Utility Library

Collaboration diagram for Utility Library:

Modules

 Assembler Support
 Assertions
 Atomic Operations
 Bit Operations
 Byte Order Conversion
 Compiler Support
 Data in Program Space
 Standard integer types
 String Operations
 Unaligned Access Helpers

Defines

#define xstr(s)   str(s)
 Stringify the result after expansion of a macro argument.
#define str(s)   #s
 Stringify a macro argument without expansion.
#define ARRAY_LEN(a)   (sizeof(a) / sizeof((a)[0]))
 Get the number of elements in array a.
#define container_of(ptr, type, member)   ((type *)((uintptr_t)(ptr) - offsetof(type, member)))
 Get the containing object.
#define round_down(x, order)
 Round down to the nearest power of two boundary.
#define round_up(x, order)
 Round up to the nearest power of two boundary.
#define div_ceil(a, b)   (((a) + (b) - 1) / (b))
 Calculate $ \left\lceil \frac{a}{b} \right\rceil $ using integer arithmetic.

Functions

static int isdigit (int c)
 Determine whether or not the character c is a digit.
static int iscntrl (int c)
 Determine whether or not the character c is a control character.
static int isspace (int c)
 Determine whether or not the character c is a space.
int_fast8_t ilog2_undefined (void)
static __always_inline int_fast8_t ilog2 (uint32_t x)
 Calculate the base-2 logarithm of a number rounded down to the nearest integer.
static __always_inline bool is_power_of_two (unsigned long x)
 Test if a given value is a power of two.
static unsigned long word_align (unsigned long x)
 Round up to the nearest word-aligned boundary.

Minimum and Maximum



#define min_s(a, b)
 Get the lowest of two signed values.
#define min_u(a, b)
 Get the lowest of two unsigned values.
#define max_s(a, b)
 Get the highest of two signed values.
#define max_u(a, b)
 Get the highest of two unsigned values.

Detailed Description

This is a collection of utility functions and macros which may be useful when dealing with certain common problems, e.g. accessing data from a byte stream, simple mathematical operations, etc.

Define Documentation

#define ARRAY_LEN ( a   )     (sizeof(a) / sizeof((a)[0]))

Get the number of elements in array a.

Definition at line 68 of file util.h.

#define container_of ( ptr,
type,
member   )     ((type *)((uintptr_t)(ptr) - offsetof(type, member)))

Get the containing object.

Parameters:
ptr Pointer to the contained object.
type Type of the containing object.
member Member name of the contained object inside the containing object.
Returns:
Pointer to the containing object.

Definition at line 120 of file util.h.

#define div_ceil ( a,
b   )     (((a) + (b) - 1) / (b))

Calculate $ \left\lceil \frac{a}{b} \right\rceil $ using integer arithmetic.

Parameters:
a An integer
b Another integer
Returns:
(a / b) rounded up to the nearest integer.

Definition at line 335 of file util.h.

Referenced by bit_array_find_first_one_bit().

#define max_s ( a,
b   ) 
Value:
((sizeof(a) == 1) && (sizeof(b) == 1) ? compiler_max_s8(a, b)   \
        : (sizeof(a) <= 2) && (sizeof(b) <= 2) ? compiler_max_s16(a, b) \
        : (sizeof(a) <= 4) && (sizeof(b) <= 4) ? compiler_max_s32(a, b) \
        : compiler_max_s64(a, b))

Get the highest of two signed values.

Parameters:
a A signed integer
b Another signed integer
Returns:
The numerically highest value of a and b.

Definition at line 156 of file util.h.

#define max_u ( a,
b   ) 
Value:
((sizeof(a) == 1) && (sizeof(b) == 1) ? compiler_max_u8(a, b)   \
        : (sizeof(a) <= 2) && (sizeof(b) <= 2) ? compiler_max_u16(a, b) \
        : (sizeof(a) <= 4) && (sizeof(b) <= 4) ? compiler_max_u32(a, b) \
        : compiler_max_u64(a, b))

Get the highest of two unsigned values.

Parameters:
a An unsigned integer
b Another unsigned integer
Returns:
The numerically highest value of a and b.

Definition at line 168 of file util.h.

#define min_s ( a,
b   ) 
Value:
((sizeof(a) == 1) && (sizeof(b) == 1) ? compiler_min_s8(a, b)   \
        : (sizeof(a) <= 2) && (sizeof(b) <= 2) ? compiler_min_s16(a, b) \
        : (sizeof(a) <= 4) && (sizeof(b) <= 4) ? compiler_min_s32(a, b) \
        : compiler_min_s64(a, b))

Get the lowest of two signed values.

Parameters:
a A signed integer
b Another signed integer
Returns:
The numerically lowest value of a and b.

Definition at line 132 of file util.h.

#define min_u ( a,
b   ) 
Value:
((sizeof(a) == 1) && (sizeof(b) == 1) ? compiler_min_u8(a, b)   \
        : (sizeof(a) <= 2) && (sizeof(b) <= 2) ? compiler_min_u16(a, b) \
        : (sizeof(a) <= 4) && (sizeof(b) <= 4) ? compiler_min_u32(a, b) \
        : compiler_min_u64(a, b))

Get the lowest of two unsigned values.

Parameters:
a An unsigned integer
b Another unsigned integer
Returns:
The numerically lowest value of a and b.

Definition at line 144 of file util.h.

#define round_down ( x,
order   ) 
Value:
(sizeof(x) == 4 ? round_down32((uint32_t)(x), (order)) :        \
                 sizeof(x) == 2 ? round_down16((uint16_t)(x), (order)) :        \
                 sizeof(x) == 1 ? round_down8 (( uint8_t)(x), (order)) :        \
                (priv_round_down_bad_type(),1))

Round down to the nearest power of two boundary.

Parameters:
x A positive integer
order log2 of the required boundary.
Returns:
x rounded down to the nearest multiple of (1 << order)

Definition at line 250 of file util.h.

#define round_up ( x,
order   ) 
Value:
(sizeof(x) == 4 ? round_up32((uint32_t)(x), (order)) :  \
                 sizeof(x) == 2 ? round_up16((uint16_t)(x), (order)) :  \
                 sizeof(x) == 1 ? round_up8 (( uint8_t)(x), (order)) :  \
                (priv_round_up_bad_type(),1))

Round up to the nearest power of two boundary.

Parameters:
x A positive integer
order log2 of the required boundary.
Returns:
x rounded up to the next multiple of (1 << order)

Definition at line 280 of file util.h.

Referenced by word_align().

#define str ( s   )     #s

Stringify a macro argument without expansion.

Definition at line 63 of file util.h.

#define xstr ( s   )     str(s)

Stringify the result after expansion of a macro argument.

Definition at line 58 of file util.h.

Function Documentation

static __always_inline int_fast8_t ilog2 ( uint32_t  x  )  [static]

Calculate the base-2 logarithm of a number rounded down to the nearest integer.

Parameters:
x A 32-bit value
Returns:
The base-2 logarithm of x, or -1 if x is 0.

Definition at line 190 of file util.h.

References compiler_clz, ilog2_undefined(), and is_constant.

int_fast8_t ilog2_undefined ( void   ) 

For internal use only.

Undefined function. Will cause a link failure if ilog2() is called with an invalid constant value.

Referenced by ilog2().

static __always_inline bool is_power_of_two ( unsigned long  x  )  [static]

Test if a given value is a power of two.

Parameters:
x The value to test
Returns:
true if x is a power of two, false otherwise

Definition at line 236 of file util.h.

static int iscntrl ( int  c  )  [inline, static]

Determine whether or not the character c is a control character.

Parameters:
c The character to consider.
Return values:
0 The character c is not a control character.
1 The character c is a control character.

Definition at line 90 of file util.h.

static int isdigit ( int  c  )  [inline, static]

Determine whether or not the character c is a digit.

Parameters:
c The character to consider.
Return values:
0 The character c is not a digit.
1 The character c is a digit.

Definition at line 77 of file util.h.

static int isspace ( int  c  )  [inline, static]

Determine whether or not the character c is a space.

Note:
This implementation is very limited in that it doesn't consider a bunch of control characters that probably should be interpreted as space.
Parameters:
c The character to consider.
Return values:
0 The character c is not a space.
1 The character c is a space.

Definition at line 106 of file util.h.

static unsigned long word_align ( unsigned long  x  )  [inline, static]

Round up to the nearest word-aligned boundary.

Parameters:
x Address or offset to be word-aligned
Returns:
The smallest number y where y >= x and y & 3 == 0.

Definition at line 307 of file util.h.

References round_up.

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