xorg-server-1.20.13/exa/exa_unaccel.c

/*
 *
 * Copyright © 1999 Keith Packard
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the name of Keith Packard not be used in
 * advertising or publicity pertaining to distribution of the software without
 * specific, written prior permission.  Keith Packard makes no
 * representations about the suitability of this software for any purpose.  It
 * is provided "as is" without express or implied warranty.
 *
 * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

#include "exa_priv.h"

#include "mipict.h"

/*
 * These functions wrap the low-level fb rendering functions and
 * synchronize framebuffer/accelerated drawing by stalling until
 * the accelerator is idle
 */

/**
 * Calls exaPrepareAccess with EXA_PREPARE_SRC for the tile, if that is the
 * current fill style.
 *
 * Solid doesn't use an extra pixmap source, and Stippled/OpaqueStippled are
 * 1bpp and never in fb, so we don't worry about them.
 * We should worry about them for completeness sake and going forward.
 */
void
exaPrepareAccessGC(GCPtr pGC)
{
    if (pGC->stipple)
        exaPrepareAccess(&pGC->stipple->drawable, EXA_PREPARE_MASK);
    if (pGC->fillStyle == FillTiled)
        exaPrepareAccess(&pGC->tile.pixmap->drawable, EXA_PREPARE_SRC);
}

/**
 * Finishes access to the tile in the GC, if used.
 */
void
exaFinishAccessGC(GCPtr pGC)
{
    if (pGC->fillStyle == FillTiled)
        exaFinishAccess(&pGC->tile.pixmap->drawable, EXA_PREPARE_SRC);
    if (pGC->stipple)
        exaFinishAccess(&pGC->stipple->drawable, EXA_PREPARE_MASK);
}

#if DEBUG_TRACE_FALL
char
exaDrawableLocation(DrawablePtr pDrawable)
{
    return exaDrawableIsOffscreen(pDrawable) ? 's' : 'm';
}
#endif                          /* DEBUG_TRACE_FALL */

void
ExaCheckFillSpans(DrawablePtr pDrawable, GCPtr pGC, int nspans,
                  DDXPointPtr ppt, int *pwidth, int fSorted)
{
    EXA_PRE_FALLBACK_GC(pGC);
    EXA_FALLBACK(("to %p (%c)\n", pDrawable, exaDrawableLocation(pDrawable)));
    exaPrepareAccess(pDrawable, EXA_PREPARE_DEST);
    exaPrepareAccessGC(pGC);
    pGC->ops->FillSpans(pDrawable, pGC, nspans, ppt, pwidth, fSorted);
    exaFinishAccessGC(pGC);
    exaFinishAccess(pDrawable, EXA_PREPARE_DEST);
    EXA_POST_FALLBACK_GC(pGC);
}

void
ExaCheckSetSpans(DrawablePtr pDrawable, GCPtr pGC, char *psrc,
                 DDXPointPtr ppt, int *pwidth, int nspans, int fSorted)
{
    EXA_PRE_FALLBACK_GC(pGC);
    EXA_FALLBACK(("to %p (%c)\n", pDrawable, exaDrawableLocation(pDrawable)));
    exaPrepareAccess(pDrawable, EXA_PREPARE_DEST);
    pGC->ops->SetSpans(pDrawable, pGC, psrc, ppt, pwidth, nspans, fSorted);
    exaFinishAccess(pDrawable, EXA_PREPARE_DEST);
    EXA_POST_FALLBACK_GC(pGC);
}

void
ExaCheckPutImage(DrawablePtr pDrawable, GCPtr pGC, int depth,
                 int x, int y, int w, int h, int leftPad, int format,
                 char *bits)
{
    PixmapPtr pPixmap = exaGetDrawablePixmap(pDrawable);

    ExaPixmapPriv(pPixmap);

    EXA_PRE_FALLBACK_GC(pGC);
    EXA_FALLBACK(("to %p (%c)\n", pDrawable, exaDrawableLocation(pDrawable)));
    if (!pExaScr->prepare_access_reg || !pExaPixmap->pDamage ||
        exaGCReadsDestination(pDrawable, pGC->planemask, pGC->fillStyle,
                              pGC->alu, pGC->clientClip != NULL))
        exaPrepareAccess(pDrawable, EXA_PREPARE_DEST);
    else
        pExaScr->prepare_access_reg(pPixmap, EXA_PREPARE_DEST,
                                    DamagePendingRegion(pExaPixmap->pDamage));
    pGC->ops->PutImage(pDrawable, pGC, depth, x, y, w, h, leftPad, format,
                       bits);
    exaFinishAccess(pDrawable, EXA_PREPARE_DEST);
    EXA_POST_FALLBACK_GC(pGC);
}

void
ExaCheckCopyNtoN(DrawablePtr pSrc, DrawablePtr pDst, GCPtr pGC,
                 BoxPtr pbox, int nbox, int dx, int dy, Bool reverse,
                 Bool upsidedown, Pixel bitplane, void *closure)
{
    RegionRec reg;
    int xoff, yoff;

    EXA_PRE_FALLBACK_GC(pGC);
    EXA_FALLBACK(("from %p to %p (%c,%c)\n", pSrc, pDst,
                  exaDrawableLocation(pSrc), exaDrawableLocation(pDst)));

    if (pExaScr->prepare_access_reg && RegionInitBoxes(&reg, pbox, nbox)) {
        PixmapPtr pPixmap = exaGetDrawablePixmap(pSrc);

        exaGetDrawableDeltas(pSrc, pPixmap, &xoff, &yoff);
        RegionTranslate(&reg, xoff + dx, yoff + dy);
        pExaScr->prepare_access_reg(pPixmap, EXA_PREPARE_SRC, &reg);
        RegionUninit(&reg);
    }
    else
        exaPrepareAccess(pSrc, EXA_PREPARE_SRC);

    if (pExaScr->prepare_access_reg &&
        !exaGCReadsDestination(pDst, pGC->planemask, pGC->fillStyle,
                               pGC->alu, pGC->clientClip != NULL) &&
        RegionInitBoxes(&reg, pbox, nbox)) {
        PixmapPtr pPixmap = exaGetDrawablePixmap(pDst);

        exaGetDrawableDeltas(pDst, pPixmap, &xoff, &yoff);
        RegionTranslate(&reg, xoff, yoff);
        pExaScr->prepare_access_reg(pPixmap, EXA_PREPARE_DEST, &reg);
        RegionUninit(&reg);
    }
    else
        exaPrepareAccess(pDst, EXA_PREPARE_DEST);

    /* This will eventually call fbCopyNtoN, with some calculation overhead. */
    while (nbox--) {
        pGC->ops->CopyArea(pSrc, pDst, pGC, pbox->x1 - pSrc->x + dx,
                           pbox->y1 - pSrc->y + dy, pbox->x2 - pbox->x1,
                           pbox->y2 - pbox->y1, pbox->x1 - pDst->x,
                           pbox->y1 - pDst->y);
        pbox++;
    }
    exaFinishAccess(pSrc, EXA_PREPARE_SRC);
    exaFinishAccess(pDst, EXA_PREPARE_DEST);
    EXA_POST_FALLBACK_GC(pGC);
}

static void
ExaFallbackPrepareReg(DrawablePtr pDrawable,
                      GCPtr pGC,
                      int x, int y, int width, int height,
                      int index, Bool checkReads)
{
    ScreenPtr pScreen = pDrawable->pScreen;

    ExaScreenPriv(pScreen);

    if (pExaScr->prepare_access_reg &&
        !(checkReads && exaGCReadsDestination(pDrawable, pGC->planemask,
                                              pGC->fillStyle, pGC->alu,
                                              pGC->clientClip != NULL))) {
        BoxRec box;
        RegionRec reg;
        int xoff, yoff;
        PixmapPtr pPixmap = exaGetDrawablePixmap(pDrawable);

        exaGetDrawableDeltas(pDrawable, pPixmap, &xoff, &yoff);
        box.x1 = pDrawable->x + x + xoff;
        box.y1 = pDrawable->y + y + yoff;
        box.x2 = box.x1 + width;
        box.y2 = box.y1 + height;

        RegionInit(&reg, &box, 1);
        pExaScr->prepare_access_reg(pPixmap, index, &reg);
        RegionUninit(&reg);
    }
    else
        exaPrepareAccess(pDrawable, index);
}

RegionPtr
ExaCheckCopyArea(DrawablePtr pSrc, DrawablePtr pDst, GCPtr pGC,
                 int srcx, int srcy, int w, int h, int dstx, int dsty)
{
    RegionPtr ret;

    EXA_PRE_FALLBACK_GC(pGC);
    EXA_FALLBACK(("from %p to %p (%c,%c)\n", pSrc, pDst,
                  exaDrawableLocation(pSrc), exaDrawableLocation(pDst)));
    ExaFallbackPrepareReg(pSrc, pGC, srcx, srcy, w, h, EXA_PREPARE_SRC, FALSE);
    ExaFallbackPrepareReg(pDst, pGC, dstx, dsty, w, h, EXA_PREPARE_DEST, TRUE);
    ret = pGC->ops->CopyArea(pSrc, pDst, pGC, srcx, srcy, w, h, dstx, dsty);
    exaFinishAccess(pSrc, EXA_PREPARE_SRC);
    exaFinishAccess(pDst, EXA_PREPARE_DEST);
    EXA_POST_FALLBACK_GC(pGC);

    return ret;
}

RegionPtr
ExaCheckCopyPlane(DrawablePtr pSrc, DrawablePtr pDst, GCPtr pGC,
                  int srcx, int srcy, int w, int h, int dstx, int dsty,
                  unsigned long bitPlane)
{
    RegionPtr ret;

    EXA_PRE_FALLBACK_GC(pGC);
    EXA_FALLBACK(("from %p to %p (%c,%c)\n", pSrc, pDst,
                  exaDrawableLocation(pSrc), exaDrawableLocation(pDst)));
    ExaFallbackPrepareReg(pSrc, pGC, srcx, srcy, w, h, EXA_PREPARE_SRC, FALSE);
    ExaFallbackPrepareReg(pDst, pGC, dstx, dsty, w, h, EXA_PREPARE_DEST, TRUE);
    ret = pGC->ops->CopyPlane(pSrc, pDst, pGC, srcx, srcy, w, h, dstx, dsty,
                              bitPlane);
    exaFinishAccess(pSrc, EXA_PREPARE_SRC);
    exaFinishAccess(pDst, EXA_PREPARE_DEST);
    EXA_POST_FALLBACK_GC(pGC);

    return ret;
}

void
ExaCheckPolyPoint(DrawablePtr pDrawable, GCPtr pGC, int mode, int npt,
                  DDXPointPtr pptInit)
{
    EXA_PRE_FALLBACK_GC(pGC);
    EXA_FALLBACK(("to %p (%c)\n", pDrawable, exaDrawableLocation(pDrawable)));
    exaPrepareAccess(pDrawable, EXA_PREPARE_DEST);
    pGC->ops->PolyPoint(pDrawable, pGC, mode, npt, pptInit);
    exaFinishAccess(pDrawable, EXA_PREPARE_DEST);
    EXA_POST_FALLBACK_GC(pGC);
}

void
ExaCheckPolylines(DrawablePtr pDrawable, GCPtr pGC,
                  int mode, int npt, DDXPointPtr ppt)
{
    EXA_PRE_FALLBACK_GC(pGC);
    EXA_FALLBACK(("to %p (%c), width %d, mode %d, count %d\n",
                  pDrawable, exaDrawableLocation(pDrawable),
                  pGC->lineWidth, mode, npt));

    exaPrepareAccess(pDrawable, EXA_PREPARE_DEST);
    exaPrepareAccessGC(pGC);
    pGC->ops->Polylines(pDrawable, pGC, mode, npt, ppt);
    exaFinishAccessGC(pGC);
    exaFinishAccess(pDrawable, EXA_PREPARE_DEST);
    EXA_POST_FALLBACK_GC(pGC);
}

void
ExaCheckPolySegment(DrawablePtr pDrawable, GCPtr pGC,
                    int nsegInit, xSegment * pSegInit)
{
    EXA_PRE_FALLBACK_GC(pGC);
    EXA_FALLBACK(("to %p (%c) width %d, count %d\n", pDrawable,
                  exaDrawableLocation(pDrawable), pGC->lineWidth, nsegInit));

    exaPrepareAccess(pDrawable, EXA_PREPARE_DEST);
    exaPrepareAccessGC(pGC);
    pGC->ops->PolySegment(pDrawable, pGC, nsegInit, pSegInit);
    exaFinishAccessGC(pGC);
    exaFinishAccess(pDrawable, EXA_PREPARE_DEST);
    EXA_POST_FALLBACK_GC(pGC);
}

void
ExaCheckPolyArc(DrawablePtr pDrawable, GCPtr pGC, int narcs, xArc * pArcs)
{
    EXA_PRE_FALLBACK_GC(pGC);
    EXA_FALLBACK(("to %p (%c)\n", pDrawable, exaDrawableLocation(pDrawable)));

    exaPrepareAccess(pDrawable, EXA_PREPARE_DEST);
    exaPrepareAccessGC(pGC);
    pGC->ops->PolyArc(pDrawable, pGC, narcs, pArcs);
    exaFinishAccessGC(pGC);
    exaFinishAccess(pDrawable, EXA_PREPARE_DEST);
    EXA_POST_FALLBACK_GC(pGC);
}

void
ExaCheckPolyFillRect(DrawablePtr pDrawable, GCPtr pGC,
                     int nrect, xRectangle *prect)
{
    EXA_PRE_FALLBACK_GC(pGC);
    EXA_FALLBACK(("to %p (%c)\n", pDrawable, exaDrawableLocation(pDrawable)));

    exaPrepareAccess(pDrawable, EXA_PREPARE_DEST);
    exaPrepareAccessGC(pGC);
    pGC->ops->PolyFillRect(pDrawable, pGC, nrect, prect);
    exaFinishAccessGC(pGC);
    exaFinishAccess(pDrawable, EXA_PREPARE_DEST);
    EXA_POST_FALLBACK_GC(pGC);
}

void
ExaCheckImageGlyphBlt(DrawablePtr pDrawable, GCPtr pGC,
                      int x, int y, unsigned int nglyph,
                      CharInfoPtr * ppci, void *pglyphBase)
{
    EXA_PRE_FALLBACK_GC(pGC);
    EXA_FALLBACK(("to %p (%c)\n", pDrawable, exaDrawableLocation(pDrawable)));
    exaPrepareAccess(pDrawable, EXA_PREPARE_DEST);
    exaPrepareAccessGC(pGC);
    pGC->ops->ImageGlyphBlt(pDrawable, pGC, x, y, nglyph, ppci, pglyphBase);
    exaFinishAccessGC(pGC);
    exaFinishAccess(pDrawable, EXA_PREPARE_DEST);
    EXA_POST_FALLBACK_GC(pGC);
}

void
ExaCheckPolyGlyphBlt(DrawablePtr pDrawable, GCPtr pGC,
                     int x, int y, unsigned int nglyph,
                     CharInfoPtr * ppci, void *pglyphBase)
{
    EXA_PRE_FALLBACK_GC(pGC);
    EXA_FALLBACK(("to %p (%c), style %d alu %d\n", pDrawable,
                  exaDrawableLocation(pDrawable), pGC->fillStyle, pGC->alu));
    exaPrepareAccess(pDrawable, EXA_PREPARE_DEST);
    exaPrepareAccessGC(pGC);
    pGC->ops->PolyGlyphBlt(pDrawable, pGC, x, y, nglyph, ppci, pglyphBase);
    exaFinishAccessGC(pGC);
    exaFinishAccess(pDrawable, EXA_PREPARE_DEST);
    EXA_POST_FALLBACK_GC(pGC);
}

void
ExaCheckPushPixels(GCPtr pGC, PixmapPtr pBitmap,
                   DrawablePtr pDrawable, int w, int h, int x, int y)
{
    EXA_PRE_FALLBACK_GC(pGC);
    EXA_FALLBACK(("from %p to %p (%c,%c)\n", pBitmap, pDrawable,
                  exaDrawableLocation(&pBitmap->drawable),
                  exaDrawableLocation(pDrawable)));
    ExaFallbackPrepareReg(pDrawable, pGC, x, y, w, h, EXA_PREPARE_DEST, TRUE);
    ExaFallbackPrepareReg(&pBitmap->drawable, pGC, 0, 0, w, h,
                          EXA_PREPARE_SRC, FALSE);
    exaPrepareAccessGC(pGC);
    pGC->ops->PushPixels(pGC, pBitmap, pDrawable, w, h, x, y);
    exaFinishAccessGC(pGC);
    exaFinishAccess(&pBitmap->drawable, EXA_PREPARE_SRC);
    exaFinishAccess(pDrawable, EXA_PREPARE_DEST);
    EXA_POST_FALLBACK_GC(pGC);
}

void
ExaCheckCopyWindow(WindowPtr pWin, DDXPointRec ptOldOrg, RegionPtr prgnSrc)
{
    DrawablePtr pDrawable = &pWin->drawable;
    ScreenPtr pScreen = pDrawable->pScreen;

    EXA_PRE_FALLBACK(pScreen);
    EXA_FALLBACK(("from %p\n", pWin));

    /* Only need the source bits, the destination region will be overwritten */
    if (pExaScr->prepare_access_reg) {
        PixmapPtr pPixmap = pScreen->GetWindowPixmap(pWin);
        int xoff, yoff;

        exaGetDrawableDeltas(&pWin->drawable, pPixmap, &xoff, &yoff);
        RegionTranslate(prgnSrc, xoff, yoff);
        pExaScr->prepare_access_reg(pPixmap, EXA_PREPARE_SRC, prgnSrc);
        RegionTranslate(prgnSrc, -xoff, -yoff);
    }
    else
        exaPrepareAccess(pDrawable, EXA_PREPARE_SRC);

    swap(pExaScr, pScreen, CopyWindow);
    pScreen->CopyWindow(pWin, ptOldOrg, prgnSrc);
    swap(pExaScr, pScreen, CopyWindow);
    exaFinishAccess(pDrawable, EXA_PREPARE_SRC);
    EXA_POST_FALLBACK(pScreen);
}

void
ExaCheckGetImage(DrawablePtr pDrawable, int x, int y, int w, int h,
                 unsigned int format, unsigned long planeMask, char *d)
{
    ScreenPtr pScreen = pDrawable->pScreen;

    EXA_PRE_FALLBACK(pScreen);
    EXA_FALLBACK(("from %p (%c)\n", pDrawable, exaDrawableLocation(pDrawable)));

    ExaFallbackPrepareReg(pDrawable, NULL, x, y, w, h, EXA_PREPARE_SRC, FALSE);
    swap(pExaScr, pScreen, GetImage);
    pScreen->GetImage(pDrawable, x, y, w, h, format, planeMask, d);
    swap(pExaScr, pScreen, GetImage);
    exaFinishAccess(pDrawable, EXA_PREPARE_SRC);
    EXA_POST_FALLBACK(pScreen);
}

void
ExaCheckGetSpans(DrawablePtr pDrawable,
                 int wMax,
                 DDXPointPtr ppt, int *pwidth, int nspans, char *pdstStart)
{
    ScreenPtr pScreen = pDrawable->pScreen;

    EXA_PRE_FALLBACK(pScreen);
    EXA_FALLBACK(("from %p (%c)\n", pDrawable, exaDrawableLocation(pDrawable)));
    exaPrepareAccess(pDrawable, EXA_PREPARE_SRC);
    swap(pExaScr, pScreen, GetSpans);
    pScreen->GetSpans(pDrawable, wMax, ppt, pwidth, nspans, pdstStart);
    swap(pExaScr, pScreen, GetSpans);
    exaFinishAccess(pDrawable, EXA_PREPARE_SRC);
    EXA_POST_FALLBACK(pScreen);
}

static void
ExaSrcValidate(DrawablePtr pDrawable,
               int x, int y, int width, int height, unsigned int subWindowMode)
{
    ScreenPtr pScreen = pDrawable->pScreen;

    ExaScreenPriv(pScreen);
    PixmapPtr pPix = exaGetDrawablePixmap(pDrawable);
    BoxRec box;
    RegionRec reg;
    RegionPtr dst;
    int xoff, yoff;

    if (pExaScr->srcPix == pPix)
        dst = &pExaScr->srcReg;
    else if (pExaScr->maskPix == pPix)
        dst = &pExaScr->maskReg;
    else
        return;

    exaGetDrawableDeltas(pDrawable, pPix, &xoff, &yoff);

    box.x1 = x + xoff;
    box.y1 = y + yoff;
    box.x2 = box.x1 + width;
    box.y2 = box.y1 + height;

    RegionInit(&reg, &box, 1);
    RegionUnion(dst, dst, &reg);
    RegionUninit(&reg);

    if (pExaScr->SavedSourceValidate) {
        swap(pExaScr, pScreen, SourceValidate);
        pScreen->SourceValidate(pDrawable, x, y, width, height, subWindowMode);
        swap(pExaScr, pScreen, SourceValidate);
    }
}

static Bool
ExaPrepareCompositeReg(ScreenPtr pScreen,
                       CARD8 op,
                       PicturePtr pSrc,
                       PicturePtr pMask,
                       PicturePtr pDst,
                       INT16 xSrc,
                       INT16 ySrc,
                       INT16 xMask,
                       INT16 yMask,
                       INT16 xDst, INT16 yDst, CARD16 width, CARD16 height)
{
    RegionRec region;
    RegionPtr dstReg = NULL;
    RegionPtr srcReg = NULL;
    RegionPtr maskReg = NULL;
    PixmapPtr pSrcPix = NULL;
    PixmapPtr pMaskPix = NULL;
    PixmapPtr pDstPix;

    ExaScreenPriv(pScreen);
    Bool ret;

    RegionNull(&region);

    if (pSrc->pDrawable) {
        pSrcPix = exaGetDrawablePixmap(pSrc->pDrawable);
        RegionNull(&pExaScr->srcReg);
        srcReg = &pExaScr->srcReg;
        pExaScr->srcPix = pSrcPix;
        if (pSrc != pDst)
            RegionTranslate(pSrc->pCompositeClip,
                            -pSrc->pDrawable->x, -pSrc->pDrawable->y);
    } else
        pExaScr->srcPix = NULL;

    if (pMask && pMask->pDrawable) {
        pMaskPix = exaGetDrawablePixmap(pMask->pDrawable);
        RegionNull(&pExaScr->maskReg);
        maskReg = &pExaScr->maskReg;
        pExaScr->maskPix = pMaskPix;
        if (pMask != pDst && pMask != pSrc)
            RegionTranslate(pMask->pCompositeClip,
                            -pMask->pDrawable->x, -pMask->pDrawable->y);
    } else
        pExaScr->maskPix = NULL;

    RegionTranslate(pDst->pCompositeClip,
                    -pDst->pDrawable->x, -pDst->pDrawable->y);

    pExaScr->SavedSourceValidate = ExaSrcValidate;
    swap(pExaScr, pScreen, SourceValidate);
    ret = miComputeCompositeRegion(&region, pSrc, pMask, pDst,
                                   xSrc, ySrc, xMask, yMask,
                                   xDst, yDst, width, height);
    swap(pExaScr, pScreen, SourceValidate);

    RegionTranslate(pDst->pCompositeClip,
                    pDst->pDrawable->x, pDst->pDrawable->y);
    if (pSrc->pDrawable && pSrc != pDst)
        RegionTranslate(pSrc->pCompositeClip,
                        pSrc->pDrawable->x, pSrc->pDrawable->y);
    if (pMask && pMask->pDrawable && pMask != pDst && pMask != pSrc)
        RegionTranslate(pMask->pCompositeClip,
                        pMask->pDrawable->x, pMask->pDrawable->y);

    if (!ret) {
        if (srcReg)
            RegionUninit(srcReg);
        if (maskReg)
            RegionUninit(maskReg);

        return FALSE;
    }

    /**
     * Don't limit alphamaps readbacks for now until we've figured out how that
     * should be done.
     */

    if (pSrc->alphaMap && pSrc->alphaMap->pDrawable)
        pExaScr->
            prepare_access_reg(exaGetDrawablePixmap(pSrc->alphaMap->pDrawable),
                               EXA_PREPARE_AUX_SRC, NULL);
    if (pMask && pMask->alphaMap && pMask->alphaMap->pDrawable)
        pExaScr->
            prepare_access_reg(exaGetDrawablePixmap(pMask->alphaMap->pDrawable),
                               EXA_PREPARE_AUX_MASK, NULL);

    if (pSrcPix)
        pExaScr->prepare_access_reg(pSrcPix, EXA_PREPARE_SRC, srcReg);

    if (pMaskPix)
        pExaScr->prepare_access_reg(pMaskPix, EXA_PREPARE_MASK, maskReg);

    if (srcReg)
        RegionUninit(srcReg);
    if (maskReg)
        RegionUninit(maskReg);

    pDstPix = exaGetDrawablePixmap(pDst->pDrawable);
    if (!exaOpReadsDestination(op)) {
        int xoff;
        int yoff;

        exaGetDrawableDeltas(pDst->pDrawable, pDstPix, &xoff, &yoff);
        RegionTranslate(&region, pDst->pDrawable->x + xoff,
                        pDst->pDrawable->y + yoff);
        dstReg = &region;
    }

    if (pDst->alphaMap && pDst->alphaMap->pDrawable)
        pExaScr->
            prepare_access_reg(exaGetDrawablePixmap(pDst->alphaMap->pDrawable),
                               EXA_PREPARE_AUX_DEST, dstReg);
    pExaScr->prepare_access_reg(pDstPix, EXA_PREPARE_DEST, dstReg);

    RegionUninit(&region);
    return TRUE;
}

void
ExaCheckComposite(CARD8 op,
                  PicturePtr pSrc,
                  PicturePtr pMask,
                  PicturePtr pDst,
                  INT16 xSrc,
                  INT16 ySrc,
                  INT16 xMask,
                  INT16 yMask,
                  INT16 xDst, INT16 yDst, CARD16 width, CARD16 height)
{
    ScreenPtr pScreen = pDst->pDrawable->pScreen;
    PictureScreenPtr ps = GetPictureScreen(pScreen);

    EXA_PRE_FALLBACK(pScreen);

    if (pExaScr->prepare_access_reg) {
        if (!ExaPrepareCompositeReg(pScreen, op, pSrc, pMask, pDst, xSrc,
                                    ySrc, xMask, yMask, xDst, yDst, width,
                                    height))
            goto out_no_clip;
    }
    else {

        /* We need to prepare access to any separate alpha maps first,
         * in case the driver doesn't support EXA_PREPARE_AUX*,
         * in which case EXA_PREPARE_SRC may be used for moving them out.
         */

        if (pSrc->alphaMap && pSrc->alphaMap->pDrawable)
            exaPrepareAccess(pSrc->alphaMap->pDrawable, EXA_PREPARE_AUX_SRC);
        if (pMask && pMask->alphaMap && pMask->alphaMap->pDrawable)
            exaPrepareAccess(pMask->alphaMap->pDrawable, EXA_PREPARE_AUX_MASK);
        if (pDst->alphaMap && pDst->alphaMap->pDrawable)
            exaPrepareAccess(pDst->alphaMap->pDrawable, EXA_PREPARE_AUX_DEST);

        exaPrepareAccess(pDst->pDrawable, EXA_PREPARE_DEST);

        EXA_FALLBACK(("from picts %p/%p to pict %p\n", pSrc, pMask, pDst));

        if (pSrc->pDrawable != NULL)
            exaPrepareAccess(pSrc->pDrawable, EXA_PREPARE_SRC);
        if (pMask && pMask->pDrawable != NULL)
            exaPrepareAccess(pMask->pDrawable, EXA_PREPARE_MASK);
    }

    swap(pExaScr, ps, Composite);
    ps->Composite(op,
                  pSrc,
                  pMask,
                  pDst, xSrc, ySrc, xMask, yMask, xDst, yDst, width, height);
    swap(pExaScr, ps, Composite);
    if (pMask && pMask->pDrawable != NULL)
        exaFinishAccess(pMask->pDrawable, EXA_PREPARE_MASK);
    if (pSrc->pDrawable != NULL)
        exaFinishAccess(pSrc->pDrawable, EXA_PREPARE_SRC);
    exaFinishAccess(pDst->pDrawable, EXA_PREPARE_DEST);
    if (pDst->alphaMap && pDst->alphaMap->pDrawable)
        exaFinishAccess(pDst->alphaMap->pDrawable, EXA_PREPARE_AUX_DEST);
    if (pSrc->alphaMap && pSrc->alphaMap->pDrawable)
        exaFinishAccess(pSrc->alphaMap->pDrawable, EXA_PREPARE_AUX_SRC);
    if (pMask && pMask->alphaMap && pMask->alphaMap->pDrawable)
        exaFinishAccess(pMask->alphaMap->pDrawable, EXA_PREPARE_AUX_MASK);

 out_no_clip:
    EXA_POST_FALLBACK(pScreen);
}

/**
 * Avoid migration ping-pong when using a mask.
 */
void
ExaCheckGlyphs(CARD8 op,
               PicturePtr pSrc,
               PicturePtr pDst,
               PictFormatPtr maskFormat,
               INT16 xSrc,
               INT16 ySrc, int nlist, GlyphListPtr list, GlyphPtr * glyphs)
{
    ScreenPtr pScreen = pDst->pDrawable->pScreen;

    EXA_PRE_FALLBACK(pScreen);

    miGlyphs(op, pSrc, pDst, maskFormat, xSrc, ySrc, nlist, list, glyphs);

    EXA_POST_FALLBACK(pScreen);
}

void
ExaCheckAddTraps(PicturePtr pPicture,
                 INT16 x_off, INT16 y_off, int ntrap, xTrap * traps)
{
    ScreenPtr pScreen = pPicture->pDrawable->pScreen;
    PictureScreenPtr ps = GetPictureScreen(pScreen);

    EXA_PRE_FALLBACK(pScreen);

    EXA_FALLBACK(("to pict %p (%c)\n", pPicture,
                  exaDrawableLocation(pPicture->pDrawable)));
    exaPrepareAccess(pPicture->pDrawable, EXA_PREPARE_DEST);
    swap(pExaScr, ps, AddTraps);
    ps->AddTraps(pPicture, x_off, y_off, ntrap, traps);
    swap(pExaScr, ps, AddTraps);
    exaFinishAccess(pPicture->pDrawable, EXA_PREPARE_DEST);
    EXA_POST_FALLBACK(pScreen);
}

/**
 * Gets the 0,0 pixel of a pixmap.  Used for doing solid fills of tiled pixmaps
 * that happen to be 1x1.  Pixmap must be at least 8bpp.
 */
CARD32
exaGetPixmapFirstPixel(PixmapPtr pPixmap)
{
    switch (pPixmap->drawable.bitsPerPixel) {
    case 32:
    {
        CARD32 pixel;

        pPixmap->drawable.pScreen->GetImage(&pPixmap->drawable, 0, 0, 1, 1,
                                            ZPixmap, ~0, (char *) &pixel);
        return pixel;
    }
    case 16:
    {
        CARD16 pixel;

        pPixmap->drawable.pScreen->GetImage(&pPixmap->drawable, 0, 0, 1, 1,
                                            ZPixmap, ~0, (char *) &pixel);
        return pixel;
    }
    case 8:
    case 4:
    case 1:
    {
        CARD8 pixel;

        pPixmap->drawable.pScreen->GetImage(&pPixmap->drawable, 0, 0, 1, 1,
                                            ZPixmap, ~0, (char *) &pixel);
        return pixel;
    }
    default:
        FatalError("%s called for invalid bpp %d\n", __func__,
                   pPixmap->drawable.bitsPerPixel);
    }
}