Me@0: /*
Me@8:  *  Copyright 2009 OpenSourceStewardshipFoundation.org
Me@0:  *  Licensed under GNU General Public License version 2
Me@0:  *
Me@0:  * Author: seanhalle@yahoo.com
Me@0:  */
Me@0: 
Me@0: 
Me@0: #include <stdio.h>
Me@0: #include <string.h>
Me@0: #include <errno.h>
Me@0: #include <stdlib.h>
Me@0: 
Me@0: #include "PrivateQueue.h"
Me@0: 
Me@0: 
Me@0: 
Me@0: //===========================================================================
Me@0: 
Me@0: /*This kind of queue is private to a single core at a time -- has no
Me@0:  * synchronizations 
Me@0:  */
Me@0: 
Me@0: PrivQueueStruc* makePrivQ()
Me@0:  {
Me@0:    PrivQueueStruc* retQ;
Me@9:    retQ = (PrivQueueStruc *) VMS__malloc( sizeof( PrivQueueStruc ) );
Me@0: 
Me@9:    retQ->startOfData = VMS__malloc( 1024 * sizeof(void *) );
Me@14:    memset( retQ->startOfData, 0, 1024 );
Me@14: 
Me@0:    retQ->extractPos = &(retQ->startOfData[0]); //side by side == empty
Me@0:    retQ->insertPos  = &(retQ->startOfData[1]); // so start pos's have to be
Me@0:    retQ->endOfData  = &(retQ->startOfData[1023]);
Me@0: 
Me@0:    return retQ;
Me@0:  }
Me@0: 
Me@2: 
Me@2: void
Me@2: enlargePrivQ( PrivQueueStruc *Q )
Me@0:  { int    oldSize, newSize;
Me@0:    void **oldStartOfData;
Me@0: 
Me@0:    oldSize           = Q->endOfData - Q->startOfData;
Me@0:    newSize           = 2 * oldSize;
Me@6:    oldStartOfData = Q->startOfData;
Me@9:    Q->startOfData = VMS__malloc( newSize * sizeof(void *) );
Me@0:    memcpy(Q->startOfData, oldStartOfData, oldSize * sizeof(void *));
Me@9:    VMS__free(oldStartOfData);
Me@0:    
Me@0:    Q->extractPos  = &(Q->startOfData[0]); //side by side == empty
Me@0:    Q->insertPos   = &(Q->startOfData[1]); // so start pos's have to be
Me@0:    Q->endOfData   = &(Q->startOfData[newSize - 1]);
Me@0:  }
Me@0: 
Me@0: 
Me@0: /*Returns NULL when queue is empty
Me@0:  */
Me@0: void* readPrivQ( PrivQueueStruc* Q )
Me@0:  { void *out    = 0;
Me@2:    void **startOfData = Q->startOfData;
Me@2:    void **endOfData   = Q->endOfData;
Me@0: 
Me@2:    void **insertPos  = Q->insertPos;
Me@2:    void **extractPos = Q->extractPos;
Me@0: 
Me@6:       //if not empty -- (extract is just below insert when empty)
Me@0:    if( insertPos - extractPos != 1 &&
Me@0:        !(extractPos == endOfData && insertPos == startOfData))
Me@0:     {    //move before read
Me@0:       if( extractPos == endOfData ) //write new pos exactly once, correctly
Me@0:        { Q->extractPos = startOfData; //can't overrun then fix it 'cause
Me@0:        }                              // other thread might read bad pos
Me@0:       else
Me@0:        { Q->extractPos++;
Me@0:        }
Me@0:       out = *(Q->extractPos);
Me@0:       return out;
Me@0:     }
Me@0:       //Q is empty
Me@0:    return NULL;
Me@0:  }
Me@0: 
Me@11: int32
Me@11: numInPrivQ( PrivQueueStruc *Q )
Me@11:  { int32 size, numIn;
Me@11:  
Me@11:    if( Q->insertPos < Q->extractPos )
Me@11:     {    //insert has wrapped around so numIn is:
Me@11:          // insertPos + size - extractPos -- Consider, is empty when
Me@11:          // extractPos = endOfData and insert = start -- correctly get zero
Me@11:       size  = Q->endOfData - Q->startOfData;
Me@11:       numIn = Q->insertPos + size - Q->extractPos;
Me@11:     }
Me@11:    else
Me@11:     {
Me@11:       numIn =  Q->insertPos -  Q->extractPos -1;//-1 bec empty @ side-by-side
Me@11:     }
Me@11:    return numIn;
Me@11:  }
Me@11: 
Me@2: 
Me@2: /*Expands the queue size automatically when it's full
Me@2:  */
Me@2: void
Me@6: writePrivQ( void * in, PrivQueueStruc* Q )
Me@2:  {
Me@2:    void **startOfData = Q->startOfData;
Me@2:    void **endOfData   = Q->endOfData;
Me@2:    
Me@2:    void **insertPos  = Q->insertPos;
Me@2:    void **extractPos = Q->extractPos;
Me@2: 
Me@2: tryAgain:
Me@6:       //Full? (insert is just below extract when full)
Me@2:    if( extractPos - insertPos != 1 &&
Me@2:        !(insertPos == endOfData && extractPos == startOfData))
Me@2:     { *(Q->insertPos) = in;   //insert before move
Me@2:       if( insertPos == endOfData ) //write new pos exactly once, correctly
Me@2:        { Q->insertPos = startOfData;
Me@2:        }
Me@2:       else
Me@2:        { Q->insertPos++;
Me@2:        }
Me@2:       return;
Me@2:     }
Me@2:       //Q is full
Me@2:    enlargePrivQ( Q );
Me@2:    goto tryAgain;
Me@2:  }
Me@2: 
Me@2: 
Me@0: /*Returns false when the queue was full.
Me@0:  * have option of calling make_larger_PrivQ to make more room, then try again
Me@0:  */
Me@6: int writeIfSpacePrivQ( void * in, PrivQueueStruc* Q )
Me@0:  {
Me@2:    void **startOfData = Q->startOfData;
Me@2:    void **endOfData   = Q->endOfData;
Me@2: 
Me@2:    void **insertPos  = Q->insertPos;
Me@2:    void **extractPos = Q->extractPos;
Me@0: 
Me@0:    if( extractPos - insertPos != 1 &&
Me@0:        !(insertPos == endOfData && extractPos == startOfData))
Me@2:     { *(Q->insertPos) = in;   //insert before move
Me@0:       if( insertPos == endOfData ) //write new pos exactly once, correctly
Me@0:        { Q->insertPos = startOfData;
Me@0:        }
Me@0:       else
Me@0:        { Q->insertPos++;
Me@0:        }
Me@0:       return TRUE;
Me@0:     }
Me@0:       //Q is full
Me@0:    return FALSE;
Me@0:  }
Me@9: 
Me@9: void
Me@9: freePrivQ( PrivQueueStruc *Q )
Me@9:  {
Me@9:    VMS__free( Q->startOfData );
Me@9:    VMS__free( Q );
Me@9:  }