Cross compile to Mac arm64 (#89)

* Cross compile to Mac arm64
* Docs changes for M1

Author: isaacbrodsky

CHANGELOG.md

@@ -7,23 +7,25 @@ file [H3Core.java](./src/main/java/com/uber/h3core/H3Core.java), and support
 for the Linux x64 and Darwin x64 platforms.
 
 ## [Unreleased]
-## Fixed
-- Fixes local build script to support Apple M1
+### Added
+- Added Apple M1 build (#89)
+### Fixed
+- Fixes local build script to support Apple M1 (#86)
 
 ## [3.7.1] - 2021-08-18
-## Fixed
+### Fixed
 - Fixes for non-English locales (#80)
 
-## Changed
+### Changed
 - Updated the core library to v3.7.2. (#81)
 
 ## [3.7.0] - 2020-12-03
-## Added
+### Added
 - Area and haversine distance functions (#70)
     - `cellArea`
     - `pointDist`
     - `exactEdgeLength`
-## Changed
+### Changed
 - Updated the core library to v3.7.1. (#70)
 
 ## [3.6.4] - 2020-06-29

README.md

@@ -54,7 +54,7 @@ H3-Java provides bindings to the H3 library, which is written in C. The built ar
 | ---------------- | -------------
 | Linux            | x64, x86, ARM64, ARMv5, ARMv7, MIPS, MIPSEL, PPC64LE, s390x
 | Windows          | x64, x86
-| Darwin (Mac OSX) | x64
+| Darwin (Mac OSX) | x64, ARM64
 | FreeBSD          | x64
 | Android          | ARM, ARM64
 

src/main/c/h3-java/build-h3.sh

@@ -107,6 +107,42 @@ esac
 mkdir -p src/main/resources/$LIBRARY_DIR
 cp target/h3-java-build/lib/libh3-java* src/main/resources/$LIBRARY_DIR
 
+# Cross compile from Mac x64 to Mac arm64
+if [ "$(uname -sm)" == "Darwin x86_64" ]; then
+    pushd target
+
+    mkdir -p h3-java-build-mac-arm64
+    pushd h3-java-build-mac-arm64
+
+    mkdir -p build
+    pushd build
+
+    cmake -DBUILD_SHARED_LIBS=OFF \
+        -DCMAKE_POSITION_INDEPENDENT_CODE=ON \
+        -DCMAKE_BUILD_TYPE=Release \
+        -DCMAKE_OSX_ARCHITECTURES="arm64" \
+        ../../h3
+    cmake --build . --target h3 --config Release
+    H3_BUILD_ROOT="$(pwd)"
+
+    popd # build
+
+    cmake -DUSE_NATIVE_JNI=ON \
+        -DBUILD_SHARED_LIBS=ON \
+        "-DH3_BUILD_ROOT=$H3_BUILD_ROOT" \
+        -DCMAKE_BUILD_TYPE=Release \
+        -DCMAKE_OSX_ARCHITECTURES="arm64" \
+        ../../src/main/c/h3-java
+    cmake --build . --target h3-java --config Release
+
+    popd # h3-java-build
+
+    popd # target
+
+    mkdir -p src/main/resources/darwin-arm64
+    cp target/h3-java-build-mac-arm64/lib/libh3-java* src/main/resources/darwin-arm64
+fi
+
 #
 # Now that H3 is downloaded, build H3-Java's native library for other platforms.
 #