#include <stdio.h>
#include <string.h>

#include "ack3d.h"
#include "ackeng.h"

//ħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħ
// Creates an overlay buffer that contains non-transparent information
// about the image. Position and length of the non-transparent areas is
// stored for later processing after the drawing phase. Theoretically the
// amount of information stored in the overlay buffer could exceed the
// actual size of the image.
//ħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħħ
short AckCreateOverlay(ACKENG *ae,UCHAR *sBuf)
{
    USHORT    bPos,vPos,vLen;
    USHORT    len,sPos,sPos1;

vLen = (ae->WinEndY - ae->WinStartY) * BYTES_PER_ROW;
vPos = ae->WinStartY * BYTES_PER_ROW;
bPos = 0;
sPos = vPos;

while (vLen > 0)
    {
    if (sBuf[sPos])
    {
    sPos1 = sPos;
    while (vLen > 0 && sBuf[sPos1++])
        vLen--;

    len = (sPos1 - sPos) - 1;
    (*(short *)&ae->ScreenBuffer[bPos]) = len;
    bPos += 2;
    (*(short *)&ae->ScreenBuffer[bPos]) = sPos;
    bPos += 2;
    memmove(&ae->ScreenBuffer[bPos],&sBuf[sPos],len);
    bPos += len;
    sPos = sPos1;
    }
    else
    {
    sPos++;
    vLen--;
    }
    }

(*(short *)&ae->ScreenBuffer[bPos]) = 0;
bPos += 2;

ae->OverlayBuffer = (UCHAR*)AckMalloc(bPos);

if (ae->OverlayBuffer != NULL)
    {
    memmove(ae->OverlayBuffer,ae->ScreenBuffer,bPos);
    return(0);
    }

return(ERR_NOMEMORY);
}

// **** End of Source ****