bitarithm.h

Helper functions for bit arithmetic.

BIT0
1
0x00000001
BIT1
1
0x00000002
BIT2
1
0x00000004
BIT3
1
0x00000008
BIT4
1
0x00000010
BIT5
1
0x00000020
BIT6
1
0x00000040
BIT7
1
0x00000080
BIT8
1
0x00000100
BIT9
1
0x00000200
BIT10
1
0x00000400
BIT11
1
0x00000800
BIT12
1
0x00001000
BIT13
1
0x00002000
BIT14
1
0x00004000
BIT15
1
0x00008000
BIT16
1
0x00010000
BIT17
1
0x00020000
BIT18
1
0x00040000
BIT19
1
0x00080000
BIT20
1
0x00100000
BIT21
1
0x00200000
BIT22
1
0x00400000
BIT23
1
0x00800000
BIT24
1
0x01000000
BIT25
1
0x02000000
BIT26
1
0x04000000
BIT27
1
0x08000000
BIT28
1
0x10000000
BIT29
1
0x20000000
BIT30
1
0x40000000
BIT31
1
0x80000000
SETBIT( val, bit)

Sets a bitmask for a bitfield. 

1
val |= (bit)

Parameters

val:The bitfield
bit:Specifies the bits to be set

Return values

  • The modified bitfield
CLRBIT( val, bit)

Clears bitmask for a bitfield. 

1
val &= (~(bit))

Parameters

val:The bitfield
bit:Specifies the bits to be cleared

Return values

  • The modified bitfield
ARCH_32_BIT

1 for 32 bit architectures, 0 otherwise 

1
(__INT_MAX__ == 2147483647)
unsigned bitarithm_msb(unsigned v)

Returns the number of the highest ‘1’ bit in a value.

Parameters

v:Input value
Source: http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogObvious

Return values

  • Bit Number
unsigned bitarithm_lsb(unsigned v)

Returns the number of the lowest ‘1’ bit in a value.

Parameters

v:Input value - must be unequal to ‘0’, otherwise the function will produce an infinite loop

Return values

  • Bit Number
unsigned bitarithm_bits_set(unsigned v)

Returns the number of bits set in a value.

Parameters

v:Input value with platform-dependent word size

Return values

  • Number of set bits
uint8_t bitarithm_bits_set_u32(uint32_t v)

Returns the (uint32_t version) number of bits set in a value.

Parameters

v:Input value with 32 bit size

Return values

  • Number of set bits