/*
Copyright (C) 2003-2008 Andrey Nazarov

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  

See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/

//
// q_fifo.h
//

typedef struct {
    byte *data;
    size_t size;
    size_t ax, ay, bs;
} fifo_t;

static inline void *FIFO_Reserve( fifo_t *fifo, size_t *len ) {
    size_t tail;

    if( fifo->bs ) {
        *len = fifo->ax - fifo->bs;
        return fifo->data + fifo->bs;
    }

    tail = fifo->size - fifo->ay;
    if( tail ) {
        *len = tail;
        return fifo->data + fifo->ay;
    }

    *len = fifo->ax;
    return fifo->data;
}

static inline void FIFO_Commit( fifo_t *fifo, size_t len ) {
    size_t tail;

    if( fifo->bs ) {
        fifo->bs += len;
        return;
    }

    tail = fifo->size - fifo->ay;
    if( tail ) {
        fifo->ay += len;
        return;
    }

    fifo->bs = len;
}

static inline void *FIFO_Peek( fifo_t *fifo, size_t *len ) {
    *len = fifo->ay - fifo->ax;
    return fifo->data + fifo->ax;
}

static inline void FIFO_Decommit( fifo_t *fifo, size_t len ) {
    if( fifo->ax + len < fifo->ay ) {
        fifo->ax += len;
        return;
    }

    fifo->ay = fifo->bs;
    fifo->ax = fifo->bs = 0;
}

static inline size_t FIFO_Usage( fifo_t *fifo ) {
    return fifo->ay - fifo->ax + fifo->bs;
}

static inline int FIFO_Percent( fifo_t *fifo ) {
    if( !fifo->size ) {
        return 0;
    }
    return ( int )( FIFO_Usage( fifo ) * 100 / fifo->size );
}

static inline void FIFO_Clear( fifo_t *fifo ) {
    fifo->ax = fifo->ay = fifo->bs = 0;
}

size_t FIFO_Read( fifo_t *fifo, void *buffer, size_t len );
size_t FIFO_Write( fifo_t *fifo, const void *buffer, size_t len );

static inline qboolean FIFO_TryRead( fifo_t *fifo, void *buffer, size_t len ) {
    if( FIFO_Read( fifo, NULL, len ) < len ) {
        return qfalse;
    }
    FIFO_Read( fifo, buffer, len );
    return qtrue;
}

static inline qboolean FIFO_TryWrite( fifo_t *fifo, void *buffer, size_t len ) {
    if( FIFO_Write( fifo, NULL, len ) < len ) {
        return qfalse;
    }
    FIFO_Write( fifo, buffer, len );
    return qtrue;
}

qboolean FIFO_ReadMessage( fifo_t *fifo, size_t msglen );