From cbb377b4b6e537f8e1f0e70e672ed6cd1e7ec2fc Mon Sep 17 00:00:00 2001
From: James Benton <james.benton2@gmail.com>
Date: Fri, 5 May 2017 17:00:33 +0100
Subject: [PATCH] Add "crt-lite", builds an empty crt0 without C runtime stuff
 (such as malloc and devoptap).

---
 CMakeLists.txt            | 10 ++++++++++
 cmake/wut-toolchain.cmake | 14 ++++++++++++++
 crt-lite/CMakeLists.txt   | 15 +++++++++++++++
 crt-lite/crt0.s           | 15 +++++++++++++++
 4 files changed, 54 insertions(+)
 create mode 100644 crt-lite/CMakeLists.txt
 create mode 100644 crt-lite/crt0.s

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 50849f07..c924a688 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,6 +21,16 @@ externalproject_add(crt
       -DCMAKE_INSTALL_PREFIX:string=<INSTALL_DIR>
       -DCMAKE_TOOLCHAIN_FILE:string=${CMAKE_SOURCE_DIR}/cmake/wut-toolchain.cmake)
 
+externalproject_add(crt-lite
+   SOURCE_DIR "${CMAKE_SOURCE_DIR}/crt-lite"
+   CMAKE_GENERATOR "Unix Makefiles"
+   INSTALL_DIR "${CMAKE_BINARY_DIR}/staging"
+   CMAKE_CACHE_ARGS
+      -DDEVKITPPC:string=${DEVKITPPC}
+      -DWUT_ROOT:string=${CMAKE_SOURCE_DIR}
+      -DCMAKE_INSTALL_PREFIX:string=<INSTALL_DIR>
+      -DCMAKE_TOOLCHAIN_FILE:string=${CMAKE_SOURCE_DIR}/cmake/wut-toolchain.cmake)
+
 externalproject_add(rpl
    SOURCE_DIR "${CMAKE_SOURCE_DIR}/rpl"
    CMAKE_GENERATOR "Unix Makefiles"
diff --git a/cmake/wut-toolchain.cmake b/cmake/wut-toolchain.cmake
index 28bb81cf..8bd75c26 100644
--- a/cmake/wut-toolchain.cmake
+++ b/cmake/wut-toolchain.cmake
@@ -70,3 +70,17 @@ macro(add_rpx target)
         COMMAND "${ELF_TO_RPL}" "$<TARGET_FILE:${target}>" "$<TARGET_FILE:${target}>.rpx"
         COMMENT "Converting $<TARGET_FILE:${target}> to rpx")
 endmacro()
+
+macro(add_rpx_lite target)
+    add_executable(${ARGV})
+    set_target_properties(${target} PROPERTIES
+        COMPILE_FLAGS "${RPX_COMPILE_FLAGS}"
+        LINK_FLAGS "${RPX_LINKER_FLAGS}")
+
+    target_include_directories(${target} PRIVATE "${WUT_ROOT}/include")
+    target_link_libraries(${target} crt-lite)
+
+    add_custom_command(TARGET ${target} POST_BUILD
+        COMMAND "${ELF_TO_RPL}" "$<TARGET_FILE:${target}>" "$<TARGET_FILE:${target}>.rpx"
+        COMMENT "Converting $<TARGET_FILE:${target}> to rpx")
+endmacro()
diff --git a/crt-lite/CMakeLists.txt b/crt-lite/CMakeLists.txt
new file mode 100644
index 00000000..c07de00b
--- /dev/null
+++ b/crt-lite/CMakeLists.txt
@@ -0,0 +1,15 @@
+cmake_minimum_required(VERSION 3.2)
+project(wut-crt-lite)
+
+include(../cmake/wut-toolchain.cmake)
+
+set_property(SOURCE crt0.S PROPERTY LANGUAGE C)
+
+add_library(crt-lite
+    crt0.S)
+set_target_properties(crt-lite PROPERTIES
+    COMPILE_FLAGS "-fno-builtin -ffreestanding"
+    LINKER_FLAGS "-fPIC")
+target_include_directories(crt-lite PRIVATE "../include")
+
+install(TARGETS crt-lite ARCHIVE DESTINATION "${CMAKE_INSTALL_PREFIX}/lib")
diff --git a/crt-lite/crt0.s b/crt-lite/crt0.s
new file mode 100644
index 00000000..65701059
--- /dev/null
+++ b/crt-lite/crt0.s
@@ -0,0 +1,15 @@
+.extern main
+.extern exit
+
+.global _start
+_start:
+   bl main
+   b exit
+
+.global __wrap___eabi
+__wrap___eabi:
+   blr
+
+.global __init
+__init:
+   blr