Common and handy function macros. More...

Defines
#define	ALIGN_UP(value, align)
	Align `value` to the next `align` boundary.
#define	MINMAX(min, x, max) (MIN(MAX(min, x), max))
	Bound x between min and max.
#define	SHUFFLE(array, len)
	Shuffle the content of array that counts len elements.
#define	SWAP_T(a, b, T)
	Macro to swap a with b, with explicit type T for dumb C89 compilers.
#define	REVERSE_UINT8(b) ((uint8_t)((((b) * 0x0802UL & 0x22110UL) \| ((b) * 0x8020UL & 0x88440UL)) * 0x10101UL >> 16))
	Reverse the bits contained in b (LSB becomes the MSB and so on).
#define	BV(x) (1<<(x))
	Convert a bit value to a binary flag.
#define	BV32(x) ((uint32_t)1<<(x))
	Same as BV() but with 32 bit result.
#define	BV16(x) ((uint16_t)1<<(x))
	Same as BV() but with 16 bit result.
#define	BV8(x) ((uint8_t)1<<(x))
	Same as BV() but with 8 bit result.
#define	DIV_ROUND(dividend, divisor) (((dividend) + (divisor) / 2) / (divisor))
	Perform an integer division rounding the result to the nearest int value.
#define	DIV_ROUNDUP(dividend, divisor) (((dividend) + (divisor) - 1) / (divisor))
	Perform an integer division rounding the result to the upper int value.
#define	INT_MULT(a, f, prec) (((a) * (long)((f) * (1 << (prec)) + 0.5)) >> (prec))
	Perform a multiply between the integer a and the float constant f.
#define	ROUND_UP2(x, pad) (((x) + ((pad) - 1)) & ~((pad) - 1))
	Round up x to an even multiple of the 2's power pad.
#define	IS_POW2(x) (!(bool)((x) & ((x)-1)))
	Check if x is an integer power of 2.
#define	IS_ALIGNED(x, byte_count) ((uintptr_t)(const void *)(x) % (byte_count) == 0)
	Check if x is aligned to byte_count bytes.
#define	UINT8_LOG2(x)
	Calculate a compile-time log2 for a uint8_t.
#define	UINT16_LOG2(x) ((x < 256) ? UINT8_LOG2(x) : UINT8_LOG2((x) >> 8) + 8)
	Calculate a compile-time log2 for a uint16_t.
#define	UINT32_LOG2(x) ((x < 65536UL) ? UINT16_LOG2(x) : UINT16_LOG2((x) >> 16) + 16)
	Calculate a compile-time log2 for a uint32_t.
#define	PP_COUNT(...) PP_COUNT__(__VA_ARGS__,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0)
	Count the number of arguments (up to 16).
#define	BIT_CHANGE(reg,...) BIT_CHANGE__(reg, 0, __VA_ARGS__)
	This macro allows for efficient and compact bit toggling in a hardware register.
#define	BIT_CHANGE_BV(reg,...) BIT_CHANGE__(reg, 1, __VA_ARGS__)
	Similar to BIT_CHANGE(), but get bits instead of masks (and applies BV() to convert them to masks).
#define	MAKE_ID(a, b, c, d)
	Make an id from 4 letters, useful for file formats and kfile ids.
#define	BCD_TO_INT_32BIT(bcd)
	Convert one 32bit bcd numbert to int.
#define	UNSTUFF_BITS(resp, start, size)
	Extract chunk of bit from gived array (uint32_t type).
Typedefs
typedef uint32_t	id_t
	Type for id generated by MAKE_ID().
Functions
bool	is_aligned (const void *addr, size_t size)
	Check if a pointer is aligned to a certain power-of-2 size.
Integer round macros.
Round x to a multiple of base. Note: If x is signed these macros generate a lot of code.
#define	ROUND_DOWN(x, base) ( (x) - ((x) % (base)) )
#define	ROUND_UP(x, base) ( ((x) + (base) - 1) - (((x) + (base) - 1) % (base)) )
#define	ROUND_NEAREST(x, base) ( ((x) + (base) / 2) - (((x) + (base) / 2) % (base)) )
#define	ROTR(var, rot) (((var) >> (rot)) \| ((var) << ((sizeof(var) * 8) - (rot))))
	Macro for rotating bit left or right.
#define	ROTL(var, rot) (((var) << (rot)) \| ((var) >> ((sizeof(var) * 8) - (rot))))
	Macro for rotating bit left or right.

Detailed Description

Common and handy function macros.

Author:: Bernie Innocenti <bernie@codewiz.org>; Giovanni Bajo <rasky@develer.com>

Define Documentation

#define BIT_CHANGE	(	reg,
		...
	)	BIT_CHANGE__(reg, 0, __VA_ARGS__)

This macro allows for efficient and compact bit toggling in a hardware register.

It is meant to replace hand-coded cruft which toggles bits in sequence.

It is possible to specify an unlimited pair of (mask, value) parameters. For instance:

 void set_timer(bool start)
 {
     BIT_CHANGE(REG_CTRL_TIMER,
        (TIMER_MODE, MODE_COUNT),
        (OVL_IRQ, 1),
        (CMP_IRQ, 1),
        (START, start)
     );
 }

The macro expansion will be roughly the following:

 REG_CTRL_TIMER = (REG_CTRL_TIMER & ~(TIMER_MODE|OVL_IRQ|CMP_IRQ|START)
                  | (MODE_COUNT|OVL_IRQ|CMP_IRQ|(start ? START : 0));

It is up to the compiler to produce the optimal code. We checked that GCC produces the best code in most cases. We preferred this expansion over the use of a block with a local variable because CodeWarrior 6.1 was not able to remove completely the allocation of the local from the stack.

Note:: This macro is available only in C99 because it makes use of variadic macros. It would be possible to make up an implementation with a slightly different syntax for use with C90 compilers, through Boost Preprocessor.

Definition at line 376 of file macros.h.

#define BV ( x ) (1<<(x))

Convert a bit value to a binary flag.

Definition at line 174 of file macros.h.

#define DIV_ROUND	(	dividend,
		divisor
	)	(((dividend) + (divisor) / 2) / (divisor))

Perform an integer division rounding the result to the nearest int value.

Note:: divisor should preferibly be a costant, otherwise this macro generates 2 division. Also divisor is evaluated twice.

Definition at line 191 of file macros.h.

#define DIV_ROUNDUP	(	dividend,
		divisor
	)	(((dividend) + (divisor) - 1) / (divisor))

Perform an integer division rounding the result to the upper int value.

Note:: divisor is evaluated twice.

Definition at line 197 of file macros.h.

#define INT_MULT	(	a,
		f,
		prec
	)	(((a) * (long)((f) * (1 << (prec)) + 0.5)) >> (prec))

Perform a multiply between the integer a and the float constant f.

This macro can be used in order to avoid floating point arithmetics in expressions like this:

 int a, b;
 a = b * 0.5579652750;

This macro rounds the floating point constant to a fraction, usign (2 ^ prec) as the denominator. For instance, with prec = 8, the constant 0.5579652750 will be rounded to: (143 / 256) = 0.55859375 So, the former code will be transformed to:

 a = b * 143 / 256;

Since the denominator is a power of 2, we rely on the compiler to optimize this to a right shift. So, when you have to multiply an integer by a float constant, this macro will not use the floating point arithmentics. The operation will be converted to a mul + shift, with a huge performance boost.

Note:: f MUST be a constant in order gain performance benefits.

Parameters:

a	integer you want to multiply
f	floating point constant which you want to multply with a
prec	conversion precision, ranges from 1 to the number of bits in a long. The higher, the better the approximation of the float constant will be.

Definition at line 232 of file macros.h.

#define IS_POW2 ( x ) (!(bool)((x) & ((x)-1)))

Check if x is an integer power of 2.

Definition at line 251 of file macros.h.

#define MINMAX	(	min,
		x,
		max
	)	(MIN(MAX(min, x), max))

Bound x between min and max.

Definition at line 107 of file macros.h.

#define PP_COUNT ( ... ) PP_COUNT__(__VA_ARGS__,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0)

Count the number of arguments (up to 16).

Definition at line 276 of file macros.h.

#define REVERSE_UINT8 ( b ) ((uint8_t)((((b) * 0x0802UL & 0x22110UL) | ((b) * 0x8020UL & 0x88440UL)) * 0x10101UL >> 16))

Reverse the bits contained in b (LSB becomes the MSB and so on).

Note:: b is evaluated twice

Definition at line 169 of file macros.h.

#define ROUND_UP2	(	x,
		pad
	)	(((x) + ((pad) - 1)) & ~((pad) - 1))

Round up x to an even multiple of the 2's power pad.

Definition at line 236 of file macros.h.

#define SWAP_T	(	a,
		b,
		T
	)

Value:

do { \
        T tmp; \
        ASSERT_TYPE_IS(a, T); \
        ASSERT_TYPE_IS(b, T); \
        tmp = (a); \
        (a) = (b); \
        (b) = tmp; \
    } while (0)

Macro to swap a with b, with explicit type T for dumb C89 compilers.

Note:: Arguments are evaluated multiple times.

Definition at line 155 of file macros.h.

#define UNSTUFF_BITS	(	resp,
		start,
		size
	)

Value:

({                              \
        const uint32_t __size = size;                \
        const uint32_t __mask = (__size < 32 ? 1 << __size : 0) - 1; \
        const uint32_t __off = 3 - ((start) / 32);           \
        const uint32_t __shft = (start) & 31;            \
        uint32_t __res;                      \
                                    \
        __res = resp[__off] >> __shft;              \
        if (__size + __shft > 32)               \
            __res |= resp[__off-1] << ((32 - __shft) % 32); \
        __res & __mask;                     \
    })

Extract chunk of bit from gived array (uint32_t type).

Parameters:

resp	array of bit 32bit aligned
start	bit position in array
size	of bit chuck from start

Returns:: uint32_t chunk value.

Definition at line 432 of file macros.h.

Context Navigation

Defines

Typedefs

Functions

Integer round macros.

Detailed Description

Define Documentation