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stdxBitManip.h Classes and Functions

Helper functions for doing various bit manipulations including log base 2 and bit field masking.

Functions

Detailed Documentation

Function Documentation

bool isPow2 (  uint32_t    val ) 
 

Returns true if the given val is a power of two otherwise returns false

uint32_t pow2himasked (  uint32_t    val,
uint32_t    pow2
) 
 

Masks off high order bits such that the return value is strictly less than the given power of 2. In other words, set the 32-lg(pow2) higher order bits to zero. For example: 

 0x0F = 15 = pow2himasked( 0xFF, 16 ) 
 0x1F = 31 = pow2himasked( 0xFF, 32 )
 0x02 = 2 = pow2himasked( 0xF2, 16 )
 0x12 = 18 = pow2himasked( 0xF2, 32 )

uint32_t pow2lomasked (  uint32_t    val,
uint32_t    pow2
) 
 

Masks off low order bits. Set the lg(pow2) low order bits equal to zero. For example: 

 0xF0 = pow2lomasked( 0xFF, 16 ) 
 0xE0 = pow2lomasked( 0xFF, 32 )
 0xF0 = pow2lomasked( 0xF2, 16 )
 0xE0 = pow2lomasked( 0xF2, 32 )

uint32_t pow2roundUp (  uint32_t    val ) 
 

Round up to the nearest power of two. If the given val is already a power of two then do nothing.

uint32_t lg (  uint32_t    val ) 
 

Return the log base two of the given value. This function assumes the input is a power of two.

uint32_t createFieldMask (  uint32_t    sizeInBits,
uint32_t    shift
) 
 

Creates a bit mask - a consecutive sequence of ones suitable for anding with a bit vector to retrieve a bit field.

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