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 16 of file BitPage.hpp.

Constructor & Destructor Documentation

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 21 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: 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:

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 );
}

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;
}

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 8 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;
  }
}

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++) );
}

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 );
}

void moab::BitPage::set_bits	(	int	offset,
		int	bits_per_ent,
		unsigned char	data
	)		`[inline]`

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));
}

Member Data Documentation

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

The actual array of bytes.

Definition at line 124 of file BitPage.hpp.

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

Public Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation