CMakeLists.txt

cmake_minimum_required(VERSION 3.20)

# XGBoost inference has been moved to P25 (Market Maker) for lower latency
# P24 now focuses solely on PCIe reception and Disruptor publishing
# Expected latency improvement: ~300µs -> ~5µs

project(OrderGateway C CXX)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

# Project 24: Order Gateway
# PCIe Input + Disruptor Output (XGBoost moved to P25)
message(STATUS "==============================================")
message(STATUS "  Project 24: Order Gateway")
message(STATUS "  PCIe + Disruptor (low-latency passthrough)")
message(STATUS "==============================================")

# Add vcpkg installed directory to CMAKE_PREFIX_PATH if it exists
# BUT: Skip vcpkg when cross-compiling (e.g., with Buildroot toolchain)
# vcpkg libraries are built with host compiler and won't work with cross-compiler
if(CMAKE_CROSSCOMPILING)
    message(STATUS "Cross-compiling detected - skipping vcpkg (use Buildroot packages instead)")
    # Explicitly remove vcpkg paths to prevent CMake from finding host-built libraries
    list(REMOVE_ITEM CMAKE_PREFIX_PATH "${CMAKE_SOURCE_DIR}/vcpkg_installed/x64-linux/share")
    # Also remove from CMAKE_FIND_ROOT_PATH if set
    list(REMOVE_ITEM CMAKE_FIND_ROOT_PATH "${CMAKE_SOURCE_DIR}/vcpkg_installed/x64-linux")
elseif(EXISTS "${CMAKE_SOURCE_DIR}/vcpkg_installed/x64-linux/share")
    list(APPEND CMAKE_PREFIX_PATH "${CMAKE_SOURCE_DIR}/vcpkg_installed/x64-linux/share")
    message(STATUS "Added vcpkg_installed to CMAKE_PREFIX_PATH")
endif()

# Required packages
find_package(Threads REQUIRED)

# spdlog - use system library when cross-compiling, FetchContent otherwise
if(CMAKE_CROSSCOMPILING)
    message(STATUS "Cross-compiling: using system spdlog with external fmt")
    find_package(spdlog REQUIRED)
    find_package(fmt REQUIRED)
    # Tell spdlog to use external fmt (Buildroot configuration)
    add_compile_definitions(SPDLOG_FMT_EXTERNAL)
else()
    # Native build: use FetchContent with bundled fmt to avoid system fmt version conflicts
    message(STATUS "Native build: using FetchContent spdlog with bundled fmt")
    include(FetchContent)
    FetchContent_Declare(
        spdlog
        GIT_REPOSITORY https://github.com/gabime/spdlog.git
        GIT_TAG v1.14.1
        GIT_SHALLOW TRUE
    )
    set(SPDLOG_FMT_EXTERNAL OFF CACHE BOOL "" FORCE)  # Use bundled fmt
    set(SPDLOG_BUILD_SHARED OFF CACHE BOOL "" FORCE)  # Static/header-only
    FetchContent_MakeAvailable(spdlog)
endif()

# nlohmann_json - try find_package first, fallback to FetchContent
find_package(nlohmann_json CONFIG QUIET)
if(NOT nlohmann_json_FOUND)
    message(STATUS "nlohmann_json not found, fetching from GitHub...")
    include(FetchContent)
    FetchContent_Declare(
        nlohmann_json
        GIT_REPOSITORY https://github.com/nlohmann/json.git
        GIT_TAG v3.11.3
        GIT_SHALLOW TRUE
    )
    FetchContent_MakeAvailable(nlohmann_json)
endif()

# Set default build type to Debug if not specified
if(NOT CMAKE_BUILD_TYPE)
    set(CMAKE_BUILD_TYPE Release CACHE STRING "Build type" FORCE)
    message(STATUS "CMAKE_BUILD_TYPE not set, defaulting to Release")
endif()

# Generate compile_commands.json for IntelliSense
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

# Include directories
include_directories(${CMAKE_SOURCE_DIR}/include)
include_directories(${CMAKE_SOURCE_DIR}/../common)

# Source files (PCIe + Disruptor passthrough)
set(SOURCES
    src/main.cpp
    src/order_gateway.cpp
    src/pcie_listener_v2.cpp
)

# Assembly optimization files (x86-64 BSWAP + AVX2)
set(ASM_SOURCES
    src/asm/bbo_parser_asm.S
)

# Enable assembly language support
enable_language(ASM)

# Executable
add_executable(order_gateway ${SOURCES} ${ASM_SOURCES})

# Link libraries
if(CMAKE_CROSSCOMPILING)
    # Cross-compile: use system spdlog with external fmt
    target_link_libraries(order_gateway PRIVATE
        spdlog::spdlog
        fmt::fmt
        nlohmann_json::nlohmann_json
        Threads::Threads
    )
else()
    # Native: spdlog_header_only with bundled fmt
    target_link_libraries(order_gateway PRIVATE
        spdlog::spdlog_header_only
        nlohmann_json::nlohmann_json
        Threads::Threads
    )
endif()

# Ensure libstdc++ is linked (required for C++ ABI functions)
# This is especially important when cross-compiling
if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
    target_link_libraries(order_gateway PRIVATE stdc++fs)  # C++17 filesystem
    if(CMAKE_CROSSCOMPILING)
        message(STATUS "Cross-compiling: ensuring libstdc++ is linked from Buildroot toolchain")
    endif()
endif()

# Linux-specific optimizations
if(UNIX AND NOT APPLE)
    target_compile_options(order_gateway PRIVATE -march=native -O3)
endif()

# Installation
install(TARGETS order_gateway DESTINATION bin)

# =============================================================================
# Benchmark target (optional - requires Google Benchmark)
# =============================================================================
find_package(benchmark QUIET)
if(benchmark_FOUND)
    message(STATUS "Google Benchmark found - building bbo_benchmark")

    add_executable(bbo_benchmark
        benchmark/bbo_benchmark.cpp
        ${ASM_SOURCES}
    )

    target_include_directories(bbo_benchmark PRIVATE ${CMAKE_SOURCE_DIR}/include)
    target_link_libraries(bbo_benchmark PRIVATE
        benchmark::benchmark
        Threads::Threads
    )
    target_compile_options(bbo_benchmark PRIVATE -march=native -O3)

    # Add benchmark to install
    install(TARGETS bbo_benchmark DESTINATION bin)
else()
    message(STATUS "Google Benchmark not found - skipping bbo_benchmark")
    message(STATUS "  Install with: sudo apt install libbenchmark-dev")
endif()

# Standalone assembly test (no external dependencies)
add_executable(bbo_test
    benchmark/bbo_test.cpp
    ${ASM_SOURCES}
)
target_include_directories(bbo_test PRIVATE ${CMAKE_SOURCE_DIR}/include)
target_compile_options(bbo_test PRIVATE -march=native -O3)

# Ring buffer benchmark (demonstrates V2 listener improvements)
add_executable(ring_buffer_benchmark
    benchmark/ring_buffer_benchmark.cpp
)
target_include_directories(ring_buffer_benchmark PRIVATE ${CMAKE_SOURCE_DIR}/include)
target_link_libraries(ring_buffer_benchmark PRIVATE Threads::Threads)
target_compile_options(ring_buffer_benchmark PRIVATE -march=native -O3)
install(TARGETS ring_buffer_benchmark DESTINATION bin)

# Print build information
message(STATUS "")
message(STATUS "Build configuration:")
message(STATUS "  CMAKE_BUILD_TYPE: ${CMAKE_BUILD_TYPE}")
message(STATUS "  CMAKE_CXX_COMPILER: ${CMAKE_CXX_COMPILER}")
message(STATUS "  CMAKE_CXX_STANDARD: ${CMAKE_CXX_STANDARD}")
message(STATUS "  Mode: Low-latency passthrough (XGBoost inference moved to P25)")
message(STATUS "")