dusk/cmake/targets/saturn.cmake

# Copyright (c) 2026 Dominic Masters
#
# This software is released under the MIT License.
# https://opensource.org/licenses/MIT

# Resolve YAUL_INSTALL_ROOT (already set by the toolchain file, but guard
# in case cmake/targets/ is loaded standalone for IDE tooling).
if(NOT DEFINED YAUL_INSTALL_ROOT)
  if(DEFINED ENV{YAUL_INSTALL_ROOT})
    set(YAUL_INSTALL_ROOT "$ENV{YAUL_INSTALL_ROOT}")
  else()
    set(YAUL_INSTALL_ROOT "/opt/yaul")
  endif()
endif()

# Yaul installs headers/libs under the arch-prefix sysroot subdirectory:
#   ${YAUL_INSTALL_ROOT}/sh2eb-elf/include/
#   ${YAUL_INSTALL_ROOT}/sh2eb-elf/lib/
# Cross-compiled zlib and libzip are installed to the same sysroot.
set(_YAUL_SYSROOT "${YAUL_INSTALL_ROOT}/sh2eb-elf")
set(_YAUL_BIN     "${YAUL_INSTALL_ROOT}/bin")

# ---------------------------------------------------------------------------
# Bypass system find_package calls for libraries we cross-compile into the
# sh2eb-elf sysroot and install into ${_YAUL_SYSROOT}.
# ---------------------------------------------------------------------------

# zlib
if(NOT TARGET ZLIB::ZLIB)
  add_library(ZLIB::ZLIB INTERFACE IMPORTED GLOBAL)
  set_target_properties(ZLIB::ZLIB PROPERTIES
    INTERFACE_INCLUDE_DIRECTORIES "${_YAUL_SYSROOT}/include"
    INTERFACE_LINK_LIBRARIES      "${_YAUL_SYSROOT}/lib/libz.a"
  )
endif()
set(ZLIB_FOUND         TRUE CACHE BOOL "" FORCE)
set(ZLIB_INCLUDE_DIR   "${_YAUL_SYSROOT}/include" CACHE PATH "" FORCE)
set(ZLIB_LIBRARY       "${_YAUL_SYSROOT}/lib/libz.a" CACHE FILEPATH "" FORCE)

# libzip — pre-installed into the sh2eb-elf sysroot; skip Findlibzip.cmake.
set(libzip_FOUND TRUE CACHE BOOL "libzip found (Saturn sysroot)" FORCE)
find_path(_sat_zip_inc NAMES zip.h
  PATHS "${_YAUL_SYSROOT}/include"
  NO_DEFAULT_PATH
)
if(_sat_zip_inc)
  target_include_directories(${DUSK_LIBRARY_TARGET_NAME} PRIVATE "${_sat_zip_inc}")
endif()

# ---------------------------------------------------------------------------
# Compile definitions
# ---------------------------------------------------------------------------
target_compile_definitions(${DUSK_LIBRARY_TARGET_NAME} PUBLIC
  DUSK_SATURN
  DUSK_INPUT_GAMEPAD
  DUSK_PLATFORM_ENDIAN_BIG
  DUSK_DISPLAY_WIDTH=320
  DUSK_DISPLAY_HEIGHT=224
  DUSK_THREAD_NONE
)

# ---------------------------------------------------------------------------
# Compile options
# ---------------------------------------------------------------------------
target_compile_options(${DUSK_LIBRARY_TARGET_NAME} PRIVATE
  -m2 -mb
  -fno-builtin
  -fomit-frame-pointer
  -w
)

# ---------------------------------------------------------------------------
# Include paths
# ---------------------------------------------------------------------------
target_include_directories(${DUSK_LIBRARY_TARGET_NAME} PRIVATE
  "${_YAUL_SYSROOT}/include"
  "${_YAUL_SYSROOT}/include/yaul"
)

# ---------------------------------------------------------------------------
# Link libraries
# ---------------------------------------------------------------------------
target_link_directories(${DUSK_LIBRARY_TARGET_NAME} PRIVATE
  "${_YAUL_SYSROOT}/lib"
)

target_link_libraries(${DUSK_LIBRARY_TARGET_NAME} PRIVATE
  # --start-group/--end-group allow circular archive references
  # (e.g. libyaul allocator symbols referenced by libzip / yyjson objects).
  -Wl,--start-group
  "${_YAUL_SYSROOT}/lib/libyaul.a"
  "${_YAUL_SYSROOT}/lib/libzip.a"
  "${_YAUL_SYSROOT}/lib/libz.a"
  # GCC soft-float / soft-divide runtime (SH-2 has no FPU or hw divider).
  # -lgcc is resolved by the compiler driver even with -nodefaultlibs.
  -lgcc
  -Wl,--end-group
)

# Yaul linker script (Saturn SH-2 memory map) and startup objects.
# Startup objects must precede all other objects so use target_link_options
# (those flags appear before the object-file list in cmake's link command).
target_link_options(${DUSK_BINARY_TARGET_NAME} PRIVATE
  "-T${_YAUL_SYSROOT}/lib/ldscripts/yaul.x"
  "${_YAUL_SYSROOT}/lib/crt0.o"
  "${_YAUL_SYSROOT}/lib/init.o"
  # Provide SH-2 stack top addresses required by crt0.o/cpu_dual_entries.o.
  # RAM region: 0x06004000 .. 0x06100000 (~1 MB).
  # Master stack grows down from the very top; slave CPU gets 4 KB below.
  "-Wl,--defsym=___master_stack=0x06100000"
  "-Wl,--defsym=___slave_stack=0x060FF000"
)


# ---------------------------------------------------------------------------
# Post-build: ELF → binary → Saturn disc image (ISO + CUE)
# ---------------------------------------------------------------------------
set(DUSK_SAT_BIN       "${CMAKE_BINARY_DIR}/Dusk.bin")
set(DUSK_SAT_IP_BIN    "${CMAKE_BINARY_DIR}/IP.BIN")
set(DUSK_SAT_CD_DIR    "${CMAKE_BINARY_DIR}/cd")
set(DUSK_SAT_AUDIO_DIR "${CMAKE_BINARY_DIR}/audio-tracks")
set(DUSK_SAT_ISO       "${CMAKE_BINARY_DIR}/Dusk.iso")
set(DUSK_SAT_CUE       "${CMAKE_BINARY_DIR}/Dusk.cue")

# Step 1: ELF → flat binary (loaded into Work RAM by IP.BIN)
add_custom_command(TARGET ${DUSK_BINARY_TARGET_NAME} POST_BUILD
  COMMAND "${_YAUL_BIN}/sh2eb-elf-objcopy"
          -O binary
          "$<TARGET_FILE:${DUSK_BINARY_TARGET_NAME}>"
          "${DUSK_SAT_BIN}"
  COMMENT "Converting ELF → ${DUSK_SAT_BIN}"
)

# Step 2: flat binary → IP.BIN (boot header with region security blobs)
# make-ip writes IP.BIN into dirname(arg1), so it lands at ${CMAKE_BINARY_DIR}/IP.BIN.
# Pass -1 for 1st-read-size so make-ip uses the actual file size.
add_custom_command(TARGET ${DUSK_BINARY_TARGET_NAME} POST_BUILD
  COMMAND ${CMAKE_COMMAND} -E env
    "YAUL_INSTALL_ROOT=${YAUL_INSTALL_ROOT}"
    "YAUL_ARCH_SH_PREFIX=sh2eb-elf"
    "${_YAUL_BIN}/make-ip"
      "${DUSK_SAT_BIN}"
      "V1.000"
      "20260101"
      "JTUE"
      "J"
      "DUSK"
      "0x06100000"
      "0x060FF000"
      "0x06004000"
      "-1"
  COMMENT "Generating IP.BIN"
)

# Step 3: build CD filesystem tree and create ISO 9660 image
add_custom_command(TARGET ${DUSK_BINARY_TARGET_NAME} POST_BUILD
  COMMAND ${CMAKE_COMMAND} -E make_directory "${DUSK_SAT_CD_DIR}"
  COMMAND ${CMAKE_COMMAND} -E make_directory "${DUSK_SAT_AUDIO_DIR}"
  COMMAND ${CMAKE_COMMAND} -E copy "${DUSK_SAT_BIN}" "${DUSK_SAT_CD_DIR}/A.BIN"
  # ISO 9660 requires these auxiliary text files
  COMMAND ${CMAKE_COMMAND} -E touch "${DUSK_SAT_CD_DIR}/ABS.TXT"
  COMMAND ${CMAKE_COMMAND} -E touch "${DUSK_SAT_CD_DIR}/BIB.TXT"
  COMMAND ${CMAKE_COMMAND} -E touch "${DUSK_SAT_CD_DIR}/CPY.TXT"
  COMMAND ${CMAKE_COMMAND} -E env
    "YAUL_INSTALL_ROOT=${YAUL_INSTALL_ROOT}"
    "MAKE_ISO_XORRISOFS=/usr/bin/xorrisofs"
    "${_YAUL_BIN}/make-iso"
      "${DUSK_SAT_CD_DIR}"
      "${DUSK_SAT_IP_BIN}"
      "${CMAKE_BINARY_DIR}"
      "Dusk"
  COMMENT "Generating ${DUSK_SAT_ISO}"
)

# Step 4: ISO → CUE sheet  (rename .iso → .bin for a classic BIN/CUE pair
# if desired; emulators accept .iso+.cue as-is)
add_custom_command(TARGET ${DUSK_BINARY_TARGET_NAME} POST_BUILD
  COMMAND ${CMAKE_COMMAND} -E env
    "YAUL_INSTALL_ROOT=${YAUL_INSTALL_ROOT}"
    "${_YAUL_BIN}/make-cue"
      "${DUSK_SAT_AUDIO_DIR}"
      "${DUSK_SAT_ISO}"
  COMMENT "Generating ${DUSK_SAT_CUE}"
)