/* vga-support.c - VGA hardware access.
   Copyright (C) 2002 Free Software Foundation, Inc.
   Written by Marcus Brinkmann.

   This file is part of the GNU Hurd.

   The GNU Hurd 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 2, or (at
   your option) any later version.

   The GNU Hurd 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, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA. */

#include <errno.h>
#include <assert.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/io.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <string.h>
#include <stdlib.h>

#include "vga-hw.h"
#include "vga-support.h"


/* The base of the video memory mapping.  */
char *vga_videomem;

/* The saved state of the VGA card.  */
struct vga_state
{
  unsigned char seq_clock_mode;
  unsigned char seq_map;
  unsigned char seq_font;
  unsigned char seq_mode;

  unsigned char gfx_map;
  unsigned char gfx_mode;
  unsigned char gfx_misc;

  unsigned char crt_max_scan_line;
  unsigned char crt_cursor_start;
  unsigned char crt_cursor_end;
  unsigned char crt_cursor_high;
  unsigned char crt_cursor_low;

  char videomem[2 * 80 * 25];
  unsigned char fontmem[2 * VGA_FONT_SIZE * VGA_FONT_HEIGHT];
};

static struct vga_state *vga_state;


error_t
vga_init (void)
{
  error_t err;
  int fd;

  /* Acquire I/O port access.  */
  if (ioperm (VGA_MIN_REG, VGA_MAX_REG - VGA_MIN_REG + 1, 1) < 0)
    {
      /* GNU Mach v1 is broken in that it doesn't implement an I/O
	 perm interface and just allows all tasks to access any I/O
	 port.  */
      if (errno != EMIG_BAD_ID && errno != ENOSYS)
	{
	  free (vga_state);
	  return errno;
	}
    }

  fd = open ("/dev/mem", O_RDWR);
  if (fd >= 0)
    {
      vga_videomem = mmap (0, VGA_VIDEO_MEM_LENGTH, PROT_READ | PROT_WRITE,
			   MAP_SHARED, fd, VGA_VIDEO_MEM_BASE_ADDR);
      err = errno;
      close (fd);
      if (vga_videomem == (void *) -1)
	return err;
    }
  else
    return errno;

  /* Save the current state.  */
  vga_state = malloc (sizeof (*vga_state));
  if (!vga_state)
    return errno;

  outb (VGA_SEQ_CLOCK_MODE_ADDR, VGA_SEQ_ADDR_REG);
  vga_state->seq_clock_mode = inb (VGA_SEQ_DATA_REG);
  outb (VGA_SEQ_MAP_ADDR, VGA_SEQ_ADDR_REG);
  vga_state->seq_map = inb (VGA_SEQ_DATA_REG);
  outb (VGA_SEQ_FONT_ADDR, VGA_SEQ_ADDR_REG);
  vga_state->seq_font = inb (VGA_SEQ_DATA_REG);
  outb (VGA_SEQ_MODE_ADDR, VGA_SEQ_ADDR_REG);
  vga_state->seq_mode = inb (VGA_SEQ_DATA_REG);

  outb (VGA_GFX_MAP_ADDR, VGA_GFX_ADDR_REG);
  vga_state->gfx_map = inb (VGA_GFX_DATA_REG);
  outb (VGA_GFX_MODE_ADDR, VGA_GFX_ADDR_REG);
  vga_state->gfx_mode = inb (VGA_GFX_DATA_REG);
  outb (VGA_GFX_MISC_ADDR, VGA_GFX_ADDR_REG);
  vga_state->gfx_misc = inb (VGA_GFX_DATA_REG);

  outb (VGA_CRT_MAX_SCAN_LINE, VGA_CRT_ADDR_REG);
  vga_state->crt_max_scan_line = inb (VGA_CRT_DATA_REG);
  outb (VGA_CRT_CURSOR_START, VGA_CRT_ADDR_REG);
  vga_state->crt_cursor_start = inb (VGA_CRT_DATA_REG);
  outb (VGA_CRT_CURSOR_END, VGA_CRT_ADDR_REG);
  vga_state->crt_cursor_end = inb (VGA_CRT_DATA_REG);
  outb (VGA_CRT_CURSOR_HIGH, VGA_CRT_ADDR_REG);
  vga_state->crt_cursor_high = inb (VGA_CRT_DATA_REG);
  outb (VGA_CRT_CURSOR_LOW, VGA_CRT_ADDR_REG);
  vga_state->crt_cursor_low = inb (VGA_CRT_DATA_REG);

  /* Read/write in interleaved mode.  */
  outb (VGA_GFX_MISC_ADDR, VGA_GFX_ADDR_REG);
  outb (VGA_GFX_MISC_CHAINOE | VGA_GFX_MISC_B8TOBF, VGA_GFX_DATA_REG);
  outb (VGA_GFX_MODE_ADDR, VGA_GFX_ADDR_REG);
  outb (VGA_GFX_MODE_HOSTOE, VGA_GFX_DATA_REG);

  memcpy (vga_state->videomem, vga_videomem, 2 * 80 * 25);
  vga_read_font_buffer (0, 0, vga_state->fontmem,
			2 * VGA_FONT_SIZE * VGA_FONT_HEIGHT);

  /* 80 cols, 25 rows, two bytes per cell and twice because with lower
     max scan line we get more lines on the screen.  */
  memset (vga_videomem, 0, 80 * 25 * 2 * 2);

  return 0;
}


/* Release the resources and privileges associated with the VGA
   hardware access.  */
void
vga_fini (void)
{
  /* Recover the saved state.  */
  vga_write_font_buffer (0, 0, vga_state->fontmem,
			 2 * VGA_FONT_SIZE * VGA_FONT_HEIGHT);
  memcpy (vga_videomem, vga_state->videomem, 2 * 80 * 25);

  /* Restore the registers.  */
  outb (VGA_SEQ_CLOCK_MODE_ADDR, VGA_SEQ_ADDR_REG);
  outb (vga_state->seq_clock_mode, VGA_SEQ_DATA_REG);
  outb (VGA_SEQ_MAP_ADDR, VGA_SEQ_ADDR_REG);
  outb (vga_state->seq_map, VGA_SEQ_DATA_REG);
  outb (VGA_SEQ_FONT_ADDR, VGA_SEQ_ADDR_REG);
  outb (vga_state->seq_font, VGA_SEQ_DATA_REG);
  outb (VGA_SEQ_MODE_ADDR, VGA_SEQ_ADDR_REG);
  outb (vga_state->seq_mode, VGA_SEQ_DATA_REG);

  outb (VGA_GFX_MAP_ADDR, VGA_GFX_ADDR_REG);
  outb (vga_state->gfx_map, VGA_GFX_DATA_REG);
  outb (VGA_GFX_MODE_ADDR, VGA_GFX_ADDR_REG);
  outb (vga_state->gfx_mode, VGA_GFX_DATA_REG);
  outb (VGA_GFX_MISC_ADDR, VGA_GFX_ADDR_REG);
  outb (vga_state->gfx_misc, VGA_GFX_DATA_REG);

  outb (VGA_CRT_MAX_SCAN_LINE, VGA_CRT_ADDR_REG);
  outb (vga_state->crt_max_scan_line, VGA_CRT_DATA_REG);
  outb (VGA_CRT_CURSOR_START, VGA_CRT_ADDR_REG);
  outb (vga_state->crt_cursor_start, VGA_CRT_DATA_REG);
  outb (VGA_CRT_CURSOR_END, VGA_CRT_ADDR_REG);
  outb (vga_state->crt_cursor_end, VGA_CRT_DATA_REG);
  outb (VGA_CRT_CURSOR_HIGH, VGA_CRT_ADDR_REG);
  outb (vga_state->crt_cursor_high, VGA_CRT_DATA_REG);
  outb (VGA_CRT_CURSOR_LOW, VGA_CRT_ADDR_REG);
  outb (vga_state->crt_cursor_low, VGA_CRT_DATA_REG);

  ioperm (VGA_MIN_REG, VGA_MAX_REG - VGA_MIN_REG + 1, 0);
  munmap (vga_videomem, VGA_VIDEO_MEM_LENGTH);
}


/* Access the font buffer BUFFER, starting from glyph INDEX, and
   either read DATALEN bytes into DATA (if WRITE is 0) or write
   DATALEN bytes from DATA (if WRITE is not 0).  */
static void
vga_read_write_font_buffer (int write, int buffer, int index,
			    char *data, size_t datalen)
{
  char saved_seq_map;
  char saved_seq_mode;
  char saved_gfx_map;
  char saved_gfx_mode;
  char saved_gfx_misc;

  int offset = buffer * VGA_FONT_SIZE + index * VGA_FONT_HEIGHT;
  assert (offset >= 0 && offset + datalen <= VGA_VIDEO_MEM_LENGTH);

  /* Select plane 2 for sequential writing.  You might think it is not
     necessary for reading, but it is.  Likewise for read settings
     when writing.  Joy.  */
  outb (VGA_SEQ_MAP_ADDR, VGA_SEQ_ADDR_REG);
  saved_seq_map = inb (VGA_SEQ_DATA_REG);
  outb (VGA_SEQ_MAP_PLANE2, VGA_SEQ_DATA_REG);
  outb (VGA_SEQ_MODE_ADDR, VGA_SEQ_ADDR_REG);
  saved_seq_mode = inb (VGA_SEQ_DATA_REG);
  outb (VGA_SEQ_MODE_SEQUENTIAL | VGA_SEQ_MODE_EXT, VGA_SEQ_DATA_REG);

  /* Read sequentially from plane 2.  */
  outb (VGA_GFX_MAP_ADDR, VGA_GFX_ADDR_REG);
  saved_gfx_map = inb (VGA_GFX_DATA_REG);
  outb (VGA_GFX_MAP_PLANE2, VGA_GFX_DATA_REG);
  outb (VGA_GFX_MODE_ADDR, VGA_GFX_ADDR_REG);
  saved_gfx_mode = inb (VGA_GFX_DATA_REG);
  outb (VGA_GFX_MODE_READ0, VGA_GFX_DATA_REG);
  outb (VGA_GFX_MISC_ADDR, VGA_GFX_ADDR_REG);
  saved_gfx_misc = inb (VGA_GFX_DATA_REG);
  outb (VGA_GFX_MISC_B8TOBF, VGA_GFX_DATA_REG);

  if (write)
    memcpy (vga_videomem + offset, data, datalen);    
  else
    memcpy (data, vga_videomem + offset, datalen);

  /* Restore sequencer and graphic register values.  */
  outb (VGA_SEQ_MAP_ADDR, VGA_SEQ_ADDR_REG);
  outb (saved_seq_map, VGA_SEQ_DATA_REG);
  outb (VGA_SEQ_MODE_ADDR, VGA_SEQ_ADDR_REG);
  outb (saved_seq_mode, VGA_SEQ_DATA_REG);

  outb (VGA_GFX_MAP_ADDR, VGA_GFX_ADDR_REG);
  outb (saved_gfx_map, VGA_GFX_DATA_REG);
  outb (VGA_GFX_MODE_ADDR, VGA_GFX_ADDR_REG);
  outb (saved_gfx_mode, VGA_GFX_DATA_REG);
  outb (VGA_GFX_MISC_ADDR, VGA_GFX_ADDR_REG);
  outb (saved_gfx_misc, VGA_GFX_DATA_REG);
}


/* Write DATALEN bytes from DATA to the font buffer BUFFER, starting
   from glyph INDEX.  */
void
vga_write_font_buffer (int buffer, int index, char *data, size_t datalen)
{
  vga_read_write_font_buffer (1, buffer, index, data, datalen);
}

/* Read DATALEN bytes into DATA from the font buffer BUFFER, starting
   from glyph INDEX.  */
void
vga_read_font_buffer (int buffer, int index, char *data, size_t datalen)
{
  vga_read_write_font_buffer (0, buffer, index, data, datalen);
}


/* Set FONT_BUFFER_SUPP to FONT_BUFFER if the font is small.  */
void
vga_select_font_buffer (int font_buffer, int font_buffer_supp)
{
  char font = ((font_buffer & 6) >> 1)  | ((font_buffer & 1) << 4)
    | ((font_buffer_supp & 6) << 1) | ((font_buffer_supp & 1) << 5);

  outb (VGA_SEQ_FONT_ADDR, VGA_SEQ_ADDR_REG);
  outb (font, VGA_SEQ_DATA_REG);
}

/* Set the font height in pixel.  */
void
vga_set_font_height (int height)
{
  char saved;

  outb (VGA_CRT_MAX_SCAN_LINE, VGA_CRT_ADDR_REG);
  saved = inb (VGA_CRT_DATA_REG);
  saved &= ~31;
  saved |= (height - 1) & 31;
  outb (saved, VGA_CRT_DATA_REG);
}


/* Get the font width in pixel.  Can be 8 or 9.  */
int
vga_get_font_width (void)
{
  outb (VGA_SEQ_CLOCK_MODE_ADDR, VGA_SEQ_ADDR_REG);
  return (inb (VGA_SEQ_DATA_REG) & VGA_SEQ_CLOCK_MODE_8) ? 8 : 9;
}

/* Set the font width in pixel.  WIDTH can be 8 or 9.  */
void
vga_set_font_width (int width)
{
  char saved;

  if (width != 8 && width != 9)
    return;

  outb (VGA_SEQ_CLOCK_MODE_ADDR, VGA_SEQ_ADDR_REG);
  saved = inb (VGA_SEQ_DATA_REG);
  if (width == 8)
    saved |= VGA_SEQ_CLOCK_MODE_8;
  else
    saved &= ~VGA_SEQ_CLOCK_MODE_8;
  outb (saved, VGA_SEQ_DATA_REG);
}


/* Enable (if ON is true) or disable (otherwise) the cursor.  Expects
   the VGA hardware to be locked.  */
void
vga_display_cursor (int on)
{
  char crs_start;

  outb (VGA_CRT_CURSOR_START, VGA_CRT_ADDR_REG);
  crs_start = inb (VGA_CRT_DATA_REG);
  if (on)
    crs_start &= ~VGA_CRT_CURSOR_DISABLE;
  else
    crs_start |= VGA_CRT_CURSOR_DISABLE;
  outb (crs_start, VGA_CRT_DATA_REG);
}


/* Set cursor size from START to END (set to -1 to not set one of the
   values).  */
void
vga_set_cursor_size (int start, int end)
{
  char saved;

  if (start >= 0)
    {
      outb (VGA_CRT_CURSOR_START, VGA_CRT_ADDR_REG);
      saved = inb (VGA_CRT_DATA_REG);
      saved &= ~31;
      saved |= start & 31;
      outb (saved, VGA_CRT_DATA_REG);
    }
  if (end >= 0)
    {
      outb (VGA_CRT_CURSOR_END, VGA_CRT_ADDR_REG);
      saved = inb (VGA_CRT_DATA_REG);
      saved &= ~31;
      saved |= end & 31;
      outb (saved, VGA_CRT_DATA_REG);
    }
}


/* Set the cursor position to POS, which is (x_pos + y_pos * width).  */
void
vga_set_cursor_pos (unsigned int pos)
{
  outb (VGA_CRT_CURSOR_HIGH, VGA_CRT_ADDR_REG);
  outb (pos >> 8, VGA_CRT_DATA_REG);
  outb (VGA_CRT_CURSOR_LOW, VGA_CRT_ADDR_REG);
  outb (pos & 0xff, VGA_CRT_DATA_REG);
}


/* Read NR entries from the color palette, starting from INDEX.  DATA
   must be able to hold at least 3 * NR bytes and will contain the
   desired colors in RGB form.  Only the lower six bits of each
   component are significant.  */
void
vga_read_palette (unsigned char index, unsigned char *data, int nr)
{
  /* Every color has three components.  */
  nr *= 3;

  outb (index, VGA_DAC_READ_ADDR_REG);
  while (nr--)
    *(data++) = inb (VGA_DAC_DATA_REG);
}


/* Write NR entries to the color palette, starting from INDEX.  DATA
   must be at least 3 * NR of bytes long and contains the desired
   colors in RGB form.  Only the lower six bits for each component are
   significant.  */
void
vga_write_palette (unsigned char index, const unsigned char *data, int nr)
{
  /* Every color has three components.  */
  nr *= 3;

  outb (index, VGA_DAC_WRITE_ADDR_REG);
  while (nr--)
    outb (*(data++), VGA_DAC_DATA_REG);
}


/* Exchange NR entries in the internal palette with the values in
   PALETTE_ATTR, starting from the internal palette entry INDEX (which
   can be betweern 0 and 15).  Only the lower six bits of each entry
   in PALETTE_ATTR is significant.

   The internal palette entry is used to look up a color in the
   palette for the color attribute in text mode with the corresponding
   value.

   Example: The attribute byte specifies 3 as the foreground color.
   This means that the character with this attribute gets the color of
   the palette entry specified by the internal palette entry 3 (the
   fourth one).  */
void
vga_exchange_palette_attributes (unsigned char index,
				 unsigned char *palette_attr,
				 int nr)
{
  if (!nr)
    return;

  /* We want to read and change the palette attribute register.  */
  while (nr--)
    {
      unsigned char attr;

      /* Side effect of reading the input status #1 register is to
	 reset the attribute mixed address/data register so that the
	 next write it expects is the address, not the data.  */
      inb (VGA_INPUT_STATUS_1_REG);

      /* Set the address.  */
      outb (index++, VGA_ATTR_ADDR_DATA_REG);
      attr = inb (VGA_ATTR_DATA_READ_REG);
      outb ((attr & ~077) | (*palette_attr & 077), VGA_ATTR_ADDR_DATA_REG);
      *(palette_attr++) = attr & 077;
    }

  /* Re-enable the screen, which was blanked during the palette
     operation.  */
  inb (VGA_INPUT_STATUS_1_REG);
  outb (0x20, VGA_ATTR_ADDR_DATA_REG);
  outb (0x00, VGA_ATTR_ADDR_DATA_REG);
}