initial commit

oscar64/samples/scrolling/colorram.c

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+#include <c64/vic.h>
+#include <c64/memmap.h>
+#include <string.h>
+#include <stdlib.h>
+
+// Screen and color space
+#define screen ((byte *)0x0400)
+#define color ((byte *)0xd800)
+
+// Macro for easy access to screen and color space
+#define sline(x, y) (screen + 40 * (y) + (x))
+#define cline(x, y) (color + 40 * (y) + (x))
+
+// Column buffer for one prepared column of screen and color data
+char rbuff[25], cbuff[25];
+
+// Split into three scrolling sections to race the beam
+#define SPLIT1	8
+#define SPLIT2	16
+
+// Scroll top section
+void scrollLeft0(void)
+{
+	for(char x=0; x<39; x++)
+	{
+		#pragma unroll(full)
+		for(char y=0; y<SPLIT1; y++)
+		{
+			sline(0, y)[x] = sline(1, y)[x];
+			cline(0, y)[x] = cline(1, y)[x];
+		}
+	}
+
+	#pragma unroll(full)
+	for(char y=0; y<SPLIT1; y++)
+	{
+		sline(0, y)[39] = rbuff[y];
+		cline(0, y)[39] = cbuff[y];
+	}
+}
+
+// Scroll bottom two sections
+void scrollLeft1(void)
+{
+	for(char x=0; x<39; x++)
+	{
+		#pragma unroll(full)
+		for(char y=SPLIT1; y<SPLIT2; y++)
+		{
+			sline(0, y)[x] = sline(1, y)[x];
+			cline(0, y)[x] = cline(1, y)[x];
+		}
+	}
+	#pragma unroll(full)
+	for(char y=SPLIT1; y<SPLIT2; y++)
+	{
+		sline(0, y)[39] = rbuff[y];
+		cline(0, y)[39] = cbuff[y];
+	}
+
+	for(char x=0; x<39; x++)
+	{
+		#pragma unroll(full)
+		for(char y=SPLIT2; y<25; y++)
+		{
+			sline(0, y)[x] = sline(1, y)[x];
+			cline(0, y)[x] = cline(1, y)[x];
+		}
+	}
+	#pragma unroll(full)
+	for(char y=SPLIT2; y<25; y++)
+	{
+		sline(0, y)[39] = rbuff[y];
+		cline(0, y)[39] = cbuff[y];
+	}
+}
+
+
+// Prepare a new column with random data
+void prepcol(void)
+{
+	for(char i=0; i<25; i++)
+	{
+		unsigned r = rand();
+		cbuff[i] = r & 15;
+		rbuff[i] = (r & 16) ? 102 : 160;
+	}
+}
+
+int main(void)
+{
+	// Clear the screen
+	memset(screen, 0x20, 1000);
+	memset(color, 7, 1000);
+
+	vic.color_back = VCOL_BLACK;
+	vic.color_border = VCOL_BLACK;
+
+	char	x = 0;
+
+	for(;;)
+	{
+		// Advance one pixel
+
+		x = (x + 1) & 7;
+
+		// If we will cross the character boundary, scroll the top section
+		if (x == 0)
+		{
+			// Wait for raster reaching bottom of first section
+			vic_waitLine(50 + 8 * SPLIT1);
+			// Scroll first section
+			scrollLeft0();
+		}
+
+		// Wait for bottom of screen
+		vic_waitBottom();
+
+		// Update the pixel offset
+		vic.ctrl2 = (7 - x) & 7;
+
+		if (x == 0)
+		{
+			// Scroll the bottom section if needed
+			scrollLeft1();
+		}
+		else 
+		{
+			// Update the new column somewhere in the middle of the character
+			if (x == 4)
+				prepcol();
+			vic_waitTop();
+		}
+	}
+
+	return 0;
+
+}