/****************************************************************************************
 * Subroutine to send a string of text to the VGA monitor 
****************************************************************************************/
void VGA_text(int x, int y, char * text_ptr)
{
	int offset;
  	volatile char * character_buffer = (char *) FPGA_CHAR_BASE;	// VGA character buffer

	/* assume that the text string fits on one line */
	offset = (y << 7) + x;
	while ( *(text_ptr) )
	{
		*(character_buffer + offset) = *(text_ptr);	// write to the character buffer
		++text_ptr;
		++offset;
	}
}

/****************************************************************************************
 * Draw a filled rectangle on the VGA monitor 
****************************************************************************************/
void VGA_box(int x1, int y1, int x2, int y2, short pixel_color)
{
	int pixel_ptr, row, col;

	/* assume that the box coordinates are valid */
	for (row = y1; row <= y2; row++)
		for (col = x1; col <= x2; ++col)
		{
			pixel_ptr = FPGA_ONCHIP_BASE + (row << 10) + (col << 1);
			*(short *)pixel_ptr = pixel_color;		// set pixel color
		}
}


/****************************************************************************************
 * Subroutine to show a string of HEX data on the HEX displays
****************************************************************************************/
void HEX_PS2(char b1, char b2, char b3)
{
	volatile int * HEX3_HEX0_ptr = (int *) HEX3_HEX0_BASE;
	volatile int * HEX5_HEX4_ptr = (int *) HEX5_HEX4_BASE;

	/* SEVEN_SEGMENT_DECODE_TABLE gives the on/off settings for all segments in 
	 * a single 7-seg display in the DE1-SoC Computer, for the hex digits 0 - F */
	unsigned char	seven_seg_decode_table[] = {	0x3F, 0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7C, 0x07, 
		  										0x7F, 0x67, 0x77, 0x7C, 0x39, 0x5E, 0x79, 0x71 };
	unsigned char	hex_segs[] = { 0, 0, 0, 0, 0, 0, 0, 0 };
	unsigned int shift_buffer, nibble;
	unsigned char code;
	int i;

	shift_buffer = (b1 << 16) | (b2 << 8) | b3;
	for ( i = 0; i < 6; ++i )
	{
		nibble = shift_buffer & 0x0000000F;		// character is in rightmost nibble
		code = seven_seg_decode_table[nibble];
		hex_segs[i] = code;
		shift_buffer = shift_buffer >> 4;
	}
	/* drive the hex displays */
	*(HEX3_HEX0_ptr) = *(int *) (hex_segs);
	*(HEX5_HEX4_ptr) = *(int *) (hex_segs+4);
}



int resample_rgb(int num_bits, int color) 
{
    if (num_bits == 8) {
        color = (((color >> 16) & 0x000000E0) | ((color >> 11) & 0x0000001C) |
                 ((color >> 6) & 0x00000003));
        color = (color << 8) | color;
    } else if (num_bits == 16) {
        color = (((color >> 8) & 0x0000F800) | ((color >> 5) & 0x000007E0) |
                 ((color >> 3) & 0x0000001F));
    }
    return color;
}