/*
LUFA Library
- Copyright (C) Dean Camera, 2010.
+ Copyright (C) Dean Camera, 2011.
dean [at] fourwalledcubicle [dot] com
www.lufa-lib.org
*/
/*
- Copyright 2010 Dean Camera (dean [at] fourwalledcubicle [dot] com)
+ Copyright 2011 Dean Camera (dean [at] fourwalledcubicle [dot] com)
Permission to use, copy, modify, distribute, and sell this
software and its documentation for any purpose is hereby granted
* \brief Common library convenience macros and functions.
*
* This file contains macros which are common to all library elements, and which may be useful in user code. It
- * also includes other common headers, such as Atomic.h, Attributes.h and BoardTypes.h.
+ * also includes other common code headers.
*/
/** @defgroup Group_Common Common Utility Headers - LUFA/Drivers/Common/Common.h
/** Macro for encasing other multi-statement macros. This should be used along with an opening brace
* before the start of any multi-statement macro, so that the macros contents as a whole are treated
* as a discrete block and not as a list of separate statements which may cause problems when used as
- * a block (such as inline IF statements).
+ * a block (such as inline \c if statements).
*/
#define MACROS do
/** Macro for encasing other multi-statement macros. This should be used along with a preceding closing
* brace at the end of any multi-statement macro, so that the macros contents as a whole are treated
* as a discrete block and not as a list of separate statements which may cause problems when used as
- * a block (such as inline IF statements).
+ * a block (such as inline \c if statements).
*/
#define MACROE while (0)
- /** Defines a volatile NOP statement which cannot be optimized out by the compiler, and thus can always
+ /** Convenience macro to determine the larger of two values.
+ *
+ * \note This macro should only be used with operands that do not have side effects from being evaluated
+ * multiple times.
+ *
+ * \param[in] x First value to compare
+ * \param[in] y First value to compare
+ *
+ * \return The larger of the two input parameters
+ */
+ #define MAX(x, y) ((x > y) ? x : y)
+
+ /** Convenience macro to determine the smaller of two values.
+ *
+ * \note This macro should only be used with operands that do not have side effects from being evaluated
+ * multiple times.
+ *
+ * \param[in] x First value to compare
+ * \param[in] y First value to compare
+ *
+ * \return The smaller of the two input parameters
+ */
+ #define MIN(x, y) ((x < y) ? x : y)
+
+ /** Defines a volatile \c NOP statement which cannot be optimized out by the compiler, and thus can always
* be set as a breakpoint in the resulting code. Useful for debugging purposes, where the optimiser
* removes/reorders code to the point where break points cannot reliably be set.
*
* \ingroup Group_Debugging
*/
- #define JTAG_DEBUG_POINT() __asm__ volatile ("NOP" ::)
+ #define JTAG_DEBUG_POINT() __asm__ __volatile__ ("NOP" ::)
- /** Defines an explicit JTAG break point in the resulting binary via the ASM BREAK statement. When
+ /** Defines an explicit JTAG break point in the resulting binary via the assembly \c BREAK statement. When
* a JTAG is used, this causes the program execution to halt when reached until manually resumed.
*
* \ingroup Group_Debugging
*/
- #define JTAG_DEBUG_BREAK() __asm__ volatile ("BREAK" ::)
+ #define JTAG_DEBUG_BREAK() __asm__ __volatile__ ("BREAK" ::)
- /** Macro for testing condition "x" and breaking via JTAG_DEBUG_BREAK() if the condition is false.
+ /** Macro for testing condition "x" and breaking via \ref JTAG_DEBUG_BREAK() if the condition is false.
+ *
+ * \param[in] Condition Condition that will be evaluated,
*
* \ingroup Group_Debugging
*/
- #define JTAG_DEBUG_ASSERT(x) MACROS{ if (!(x)) { JTAG_DEBUG_BREAK(); } }MACROE
+ #define JTAG_DEBUG_ASSERT(Condition) MACROS{ if (!(Condition)) { JTAG_DEBUG_BREAK(); } }MACROE
- /** Macro for testing condition "x" and writing debug data to the stdout stream if false. The stdout stream
+ /** Macro for testing condition "x" and writing debug data to the stdout stream if \c false. The stdout stream
* must be pre-initialized before this macro is run and linked to an output device, such as the AVR's USART
* peripheral.
*
- * The output takes the form "{FILENAME}: Function {FUNCTION NAME}, Line {LINE NUMBER}: Assertion {x} failed."
+ * The output takes the form "{FILENAME}: Function {FUNCTION NAME}, Line {LINE NUMBER}: Assertion {Condition} failed."
+ *
+ * \param[in] Condition Condition that will be evaluated,
*
* \ingroup Group_Debugging
*/
- #define STDOUT_ASSERT(x) MACROS{ if (!(x)) { printf_P(PSTR("%s: Function \"%s\", Line %d: " \
- "Assertion \"%s\" failed.\r\n"), \
- __FILE__, __func__, __LINE__, #x); } }MACROE
+ #define STDOUT_ASSERT(Condition) MACROS{ if (!(x)) { printf_P(PSTR("%s: Function \"%s\", Line %d: " \
+ "Assertion \"%s\" failed.\r\n"), \
+ __FILE__, __func__, __LINE__, #Condition); } }MACROE
+
+ /** Forces GCC to use pointer indirection (via the AVR's pointer register pairs) when accessing the given
+ * struct pointer. In some cases GCC will emit non-optimal assembly code when accessing a structure through
+ * a pointer, resulting in a larger binary. When this macro is used on a (non \c const) structure pointer before
+ * use, it will force GCC to use pointer indirection on the elements rather than direct store and load
+ * instructions.
+ *
+ * \param[in, out] StructPtr Pointer to a structure which is to be forced into indirect access mode.
+ */
+ #define GCC_FORCE_POINTER_ACCESS(StructPtr) __asm__ __volatile__("" : "=b" (StructPtr) : "0" (StructPtr))
#if !defined(pgm_read_ptr) || defined(__DOXYGEN__)
- /** Reads a pointer out of PROGMEM space. This is currently a wrapper for the avr-libc pgm_read_ptr()
- * macro with a void* cast, so that its value can be assigned directly to a pointer variable or used
+ /** Reads a pointer out of PROGMEM space. This is currently a wrapper for the avr-libc \c pgm_read_ptr()
+ * macro with a \c void* cast, so that its value can be assigned directly to a pointer variable or used
* in pointer arithmetic without further casting in C. In a future avr-libc distribution this will be
* part of the standard API and will be implemented in a more formal manner.
*
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