C/C++ efficient bit array

boost::dynamic_bitset if the length is only known in run time.

std::bitset if the length is known in compile time (although arbitrary).

This posting is rather old, but there is an efficient bit array suite in C in my ALFLB library.

For many microcontrollers without a hardware-division opcode, this library is EFFICIENT because it doesn't use division: instead, masking and bit-shifting are used. (Yes, I know some compilers will convert division by 8 to a shift, but this varies from compiler to compiler.)

It has been tested on arrays up to 2^32-2 bits (about 4 billion bits stored in 536 MBytes), although last 2 bits should be accessible if not used in a for-loop in your application.

See below for an extract from the doco. Doco is http://alfredo4570.net/src/alflb_doco/alflb.pdf, library is http://alfredo4570.net/src/alflb.zip

Enjoy,
Alf

//------------------------------------------------------------------
BM_DECLARE( arrayName, bitmax);
        Macro to instantiate an array to hold bitmax bits.
//------------------------------------------------------------------
UCHAR *BM_ALLOC( BM_SIZE_T bitmax); 
        mallocs an array (of unsigned char) to hold bitmax bits.
        Returns: NULL if memory could not be allocated.
//------------------------------------------------------------------
void BM_SET( UCHAR *bit_array, BM_SIZE_T bit_index);
        Sets a bit to 1.
//------------------------------------------------------------------
void BM_CLR( UCHAR *bit_array, BM_SIZE_T bit_index);
        Clears a bit to 0.
//------------------------------------------------------------------
int BM_TEST( UCHAR *bit_array, BM_SIZE_T bit_index); 
        Returns: TRUE (1) or FALSE (0) depending on a bit.
//------------------------------------------------------------------
int BM_ANY( UCHAR *bit_array, int value, BM_SIZE_T bitmax); 
        Returns: TRUE (1) if array contains the requested value (i.e. 0 or 1).
//------------