/* Copyright (C) 2004  David Decotigny
    Copyright (C) 1999  Free Software Foundation, Inc.
 
    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 2
    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, write to the Free Software
    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
    USA. 
 */
 #include <sos/klibc.h>
 #include <hwcore/ioports.h>
 
 #include "x86_videomem.h"
 
 /* The text video memory starts at address 0xB8000. Odd bytes are the
    ASCII value of the character, even bytes are attribute for the
    preceding character. */
 #define VIDEO   0xb8000
 
 
 /* Console screen size */
 #define LINES   25
 #define COLUMNS 80
 
 
 /** The structure of a character element in the video memory. @see
     http://webster.cs.ucr.edu/AoA DOS edition chapter 23 */
 typedef struct {
   unsigned char character;
   unsigned char attribute;
 } __attribute__ ((packed)) x86_video_mem[LINES*COLUMNS];
 
 
 
 /** The base pointer for the video memory */
 static volatile x86_video_mem *video = (volatile x86_video_mem*)VIDEO;
 
 sos_ret_t sos_x86_videomem_setup(void)
 {
   /*
    * Hide cursor. @see Ralf Brown's interrupt (and port) list
    * http://www-2.cs.cmu.edu/~ralf/files.html
    */
 #define CRT_REG_INDEX 0x3d4
 #define CRT_REG_DATA  0x3d5
 
   /* CRT index port => ask for access to register 0xa ("cursor
      start") */
   outb(0x0a, CRT_REG_INDEX);
 
   /* (RBIL Tables 708 & 654) CRT Register 0xa => bit 5 = cursor OFF */
   outb(1 << 5, CRT_REG_DATA);
 
   return SOS_OK;
 }
 
 
 sos_ret_t sos_x86_videomem_cls(unsigned char attribute)
 {
   /* Clears the screen */
   int i;
   for(i = 0 ; i < LINES*COLUMNS ; i++)
     {
       (*video)[i].character = 0;
       (*video)[i].attribute = attribute;
     }
 
   return SOS_OK;  
 }
 
 
 sos_ret_t sos_x86_videomem_putstring(unsigned char row, unsigned char col,
                                      unsigned char attribute,
                                      const char *str)
 {
   unsigned video_offs = row*COLUMNS + col;
 
   if (video_offs >= LINES*COLUMNS)
     return -SOS_EINVAL;
   
   for ( ; str && *str && (video_offs < LINES*COLUMNS) ; str++, video_offs++)
     {
       (*video)[video_offs].character = (unsigned char)*str;
       (*video)[video_offs].attribute = attribute;
     }
 
   return SOS_OK;
 }
 
 
 sos_ret_t sos_x86_videomem_putchar(unsigned char row, unsigned char col,
                                    unsigned char attribute,
                                    unsigned char c)
 {
   unsigned video_offs = row*COLUMNS + col;
 
   if (video_offs >= LINES*COLUMNS)
     return -SOS_EINVAL;
   
   (*video)[video_offs].character = c;
   (*video)[video_offs].attribute = attribute;
 
   return SOS_OK;
 }
 
 
 sos_ret_t sos_x86_videomem_printf(unsigned char row, unsigned char col,
                                   unsigned char attribute,
                                   const char *format, /* args */...)
 {
   char buff[256];
   va_list ap;
   
   va_start(ap, format);
   vsnprintf(buff, sizeof(buff), format, ap);
   va_end(ap);
   
   return sos_x86_videomem_putstring(row, col, attribute, buff);
 }