msach@24: /*
msach@24:  *  Copyright 2009 OpenSourceStewardshipFoundation.org
msach@24:  *  Licensed under GNU General Public License version 2
msach@24:  *
msach@24:  * Author: seanhalle@yahoo.com
msach@24:  */
msach@24: 
msach@24: 
msach@24: #include <stdio.h>
msach@24: #include <string.h>
msach@24: #include <errno.h>
msach@24: #include <stdlib.h>
msach@24: 
msach@24: #include "PrivateQueue.h"
msach@24: #include "VMS_Implementations/VMS_impl/vmalloc.h"
msach@24: 
msach@24: 
msach@24: 
msach@24: //===========================================================================
msach@24: 
msach@24: /*This kind of queue is private to a single core at a time -- has no
msach@24:  * synchronizations 
msach@24:  */
msach@24: 
msach@24: PrivQueueStruc* makePrivQ()
msach@24:  {
msach@24:    PrivQueueStruc *retQ;
msach@24:    retQ = VMS_int__malloc( sizeof( PrivQueueStruc ) );
msach@24:    retQ->startOfData = (void*)VMS_int__malloc( 1024 * sizeof(void *) );
msach@24:    memset( retQ->startOfData, 0, 1024 );
msach@24: 
msach@24:    retQ->extractPos = &(retQ->startOfData[0]); //side by side == empty
msach@24:    retQ->insertPos  = &(retQ->startOfData[1]); // so start pos's have to be
msach@24:    retQ->endOfData  = &(retQ->startOfData[1023]);
msach@24: 
msach@24:    return retQ;
msach@24:  }
msach@24: 
msach@24: 
msach@24: void
msach@24: enlargePrivQ( PrivQueueStruc *Q )
msach@24:  { size_t    oldSize, newSize;
msach@24:    void **oldStartOfData;
msach@24: 
msach@24:    oldSize           = Q->endOfData - Q->startOfData + 1;
msach@24:    newSize           = 2 * oldSize;
msach@24:    oldStartOfData = Q->startOfData;
msach@24:    Q->startOfData = VMS_int__malloc( newSize * sizeof(void*));
msach@24:    //copy second half
msach@24:    size_t secondHalfSize = Q->endOfData - Q->extractPos + 1;
msach@24:    memcpy(Q->startOfData,Q->extractPos, secondHalfSize * sizeof(void*));
msach@24:    //copy first half
msach@24:    memcpy(Q->startOfData + secondHalfSize, oldStartOfData, 
msach@24:                         (oldSize-secondHalfSize) * sizeof(void*));
msach@24:    VMS_int__free(oldStartOfData);
msach@24:    
msach@24:    Q->extractPos  = Q->startOfData;
msach@24:    Q->insertPos   = Q->startOfData + oldSize - 1;
msach@24:    Q->endOfData   = &(Q->startOfData[newSize - 1]);
msach@24:  }
msach@24: 
msach@24: 
msach@24: /*Returns NULL when queue is empty
msach@24:  */
msach@24: void* readPrivQ( PrivQueueStruc* Q )
msach@24:  { void *out    = 0;
msach@24:    void **startOfData = Q->startOfData;
msach@24:    void **endOfData   = Q->endOfData;
msach@24: 
msach@24:    void **insertPos  = Q->insertPos;
msach@24:    void **extractPos = Q->extractPos;
msach@24: 
msach@24:       //if not empty -- (extract is just below insert when empty)
msach@24:    if( insertPos - extractPos != 1 &&
msach@24:        !(extractPos == endOfData && insertPos == startOfData))
msach@24:     {    //move before read
msach@24:       if( extractPos == endOfData ) //write new pos exactly once, correctly
msach@24:        { Q->extractPos = startOfData; //can't overrun then fix it 'cause
msach@24:        }                              // other thread might read bad pos
msach@24:       else
msach@24:        { Q->extractPos++;
msach@24:        }
msach@24:       out = *(Q->extractPos);
msach@24:       return out;
msach@24:     }
msach@24:       //Q is empty
msach@24:    return NULL;
msach@24:  }
msach@24: 
msach@24: int32
msach@24: numInPrivQ( PrivQueueStruc *Q )
msach@24:  { int32 size, numIn;
msach@24:  
msach@24:    if( Q->insertPos < Q->extractPos )
msach@24:     {    //insert has wrapped around so numIn is:
msach@24:          // insertPos + size - extractPos -- Consider, is empty when
msach@24:          // extractPos = endOfData and insert = start -- correctly get zero
msach@24:       size  = Q->endOfData - Q->startOfData;
msach@24:       numIn = Q->insertPos + size - Q->extractPos;
msach@24:     }
msach@24:    else
msach@24:     {
msach@24:       numIn =  Q->insertPos -  Q->extractPos -1;//-1 bec empty @ side-by-side
msach@24:     }
msach@24:    return numIn;
msach@24:  }
msach@24: 
msach@24: 
msach@24: /*Expands the queue size automatically when it's full
msach@24:  */
msach@24: void
msach@24: writePrivQ( void * in, PrivQueueStruc* Q )
msach@24:  {
msach@24:    while(1){
msach@24:        void **startOfData = Q->startOfData;
msach@24:        void **endOfData   = Q->endOfData;
msach@24: 
msach@24:        void **insertPos  = Q->insertPos;
msach@24:        void **extractPos = Q->extractPos;
msach@24: 
msach@24:           //Full? (insert is just below extract when full)
msach@24:        if( extractPos - insertPos != 1 &&
msach@24:            !(insertPos == endOfData && extractPos == startOfData))
msach@24:         { *(Q->insertPos) = in;   //insert before move
msach@24:           if( insertPos == endOfData ) //write new pos exactly once, correctly
msach@24:            { Q->insertPos = startOfData;
msach@24:            }
msach@24:           else
msach@24:            { Q->insertPos++;
msach@24:            }
msach@24:           return;
msach@24:         }
msach@24:           //Q is full
msach@24:        enlargePrivQ( Q );
msach@24:    }
msach@24:  }
msach@24: 
msach@24: 
msach@24: /*Returns false when the queue was full.
msach@24:  * have option of calling make_larger_PrivQ to make more room, then try again
msach@24:  */
msach@24: int writeIfSpacePrivQ( void * in, PrivQueueStruc* Q )
msach@24:  {
msach@24:    void **startOfData = Q->startOfData;
msach@24:    void **endOfData   = Q->endOfData;
msach@24: 
msach@24:    void **insertPos  = Q->insertPos;
msach@24:    void **extractPos = Q->extractPos;
msach@24: 
msach@24:    if( extractPos - insertPos != 1 &&
msach@24:        !(insertPos == endOfData && extractPos == startOfData))
msach@24:     { *(Q->insertPos) = in;   //insert before move
msach@24:       if( insertPos == endOfData ) //write new pos exactly once, correctly
msach@24:        { Q->insertPos = startOfData;
msach@24:        }
msach@24:       else
msach@24:        { Q->insertPos++;
msach@24:        }
msach@24:       return TRUE;
msach@24:     }
msach@24:       //Q is full
msach@24:    return FALSE;
msach@24:  }
msach@24: 
msach@24: /*Treats queue as a stack -- no matter contents, if read done right after
msach@24:  * a push, then the pushed item is what comes out.
msach@24:  * Expands the queue size automatically when it's full.
msach@24:  */
msach@24: void
msach@24: pushPrivQ( void * in, PrivQueueStruc* Q )
msach@24:  {
msach@24:    while(1){
msach@24:        void **startOfData = Q->startOfData;
msach@24:        void **endOfData   = Q->endOfData;
msach@24: 
msach@24:        void **insertPos  = Q->insertPos;
msach@24:        void **extractPos = Q->extractPos;
msach@24: 
msach@24:           //Full? (insert is just below extract when full)
msach@24:        if( extractPos - insertPos != 1 &&
msach@24:            !(insertPos == endOfData && extractPos == startOfData))
msach@24:         {    //insert -- but go backwards, inserting at read position then
msach@24:              // move read pos backwards
msach@24:           *(Q->extractPos) = in;
msach@24:           if( extractPos == startOfData ) //write new pos exactly once, correctly
msach@24:            { Q->extractPos = endOfData;   //can't overrun then fix it 'cause
msach@24:            }                              // other thread might read bad pos
msach@24:           else
msach@24:            { Q->extractPos--;
msach@24:            }
msach@24:           return;
msach@24:         }
msach@24:           //Q is full
msach@24:        enlargePrivQ( Q );
msach@24:    }
msach@24:  }
msach@24: 
msach@24: void
msach@24: freePrivQ( PrivQueueStruc *Q )
msach@24:  {
msach@24:    VMS_int__free( Q->startOfData );
msach@24:    VMS_int__free( Q );
Me@9:  }