#if !defined(__PETSCBT_H)
#define __PETSCBT_H

#include <petscconf.h>
#include <petscviewer.h>

/*S
     PetscBT - PETSc bitarrays

     Level: advanced

     PetscBTCreate(m,&bt)         - creates a bit array with enough room to hold m values
     PetscBTDestroy(&bt)          - destroys the bit array
     PetscBTMemzero(m,bt)         - zeros the entire bit array (sets all values to false)
     PetscBTSet(bt,index)         - sets a particular entry as true
     PetscBTClear(bt,index)       - sets a particular entry as false
     PetscBTLookup(bt,index)      - returns the value
     PetscBTLookupSet(bt,index)   - returns the value and then sets it true
     PetscBTLookupClear(bt,index) - returns the value and then sets it false
     PetscBTLength(m)             - returns number of bytes in array with m bits
     PetscBTView(m,bt,viewer)     - prints all the entries in a bit array

    We do not currently check error flags on PetscBTSet(), PetscBTClear(), PetscBTLookup(),
    PetcBTLookupSet(), PetscBTLength() cause error checking would cost hundreds more cycles then
    the operation.

S*/
typedef char* PetscBT;


PETSC_STATIC_INLINE PetscInt PetscBTLength(PetscInt m)
{
  return  m/PETSC_BITS_PER_BYTE+1;
}

PETSC_STATIC_INLINE PetscErrorCode PetscBTMemzero(PetscInt m,PetscBT array)
{
  return PetscMemzero(array,sizeof(char)*((size_t)m/PETSC_BITS_PER_BYTE+1));
}

PETSC_STATIC_INLINE PetscErrorCode PetscBTDestroy(PetscBT *array)
{
  return PetscFree(*array);
}

PETSC_STATIC_INLINE char PetscBTLookup(PetscBT array,PetscInt index)
{
  char      BT_mask,BT_c;
  PetscInt  BT_idx;

 return  (BT_idx        = index/PETSC_BITS_PER_BYTE,
          BT_c          = array[BT_idx],
          BT_mask       = (char)(1 << index%PETSC_BITS_PER_BYTE),
          (char)(BT_c & BT_mask));
}

PETSC_STATIC_INLINE PetscErrorCode PetscBTView(PetscInt m,const PetscBT bt,PetscViewer viewer)
{
  PetscInt       i;
  PetscErrorCode ierr;

  if (!viewer) {ierr = PetscViewerASCIIGetStdout(PETSC_COMM_SELF,&viewer);CHKERRQ(ierr);}
  ierr = PetscViewerASCIISynchronizedAllow(viewer,PETSC_TRUE);CHKERRQ(ierr);
  for (i=0; i<m; i++) {
    ierr = PetscViewerASCIISynchronizedPrintf(viewer,"%D %d\n",i,(int)PetscBTLookup(bt,i));CHKERRQ(ierr);
  }
  ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
  ierr = PetscViewerASCIISynchronizedAllow(viewer,PETSC_FALSE);CHKERRQ(ierr);
  return 0;
}

PETSC_STATIC_INLINE PetscErrorCode PetscBTCreate(PetscInt m,PetscBT *array)
{
  return PetscMalloc1((size_t)m/PETSC_BITS_PER_BYTE+1,array) || PetscBTMemzero(m,*array);
}

PETSC_STATIC_INLINE char PetscBTLookupSet(PetscBT array,PetscInt index)
{
  char      BT_mask,BT_c;
  PetscInt  BT_idx;

  return (BT_idx        = index/PETSC_BITS_PER_BYTE,
          BT_c          = array[BT_idx],
          BT_mask       = (char)(1 << index%PETSC_BITS_PER_BYTE),
          array[BT_idx] = (char)(BT_c | BT_mask),
          (char)(BT_c & BT_mask));
}

PETSC_STATIC_INLINE PetscErrorCode PetscBTSet(PetscBT array,PetscInt index)
{
  char      BT_mask,BT_c;
  PetscInt  BT_idx;

  BT_idx        = index/PETSC_BITS_PER_BYTE;
  BT_c          = array[BT_idx];
  BT_mask       = (char)(1 << index%PETSC_BITS_PER_BYTE);
  array[BT_idx] = (char)(BT_c | BT_mask);
  return 0;
}

PETSC_STATIC_INLINE PetscErrorCode PetscBTNegate(PetscBT array,PetscInt index)
{
  const PetscInt BT_idx  = index/PETSC_BITS_PER_BYTE;
  const char     BT_mask = (char)(1 << index%PETSC_BITS_PER_BYTE);

  array[BT_idx] ^= BT_mask;
  return 0;
}

PETSC_STATIC_INLINE char PetscBTLookupClear(PetscBT array,PetscInt index)
{
  char      BT_mask,BT_c;
  PetscInt  BT_idx;

  return (BT_idx        = index/PETSC_BITS_PER_BYTE,
          BT_c          = array[BT_idx],
          BT_mask       = (char)(1 << index%PETSC_BITS_PER_BYTE),
          array[BT_idx] = (char)(BT_c & ~BT_mask),
          (char)(BT_c & BT_mask));
}

PETSC_STATIC_INLINE PetscErrorCode PetscBTClear(PetscBT array,PetscInt index)
{
  char      BT_mask,BT_c;
  PetscInt  BT_idx;

  BT_idx        = index/PETSC_BITS_PER_BYTE;
  BT_c          = array[BT_idx];
  BT_mask       = (char)(1 << index%PETSC_BITS_PER_BYTE);
  array[BT_idx] = (char)(BT_c & ~BT_mask);
 return 0;
}


#endif