gqueue.h

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/*****************************************************************************
// File: GQueue.h 
// Contents: Header of C functions for circular queue access and control.
// Author: G. A. Borges.
// Description: Circular queues are FIFOS implemented with limited length vectors.
//                              Their control variables are defined in a structure named GQUEUECONTROL. 
//                              It means that no data is stored in GQUEUECONTROL, but read/write indexes and
//                              control variables. The data is stored in a separate array. Indexes to access
//                              the array are computed using GQUEUECONTROL internal values.
//                              The circular queues may have up to MAXSIZE_QUEUE_READ_GATES reading heads but 
//                              only one writing head. 
//                              
//                              
*****************************************************************************/

#ifndef GQUEUE_H
#define GQUEUE_H

#define TRUE 1
#define FALSE 0

#define MAXSIZE_QUEUE_READ_GATES        5
#define QUEUE_READ_GATE_0                       0
#define QUEUE_READ_GATE_1                       1
#define QUEUE_READ_GATE_2                       2
#define QUEUE_READ_GATE_3                       3
#define QUEUE_READ_GATE_4                       4

#define GQUEUE_RTAI_SUPPORT     0

#if GQUEUE_RTAI_SUPPORT
#include <rtai_spl.h>
#endif

typedef struct{
        int        Size;
        int        ReadIndex[MAXSIZE_QUEUE_READ_GATES];
        int        WriteIndex;
#if GQUEUE_RTAI_SUPPORT
        SPL        SPLAtomicAccess;
#endif
        int        NReaders;
        int        FlagStillNotWritten;
        int        FlagStillNotRead[MAXSIZE_QUEUE_READ_GATES];
        int        FlagFull[MAXSIZE_QUEUE_READ_GATES];
}GQUEUECONTROL, *PGQUEUECONTROL;

/* Example:
#define QUEUESIZE       100

double buffer[QUEUESIZE];
GQUEUECONTROL gQueueControlBuffer;

gQUEUE_Init(&gQueueControlBuffer, QUEUESIZE, 1);

int Index;
if(gQUEUE_RequestWriteIndex(&gQueueControlBuffer, &Index)){
        buffer[Index] = 100;
}

int Index;
if(gQUEUE_RequestReadIndex(&gQueueControlBuffer, QUEUE_READ_GATE_0, &Index)){
        x = buffer[Index];
}

*/

/* Prototypes: */
int gQUEUE_Init(PGQUEUECONTROL pQueueControl, int Size, int NReaders);
int gQUEUE_GetReadIndex(PGQUEUECONTROL pQueueControl, int NReader, int* Index, int IndexHorizon);
int gQUEUE_GetWriteIndex(PGQUEUECONTROL pQueueControl, int* Index, int IndexHorizon);
int gQUEUE_RequestReadIndex(PGQUEUECONTROL pQueueControl, int NReader, int* Index);
int gQUEUE_RequestWriteIndex(PGQUEUECONTROL pQueueControl, int* Index);
int gQUEUE_RequestLastReadIndex(PGQUEUECONTROL pQueueControl, int NReader, int* Index);
int gQUEUE_UnwrapWriteIndex(PGQUEUECONTROL pQueueControl);
int gQUEUE_UnwrapReadIndex(PGQUEUECONTROL pQueueControl, int NReader);
int gQUEUE_GetNumberOfUnreadData(PGQUEUECONTROL pQueueControl, int NReader, int *Index);

#endif