/** @file
 *
 * VBox Host Guest Shared Memory Interface (HGSMI).
 * Host/Guest shared part.
 */

/*
 * Copyright (C) 2006-2016 Oracle Corporation
 *
 * This file is part of VirtualBox Open Source Edition (OSE), as
 * available from http://www.virtualbox.org. This file is free software;
 * you can redistribute it and/or modify it under the terms of the GNU
 * General Public License (GPL) as published by the Free Software
 * Foundation, in version 2 as it comes in the "COPYING" file of the
 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
 *
 * The contents of this file may alternatively be used under the terms
 * of the Common Development and Distribution License Version 1.0
 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
 * VirtualBox OSE distribution, in which case the provisions of the
 * CDDL are applicable instead of those of the GPL.
 *
 * You may elect to license modified versions of this file under the
 * terms and conditions of either the GPL or the CDDL or both.
 */


#ifndef ___VBox_HGSMI_HGSMI_h
#define ___VBox_HGSMI_HGSMI_h

#include <iprt/assert.h>
#include <iprt/types.h>

#include <VBox/HGSMI/HGSMIDefs.h>
#include <VBox/HGSMI/HGSMIChannels.h>
#include <VBox/HGSMI/HGSMIMemAlloc.h>

/*
 * Basic mechanism for the HGSMI is to prepare and pass data buffer to the host and the guest.
 * Data inside these buffers are opaque for the HGSMI and are interpreted by higher levels.
 *
 * Every shared memory buffer passed between the guest/host has the following structure:
 *
 * HGSMIBUFFERHEADER header;
 * uint8_t data[header.u32BufferSize];
 * HGSMIBUFFERTAIL tail;
 *
 * Note: Offset of the 'header' in the memory is used for virtual hardware IO.
 *
 * Buffers are verifyed using the offset and the content of the header and the tail,
 * which are constant during a call.
 *
 * Invalid buffers are ignored.
 *
 * Actual 'data' is not verifyed, as it is expected that the data can be changed by the
 * called function.
 *
 * Since only the offset of the buffer is passed in a IO operation, the header and tail
 * must contain:
 *     * size of data in this buffer;
 *     * checksum for buffer verification.
 *
 * For segmented transfers:
 *     * the sequence identifier;
 *     * offset of the current segment in the sequence;
 *     * total bytes in the transfer.
 *
 * Additionally contains:
 *     * the channel ID;
 *     * the channel information.
 */

typedef struct HGSMIHEAP
{
    HGSMIAREA area; /* Description. */
    HGSMIMADATA ma; /* Memory allocator */
} HGSMIHEAP;

/* The size of the array of channels. Array indexes are uint8_t. Note: the value must not be changed. */
#define HGSMI_NUMBER_OF_CHANNELS 0x100

/* Channel handler called when the guest submits a buffer. */
typedef DECLCALLBACK(int) FNHGSMICHANNELHANDLER(void *pvHandler, uint16_t u16ChannelInfo, void *pvBuffer, HGSMISIZE cbBuffer);
typedef FNHGSMICHANNELHANDLER *PFNHGSMICHANNELHANDLER;

/* Information about a handler: pfn + context. */
typedef struct _HGSMICHANNELHANDLER
{
    PFNHGSMICHANNELHANDLER pfnHandler;
    void *pvHandler;
} HGSMICHANNELHANDLER;

/* Channel description. */
typedef struct _HGSMICHANNEL
{
    HGSMICHANNELHANDLER handler;       /* The channel handler. */
    const char *pszName;               /* NULL for hardcoded channels or RTStrDup'ed name. */
    uint8_t u8Channel;                 /* The channel id, equal to the channel index in the array. */
    uint8_t u8Flags;                   /* HGSMI_CH_F_* */
} HGSMICHANNEL;

typedef struct _HGSMICHANNELINFO
{
    HGSMICHANNEL Channels[HGSMI_NUMBER_OF_CHANNELS]; /* Channel handlers indexed by the channel id.
                                                      * The array is accessed under the instance lock.
                                                      */
}  HGSMICHANNELINFO;


RT_C_DECLS_BEGIN

DECLINLINE(HGSMIBUFFERHEADER *) HGSMIBufferHeaderFromPtr(void *pvBuffer)
{
    return (HGSMIBUFFERHEADER *)pvBuffer;
}

DECLINLINE(uint8_t *) HGSMIBufferDataFromPtr(void *pvBuffer)
{
    return (uint8_t *)pvBuffer + sizeof(HGSMIBUFFERHEADER);
}

DECLINLINE(HGSMIBUFFERTAIL *) HGSMIBufferTailFromPtr(void *pvBuffer,
                                                     uint32_t u32DataSize)
{
    return (HGSMIBUFFERTAIL *)(HGSMIBufferDataFromPtr(pvBuffer) + u32DataSize);
}

DECLINLINE(HGSMISIZE) HGSMIBufferMinimumSize(void)
{
    return sizeof(HGSMIBUFFERHEADER) + sizeof(HGSMIBUFFERTAIL);
}

DECLINLINE(HGSMIBUFFERHEADER *) HGSMIBufferHeaderFromData(const void *pvData)
{
    return (HGSMIBUFFERHEADER *)((uint8_t *)pvData - sizeof(HGSMIBUFFERHEADER));
}

DECLINLINE(HGSMISIZE) HGSMIBufferRequiredSize(uint32_t u32DataSize)
{
    return HGSMIBufferMinimumSize() + u32DataSize;
}

DECLINLINE(HGSMIOFFSET) HGSMIPointerToOffset(const HGSMIAREA *pArea,
                                             const void *pv)
{
    return pArea->offBase + (HGSMIOFFSET)((uint8_t *)pv - pArea->pu8Base);
}

DECLINLINE(void *) HGSMIOffsetToPointer(const HGSMIAREA *pArea,
                                        HGSMIOFFSET offBuffer)
{
    return pArea->pu8Base + (offBuffer - pArea->offBase);
}

DECLINLINE(uint8_t *) HGSMIBufferDataFromOffset(const HGSMIAREA *pArea,
                                                HGSMIOFFSET offBuffer)
{
    void *pvBuffer = HGSMIOffsetToPointer(pArea, offBuffer);
    return HGSMIBufferDataFromPtr(pvBuffer);
}

DECLINLINE(HGSMIOFFSET) HGSMIBufferOffsetFromData(const HGSMIAREA *pArea,
                                                  void *pvData)
{
    HGSMIBUFFERHEADER *pHeader = HGSMIBufferHeaderFromData(pvData);
    return HGSMIPointerToOffset(pArea, pHeader);
}

DECLINLINE(uint8_t *) HGSMIBufferDataAndChInfoFromOffset(const HGSMIAREA *pArea,
                                                         HGSMIOFFSET offBuffer,
                                                         uint16_t *pu16ChannelInfo)
{
    HGSMIBUFFERHEADER *pHeader = (HGSMIBUFFERHEADER *)HGSMIOffsetToPointer(pArea, offBuffer);
    *pu16ChannelInfo = pHeader->u16ChannelInfo;
    return HGSMIBufferDataFromPtr(pHeader);
}

uint32_t HGSMIChecksum(HGSMIOFFSET offBuffer,
                       const HGSMIBUFFERHEADER *pHeader,
                       const HGSMIBUFFERTAIL *pTail);

int HGSMIAreaInitialize(HGSMIAREA *pArea,
                        void *pvBase,
                        HGSMISIZE cbArea,
                        HGSMIOFFSET offBase);

void HGSMIAreaClear(HGSMIAREA *pArea);

DECLINLINE(bool) HGSMIAreaContainsOffset(const HGSMIAREA *pArea, HGSMIOFFSET off)
{
    return off >= pArea->offBase && off - pArea->offBase < pArea->cbArea;
}

DECLINLINE(bool) HGSMIAreaContainsPointer(const HGSMIAREA *pArea, const void *pv)
{
    return (uintptr_t)pv >= (uintptr_t)pArea->pu8Base && (uintptr_t)pv - (uintptr_t)pArea->pu8Base < pArea->cbArea;
}

HGSMIOFFSET HGSMIBufferInitializeSingle(const HGSMIAREA *pArea,
                                        HGSMIBUFFERHEADER *pHeader,
                                        HGSMISIZE cbBuffer,
                                        uint8_t u8Channel,
                                        uint16_t u16ChannelInfo);

int HGSMIHeapSetup(HGSMIHEAP *pHeap,
                   void *pvBase,
                   HGSMISIZE cbArea,
                   HGSMIOFFSET offBase,
                   const HGSMIENV *pEnv);

void HGSMIHeapDestroy(HGSMIHEAP *pHeap);

void *HGSMIHeapBufferAlloc(HGSMIHEAP *pHeap,
                           HGSMISIZE cbBuffer);

void HGSMIHeapBufferFree(HGSMIHEAP *pHeap,
                         void *pvBuf);

void *HGSMIHeapAlloc(HGSMIHEAP *pHeap,
                     HGSMISIZE cbData,
                     uint8_t u8Channel,
                     uint16_t u16ChannelInfo);

void HGSMIHeapFree(HGSMIHEAP *pHeap,
                   void *pvData);

DECLINLINE(const HGSMIAREA *) HGSMIHeapArea(HGSMIHEAP *pHeap)
{
    return &pHeap->area;
}

DECLINLINE(HGSMIOFFSET) HGSMIHeapOffset(HGSMIHEAP *pHeap)
{
    return HGSMIHeapArea(pHeap)->offBase;
}

DECLINLINE(HGSMISIZE) HGSMIHeapSize(HGSMIHEAP *pHeap)
{
    return HGSMIHeapArea(pHeap)->cbArea;
}

DECLINLINE(HGSMIOFFSET) HGSMIHeapBufferOffset(HGSMIHEAP *pHeap,
                                              void *pvData)
{
    return HGSMIBufferOffsetFromData(HGSMIHeapArea(pHeap), pvData);
}

HGSMICHANNEL *HGSMIChannelFindById(HGSMICHANNELINFO *pChannelInfo,
                                   uint8_t u8Channel);

int HGSMIChannelRegister(HGSMICHANNELINFO *pChannelInfo,
                         uint8_t u8Channel,
                         const char *pszName,
                         PFNHGSMICHANNELHANDLER pfnChannelHandler,
                         void *pvChannelHandler);

int HGSMIBufferProcess(const HGSMIAREA *pArea,
                       HGSMICHANNELINFO *pChannelInfo,
                       HGSMIOFFSET offBuffer);
RT_C_DECLS_END

#endif /* !___VBox_HGSMI_HGSMI_h */