/*
======================
=
= HuffExpand
=
======================
*/
public static void HuffExpand(byte[] sourceBuffer, int sourceIndex, byte[] destBuffer, int destIndex, int length, huffnode hufftable)
{
memptr source = new memptr(sourceBuffer, sourceIndex);
memptr dest = new memptr(destBuffer, destIndex);
ushort bit, _byte, code;
huffnode nodeon, headptr;
headptr = new huffnode(hufftable, 254); // head node is allways node 254
// as: The disabled C code that was in this function appears to be the C version of the asm code
// this came in handy during the conversion
nodeon = new huffnode(headptr);
// as: bugfix - refactored to prevent the out of bounds read that can occur occasionally with the final byte
bit = 256;
_byte = 0;
while(length != 0)
{
if(bit == 256)
{
bit = 1;
_byte = source.GetUInt8(0);
source.Offset(1);
}
if((_byte & bit) != 0)
code = nodeon.bit1;
else
code = nodeon.bit0;
bit <<= 1;
if(code < 256)
{
dest.SetUInt8(0, (byte) code);
dest.Offset(1);
nodeon = headptr;
length--;
}
else
{
nodeon = new huffnode(hufftable, code - 256);
}
}
}
/*
===========================
=
= MakeShape
=
= Takes a raw bit map of width bytes by height and creates a scaleable shape
=
= Returns the length of the shape in bytes
=
===========================
*/
private void SC_MakeShape(memptr src, short width, short height, ref memptr shapeseg)
{
short pixwidth = (short) (width * 8);
memptr tempseg_memptr = new memptr(); // as: added
MMGetPtr(ref tempseg_memptr, pixwidth * (height + 20)); // larger than needed buffer
scaleshape tempseg = new scaleshape(tempseg_memptr);
tempseg.width = pixwidth; // pixel dimensions
tempseg.height = height;
//
// convert ega pixels to byte color values in a temp buffer
//
// Stored in a collumn format, not rows!
//
memptr byteseg = new memptr();
MMGetPtr(ref byteseg, pixwidth * height);
memptr byteptr = new memptr(byteseg);
memptr plane0 = new memptr(src);
memptr plane1 = new memptr(plane0, width * height);
memptr plane2 = new memptr(plane1, width * height);
memptr plane3 = new memptr(plane2, width * height);
for(short x = 0; x < width; x++)
{
for(ushort b = 0; b < 8; b++)
{
ushort shift = (ushort) (8 - b);
ushort offset = (ushort) x;
for(short y = 0; y < height; y++)
{
byte by0 = plane0.GetUInt8(offset);
byte by1 = plane1.GetUInt8(offset);
byte by2 = plane2.GetUInt8(offset);
byte by3 = plane3.GetUInt8(offset);
offset += (ushort) width;
ushort color = 0;
// as: converted from asm
color |= AsmRotate(by3, shift);
color <<= 1;
color |= AsmRotate(by2, shift);
color <<= 1;
color |= AsmRotate(by1, shift);
color <<= 1;
color |= AsmRotate(by0, shift);
byteptr.SetUInt8(0, (byte) color);
byteptr.Offset(1);
} // Y
} // B
} // X
//
// convert byte map to sparse scaling format
//
memptr saveptr = tempseg.PointerTofirst(pixwidth);
// start filling in data after all pointers to line segments
byteptr = new memptr(byteseg); // first pixel in byte array
for(short x = 0; x < pixwidth; x++)
{
//
// each vertical line can have 0 or more segments of pixels in it
//
short y = 0;
memptr segptr = tempseg.PointerTofirst(x);
segptr.SetUInt16(0, 0); // in case there are no segments on line
do
{
// scan for first pixel to be scaled
while(y < height && byteptr.GetUInt8(0) == BACKGROUND) // as: bugfix - re-ordered to prevent out of bounds read
{
byteptr.Offset(1);
y++;
}
if(y == height) // if not, the line is finished
continue;
//
// start a segment by pointing the last link (either shape.first[x] if it
// is the first segment, or a seg.next if not) to the current spot in
// the tempseg, setting segptr to this segments next link, and copying
// all the pixels in the segment
//
segptr.SetUInt16(0, _sys.FP_OFF(saveptr)); // pointer to start of this segment
short start = y;
short length = 0;
scaleseg scale_seg = new scaleseg(saveptr);
memptr dataptr = scale_seg.PointerToData(0);
//
// copy bytes in the segment to the shape
//
while(y < height && byteptr.GetUInt8(0) != BACKGROUND) // as: bugfix - re-ordered to prevent out of bounds read
{
length++;
dataptr.SetUInt8(0, byteptr.GetUInt8(0));
dataptr.Offset(1);
byteptr.Offset(1);
y++;
}
scale_seg.start = start;
scale_seg.length = length;
scale_seg.next = 0;
// get ready for next segment
segptr = new memptr(saveptr, scaleseg.FieldOffset_next);
saveptr = dataptr; // next free byte to be used
} while(y < height);
}
//
// allocate exact space needed and copy shape to it, then free buffers
//
MMGetPtr(ref shapeseg, _sys.FP_OFF(saveptr));
Array.Copy(tempseg.Pointer.Buffer, shapeseg.Buffer, _sys.FP_OFF(saveptr));
MMFreePtr(ref byteseg);
MMFreePtr(ref tempseg_memptr);
}
