Squashed 'third_party/pico-sdk/' content from commit 2062372d2

Change-Id: Ic20f199d3ed0ea8d3a6a1bbf513f875ec7500cc6
git-subtree-dir: third_party/pico-sdk
git-subtree-split: 2062372d203b372849d573f252cf7c6dc2800c0a
Signed-off-by: Austin Schuh <austin.linux@gmail.com>
diff --git a/cmake/preload/toolchains/find_compiler.cmake b/cmake/preload/toolchains/find_compiler.cmake
new file mode 100644
index 0000000..6052369
--- /dev/null
+++ b/cmake/preload/toolchains/find_compiler.cmake
@@ -0,0 +1,31 @@
+# Toolchain file is processed multiple times, however, it cannot access CMake cache on some runs.
+# We store the search path in an environment variable so that we can always access it.
+if (NOT "${PICO_TOOLCHAIN_PATH}" STREQUAL "")
+    set(ENV{PICO_TOOLCHAIN_PATH} "${PICO_TOOLCHAIN_PATH}")
+endif ()
+
+# Find the compiler executable and store its path in a cache entry ${compiler_path}.
+# If not found, issue a fatal message and stop processing. PICO_TOOLCHAIN_PATH can be provided from
+# commandline as additional search path.
+function(pico_find_compiler compiler_path compiler_exe)
+    # Search user provided path first.
+    find_program(
+            ${compiler_path} ${compiler_exe}
+            PATHS ENV PICO_TOOLCHAIN_PATH
+            PATH_SUFFIXES bin
+            NO_DEFAULT_PATH
+    )
+
+    # If not then search system paths.
+    if ("${${compiler_path}}" STREQUAL "${compiler_path}-NOTFOUND")
+        if (DEFINED ENV{PICO_TOOLCHAIN_PATH})
+            message(WARNING "PICO_TOOLCHAIN_PATH specified ($ENV{PICO_TOOLCHAIN_PATH}), but ${compiler_exe} not found there")
+        endif()
+        find_program(${compiler_path} ${compiler_exe})
+    endif ()
+    if ("${${compiler_path}}" STREQUAL "${compiler_path}-NOTFOUND")
+        set(PICO_TOOLCHAIN_PATH "" CACHE PATH "Path to search for compiler.")
+        message(FATAL_ERROR "Compiler '${compiler_exe}' not found, you can specify search path with\
+            \"PICO_TOOLCHAIN_PATH\".")
+    endif ()
+endfunction()