os161-assignments/kern/dev/lamebus/lscreen.c

/*
 * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
 *	The President and Fellows of Harvard College.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Driver for full-screen console.
 *
 * As of this writing the full-screen console is not supported in
 * System/161, so this driver is untested and probably broken.
 */
#include <types.h>
#include <lib.h>
#include <spinlock.h>
#include <platform/bus.h>
#include <lamebus/lscreen.h>
#include "autoconf.h"

/* Registers (offsets within slot) */
#define LSCR_REG_POSN 0  /* Cursor position */
#define LSCR_REG_SIZE 4  /* Display size */
#define LSCR_REG_CHAR 8  /* Character in */
#define LSCR_REG_RIRQ 12 /* Read interrupt status */

/* Bits in the IRQ registers */
#define LSCR_IRQ_ENABLE 1
#define LSCR_IRQ_ACTIVE 2

/* Offset within slot of screen buffer */
#define LSCR_SCREEN 32768

/* Convert a 32-bit X/Y pair to X and Y coordinates. */
static inline void splitxy(uint32_t xy, unsigned *x, unsigned *y) {
  *x = xy >> 16;
  *y = xy & 0xffff;
}

/* Convert X and Y coordinates to a single 32-bit value. */
static inline uint32_t mergexy(unsigned x, unsigned y) {
  uint32_t val = x;

  return (val << 16) | y;
}

////////////////////////////////////////////////////////////

/*
 * Interrupt handler.
 */
void lscreen_irq(void *vsc) {
  struct lscreen_softc *sc = vsc;
  uint32_t ch, x;

  spinlock_acquire(&sc->ls_lock);

  x = bus_read_register(sc->ls_busdata, sc->ls_buspos, LSCR_REG_RIRQ);
  if (x & LSCR_IRQ_ACTIVE) {
    ch = bus_read_register(sc->ls_busdata, sc->ls_buspos, LSCR_REG_CHAR);
    bus_write_register(sc->ls_busdata, sc->ls_buspos, LSCR_REG_RIRQ,
                       LSCR_IRQ_ENABLE);

    spinlock_release(&sc->ls_lock);
    if (sc->ls_input) {
      sc->ls_input(sc->ls_devdata, ch);
    }
  } else {
    spinlock_release(&sc->ls_lock);
  }
}

////////////////////////////////////////////////////////////

/*
 * Handle a newline on the screen.
 */
static void lscreen_newline(struct lscreen_softc *sc) {
  if (sc->ls_cy >= sc->ls_height - 1) {
    /*
     * Scroll
     */

    memmove(sc->ls_screen, sc->ls_screen + sc->ls_width,
            sc->ls_width * (sc->ls_height - 1));
    bzero(sc->ls_screen + sc->ls_width * (sc->ls_height - 1), sc->ls_width);
  } else {
    sc->ls_cy++;
  }
  sc->ls_cx = 0;
}

/*
 * Handle a printable character being written to the screen.
 */
static void lscreen_char(struct lscreen_softc *sc, int ch) {
  if (sc->ls_cx >= sc->ls_width) {
    lscreen_newline(sc);
  }

  sc->ls_screen[sc->ls_cy * sc->ls_width + sc->ls_cx] = ch;
  sc->ls_cx++;
}

/*
 * Send a character to the screen.
 * This should probably know about backspace and tab.
 */
void lscreen_write(void *vsc, int ch) {
  struct lscreen_softc *sc = vsc;
  int ccx, ccy;

  spinlock_acquire(&sc->ls_lock);

  switch (ch) {
  case '\n':
    lscreen_newline(sc);
    break;
  default:
    lscreen_char(sc, ch);
    break;
  }

  /*
   * ccx/ccy = corrected cursor position
   * (The cursor marks the next space text will appear in. But
   * at the very end of the line, it should not move off the edge.)
   */
  ccx = sc->ls_cx;
  ccy = sc->ls_cy;
  if (ccx == sc->ls_width) {
    ccx--;
  }

  /* Set the cursor position */
  bus_write_register(sc->ls_busdata, sc->ls_buspos, LSCR_REG_POSN,
                     mergexy(ccx, ccy));

  spinlock_release(&sc->ls_lock);
}

////////////////////////////////////////////////////////////

/*
 * Setup routine called by autoconf.c when an lscreen is found.
 */
int config_lscreen(struct lscreen_softc *sc, int lscreenno) {
  uint32_t val;

  (void)lscreenno;

  spinlock_init(&sc->ls_lock);

  /*
   * Enable interrupting.
   */

  bus_write_register(sc->ls_busdata, sc->ls_buspos, LSCR_REG_RIRQ,
                     LSCR_IRQ_ENABLE);

  /*
   * Get screen size.
   */
  val = bus_read_register(sc->ls_busdata, sc->ls_buspos, LSCR_REG_SIZE);
  splitxy(val, &sc->ls_width, &sc->ls_height);

  /*
   * Get cursor position.
   */
  val = bus_read_register(sc->ls_busdata, sc->ls_buspos, LSCR_REG_POSN);
  splitxy(val, &sc->ls_cx, &sc->ls_cy);

  /*
   * Get a pointer to the memory-mapped screen area.
   */
  sc->ls_screen = bus_map_area(sc->ls_busdata, sc->ls_buspos, LSCR_SCREEN);

  return 0;
}