Import backup from 2004-04-03

kernel/video/video.c

@@ -68,13 +68,13 @@ void	video_horiz(int y, int x1, int x2, dword color)
 	}
 	if (x2 < 0)
 		return;
-	if (x1 > video_mode.XResolution)
+	if (x1 >= video_mode.XResolution)
 		return;
 	if (x1 < 0)
 		x1 = 0;
-	if (x2 > video_mode.XResolution)
-		x2 = video_mode.XResolution;
-	int pixel = y*video_mode.XResolution+x1;
+	if (x2 >= video_mode.XResolution)
+		x2 = video_mode.XResolution - 1;
+	int pixel = y * video_mode.XResolution + x1;
 	for (; x1 <= x2; x1++)
 	{
 		video_psetp(pixel++, color);
@@ -84,12 +84,13 @@ void	video_horiz(int y, int x1, int x2, dword color)
 //Draws a single pixel
 void	video_pset(int x, int y, dword color)
 {
-	if ((x < 0) || (x > video_mode.XResolution) || (y < 0) || (y > video_mode.YResolution))
+	if ((x < 0) || (x >= video_mode.XResolution) || (y < 0) || (y >= video_mode.YResolution))
 		return;
-	video_psetp(y*video_mode.XResolution+x, color);
+	video_psetp(y * video_mode.XResolution + x, color);
 }
 
 //Draws a pixel at the specified pixel position
+//This function is needed because external modules do not have access to the function pointer video_psetp
 void	video_pseti(int pixel, dword color)
 {
 	video_psetp(pixel, color);
@@ -106,17 +107,17 @@ void	video_vert(int x, int y1, int y2, dword color)
 	}
 	if (y2 < 0)
 		return;
-	if (y1 > video_mode.YResolution)
+	if (y1 >= video_mode.YResolution)
 		return;
 	if (y1 < 0)
 		y1 = 0;
-	if (y2 > video_mode.YResolution)
-		y2 = video_mode.YResolution;
-	int pixel = y1*video_mode.XResolution+x;
+	if (y2 >= video_mode.YResolution)
+		y2 = video_mode.YResolution - 1;
+	int pixel = y1 * video_mode.XResolution + x;
 	for (; y1 <= y2; y1++)
 	{
 		video_psetp(pixel, color);
-		pixel+=video_mode.XResolution;
+		pixel += video_mode.XResolution;
 	}
 }
 
@@ -191,3 +192,63 @@ dword	video_Mode()
 	return videoMode;
 }
 
+void	video_line(int x0, int y0, int x1, int y1, dword color)
+{
+	int dy = y1 - y0;
+	int dx = x1 - x0;
+	int stepx, stepy;
+	if (dy < 0)
+	{
+		dy = -dy;
+		stepy = -1; 
+	}
+	else
+	{
+		stepy = 1; 
+	}	
+ 	if (dx < 0)
+	{
+		dx = -dx;
+		stepx = -1; 
+	}
+	else
+	{
+		stepx = 1; 
+	}
+	dy <<= 1; 						// dy is now 2*dy
+	dx <<= 1; 						// dx is now 2*dx
+ 	video_pset(x0, y0, color);
+
+	if (dx > dy)
+	{
+		int fraction = dy - (dx >> 1);			// same as 2*dy - dx
+		while (x0 != x1)
+		{
+			if (fraction >= 0)
+			{
+				y0 += stepy;
+				fraction -= dx; 		// same as fraction -= 2*dx
+			}
+   		x0 += stepx;
+   		fraction += dy; 				// same as fraction -= 2*dy
+   		video_pset(x0, y0, color);
+		}
+	}
+	else
+	{
+		int fraction = dx - (dy >> 1);
+		while (y0 != y1)
+		{
+			if (fraction >= 0)
+			{
+				x0 += stepx;
+				fraction -= dy;
+			}
+		y0 += stepy;
+		fraction += dx;
+		video_pset(x0, y0, color);
+		}
+	}
+}
+
+

kernel/video/video.h

@@ -24,6 +24,7 @@ int	video_getHeight();
 byte	video_getBitsPerPixel();
 dword	video_getPhysBasePtr();
 dword	video_Mode();
+void	video_line(int x0, int y0, int x1, int y1, dword color);
 
 
 typedef struct{