CMakeLists.txt

cmake_minimum_required(VERSION 3.24)
project(sensor_processing_native)

# Set C++ standard
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

# Set build type to Release for optimization
if(NOT CMAKE_BUILD_TYPE)
    set(CMAKE_BUILD_TYPE Release)
endif()

# Compiler-specific optimizations
# Note: -ffast-math is intentionally omitted — it breaks FINUFFT (IEEE-754 violations)
# CI runners use a portable baseline -- x86-64-v3 (AVX2) on x86, the Apple M1
# on Apple Silicon -- so release wheels run on any CPU of that family; local
# builds use native.
if(DEFINED ENV{CI} AND "$ENV{CI}" STREQUAL "true")
    if(APPLE AND CMAKE_SYSTEM_PROCESSOR MATCHES "arm64|aarch64")
        set(MARCH_FLAG "-mcpu=apple-m1")
    else()
        set(MARCH_FLAG "-march=x86-64-v3")
    endif()
    # FINUFFT defaults FINUFFT_ARCH_FLAGS to "native" (-march=native), which bakes
    # the build machine's ISA (e.g. AVX-512) into libfinufft.so. Release wheels
    # must be portable, so pin the dependency to the same baseline as the rest of
    # the build. This must be a CACHE variable: FINUFFT's own CMakeLists declares
    # it with `CACHE`, and normal variables do not propagate into its scope.
    set(FINUFFT_ARCH_FLAGS "${MARCH_FLAG}" CACHE STRING "" FORCE)
else()
    set(MARCH_FLAG "-march=native -mtune=native")
    set(FINUFFT_ARCH_FLAGS "-march=native" CACHE STRING "" FORCE)
endif()
if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
    set(CMAKE_CXX_FLAGS_RELEASE "-O3 ${MARCH_FLAG}")
elseif(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
    set(CMAKE_CXX_FLAGS_RELEASE "-O3 ${MARCH_FLAG}")
elseif(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
    set(CMAKE_CXX_FLAGS_RELEASE "/O2 /arch:AVX2")
endif()

# Apple Clang needs explicit help finding Homebrew's libomp.
# Flags must be semicolon-separated CMake lists, not space-separated strings,
# so that each flag is passed as a separate argument to the compiler.
if(APPLE)
    if(DEFINED ENV{LIBOMP_PREFIX})
        set(LIBOMP_PREFIX "$ENV{LIBOMP_PREFIX}")
    else()
        # Only use Homebrew-specific hints if Homebrew is available.
        find_program(HOMEBREW_EXECUTABLE brew)
    endif()
    if(NOT LIBOMP_PREFIX AND HOMEBREW_EXECUTABLE)
        execute_process(
            COMMAND "${HOMEBREW_EXECUTABLE}" --prefix libomp
            OUTPUT_VARIABLE LIBOMP_PREFIX
            OUTPUT_STRIP_TRAILING_WHITESPACE
        )
    endif()
    if(LIBOMP_PREFIX)
        set(OpenMP_C_FLAGS "-Xpreprocessor;-fopenmp;-I${LIBOMP_PREFIX}/include")
        set(OpenMP_CXX_FLAGS "-Xpreprocessor;-fopenmp;-I${LIBOMP_PREFIX}/include")
        set(OpenMP_C_LIB_NAMES "omp")
        set(OpenMP_CXX_LIB_NAMES "omp")
        set(OpenMP_omp_LIBRARY "${LIBOMP_PREFIX}/lib/libomp.dylib")
    endif()
endif()

# Download CPM.cmake
file(
  DOWNLOAD
  https://github.com/cpm-cmake/CPM.cmake/releases/download/v0.40.8/CPM.cmake
  ${CMAKE_CURRENT_BINARY_DIR}/cmake/CPM.cmake
  EXPECTED_HASH SHA256=78ba32abdf798bc616bab7c73aac32a17bbd7b06ad9e26a6add69de8f3ae4791
)
include(${CMAKE_CURRENT_BINARY_DIR}/cmake/CPM.cmake)

# Add finufft dependency
CPMAddPackage("gh:flatironinstitute/finufft@2.5.0")

# Find required packages
find_package(PkgConfig)

# Add src/ to include paths
include_directories(${CMAKE_CURRENT_SOURCE_DIR}/src)

# Add the shared library
add_library(sensor_processing SHARED
    src/sensor_processing_native.cpp
)

# Set library properties
set_target_properties(sensor_processing PROPERTIES
    CXX_VISIBILITY_PRESET default
    VERSION 2.0.0
    SOVERSION 2
)

# Include directories
target_include_directories(sensor_processing PRIVATE
    ${CMAKE_CURRENT_SOURCE_DIR}
)

# Link required FINUFFT dependency
target_link_libraries(sensor_processing PRIVATE finufft)

# Platform-specific settings
if(ANDROID)
    # Android-specific settings
    find_library(log-lib log)
    target_link_libraries(sensor_processing PRIVATE ${log-lib})
    
elseif(APPLE)
    # macOS/iOS-specific settings
    set_target_properties(sensor_processing PROPERTIES
        MACOSX_RPATH TRUE
        INSTALL_RPATH "@loader_path"
    )
    
elseif(WIN32)
    # Windows-specific settings
    target_compile_definitions(sensor_processing PRIVATE WIN32_LEAN_AND_MEAN)
    
elseif(UNIX)
    # Linux-specific settings
    target_link_libraries(sensor_processing PRIVATE m pthread)
endif()

# Install rules
install(TARGETS sensor_processing
    LIBRARY DESTINATION lib
    ARCHIVE DESTINATION lib
    RUNTIME DESTINATION bin
)

# Export compile commands for IDEs
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)