#include "diablo.h"
#include "../3rdParty/Storm/Source/storm.h"

DEVILUTION_BEGIN_NAMESPACE

char gbPixelCol;  // automap pixel color 8-bit (palette entry)
BOOL gbRotateMap; // flip - if y < x
int orgseed;
int sgnWidth;
int sglGameSeed;
static CCritSect sgMemCrit;
int SeedCount;
BOOL gbNotInView; // valid - if x/y are in bounds

const int RndInc = 1;
const int RndMult = 0x015A4E35;

void CelDraw(int sx, int sy, BYTE *pCelBuff, int nCel, int nWidth)
{
	CelBlitFrame(&gpBuffer[sx + BUFFER_WIDTH * sy], pCelBuff, nCel, nWidth);
}

void CelBlitFrame(BYTE *pBuff, BYTE *pCelBuff, int nCel, int nWidth)
{
	int nDataSize;
	BYTE *pRLEBytes;

	/// ASSERT: assert(pCelBuff != NULL);
	if (!pCelBuff)
		return;
	/// ASSERT: assert(pBuff != NULL);
	if (!pBuff)
		return;

	pRLEBytes = CelGetFrame(pCelBuff, nCel, &nDataSize);
	CelBlitSafe(pBuff, pRLEBytes, nDataSize, nWidth);
}

/**
 * @param CelSkip Skip lower parts of sprite, must be multiple of 2, max 8
 * @param CelCap Amount of sprite to render from lower to upper, must be multiple of 2, max 8
 */
void CelClippedDraw(int sx, int sy, BYTE *pCelBuff, int nCel, int nWidth, int CelSkip, int CelCap)
{
	BYTE *pRLEBytes;
	int nDataSize;

	/// ASSERT: assert(gpBuffer);
	if (!gpBuffer)
		return;
	/// ASSERT: assert(pCelBuff != NULL);
	if (!pCelBuff)
		return;

	pRLEBytes = CelGetFrameClipped(pCelBuff, nCel, CelSkip, CelCap, &nDataSize);
	if (pRLEBytes == NULL)
		return;

	CelBlitSafe(
	    &gpBuffer[sx + BUFFER_WIDTH * (sy - 16 * CelSkip)],
	    pRLEBytes,
	    nDataSize,
	    nWidth);
}

void CelDrawLight(int sx, int sy, BYTE *pCelBuff, int nCel, int nWidth, BYTE *tbl)
{
	int nDataSize;
	BYTE *pDecodeTo, *pRLEBytes;

	/// ASSERT: assert(gpBuffer);
	if (!gpBuffer)
		return;
	/// ASSERT: assert(pCelBuff != NULL);
	if (!pCelBuff)
		return;

	pRLEBytes = CelGetFrame(pCelBuff, nCel, &nDataSize);
	pDecodeTo = &gpBuffer[sx + BUFFER_WIDTH * sy];

	if (light_table_index || tbl)
		CelBlitLightSafe(pDecodeTo, pRLEBytes, nDataSize, nWidth, tbl);
	else
		CelBlitSafe(pDecodeTo, pRLEBytes, nDataSize, nWidth);
}

/**
 * @param CelSkip Skip lower parts of sprite, must be multiple of 2, max 8
 * @param CelCap Amount of sprite to render from lower to upper, must be multiple of 2, max 8
 */
void CelClippedDrawLight(int sx, int sy, BYTE *pCelBuff, int nCel, int nWidth, int CelSkip, int CelCap)
{
	int nDataSize;
	BYTE *pRLEBytes, *pDecodeTo;

	/// ASSERT: assert(gpBuffer);
	if (!gpBuffer)
		return;
	/// ASSERT: assert(pCelBuff != NULL);
	if (!pCelBuff)
		return;

	pRLEBytes = CelGetFrameClipped(pCelBuff, nCel, CelSkip, CelCap, &nDataSize);
	if (pRLEBytes == NULL)
		return;

	pDecodeTo = &gpBuffer[sx + BUFFER_WIDTH * (sy - 16 * CelSkip)];

	if (light_table_index)
		CelBlitLightSafe(pDecodeTo, pRLEBytes, nDataSize, nWidth);
	else
		CelBlitSafe(pDecodeTo, pRLEBytes, nDataSize, nWidth);
}

/**
 * @param CelSkip Skip lower parts of sprite, must be multiple of 2, max 8
 * @param CelCap Amount of sprite to render from lower to upper, must be multiple of 2, max 8
 */
void CelDrawLightRed(int sx, int sy, BYTE *pCelBuff, int nCel, int nWidth, int CelSkip, int CelCap, char light)
{
	int nDataSize, w, idx;
	BYTE *pRLEBytes, *dst, *tbl;

	/// ASSERT: assert(gpBuffer);
	if (!gpBuffer)
		return;
	/// ASSERT: assert(pCelBuff != NULL);
	if (!pCelBuff)
		return;

	pRLEBytes = CelGetFrameClipped(pCelBuff, nCel, CelSkip, CelCap, &nDataSize);
	if (pRLEBytes == NULL)
		return;

	dst = &gpBuffer[sx + BUFFER_WIDTH * (sy - 16 * CelSkip)];

	idx = light4flag ? 1024 : 4096;
	if (light == 2)
		idx += 256;
	if (light >= 4)
		idx += (light - 1) << 8;

	BYTE width;
	BYTE *end;

	tbl = &pLightTbl[idx];
	end = &pRLEBytes[nDataSize];

	for (; pRLEBytes != end; dst -= BUFFER_WIDTH + nWidth) {
		for (w = nWidth; w;) {
			width = *pRLEBytes++;
			if (!(width & 0x80)) {
				w -= width;
				while (width) {
					*dst = tbl[*pRLEBytes];
					pRLEBytes++;
					dst++;
					width--;
				}
			} else {
				width = -(char)width;
				dst += width;
				w -= width;
			}
		}
	}
}

/**
 * @brief Same as CelBlit but checks for drawing outside the buffer
 */
void CelBlitSafe(BYTE *pDecodeTo, BYTE *pRLEBytes, int nDataSize, int nWidth)
{
	int w;

	/// ASSERT: assert(pDecodeTo != NULL);
	if (!pDecodeTo)
		return;
	/// ASSERT: assert(pRLEBytes != NULL);
	if (!pRLEBytes)
		return;
	/// ASSERT: assert(gpBuffer);
	if (!gpBuffer)
		return;

	int i;
	BYTE width;
	BYTE *src, *dst;

	src = pRLEBytes;
	dst = pDecodeTo;
	w = nWidth;

	for (; src != &pRLEBytes[nDataSize]; dst -= BUFFER_WIDTH + w) {
		for (i = w; i;) {
			width = *src++;
			if (!(width & 0x80)) {
				i -= width;
				if (dst < gpBufEnd && dst > gpBufStart) {
					if (width & 1) {
						dst[0] = src[0];
						src++;
						dst++;
					}
					width >>= 1;
					if (width & 1) {
						dst[0] = src[0];
						dst[1] = src[1];
						src += 2;
						dst += 2;
					}
					width >>= 1;
					for (; width; width--) {
						dst[0] = src[0];
						dst[1] = src[1];
						dst[2] = src[2];
						dst[3] = src[3];
						src += 4;
						dst += 4;
					}
				} else {
					src += width;
					dst += width;
				}
			} else {
				width = -(char)width;
				dst += width;
				i -= width;
			}
		}
	}
}

/**
 * @param CelSkip Skip lower parts of sprite, must be multiple of 2, max 8
 * @param CelCap Amount of sprite to render from lower to upper, must be multiple of 2, max 8
 */
void CelClippedDrawSafe(int sx, int sy, BYTE *pCelBuff, int nCel, int nWidth, int CelSkip, int CelCap)
{
	BYTE *pRLEBytes;
	int nDataSize;

	/// ASSERT: assert(gpBuffer);
	if (!gpBuffer)
		return;
	/// ASSERT: assert(pCelBuff != NULL);
	if (!pCelBuff)
		return;

	pRLEBytes = CelGetFrameClipped(pCelBuff, nCel, CelSkip, CelCap, &nDataSize);
	if (pRLEBytes == NULL)
		return;

	CelBlitSafe(
	    &gpBuffer[sx + BUFFER_WIDTH * (sy - 16 * CelSkip)],
	    pRLEBytes,
	    nDataSize,
	    nWidth);
}

/**
 * @brief Same as CelBlitLight but checks for drawing outside the buffer
 */
void CelBlitLightSafe(BYTE *pDecodeTo, BYTE *pRLEBytes, int nDataSize, int nWidth, BYTE *tbl)
{
	int w;

	/// ASSERT: assert(pDecodeTo != NULL);
	if (!pDecodeTo)
		return;
	/// ASSERT: assert(pRLEBytes != NULL);
	if (!pRLEBytes)
		return;
	/// ASSERT: assert(gpBuffer);
	if (!gpBuffer)
		return;

	int i;
	BYTE width;
	BYTE *src, *dst;

	src = pRLEBytes;
	dst = pDecodeTo;
	if (tbl == NULL)
		tbl = &pLightTbl[light_table_index * 256];
	w = nWidth;

	for (; src != &pRLEBytes[nDataSize]; dst -= BUFFER_WIDTH + w) {
		for (i = w; i;) {
			width = *src++;
			if (!(width & 0x80)) {
				i -= width;
				if (dst < gpBufEnd && dst > gpBufStart) {
					if (width & 1) {
						dst[0] = tbl[src[0]];
						src++;
						dst++;
					}
					width >>= 1;
					if (width & 1) {
						dst[0] = tbl[src[0]];
						dst[1] = tbl[src[1]];
						src += 2;
						dst += 2;
					}
					width >>= 1;
					for (; width; width--) {
						dst[0] = tbl[src[0]];
						dst[1] = tbl[src[1]];
						dst[2] = tbl[src[2]];
						dst[3] = tbl[src[3]];
						src += 4;
						dst += 4;
					}
				} else {
					src += width;
					dst += width;
				}
			} else {
				width = -(char)width;
				dst += width;
				i -= width;
			}
		}
	}
}

/**
 * @brief Same as CelBlitLightTrans but checks for drawing outside the buffer
 */
void CelBlitLightTransSafe(BYTE *pDecodeTo, BYTE *pRLEBytes, int nDataSize, int nWidth)
{
	int w;
	BOOL shift;
	BYTE *tbl;

	/// ASSERT: assert(pDecodeTo != NULL);
	if (!pDecodeTo)
		return;
	/// ASSERT: assert(pRLEBytes != NULL);
	if (!pRLEBytes)
		return;
	/// ASSERT: assert(gpBuffer);
	if (!gpBuffer)
		return;

	int i;
	BYTE width;
	BYTE *src, *dst;

	src = pRLEBytes;
	dst = pDecodeTo;
	tbl = &pLightTbl[light_table_index * 256];
	w = nWidth;
	shift = (BYTE)(size_t)dst & 1;

	for (; src != &pRLEBytes[nDataSize]; dst -= BUFFER_WIDTH + w, shift = (shift + 1) & 1) {
		for (i = w; i;) {
			width = *src++;
			if (!(width & 0x80)) {
				i -= width;
				if (dst < gpBufEnd && dst > gpBufStart) {
					if (((BYTE)(size_t)dst & 1) == shift) {
						if (!(width & 1)) {
							goto L_ODD;
						} else {
							src++;
							dst++;
						L_EVEN:
							width >>= 1;
							if (width & 1) {
								dst[0] = tbl[src[0]];
								src += 2;
								dst += 2;
							}
							width >>= 1;
							for (; width; width--) {
								dst[0] = tbl[src[0]];
								dst[2] = tbl[src[2]];
								src += 4;
								dst += 4;
							}
						}
					} else {
						if (!(width & 1)) {
							goto L_EVEN;
						} else {
							dst[0] = tbl[src[0]];
							src++;
							dst++;
						L_ODD:
							width >>= 1;
							if (width & 1) {
								dst[1] = tbl[src[1]];
								src += 2;
								dst += 2;
							}
							width >>= 1;
							for (; width; width--) {
								dst[1] = tbl[src[1]];
								dst[3] = tbl[src[3]];
								src += 4;
								dst += 4;
							}
						}
					}
				} else {
					src += width;
					dst += width;
				}
			} else {
				width = -(char)width;
				dst += width;
				i -= width;
			}
		}
	}
}

/**
 * @param CelSkip Skip lower parts of sprite, must be multiple of 2, max 8
 * @param CelCap Amount of sprite to render from lower to upper, must be multiple of 2, max 8
 */
void CelClippedBlitLightTrans(BYTE *pBuff, BYTE *pCelBuff, int nCel, int nWidth, int CelSkip, int CelCap)
{
	int nDataSize;
	BYTE *pRLEBytes;

	/// ASSERT: assert(pCelBuff != NULL);
	if (!pCelBuff)
		return;

	pRLEBytes = CelGetFrameClipped(pCelBuff, nCel, CelSkip, CelCap, &nDataSize);
	if (pRLEBytes == NULL)
		return;

	if (cel_transparency_active)
		CelBlitLightTransSafe(pBuff, pRLEBytes, nDataSize, nWidth);
	else if (light_table_index)
		CelBlitLightSafe(pBuff, pRLEBytes, nDataSize, nWidth);
	else
		CelBlitSafe(pBuff, pRLEBytes, nDataSize, nWidth);
}

/**
 * @brief Same as CelDrawLightRed but checks for drawing outside the buffer
 * @param CelSkip Skip lower parts of sprite, must be multiple of 2, max 8
 * @param CelCap Amount of sprite to render from lower to upper, must be multiple of 2, max 8
 */
void CelDrawLightRedSafe(int sx, int sy, BYTE *pCelBuff, int nCel, int nWidth, int CelSkip, int CelCap, char light)
{
	int nDataSize, w, idx;
	BYTE *pRLEBytes, *dst, *tbl;

	/// ASSERT: assert(gpBuffer);
	if (!gpBuffer)
		return;
	/// ASSERT: assert(pCelBuff != NULL);
	if (!pCelBuff)
		return;

	pRLEBytes = CelGetFrameClipped(pCelBuff, nCel, CelSkip, CelCap, &nDataSize);
	if (pRLEBytes == NULL)
		return;

	dst = &gpBuffer[sx + BUFFER_WIDTH * (sy - 16 * CelSkip)];

	idx = light4flag ? 1024 : 4096;
	if (light == 2)
		idx += 256;
	if (light >= 4)
		idx += (light - 1) << 8;

	tbl = &pLightTbl[idx];

	BYTE width;
	BYTE *end;

	end = &pRLEBytes[nDataSize];

	for (; pRLEBytes != end; dst -= BUFFER_WIDTH + nWidth) {
		for (w = nWidth; w;) {
			width = *pRLEBytes++;
			if (!(width & 0x80)) {
				w -= width;
				if (dst < gpBufEnd && dst > gpBufStart) {
					while (width) {
						*dst = tbl[*pRLEBytes];
						pRLEBytes++;
						dst++;
						width--;
					}
				} else {
					pRLEBytes += width;
					dst += width;
				}
			} else {
				width = -(char)width;
				dst += width;
				w -= width;
			}
		}
	}
}

/**
 * @brief Same as CelBlit but cropped to given width
 */
void CelBlitWidth(BYTE *pBuff, int CelSkip, int hgt, int wdt, BYTE *pCelBuff, int nCel, int nWidth)
{
	BYTE *pRLEBytes, *dst, *end;

	/// ASSERT: assert(pCelBuff != NULL);
	if (!pCelBuff)
		return;
	/// ASSERT: assert(pBuff != NULL);
	if (!pBuff)
		return;

	int i, nDataSize;
	BYTE width;

	pRLEBytes = CelGetFrame(pCelBuff, nCel, &nDataSize);
	end = &pRLEBytes[nDataSize];
	dst = &pBuff[hgt * wdt + CelSkip];

	for (; pRLEBytes != end; dst -= wdt + nWidth) {
		for (i = nWidth; i;) {
			width = *pRLEBytes++;
			if (!(width & 0x80)) {
				i -= width;
				if (width & 1) {
					dst[0] = pRLEBytes[0];
					pRLEBytes++;
					dst++;
				}
				width >>= 1;
				if (width & 1) {
					dst[0] = pRLEBytes[0];
					dst[1] = pRLEBytes[1];
					pRLEBytes += 2;
					dst += 2;
				}
				width >>= 1;
				while (width) {
					dst[0] = pRLEBytes[0];
					dst[1] = pRLEBytes[1];
					dst[2] = pRLEBytes[2];
					dst[3] = pRLEBytes[3];
					pRLEBytes += 4;
					dst += 4;
					width--;
				}
			} else {
				width = -(char)width;
				dst += width;
				i -= width;
			}
		}
	}
}

/**
 * @brief Same as CelBlitOutline but checks for drawing outside the buffer
 * @param CelSkip Skip lower parts of sprite, must be multiple of 2, max 8
 * @param CelCap Amount of sprite to render from lower to upper, must be multiple of 2, max 8
 */
void CelBlitOutline(char col, int sx, int sy, BYTE *pCelBuff, int nCel, int nWidth, int CelSkip, int CelCap)
{
	int nDataSize, w;
	BYTE *src, *dst, *end;
	BYTE width;

	/// ASSERT: assert(pCelBuff != NULL);
	if (!pCelBuff)
		return;
	/// ASSERT: assert(gpBuffer);
	if (!gpBuffer)
		return;

	src = CelGetFrameClipped(pCelBuff, nCel, CelSkip, CelCap, &nDataSize);
	if (src == NULL)
		return;

	end = &src[nDataSize];
	dst = &gpBuffer[sx + BUFFER_WIDTH * (sy - 16 * CelSkip)];

	for (; src != end; dst -= BUFFER_WIDTH + nWidth) {
		for (w = nWidth; w;) {
			width = *src++;
			if (!(width & 0x80)) {
				w -= width;
				if (dst < gpBufEnd && dst > gpBufStart) {
					if (dst >= gpBufEnd - BUFFER_WIDTH) {
						while (width) {
							if (*src++) {
								dst[-BUFFER_WIDTH] = col;
								dst[-1] = col;
								dst[1] = col;
							}
							dst++;
							width--;
						}
					} else {
						while (width) {
							if (*src++) {
								dst[-BUFFER_WIDTH] = col;
								dst[-1] = col;
								dst[1] = col;
								dst[BUFFER_WIDTH] = col;
							}
							dst++;
							width--;
						}
					}
				} else {
					src += width;
					dst += width;
				}
			} else {
				width = -(char)width;
				dst += width;
				w -= width;
			}
		}
	}
}

void ENG_set_pixel(int sx, int sy, BYTE col)
{
	BYTE *dst;

	/// ASSERT: assert(gpBuffer);

	if (sy < 0 || sy >= SCREEN_HEIGHT + SCREEN_Y || sx < SCREEN_X || sx >= SCREEN_WIDTH + SCREEN_X)
		return;

	dst = &gpBuffer[sx + BUFFER_WIDTH * sy];

	if (dst < gpBufEnd && dst > gpBufStart)
		*dst = col;
}

void engine_draw_pixel(int sx, int sy)
{
	BYTE *dst;

	/// ASSERT: assert(gpBuffer);

	if (gbRotateMap) {
		if (gbNotInView && (sx < 0 || sx >= SCREEN_HEIGHT + SCREEN_Y || sy < SCREEN_X || sy >= SCREEN_WIDTH + SCREEN_X))
			return;
		dst = &gpBuffer[sy + BUFFER_WIDTH * sx];
	} else {
		if (gbNotInView && (sy < 0 || sy >= SCREEN_HEIGHT + SCREEN_Y || sx < SCREEN_X || sx >= SCREEN_WIDTH + SCREEN_X))
			return;
		dst = &gpBuffer[sx + BUFFER_WIDTH * sy];
	}

	if (dst < gpBufEnd && dst > gpBufStart)
		*dst = gbPixelCol;
}

// Exact copy from https://github.com/erich666/GraphicsGems/blob/dad26f941e12c8bf1f96ea21c1c04cd2206ae7c9/gems/DoubleLine.c
// Except:
// * not in view checks
// * global variable instead of reverse flag
// * condition for pixels_left < 0 removed

/*
Symmetric Double Step Line Algorithm
by Brian Wyvill
from "Graphics Gems", Academic Press, 1990
*/

#define GG_SWAP(A, B) \
	{                 \
		(A) ^= (B);   \
		(B) ^= (A);   \
		(A) ^= (B);   \
	}
#define GG_ABSOLUTE(I, J, K) (((I) - (J)) * ((K) = (((I) - (J)) < 0 ? -1 : 1)))

void DrawLine(int x0, int y0, int x1, int y1, BYTE col)
{
	int dx, dy, incr1, incr2, D, x, y, xend, c, pixels_left;
	int sign_x, sign_y, step, i;
	int x1_, y1_;

	gbPixelCol = col;

	gbNotInView = FALSE;
	if (x0 < 0 + SCREEN_X || x0 >= SCREEN_WIDTH + SCREEN_X) {
		gbNotInView = TRUE;
	}
	if (x1 < 0 + SCREEN_X || x1 >= SCREEN_WIDTH + SCREEN_X) {
		gbNotInView = TRUE;
	}
	if (y0 < 0 + SCREEN_Y || y0 >= PANEL_Y) {
		gbNotInView = TRUE;
	}
	if (y1 < 0 + SCREEN_Y || y1 >= PANEL_Y) {
		gbNotInView = TRUE;
	}

	dx = GG_ABSOLUTE(x1, x0, sign_x);
	dy = GG_ABSOLUTE(y1, y0, sign_y);
	/* decide increment sign by the slope sign */
	if (sign_x == sign_y)
		step = 1;
	else
		step = -1;

	if (dy > dx) { /* chooses axis of greatest movement (make
						* dx) */
		GG_SWAP(x0, y0);
		GG_SWAP(x1, y1);
		GG_SWAP(dx, dy);
		gbRotateMap = TRUE;
	} else
		gbRotateMap = FALSE;
	/* note error check for dx==0 should be included here */
	if (x0 > x1) { /* start from the smaller coordinate */
		x = x1;
		y = y1;
		x1_ = x0;
		y1_ = y0;
	} else {
		x = x0;
		y = y0;
		x1_ = x1;
		y1_ = y1;
	}

	/* Note dx=n implies 0 - n or (dx+1) pixels to be set */
	/* Go round loop dx/4 times then plot last 0,1,2 or 3 pixels */
	/* In fact (dx-1)/4 as 2 pixels are already plotted */
	xend = (dx - 1) / 4;
	pixels_left = (dx - 1) % 4; /* number of pixels left over at the end */
	engine_draw_pixel(x, y);
	engine_draw_pixel(x1_, y1_); /* plot first two points */
	incr2 = 4 * dy - 2 * dx;
	if (incr2 < 0) { /* slope less than 1/2 */
		c = 2 * dy;
		incr1 = 2 * c;
		D = incr1 - dx;

		for (i = 0; i < xend; i++) { /* plotting loop */
			++x;
			--x1_;
			if (D < 0) {
				/* pattern 1 forwards */
				engine_draw_pixel(x, y);
				engine_draw_pixel(++x, y);
				/* pattern 1 backwards */
				engine_draw_pixel(x1_, y1_);
				engine_draw_pixel(--x1_, y1_);
				D += incr1;
			} else {
				if (D < c) {
					/* pattern 2 forwards */
					engine_draw_pixel(x, y);
					engine_draw_pixel(++x, y += step);
					/* pattern 2 backwards */
					engine_draw_pixel(x1_, y1_);
					engine_draw_pixel(--x1_, y1_ -= step);
				} else {
					/* pattern 3 forwards */
					engine_draw_pixel(x, y += step);
					engine_draw_pixel(++x, y);
					/* pattern 3 backwards */
					engine_draw_pixel(x1_, y1_ -= step);
					engine_draw_pixel(--x1_, y1_);
				}
				D += incr2;
			}
		} /* end for */

		/* plot last pattern */
		if (pixels_left) {
			if (D < 0) {
				engine_draw_pixel(++x, y); /* pattern 1 */
				if (pixels_left > 1)
					engine_draw_pixel(++x, y);
				if (pixels_left > 2)
					engine_draw_pixel(--x1_, y1_);
			} else {
				if (D < c) {
					engine_draw_pixel(++x, y); /* pattern 2  */
					if (pixels_left > 1)
						engine_draw_pixel(++x, y += step);
					if (pixels_left > 2)
						engine_draw_pixel(--x1_, y1_);
				} else {
					/* pattern 3 */
					engine_draw_pixel(++x, y += step);
					if (pixels_left > 1)
						engine_draw_pixel(++x, y);
					if (pixels_left > 2)
						engine_draw_pixel(--x1_, y1_ -= step);
				}
			}
		} /* end if pixels_left */
	}
	/* end slope < 1/2 */
	else { /* slope greater than 1/2 */
		c = 2 * (dy - dx);
		incr1 = 2 * c;
		D = incr1 + dx;
		for (i = 0; i < xend; i++) {
			++x;
			--x1_;
			if (D > 0) {
				/* pattern 4 forwards */
				engine_draw_pixel(x, y += step);
				engine_draw_pixel(++x, y += step);
				/* pattern 4 backwards */
				engine_draw_pixel(x1_, y1_ -= step);
				engine_draw_pixel(--x1_, y1_ -= step);
				D += incr1;
			} else {
				if (D < c) {
					/* pattern 2 forwards */
					engine_draw_pixel(x, y);
					engine_draw_pixel(++x, y += step);

					/* pattern 2 backwards */
					engine_draw_pixel(x1_, y1_);
					engine_draw_pixel(--x1_, y1_ -= step);
				} else {
					/* pattern 3 forwards */
					engine_draw_pixel(x, y += step);
					engine_draw_pixel(++x, y);
					/* pattern 3 backwards */
					engine_draw_pixel(x1_, y1_ -= step);
					engine_draw_pixel(--x1_, y1_);
				}
				D += incr2;
			}
		} /* end for */
		/* plot last pattern */
		if (pixels_left) {
			if (D > 0) {
				engine_draw_pixel(++x, y += step); /* pattern 4 */
				if (pixels_left > 1)
					engine_draw_pixel(++x, y += step);
				if (pixels_left > 2)
					engine_draw_pixel(--x1_, y1_ -= step);
			} else {
				if (D < c) {
					engine_draw_pixel(++x, y); /* pattern 2  */
					if (pixels_left > 1)
						engine_draw_pixel(++x, y += step);
					if (pixels_left > 2)
						engine_draw_pixel(--x1_, y1_);
				} else {
					/* pattern 3 */
					engine_draw_pixel(++x, y += step);
					if (pixels_left > 1)
						engine_draw_pixel(++x, y);
					if (pixels_left > 2) {
						if (D > c) /* step 3 */
							engine_draw_pixel(--x1_, y1_ -= step);
						else /* step 2 */
							engine_draw_pixel(--x1_, y1_);
					}
				}
			}
		}
	}
}

int GetDirection(int x1, int y1, int x2, int y2)
{
	int mx, my;
	int md, ny;

	mx = x2 - x1;
	my = y2 - y1;

	if (mx >= 0) {
		if (my >= 0) {
			md = DIR_S;
			if (2 * mx < my)
				md = DIR_SW;
		} else {
			my = -my;
			md = DIR_E;
			if (2 * mx < my)
				md = DIR_NE;
		}
		if (2 * my < mx)
			return DIR_SE;
	} else {
		if (my >= 0) {
			ny = -mx;
			md = DIR_W;
			if (2 * ny < my)
				md = DIR_SW;
		} else {
			ny = -mx;
			my = -my;
			md = DIR_N;
			if (2 * ny < my)
				md = DIR_NE;
		}
		if (2 * my < ny)
			return DIR_NW;
	}

	return md;
}

void SetRndSeed(int s)
{
	SeedCount = 0;
	sglGameSeed = s;
	orgseed = s;
}

int GetRndSeed()
{
	SeedCount++;
	sglGameSeed = static_cast<unsigned int>(RndMult) * sglGameSeed + RndInc;
	return abs(sglGameSeed);
}

int random(BYTE idx, int v)
{
	if (v <= 0)
		return 0;
	if (v < 0xFFFF)
		return (GetRndSeed() >> 16) % v;
	return GetRndSeed() % v;
}

BYTE *DiabloAllocPtr(DWORD dwBytes)
{
	BYTE *buf;

	sgMemCrit.Enter();
	buf = (BYTE *)SMemAlloc(dwBytes, __FILE__, __LINE__, 0);
	sgMemCrit.Leave();

	if (buf == NULL) {
		char *text = "System memory exhausted.\n"
		"Make sure you have at least 64MB of free system memory before running the game";
		ERR_DLG("Out of Memory Error", text);
	}

	return buf;
}

void mem_free_dbg(void *p)
{
	if (p) {
		sgMemCrit.Enter();
		SMemFree(p, __FILE__, __LINE__, 0);
		sgMemCrit.Leave();
	}
}

BYTE *LoadFileInMem(char *pszName, DWORD *pdwFileLen)
{
	HANDLE file;
	BYTE *buf;
	int fileLen;

	WOpenFile(pszName, &file, FALSE);
	fileLen = WGetFileSize(file, NULL, pszName);

	if (pdwFileLen)
		*pdwFileLen = fileLen;

	if (!fileLen)
		app_fatal("Zero length SFILE:\n%s", pszName);

	buf = (BYTE *)DiabloAllocPtr(fileLen);

	WReadFile(file, buf, fileLen, pszName);
	WCloseFile(file);

	return buf;
}

DWORD LoadFileWithMem(const char *pszName, void *p)
{
	DWORD dwFileLen;
	HANDLE hsFile;

	/// ASSERT: assert(pszName);
	if (p == NULL) {
		app_fatal("LoadFileWithMem(NULL):\n%s", pszName);
	}

	WOpenFile(pszName, &hsFile, FALSE);

	dwFileLen = WGetFileSize(hsFile, NULL, pszName);
	if (dwFileLen == 0) {
		app_fatal("Zero length SFILE:\n%s", pszName);
	}

	WReadFile(hsFile, p, dwFileLen, pszName);
	WCloseFile(hsFile);

	return dwFileLen;
}

/**
 * @brief Apply the color swaps to a CL2 sprite
 */
void Cl2ApplyTrans(BYTE *p, BYTE *ttbl, int nCel)
{
	int i, nDataSize;
	char width;
	BYTE *dst;

	/// ASSERT: assert(p != NULL);
	/// ASSERT: assert(ttbl != NULL);

	for (i = 1; i <= nCel; i++) {
		dst = CelGetFrame(p, i, &nDataSize) + 10;
		nDataSize -= 10;
		while (nDataSize) {
			width = *dst++;
			nDataSize--;
			/// ASSERT: assert(nDataSize >= 0);
			if (width < 0) {
				width = -width;
				if (width > 65) {
					nDataSize--;
					/// ASSERT: assert(nDataSize >= 0);
					*dst = ttbl[*dst];
					dst++;
				} else {
					nDataSize -= width;
					/// ASSERT: assert(nDataSize >= 0);
					while (width) {
						*dst = ttbl[*dst];
						dst++;
						width--;
					}
				}
			}
		}
	}
}

/**
 * @param CelSkip Skip lower parts of sprite, must be multiple of 2, max 8
 * @param CelCap Amount of sprite to render from lower to upper, must be multiple of 2, max 8
 */
void Cl2Draw(int sx, int sy, BYTE *pCelBuff, int nCel, int nWidth, int CelSkip, int CelCap)
{
	BYTE *pRLEBytes;
	int nDataSize;

	/// ASSERT: assert(gpBuffer != NULL);
	if (!gpBuffer)
		return;
	/// ASSERT: assert(pCelBuff != NULL);
	if (!pCelBuff)
		return;
	/// ASSERT: assert(nCel > 0);
	if (nCel <= 0)
		return;

	pRLEBytes = CelGetFrameClipped(pCelBuff, nCel, CelSkip, CelCap, &nDataSize);
	if (pRLEBytes == NULL)
		return;

	Cl2BlitSafe(
	    &gpBuffer[sx + BUFFER_WIDTH * (sy - 16 * CelSkip)],
	    pRLEBytes,
	    nDataSize,
	    nWidth);
}

void Cl2BlitSafe(BYTE *pDecodeTo, BYTE *pRLEBytes, int nDataSize, int nWidth)
{
	int w;
	char width;
	BYTE fill;
	BYTE *src, *dst;

	src = pRLEBytes;
	dst = pDecodeTo;
	w = nWidth;

	while (nDataSize) {
		width = *src++;
		nDataSize--;
		if (width < 0) {
			width = -width;
			if (width > 65) {
				width -= 65;
				nDataSize--;
				fill = *src++;
				if (dst < gpBufEnd && dst > gpBufStart) {
					w -= width;
					while (width) {
						*dst = fill;
						dst++;
						width--;
					}
					if (!w) {
						w = nWidth;
						dst -= BUFFER_WIDTH + w;
					}
					continue;
				}
			} else {
				nDataSize -= width;
				if (dst < gpBufEnd && dst > gpBufStart) {
					w -= width;
					while (width) {
						*dst = *src;
						src++;
						dst++;
						width--;
					}
					if (!w) {
						w = nWidth;
						dst -= BUFFER_WIDTH + w;
					}
					continue;
				} else {
					src += width;
				}
			}
		}
		while (width) {
			if (width > w) {
				dst += w;
				width -= w;
				w = 0;
			} else {
				dst += width;
				w -= width;
				width = 0;
			}
			if (!w) {
				w = nWidth;
				dst -= BUFFER_WIDTH + w;
			}
		}
	}
}

/**
 * @param CelSkip Skip lower parts of sprite, must be multiple of 2, max 8
 * @param CelCap Amount of sprite to render from lower to upper, must be multiple of 2, max 8
 */
void Cl2DrawOutline(char col, int sx, int sy, BYTE *pCelBuff, int nCel, int nWidth, int CelSkip, int CelCap)
{
	int nDataSize;
	BYTE *pRLEBytes;

	/// ASSERT: assert(gpBuffer != NULL);
	if (!gpBuffer)
		return;
	/// ASSERT: assert(pCelBuff != NULL);
	if (!pCelBuff)
		return;
	/// ASSERT: assert(nCel > 0);
	if (nCel <= 0)
		return;

	pRLEBytes = CelGetFrameClipped(pCelBuff, nCel, CelSkip, CelCap, &nDataSize);
	if (pRLEBytes == NULL)
		return;

	gpBufEnd -= BUFFER_WIDTH;
	Cl2BlitOutlineSafe(
	    &gpBuffer[sx + BUFFER_WIDTH * (sy - 16 * CelSkip)],
	    pRLEBytes,
	    nDataSize,
	    nWidth,
	    col);
	gpBufEnd += BUFFER_WIDTH;
}

void Cl2BlitOutlineSafe(BYTE *pDecodeTo, BYTE *pRLEBytes, int nDataSize, int nWidth, char col)
{
	int w;
	char width;
	BYTE *src, *dst;

	src = pRLEBytes;
	dst = pDecodeTo;
	w = nWidth;

	while (nDataSize) {
		width = *src++;
		nDataSize--;
		if (width < 0) {
			width = -width;
			if (width > 65) {
				width -= 65;
				nDataSize--;
				if (*src++ && dst < gpBufEnd && dst > gpBufStart) {
					w -= width;
					dst[-1] = col;
					dst[width] = col;
					while (width) {
						dst[-BUFFER_WIDTH] = col;
						dst[BUFFER_WIDTH] = col;
						dst++;
						width--;
					}
					if (!w) {
						w = nWidth;
						dst -= BUFFER_WIDTH + w;
					}
					continue;
				}
			} else {
				nDataSize -= width;
				if (dst < gpBufEnd && dst > gpBufStart) {
					w -= width;
					while (width) {
						if (*src++) {
							dst[-1] = col;
							dst[1] = col;
							dst[-BUFFER_WIDTH] = col;
							dst[BUFFER_WIDTH] = col;
						}
						dst++;
						width--;
					}
					if (!w) {
						w = nWidth;
						dst -= BUFFER_WIDTH + w;
					}
					continue;
				} else {
					src += width;
				}
			}
		}
		while (width) {
			if (width > w) {
				dst += w;
				width -= w;
				w = 0;
			} else {
				dst += width;
				w -= width;
				width = 0;
			}
			if (!w) {
				w = nWidth;
				dst -= BUFFER_WIDTH + w;
			}
		}
	}
}

/**
 * @param CelSkip Skip lower parts of sprite, must be multiple of 2, max 8
 * @param CelCap Amount of sprite to render from lower to upper, must be multiple of 2, max 8
 */
void Cl2DrawLightTbl(int sx, int sy, BYTE *pCelBuff, int nCel, int nWidth, int CelSkip, int CelCap, char light)
{
	int nDataSize, idx;
	BYTE *pRLEBytes, *pDecodeTo;

	/// ASSERT: assert(gpBuffer != NULL);
	if (!gpBuffer)
		return;
	/// ASSERT: assert(pCelBuff != NULL);
	if (!pCelBuff)
		return;
	/// ASSERT: assert(nCel > 0);
	if (nCel <= 0)
		return;

	pRLEBytes = CelGetFrameClipped(pCelBuff, nCel, CelSkip, CelCap, &nDataSize);
	if (pRLEBytes == NULL)
		return;

	pDecodeTo = &gpBuffer[sx + BUFFER_WIDTH * (sy - 16 * CelSkip)];

	idx = light4flag ? 1024 : 4096;
	if (light == 2)
		idx += 256;
	if (light >= 4)
		idx += (light - 1) << 8;

	Cl2BlitLightSafe(
	    pDecodeTo,
	    pRLEBytes,
	    nDataSize,
	    nWidth,
	    &pLightTbl[idx]);
}

void Cl2BlitLightSafe(BYTE *pDecodeTo, BYTE *pRLEBytes, int nDataSize, int nWidth, BYTE *pTable)
{
	int w;
	char width;
	BYTE fill;
	BYTE *src, *dst;

	src = pRLEBytes;
	dst = pDecodeTo;
	w = nWidth;
	sgnWidth = nWidth;

	while (nDataSize) {
		width = *src++;
		nDataSize--;
		if (width < 0) {
			width = -width;
			if (width > 65) {
				width -= 65;
				nDataSize--;
				fill = pTable[*src++];
				if (dst < gpBufEnd && dst > gpBufStart) {
					w -= width;
					while (width) {
						*dst = fill;
						dst++;
						width--;
					}
					if (!w) {
						w = sgnWidth;
						dst -= BUFFER_WIDTH + w;
					}
					continue;
				}
			} else {
				nDataSize -= width;
				if (dst < gpBufEnd && dst > gpBufStart) {
					w -= width;
					while (width) {
						*dst = pTable[*src];
						src++;
						dst++;
						width--;
					}
					if (!w) {
						w = sgnWidth;
						dst -= BUFFER_WIDTH + w;
					}
					continue;
				} else {
					src += width;
				}
			}
		}
		while (width) {
			if (width > w) {
				dst += w;
				width -= w;
				w = 0;
			} else {
				dst += width;
				w -= width;
				width = 0;
			}
			if (!w) {
				w = sgnWidth;
				dst -= BUFFER_WIDTH + w;
			}
		}
	}
}

/**
 * @param CelSkip Skip lower parts of sprite, must be multiple of 2, max 8
 * @param CelCap Amount of sprite to render from lower to upper, must be multiple of 2, max 8
 */
void Cl2DrawLight(int sx, int sy, BYTE *pCelBuff, int nCel, int nWidth, int CelSkip, int CelCap)
{
	int nDataSize;
	BYTE *pRLEBytes, *pDecodeTo;

	/// ASSERT: assert(gpBuffer != NULL);
	if (!gpBuffer)
		return;
	/// ASSERT: assert(pCelBuff != NULL);
	if (!pCelBuff)
		return;
	/// ASSERT: assert(nCel > 0);
	if (nCel <= 0)
		return;

	pRLEBytes = CelGetFrameClipped(pCelBuff, nCel, CelSkip, CelCap, &nDataSize);
	if (pRLEBytes == NULL)
		return;

	pDecodeTo = &gpBuffer[sx + BUFFER_WIDTH * (sy - 16 * CelSkip)];

	if (light_table_index)
		Cl2BlitLightSafe(pDecodeTo, pRLEBytes, nDataSize, nWidth, &pLightTbl[light_table_index * 256]);
	else
		Cl2BlitSafe(pDecodeTo, pRLEBytes, nDataSize, nWidth);
}

void PlayInGameMovie(char *pszMovie)
{
	PaletteFadeOut(8);
	play_movie(pszMovie, 0);
	ClearScreenBuffer();
	drawpanflag = 255;
	scrollrt_draw_game_screen(1);
	PaletteFadeIn(8);
	drawpanflag = 255;
}

DEVILUTION_END_NAMESPACE