, {100, 0}, {102, 0}}    // j 2
     },
     {
         // i 2
         {{117, 0}, {121, 5}, {119, 5}},  // j 0
         {{109, 1}, {118, 0}, {120, 0}},  // j 1
         {{95, 1}, {108, 1}, {114, 0}}    // j 2
     }}};

/** @brief Resolution 0 base cell data table.
 *
 * For each base cell, gives the "home" face and ijk+ coordinates on that face,
 * whether or not the base cell is a pentagon. Additionally, if the base cell
 * is a pentagon, the two cw offset rotation adjacent faces are given (-1
 * indicates that no cw offset rotation faces exist for this base cell).
 */
const BaseCellData baseCellData[NUM_BASE_CELLS] = {

    {{1, {1, 0, 0}}, 0, {0, 0}},     // base cell 0
    {{2, {1, 1, 0}}, 0, {0, 0}},     // base cell 1
    {{1, {0, 0, 0}}, 0, {0, 0}},     // base cell 2
    {{2, {1, 0, 0}}, 0, {0, 0}},     // base cell 3
    {{0, {2, 0, 0}}, 1, {-1, -1}},   // base cell 4
    {{1, {1, 1, 0}}, 0, {0, 0}},     // base cell 5
    {{1, {0, 0, 1}}, 0, {0, 0}},     // base cell 6
    {{2, {0, 0, 0}}, 0, {0, 0}},     // base cell 7
    {{0, {1, 0, 0}}, 0, {0, 0}},     // base cell 8
    {{2, {0, 1, 0}}, 0, {0, 0}},     // base cell 9
    {{1, {0, 1, 0}}, 0, {0, 0}},     // base cell 10
    {{1, {0, 1, 1}}, 0, {0, 0}},     // base cell 11
    {{3, {1, 0, 0}}, 0, {0, 0}},     // base cell 12
    {{3, {1, 1, 0}}, 0, {0, 0}},     // base cell 13
    {{11, {2, 0, 0}}, 1, {2, 6}},    // base cell 14
    {{4, {1, 0, 0}}, 0, {0, 0}},     // base cell 15
    {{0, {0, 0, 0}}, 0, {0, 0}},     // base cell 16
    {{6, {0, 1, 0}}, 0, {0, 0}},     // base cell 17
    {{0, {0, 0, 1}}, 0, {0, 0}},     // base cell 18
    {{2, {0, 1, 1}}, 0, {0, 0}},     // base cell 19
    {{7, {0, 0, 1}}, 0, {0, 0}},     // base cell 20
    {{2, {0, 0, 1}}, 0, {0, 0}},     // base cell 21
    {{0, {1, 1, 0}}, 0, {0, 0}},     // base cell 22
    {{6, {0, 0, 1}}, 0, {0, 0}},     // base cell 23
    {{10, {2, 0, 0}}, 1, {1, 5}},    // base cell 24
    {{6, {0, 0, 0}}, 0, {0, 0}},     // base cell 25
    {{3, {0, 0, 0}}, 0, {0, 0}},     // base cell 26
    {{11, {1, 0, 0}}, 0, {0, 0}},    // base cell 27
    {{4, {1, 1, 0}}, 0, {0, 0}},     // base cell 28
    {{3, {0, 1, 0}}, 0, {0, 0}},     // base cell 29
    {{0, {0, 1, 1}}, 0, {0, 0}},     // base cell 30
    {{4, {0, 0, 0}}, 0, {0, 0}},     // base cell 31
    {{5, {0, 1, 0}}, 0, {0, 0}},     // base cell 32
    {{0, {0, 1, 0}}, 0, {0, 0}},     // base cell 33
    {{7, {0, 1, 0}}, 0, {0, 0}},     // base cell 34
    {{11, {1, 1, 0}}, 0, {0, 0}},    // base cell 35
    {{7, {0, 0, 0}}, 0, {0, 0}},     // base cell 36
    {{10, {1, 0, 0}}, 0, {0, 0}},    // base cell 37
    {{12, {2, 0, 0}}, 1, {3, 7}},    // base cell 38
    {{6, {1, 0, 1}}, 0, {0, 0}},     // base cell 39
    {{7, {1, 0, 1}}, 0, {0, 0}},     // base cell 40
    {{4, {0, 0, 1}}, 0, {0, 0}},     // base cell 41
    {{3, {0, 0, 1}}, 0, {0, 0}},     // base cell 42
    {{3, {0, 1, 1}}, 0, {0, 0}},     // base cell 43
    {{4, {0, 1, 0}}, 0, {0, 0}},     // base cell 44
    {{6, {1, 0, 0}}, 0, {0, 0}},     // base cell 45
    {{11, {0, 0, 0}}, 0, {0, 0}},    // base cell 46
    {{8, {0, 0, 1}}, 0, {0, 0}},     // base cell 47
    {{5, {0, 0, 1}}, 0, {0, 0}},     // base cell 48
    {{14, {2, 0, 0}}, 1, {0, 9}},    // base cell 49
    {{5, {0, 0, 0}}, 0, {0, 0}},     // base cell 50
    {{12, {1, 0, 0}}, 0, {0, 0}},    // base cell 51
    {{10, {1, 1, 0}}, 0, {0, 0}},    // base cell 52
    {{4, {0, 1, 1}}, 0, {0, 0}},     // base cell 53
    {{12, {1, 1, 0}}, 0, {0, 0}},    // base cell 54
    {{7, {1, 0, 0}}, 0, {0, 0}},     // base cell 55
    {{11, {0, 1, 0}}, 0, {0, 0}},    // base cell 56
    {{10, {0, 0, 0}}, 0, {0, 0}},    // base cell 57
    {{13, {2, 0, 0}}, 1, {4, 8}},    // base cell 58
    {{10, {0, 0, 1}}, 0, {0, 0}},    // base cell 59
    {{11, {0, 0, 1}}, 0, {0, 0}},    // base cell 60
    {{9, {0, 1, 0}}, 0, {0, 0}},     // base cell 61
    {{8, {0, 1, 0}}, 0, {0, 0}},     // base cell 62
    {{6, {2, 0, 0}}, 1, {11, 15}},   // base cell 63
    {{8, {0, 0, 0}}, 0, {0, 0}},     // base cell 64
    {{9, {0, 0, 1}}, 0, {0, 0}},     // base cell 65
    {{14, {1, 0, 0}}, 0, {0, 0}},    // base cell 66
    {{5, {1, 0, 1}}, 0, {0, 0}},     // base cell 67
    {{16, {0, 1, 1}}, 0, {0, 0}},    // base cell 68
    {{8, {1, 0, 1}}, 0, {0, 0}},     // base cell 69
    {{5, {1, 0, 0}}, 0, {0, 0}},     // base cell 70
    {{12, {0, 0, 0}}, 0, {0, 0}},    // base cell 71
    {{7, {2, 0, 0}}, 1, {12, 16}},   // base cell 72
    {{12, {0, 1, 0}}, 0, {0, 0}},    // base cell 73
    {{10, {0, 1, 0}}, 0, {0, 0}},    // base cell 74
    {{9, {0, 0, 0}}, 0, {0, 0}},     // base cell 75
    {{13, {1, 0, 0}}, 0, {0, 0}},    // base cell 76
    {{16, {0, 0, 1}}, 0, {0, 0}},    // base cell 77
    {{15, {0, 1, 1}}, 0, {0, 0}},    // base cell 78
    {{15, {0, 1, 0}}, 0, {0, 0}},    // base cell 79
    {{16, {0, 1, 0}}, 0, {0, 0}},    // base cell 80
    {{14, {1, 1, 0}}, 0, {0, 0}},    // base cell 81
    {{13, {1, 1, 0}}, 0, {0, 0}},    // base cell 82
    {{5, {2, 0, 0}}, 1, {10, 19}},   // base cell 83
    {{8, {1, 0, 0}}, 0, {0, 0}},     // base cell 84
    {{14, {0, 0, 0}}, 0, {0, 0}},    // base cell 85
    {{9, {1, 0, 1}}, 0, {0, 0}},     // base cell 86
    {{14, {0, 0, 1}}, 0, {0, 0}},    // base cell 87
    {{17, {0, 0, 1}}, 0, {0, 0}},    // base cell 88
    {{12, {0, 0, 1}}, 0, {0, 0}},    // base cell 89
    {{16, {0, 0, 0}}, 0, {0, 0}},    // base cell 90
    {{17, {0, 1, 1}}, 0, {0, 0}},    // base cell 91
    {{15, {0, 0, 1}}, 0, {0, 0}},    // base cell 92
    {{16, {1, 0, 1}}, 0, {0, 0}},    // base cell 93
    {{9, {1, 0, 0}}, 0, {0, 0}},     // base cell 94
    {{15, {0, 0, 0}}, 0, {0, 0}},    // base cell 95
    {{13, {0, 0, 0}}, 0, {0, 0}},    // base cell 96
    {{8, {2, 0, 0}}, 1, {13, 17}},   // base cell 97
    {{13, {0, 1, 0}}, 0, {0, 0}},    // base cell 98
    {{17, {1, 0, 1}}, 0, {0, 0}},    // base cell 99
    {{19, {0, 1, 0}}, 0, {0, 0}},    // base cell 100
    {{14, {0, 1, 0}}, 0, {0, 0}},    // base cell 101
    {{19, {0, 1, 1}}, 0, {0, 0}},    // base cell 102
    {{17, {0, 1, 0}}, 0, {0, 0}},    // base cell 103
    {{13, {0, 0, 1}}, 0, {0, 0}},    // base cell 104
    {{17, {0, 0, 0}}, 0, {0, 0}},    // base cell 105
    {{16, {1, 0, 0}}, 0, {0, 0}},    // base cell 106
    {{9, {2, 0, 0}}, 1, {14, 18}},   // base cell 107
    {{15, {1, 0, 1}}, 0, {0, 0}},    // base cell 108
    {{15, {1, 0, 0}}, 0, {0, 0}},    // base cell 109
    {{18, {0, 1, 1}}, 0, {0, 0}},    // base cell 110
    {{18, {0, 0, 1}}, 0, {0, 0}},    // base cell 111
    {{19, {0, 0, 1}}, 0, {0, 0}},    // base cell 112
    {{17, {1, 0, 0}}, 0, {0, 0}},    // base cell 113
    {{19, {0, 0, 0}}, 0, {0, 0}},    // base cell 114
    {{18, {0, 1, 0}}, 0, {0, 0}},    // base cell 115
    {{18, {1, 0, 1}}, 0, {0, 0}},    // base cell 116
    {{19, {2, 0, 0}}, 1, {-1, -1}},  // base cell 117
    {{19, {1, 0, 0}}, 0, {0, 0}},    // base cell 118
    {{18, {0, 0, 0}}, 0, {0, 0}},    // base cell 119
    {{19, {1, 0, 1}}, 0, {0, 0}},    // base cell 120
    {{18, {1, 0, 0}}, 0, {0, 0}}     // base cell 121
};

/** @brief Return whether or not the indicated base cell is a pentagon. */
int _isBaseCellPentagon(int baseCell) {
    if (baseCell < 0 || baseCell >= NUM_BASE_CELLS) {
        // Base cells less than zero can not be represented in an index
        return false;
    }
    return baseCellData[baseCell].isPentagon;
}

/** @brief Return whether the indicated base cell is a pentagon where all
 * neighbors are oriented towards it. */
bool _isBaseCellPolarPentagon(int baseCell) {
    return baseCell == 4 || baseCell == 117;
}

/** @brief Find base cell given FaceIJK.
 *
 * Given the face number and a resolution 0 ijk+ coordinate in that face's
 * face-centered ijk coordinate system, return the base cell located at that
 * coordinate.
 *
 * Valid ijk+ lookup coordinates are from (0, 0, 0) to (2, 2, 2).
 */
int _faceIjkToBaseCell(const FaceIJK *h) {
    return faceIjkBaseCells[h->face][h->coord.i][h->coord.j][h->coord.k]
        .baseCell;
}

/** @brief Find base cell given FaceIJK.
 *
 * Given the face number and a resolution 0 ijk+ coordinate in that face's
 * face-centered ijk coordinate system, return the number of 60' ccw rotations
 * to rotate into the coordinate system of the base cell at that coordinates.
 *
 * Valid ijk+ lookup coordinates are from (0, 0, 0) to (2, 2, 2).
 */
int _faceIjkToBaseCellCCWrot60(const FaceIJK *h) {
    return faceIjkBaseCells[h->face][h->coord.i][h->coord.j][h->coord.k]
        .ccwRot60;
}

/** @brief Find the FaceIJK given a base cell.
 */
void _baseCellToFaceIjk(int baseCell, FaceIJK *h) {
    *h = baseCellData[baseCell].homeFijk;
}

/**
 * @brief Given a base cell and the face it appears on, return
 *        the number of 60' ccw rotations for that base cell's
 *        coordinate system.
 * @returns The number of rotations, or INVALID_ROTATIONS if the base
 *          cell is not found on the given face
 */
int _baseCellToCCWrot60(int baseCell, int face) {
    if (face < 0 || face > NUM_ICOSA_FACES) return INVALID_ROTATIONS;
    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < 3; j++) {
            for (int k = 0; k < 3; k++) {
                if (faceIjkBaseCells[face][i][j][k].baseCell == baseCell) {
                    return faceIjkBaseCells[face][i][j][k].ccwRot60;
                }
            }
        }
    }
    return INVALID_ROTATIONS;
}

/** @brief Return whether or not the tested face is a cw offset face.
 */
bool _baseCellIsCwOffset(int baseCell, int testFace) {
    return baseCellData[baseCell].cwOffsetPent[0] == testFace ||
           baseCellData[baseCell].cwOffsetPent[1] == testFace;
}

/** @brief Return the neighboring base cell in the given direction.
 */
int _getBaseCellNeighbor(int baseCell, Direction dir) {
    return baseCellNeighbors[baseCell][dir];
}

/** @brief Return the direction from the origin base cell to the neighbor.
 * Returns INVALID_DIGIT if the base cells are not neighbors.
 */
Direction _getBaseCellDirection(int originBaseCell, int neighboringBaseCell) {
    for (Direction dir = CENTER_DIGIT; dir < NUM_DIGITS; dir++) {
        int testBaseCell = _getBaseCellNeighbor(originBaseCell, dir);
        if (testBaseCell == neighboringBaseCell) {
            return dir;
        }
    }
    return INVALID_DIGIT;
}

/**
 * res0CellCount returns the number of resolution 0 cells
 *
 * @return int count of resolution 0 cells
 */
int H3_EXPORT(res0CellCount)() { return NUM_BASE_CELLS; }

/**
 * getRes0Cells generates all base cells storing them into the provided
 * memory pointer. Buffer must be of size NUM_BASE_CELLS * sizeof(H3Index).
 *
 * @param out H3Index* the memory to store the resulting base cells in
 * @returns E_SUCCESS.
 */
H3Error H3_EXPORT(getRes0Cells)(H3Index *out) {
    for (int bc = 0; bc < NUM_BASE_CELLS; bc++) {
        H3Index baseCell = H3_INIT;
        H3_SET_MODE(baseCell, H3_CELL_MODE);
        H3_SET_BASE_CELL(baseCell, bc);
        out[bc] = baseCell;
    }
    return E_SUCCESS;
}