Some cmake build improvements (#376)

* Change some cmake output to DEBUG level
Make SDK build more consistent with other libraries (use an INTERFACE marker library for inclusion tests)
Add PICO_SDK_PRE_LIST_FILES, PICO_SDK_POST_LIST_FILES build vars

* fix typo

* remove leftover debugging message

CMakeLists.txt

@@ -1,6 +1,10 @@
 cmake_minimum_required(VERSION 3.13)
+
+# Note: this CMakeLists.txt can be used as a top-level CMakeLists.txt for the SDK itself. For all other uses
+# it is included as a subdirectory via the pico_sdk_init() method provided by pico_sdk_init.cmake
 if (NOT TARGET _pico_sdk_inclusion_marker)
     add_library(_pico_sdk_inclusion_marker INTERFACE)
+    # This is a no-op unless we are the top-level CMakeLists.txt
     include(pico_sdk_init.cmake)
 
     project(pico_sdk C CXX ASM)
@@ -24,6 +28,7 @@ if (NOT TARGET _pico_sdk_inclusion_marker)
 
     # allow customization
     add_sub_list_dirs(PICO_SDK_PRE_LIST_DIRS)
+    add_sub_list_files(PICO_SDK_PRE_LIST_FILES)
 
     add_subdirectory(tools)
     add_subdirectory(src)
@@ -32,6 +37,7 @@ if (NOT TARGET _pico_sdk_inclusion_marker)
 
     # allow customization
     add_sub_list_dirs(PICO_SDK_POST_LIST_DIRS)
+    add_sub_list_files(PICO_SDK_POST_LIST_FILES)
 
     if (PICO_SDK_TOP_LEVEL_PROJECT AND NOT DEFINED PICO_SDK_TESTS_ENABLED)
         set(PICO_SDK_TESTS_ENABLED 1)

cmake/preload/toolchains/pico_arm_gcc.cmake

@@ -12,7 +12,7 @@ if (NOT PICO_GCC_TRIPLE)
         message("PICO_GCC_TRIPLE set from environment: $ENV{PICO_GCC_TRIPLE}")
     else()
         set(PICO_GCC_TRIPLE arm-none-eabi)
-        message("PICO_GCC_TRIPLE defaulted to arm-none-eabi")
+        message(DEBUG "PICO_GCC_TRIPLE defaulted to arm-none-eabi")
     endif()
 endif()
 

pico_sdk_init.cmake

@@ -1,10 +1,12 @@
-# Initialize the Raspberry Pi Pico SDK
+# Pre-initialize the Raspberry Pi Pico SDK, setting up the platform and toolchain and some CMake utility functions
 # This file must be included prior to the project() call
 
-if (_PICO_SDK_INIT)
+# Note: this file is perhaps named badly, as it provides a method pico_sdk_init which
-    return()
+# the enclosing project calls LATER to actually "initialize" the SDK (by including the CMakeLists.txt from this
-endif ()
+# same directory)
-set(_PICO_SDK_INIT 1)
+
+if (NOT TARGET _pico_sdk_pre_init_marker)
+    add_library(_pico_sdk_pre_init_marker INTERFACE)
 
     function(pico_is_top_level_project VAR)
         string(TOLOWER ${CMAKE_CURRENT_LIST_DIR} __list_dir)
@@ -47,8 +49,15 @@ endmacro()
     macro(add_sub_list_dirs var)
         foreach(LIST_DIR IN LISTS ${var})
             get_filename_component(SHORT_NAME "${LIST_DIR}" NAME)
-        message("Including custom CMakeLists.txt ${SHORT_NAME}")
+            message(DEBUG "Including custom CMakeLists.txt ${SHORT_NAME}")
             add_subdirectory(${LIST_DIR} ${SHORT_NAME})
         endforeach()
     endmacro()
 
+    macro(add_sub_list_files var)
+        foreach(LIST_FILE IN LISTS ${var})
+            message(DEBUG "Including custom CMake file ${LIST_FILE}")
+            include(${LIST_FILE})
+        endforeach()
+    endmacro()
+endif()

src/common/pico_sync/sem.c

@@ -6,6 +6,7 @@
 
 #include "pico/sem.h"
 #include "pico/time.h"
+#include "sys/select.h"
 
 void sem_init(semaphore_t *sem, int16_t initial_permits, int16_t max_permits) {
     lock_init(&sem->core, next_striped_spin_lock_num());