Provide better access to compiler optimisations for the raw scheduler

gfxconf.example.h

@@ -40,6 +40,7 @@
 //    #define INTERRUPTS_ON()                          optional_code
 
 // Options that (should where relevant) apply to all operating systems
+//    #define GFX_COMPILER                             GFX_COMPILER_UNKNOWN
 //    #define GFX_NO_OS_INIT                           FALSE
 //    #define GFX_OS_EXTRA_INIT_FUNCTION               myOSInitRoutine
 //    #define GFX_OS_EXTRA_DEINIT_FUNCTION             myOSDeInitRoutine

src/gos/gos_arduino.c

@@ -229,18 +229,19 @@ void gfxSleepMicroseconds(delaytime_t ms) {
  * For those it doesn't - read the compiler manuals and the library source code to
  * work out the correct macro values.
  * You can use the debugger to work out the values for your compiler and put them here.
- * Defining these macros as constant values makes the system behaviour guaranteed but also
+ * Defining these macros as constant values makes the system behavior guaranteed but also
- * makes your code compiler and cpu architecture dependant.
+ * makes your code compiler and cpu architecture dependent. It also saves a heap of code
+ * and a few bytes of RAM.
  */
-#if 0
+#if GFX_COMPILER == GFX_COMPILER_MINGW32
-	// Define your compiler constant values here.
-	//	These example values are for mingw32 compiler (x86).
 	#define AUTO_DETECT_MASK	FALSE
 	#define STACK_DIR_UP		FALSE
 	#define MASK1				0x00000011
 	#define MASK2				0x00000000
 	#define STACK_BASE			12
 #else
+	// Use auto-detection of the stack frame format
+	// Assumes all the relevant stuff to be relocated is in the first 256 bytes of the jmpbuf.
 	#define AUTO_DETECT_MASK	TRUE
 	#define STACK_DIR_UP		stackdirup			// TRUE if the stack grow up instead of down
 	#define MASK1				jmpmask1			// The 1st mask of jmp_buf elements that need relocation

src/gos/gos_options.h

@@ -82,6 +82,18 @@
  * @name    GOS Optional Parameters
  * @{
  */
+	/**
+	 * @brief	Enable compiler specific code
+	 * @details	Defaults to GFX_COMPILER_UNKNOWN
+	 * @note	This is setting enables optimisations that are compiler specific. It does
+	 * 			not need to be specified as reasonable defaults and various auto-detection
+	 * 			will happen as required.
+	 */
+	#ifndef GFX_COMPILER
+		#define GFX_COMPILER			GFX_COMPILER_UNKNOWN
+	#endif
+	#define GFX_COMPILER_UNKNOWN		0		// Unknown compiler
+	#define GFX_COMPILER_MINGW32		1		// MingW32 (x86) compiler for windows
  	/**
  	 * @brief	Should uGFX avoid initializing the operating system
  	 * @details	Defaults to FALSE

src/gos/gos_raw32.c

@@ -438,17 +438,18 @@ void gfxSleepMicroseconds(delaytime_t ms) {
  * work out the correct macro values.
  * You can use the debugger to work out the values for your compiler and put them here.
  * Defining these macros as constant values makes the system behavior guaranteed but also
- * makes your code compiler and cpu architecture dependent.
+ * makes your code compiler and cpu architecture dependent. It also saves a heap of code
+ * and a few bytes of RAM.
  */
-#if 0
+#if GFX_COMPILER == GFX_COMPILER_MINGW32
-	// Define your compiler constant values here.
-	//	These example values are for mingw32 compiler (x86).
 	#define AUTO_DETECT_MASK	FALSE
 	#define STACK_DIR_UP		FALSE
 	#define MASK1				0x00000011
 	#define MASK2				0x00000000
 	#define STACK_BASE			12
 #else
+	// Use auto-detection of the stack frame format
+	// Assumes all the relevant stuff to be relocated is in the first 256 bytes of the jmpbuf.
 	#define AUTO_DETECT_MASK	TRUE
 	#define STACK_DIR_UP		stackdirup			// TRUE if the stack grow up instead of down
 	#define MASK1				jmpmask1			// The 1st mask of jmp_buf elements that need relocation