moab::BitPage Class Reference

bit tag data More...

#include <BitPage.hpp>

Public Member Functions
	BitPage (int bits_per_ent, unsigned char init_val)
	Initialize memory. More...
void	get_bits (int offset, int count, int bits_per_ent, unsigned char *data) const
	Get tag values. More...
void	set_bits (int offset, int count, int bits_per_ent, const unsigned char *data)
	Set tag values. More...
void	set_bits (int offset, int count, int bits_per_ent, unsigned char value)
	Set several tag values to the same value. More...
unsigned char	get_bits (int offset, int bits_per_ent) const
	Get tag value. More...
void	set_bits (int offset, int bits_per_ent, unsigned char data)
	Set tag value. More...
void	search (unsigned char value, int offset, int count, int bits_per_ent, Range &results, EntityHandle start) const
	Search stored values for specified value. More...

Private Attributes
char	byteArray [BitTag::PageSize]
	The actual array of bytes. More...

Detailed Description

bit tag data

This class represents a fixed-size block of memory in which bit tag values are stored.

Definition at line 17 of file BitPage.hpp.

Constructor & Destructor Documentation

BitPage()

moab::BitPage::BitPage	(	int	bits_per_ent,
		unsigned char	init_val
	)

Initialize memory.

Parameters

bits_per_ent	Number of bits in each tag value. MUST BE A POWER OF TWO.
init_val	The lower bits_per_ent bits of this byte are used to initialize each tag value.

Definition at line 22 of file BitPage.cpp.

{
    unsigned char mask = (unsigned char)( 1 << per_ent ) - 1;  // 2^per_ent - 1
    init_val &= (unsigned char)mask;
    switch( per_ent )
    {
        default:
            assert( false );
            abort();
            break;  // must be power of two
 
            // Note: fall through such that all bits in init_val are set, but with odd structure to avoid
        // fall-through warnings
        case 1:
            init_val |= (unsigned char)( init_val << 1 );
            // fall through
        case 2:
            init_val |= (unsigned char)( init_val << 2 );
            // fall through
        case 4:
            init_val |= (unsigned char)( init_val << 4 );
            // fall through
        case 8:;
    }
    memset( byteArray, init_val, BitTag::PageSize );
}

References byteArray, and moab::BitTag::PageSize.

Member Function Documentation

get_bits() [1/2]

unsigned char moab::BitPage::get_bits ( int  offset, int  bits_per_ent  ) const

inline

Get tag value.

Get one tag value.

Parameters

offset	Offset into list of values, where a value of zero indicates the first tag value, a value of one indicates the second tag value, etc. NOTE: This is the value offset, not the bit offset.
bits_per_ent	Number of bits composing each tag value. NOTE: Must be a power of two.

Returns

A byte containing the tag value in the lower bits with any unused higher bits zeroed.

Definition at line 127 of file BitPage.hpp.

{
    // Assume per_ent is a power of two, which should be guaranteed
    // by higher-level code.
    unsigned char mask = (unsigned char)( 1 << per_ent ) - 1;  // 2^per_ent - 1
    int byte           = ( offset * per_ent ) >> 3;            // shifting 3 is dividing by eight
    int bit            = ( offset * per_ent ) & 7;             // masking with 7 is modulo eight
    assert( byte < BitTag::PageSize );
    return (unsigned char)( byteArray[byte] >> bit ) & mask;
}

References byteArray, and moab::BitTag::PageSize.

get_bits() [2/2]

void moab::BitPage::get_bits ( int  offset, int  count, int  bits_per_ent, unsigned char *  data  ) const

inline

Get tag values.

Get 'count' tag values, beginning with the one at 'offset'.

Parameters

offset	Offset into list of values, where a value of zero indicates the first tag value, a value of one indicates the second tag value, etc. NOTE: This is the value offset, not the bit offset.
count	Number of consecutive tag values to get.
bits_per_ent	Number of bits composing each tag value. NOTE: Must be a power of two.
data	Memory into which to copy tag values. Each value is copied into a separate byte, such that the lower bits of the bit contain the tag value and any unused higher bits are zero.

Definition at line 149 of file BitPage.hpp.

{
    unsigned char* end = data + count;
    while( data != end )
        *( data++ ) = get_bits( offset++, per_ent );
}

Referenced by search().

search()

void moab::BitPage::search	(	unsigned char	value,
		int	offset,
		int	count,
		int	bits_per_ent,
		Range &	results,
		EntityHandle	start
	)		const

Search stored values for specified value.

Find the offsets n in the data at which the specified value occurs, and for each one insert 'start + n' into the passed Range.

Parameters

value	The value to look for
offset	The offset at which to begin searching
count	The number of values to search
bits_per_ent	Number of bits composing each tag value.
results	Result list.
start	The handle of the entity corresponding to the tag value stored at 'offset'

Definition at line 9 of file BitPage.cpp.

{
    const int end        = offset + count;
    Range::iterator hint = results.begin();
    while( offset != end )
    {
        if( get_bits( offset, per_ent ) == value ) hint = results.insert( hint, start );
        ++offset;
        ++start;
    }
}

References moab::Range::begin(), get_bits(), and moab::Range::insert().

set_bits() [1/3]

void moab::BitPage::set_bits ( int  offset, int  bits_per_ent, unsigned char  data  )

inline

Set tag value.

Set tag value.

Parameters

offset	Offset into list of values, where a value of zero indicates the first tag value, a value of one indicates the second tag value, etc. NOTE: This is the value offset, not the bit offset.
bits_per_ent	Number of bits composing each tag value. NOTE: Must be a power of two.
value	The lower 'bits_per_ent' of this byte are used as the tag value. Any additional higher bits are ignored.

Definition at line 138 of file BitPage.hpp.

{
    int byte = ( offset * per_ent ) >> 3;  // shifting 3 is dividing by eight
    int bit  = ( offset * per_ent ) & 7;   // masking with 7 is modulo eight
    assert( byte < BitTag::PageSize );
    // Assume per_ent is a power of two, which should be guaranteed
    // by higher-level code.
    unsigned char mask = (unsigned char)( ( 1 << per_ent ) - 1 ) << bit;
    byteArray[byte]    = (char)( ( byteArray[byte] & ~mask ) | ( ( bits << bit ) & mask ) );
}

References byteArray, and moab::BitTag::PageSize.

set_bits() [2/3]

void moab::BitPage::set_bits ( int  offset, int  count, int  bits_per_ent, const unsigned char *  data  )

inline

Set tag values.

Set 'count' tag values, beginning with the one at 'offset'.

Parameters

offset	Offset into list of values, where a value of zero indicates the first tag value, a value of one indicates the second tag value, etc. NOTE: This is the value offset, not the bit offset.
count	Number of consecutive tag values to set.
bits_per_ent	Number of bits composing each tag value. NOTE: Must be a power of two.
data	Memory from which to copy tag values. Each value is copied from a separate byte. The lower 'bits_per_ent' of each byte are used as the tag value. Any additional higher bits are ignored.

Definition at line 156 of file BitPage.hpp.

{
    const unsigned char* end = data + count;
    while( data != end )
        set_bits( offset++, per_ent, *( data++ ) );
}

Referenced by set_bits().

set_bits() [3/3]

void moab::BitPage::set_bits ( int  offset, int  count, int  bits_per_ent, unsigned char  value  )

inline

Set several tag values to the same value.

Set 'count' tag values to specified value.

Parameters

offset	Offset into list of values, where a value of zero indicates the first tag value, a value of one indicates the second tag value, etc. NOTE: This is the value offset, not the bit offset.
count	Number of consecutive tag values to set.
bits_per_ent	Number of bits composing each tag value. NOTE: Must be a power of two.
value	The lower 'bits_per_ent' of this byte are used as the tag value. Any additional higher bits are ignored.

Definition at line 163 of file BitPage.hpp.

{
    int end = offset + count;
    while( offset < end )
        set_bits( offset++, per_ent, value );
}

References set_bits().

Member Data Documentation

byteArray

char moab::BitPage::byteArray[BitTag::PageSize]

private

The actual array of bytes.

Definition at line 124 of file BitPage.hpp.

Referenced by BitPage(), get_bits(), and set_bits().

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The documentation for this class was generated from the following files:

• BitPage.hpp
• BitPage.cpp