MOAB: Mesh Oriented datABase  (version 5.2.1)
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.
void get_bits (int offset, int count, int bits_per_ent, unsigned char *data) const
 Get tag values.
void set_bits (int offset, int count, int bits_per_ent, const unsigned char *data)
 Set tag values.
void set_bits (int offset, int count, int bits_per_ent, unsigned char value)
 Set several tag values to the same value.
unsigned char get_bits (int offset, int bits_per_ent) const
 Get tag value.
void set_bits (int offset, int bits_per_ent, unsigned char data)
 Set tag value.
void search (unsigned char value, int offset, int count, int bits_per_ent, Range &results, EntityHandle start) const
 Search stored values for specified value.

Private Attributes

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

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

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

Initialize memory.

Parameters:
bits_per_entNumber of bits in each tag value. MUST BE A POWER OF TWO.
init_valThe lower bits_per_ent bits of this byte are used to initialize each tag value.

Definition at line 22 of file BitPage.cpp.

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

{
    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: no breaks. fall through such that all bits in init_val are set
        case 1:
            init_val |= (unsigned char)( init_val << 1 );
        case 2:
            init_val |= (unsigned char)( init_val << 2 );
        case 4:
            init_val |= (unsigned char)( init_val << 4 );
        case 8:;
    }
    memset( byteArray, init_val, BitTag::PageSize );
}

Member Function Documentation

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:
offsetOffset 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.
countNumber of consecutive tag values to get.
bits_per_entNumber of bits composing each tag value. NOTE: Must be a power of two.
dataMemory 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.

Referenced by search().

{
    unsigned char* end = data + count;
    while( data != end )
        *( data++ ) = get_bits( offset++, per_ent );
}
unsigned char moab::BitPage::get_bits ( int  offset,
int  bits_per_ent 
) const [inline]

Get tag value.

Get one tag value.

Parameters:
offsetOffset 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_entNumber 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.

References byteArray, and moab::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;  // 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;
}
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:
valueThe value to look for
offsetThe offset at which to begin searching
countThe number of values to search
bits_per_entNumber of bits composing each tag value.
resultsResult list.
startThe handle of the entity corresponding to the tag value stored at 'offset'

Definition at line 9 of file BitPage.cpp.

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

{
    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;
    }
}
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:
offsetOffset 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.
countNumber of consecutive tag values to set.
bits_per_entNumber of bits composing each tag value. NOTE: Must be a power of two.
dataMemory 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.

Referenced by set_bits().

{
    const unsigned char* end = data + count;
    while( data != end )
        set_bits( offset++, per_ent, *( data++ ) );
}
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:
offsetOffset 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.
countNumber of consecutive tag values to set.
bits_per_entNumber of bits composing each tag value. NOTE: Must be a power of two.
valueThe 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.

References set_bits().

{
    int end = offset + count;
    while( offset < end )
        set_bits( offset++, per_ent, value );
}
void moab::BitPage::set_bits ( int  offset,
int  bits_per_ent,
unsigned char  data 
) [inline]

Set tag value.

Set tag value.

Parameters:
offsetOffset 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_entNumber of bits composing each tag value. NOTE: Must be a power of two.
valueThe 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.

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

{
    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 ) );
}

Member Data Documentation

The actual array of bytes.

Definition at line 124 of file BitPage.hpp.

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

List of all members.


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