Dynamically configure path to DSP library for STM32Cube

This commit also adds new functionality that allows developers to
exclude the default DSP lib and use custom one per project if needed

Resolves #569, resolves #570

builder/frameworks/stm32cube.py

@@ -175,6 +175,21 @@ def build_usb_libs(usb_libs_root):
             build_custom_lib(os.path.join(usb_class_dir, device_class), manifest)
 
 
+def process_dsp_lib():
+    dsp_lib_path = os.path.join(FRAMEWORK_DIR, "Drivers", "CMSIS", "DSP", "Lib", "GCC")
+    if not os.path.isdir(dsp_lib_path):
+        dsp_lib_path = os.path.join(FRAMEWORK_DIR, "Drivers", "CMSIS", "Lib", "GCC")
+
+    env.Append(
+        CPPPATH=[
+            os.path.join(FRAMEWORK_DIR, "Drivers", "CMSIS", "DSP", "Include"),
+        ],
+        LIBPATH=[
+            dsp_lib_path,
+        ]
+    )
+
+
 env.Replace(AS="$CC", ASCOM="$ASPPCOM")
 
 env.Append(
@@ -198,7 +213,6 @@ def build_usb_libs(usb_libs_root):
     CPPPATH=[
         "$PROJECT_SRC_DIR",
         "$PROJECT_INCLUDE_DIR",
-        os.path.join(FRAMEWORK_DIR, "Drivers", "CMSIS", "DSP", "Include"),
         os.path.join(FRAMEWORK_DIR, "Drivers", "CMSIS", "Include"),
         os.path.join(
             FRAMEWORK_DIR,
@@ -238,7 +252,6 @@ def build_usb_libs(usb_libs_root):
     ],
 
     LIBPATH=[
-        os.path.join(FRAMEWORK_DIR, "Drivers", "CMSIS", "Lib", "GCC"),
         os.path.join(FRAMEWORK_DIR, "platformio", "ldscripts"),
     ],
 
@@ -314,6 +327,13 @@ def build_usb_libs(usb_libs_root):
     if os.path.isdir(bsp_variant_dir):
         build_custom_lib(os.path.join(bsp_variant_dir), {"name": "FrameworkVariantBSP"})
 
+#
+# DSP Library processing
+#
+
+if board.get("build.stm32cube.custom_dsp_library", "no") == "no":
+    process_dsp_lib()
+
 #
 # HAL libraries
 #