Added lots of comments.

Added comments about the file, specs, compile and build options.

stm32-toolchain.cmake

@@ -2,17 +2,23 @@
 # STM32 toolchain file 
 # ###############################
 
+# ----------------------------------------
+# File: stm32-toolchain.cmake
+# Description: Cmake file for the stm32 controllers. It has two differnt
+# types of kinds things it can output. It can output or build release binaries
+# or it output debug builds.
+# ----------------------------------------
+
+
 ##################################################
 # Configurable Section
 ##################################################
 
-
-
 # Specify the cross-compiler
 set(CROSS_TOOLCHAIN arm-none-eabi-)
 set(CMAKE_SYSTEM_NAME Generic)
 set(CMAKE_SYSTEM_PROCESSOR arm)
-set(CMAKE_CROSSCOMPILING 1)
+set(DEBUG_BINARY 1)
 set(CMAKE_SYSTEM_VERSION 1)
 
 
@@ -31,6 +37,8 @@ set(MCU_DIR inc/${MCU}/)
 #set(MCU_SPEC cortex-m3)
 #set(MCU_SPEC cortex-m4)
 set(MCU_SPEC cortex-m0plus) # Might need to change?
+
+set(FLOAT_SPEC "") # Use when you have no FPU.
 # set(FLOAT_SPEC "-mfloat-abi=hard -mfpu=fpv4-sp-d16")
 
 # The Startup(ASM) files
@@ -120,7 +128,7 @@ set(CMAKE_CXX_FLAGS_RELEASE "-Os -flto " CACHE INTERNAL "C++ Compiler options fo
 set(CMAKE_ASM_FLAGS_RELEASE "" CACHE INTERNAL "ASM Compiler options for release build type")
 set(CMAKE_EXE_LINKER_FLAGS_RELEASE "-flto " CACHE INTERNAL "Linker options for release build type")
 
-if(CMAKE_CROSSCOMPILING STREQUAL "1")
+if(DEBUG_BINARY STREQUAL "1") # -- START: Debug Binary
     # Control specific options if crosscompiling
 
     message(STATUS "[INFO] Cross compiling for ${MCU}")
@@ -135,6 +143,12 @@ if(CMAKE_CROSSCOMPILING STREQUAL "1")
     #-------------------
     # General Flags for cross
     #-------------------
+    # "thumb":: Compressed instructions, 16bits. Using only ARM is an option
+    # as well.
+    # "-mcpu":: The selected and in use CPU.
+    # "-mthumb":: Enable the thumb(16bit) instructions.
+    # "-mthumb-interwork":: Support calling between ARM and Thumb instructions
+    # "-mabi":: Generate code for the given application binary interface.
     string(APPEND OBJECT_GEN_FLAGS " \
     -mcpu=${MCU_SPEC} \
     -mthumb \
@@ -142,6 +156,8 @@ if(CMAKE_CROSSCOMPILING STREQUAL "1")
     -mabi=aapcs \
     ${FLOAT_SPEC} \
     ")
+    # "aapcs":: Procedure Call Standard for Arm Architecture
+
 
     #-------------------
     # CFLAGS for cross
@@ -178,49 +194,20 @@ if(CMAKE_CROSSCOMPILING STREQUAL "1")
         message(FATAL_ERROR "[ERRR] Could not find linker script ${LINKER_SCRIPT}")
     endif()
 
+    # semihosting:: is a mechanism that enables code running on an ARM target 
+    # to communicate and use the Input/Output facilities on a host computer 
+    # that is running a debugger.
     if("${SEMIHOSTING}" STREQUAL "1")
+        #"rdimon":: remote dispatch interface monitor
         string(APPEND CMAKE_EXE_LINKER_FLAGS "--specs=rdimon.specs -lc -lrdimon ")
     else()
+        #"nosys":: systems call are stubbed out.
         string(APPEND CMAKE_EXE_LINKER_FLAGS "--specs=nosys.specs ")
     endif()
 
 else()
-    # Flags and options to set while compiling natively
-    message(STATUS "[INFO] Compiling natively")
-
-    #-------------------
-    # General Flags for native
-    #-------------------
-    string(APPEND OBJECT_GEN_FLAGS " \
-    --coverage \
-    ")
-
-    #-------------------
-    # CFLAGS for native
-    #-------------------
-    string(APPEND CMAKE_C_FLAGS " \
-    ${OBJECT_GEN_FLAGS} \
-    ")
-
-    #-------------------
-    # ASMFLAGS for native
-    #-------------------
-    string(APPEND CMAKE_ASM_FLAGS " \
-    ${OBJECT_GEN_FLAGS} \
-    ")
-
-    #-------------------
-    # LFLAGS for native
-    #-------------------
-    string(APPEND CMAKE_EXE_LINKER_FLAGS " \
-    ${OBJECT_GEN_FLAGS} \
-    ")
-
-endif()
-
-
     # Actual build which will go onto the board
-if(TARGET_GROUP STREQUAL production)
+    # AKA production build.
 
     ######################################################################
     # @Target: ${PROJECT_NAME}.elf
@@ -281,7 +268,7 @@ if(TARGET_GROUP STREQUAL production)
         )
 else()
     message(FATAL_ERROR "Given TARGET_GROUP unknown")
-endif()
+endif() # -- END: DEBUG/RELEASE Binary 
 
 # Unset all cache
 unset(SEMIHOSTING)