/*

 * Generate a VGA signal using a PIC32 microcontroller.

 *

 * Copyright (C) 2017, 2018 Paul Boddie <paul@boddie.org.uk>

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

#ifndef __VGA_H__

#define __VGA_H__

#include "vga_common.h"

#define LINE_LENGTH             160 /* pixels */

#define LINE_COUNT              128 /* display lines per frame */

#define FRAME_COUNT             2   /* double-buffered display */

/* 24MHz cycle measurements. */

#define HFREQ_LIMIT             643

#define HSYNC_START             520

#define HSYNC_LIMIT             64

#define HSYNC_END               (HSYNC_START + HSYNC_LIMIT)

/* Framebuffer properties. */

#define SCREEN_SIZE             (LINE_LENGTH * LINE_COUNT)

/* A frame has an entire screen plus one line to allow horizontal scrolling,

   since a horizontal scroll offset causes the final transfer line to exceed the

   screen limit. */

#define FRAME_SIZE              (SCREEN_SIZE + LINE_LENGTH)

/* Transfer and pixel allocation properties. */

#define TRANSFER_CELL_SIZE      LINE_LENGTH

#define CELL_SIZE               LINE_LENGTH

#endif /* __VGA_H__ */