source: rtems/c/src/lib/libbsp/powerpc/ppcn_60x/console/vga.c @ 0c04c377

/*
 *  This file contains the TTY driver for VGA
 *
 *  COPYRIGHT (c) 1998 by Radstone Technology
 *
 *
 * THIS FILE IS PROVIDED TO YOU, THE USER, "AS IS", WITHOUT WARRANTY OF ANY
 * KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK
 * AS TO THE QUALITY AND PERFORMANCE OF ALL CODE IN THIS FILE IS WITH YOU.
 *
 * You are hereby granted permission to use, copy, modify, and distribute
 * this file, provided that this notice, plus the above copyright notice
 * and disclaimer, appears in all copies. Radstone Technology will provide
 * no support for this code.
 *
 *  This driver uses the termios pseudo driver.
 */
/*-------------------------------------------------------------------------+
| (C) Copyright 1997 -
| - NavIST Group - Real-Time Distributed Systems and Industrial Automation
|
| http://pandora.ist.utl.pt
|
| Instituto Superior Tecnico * Lisboa * PORTUGAL
+--------------------------------------------------------------------------+
| Disclaimer:
|
| This file is provided "AS IS" without warranty of any kind, either
| expressed or implied.
+--------------------------------------------------------------------------+
| This code is based on:
|   outch.c,v 1.4 1995/12/19 20:07:27 joel Exp - go32 BSP
| With the following copyright notice:
| **************************************************************************
| * COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994.                      *
| * On-Line Applications Research Corporation (OAR).                       *
| * All rights assigned to U.S. Government, 1994.                          *
| *                                                                        *
| * This material may be reproduced by or for the U.S. Government pursuant *
| * to the copyright license under the clause at DFARS 252.227-7013.  This *
| * notice must appear in all copies of this file and its derivatives.     *
| **************************************************************************
+--------------------------------------------------------------------------*/


#include <bsp.h>

#include <stdlib.h>
#include <string.h>

#include "vga_p.h"

/*-------------------------------------------------------------------------+
| Constants
+--------------------------------------------------------------------------*/
#define DISPLAY_CELL_COUNT (VGA_NUM_ROWS * VGA_NUM_COLS)
                                       /* Number of display cells.            */
#define TABSIZE 4                      /* Number of spaces for TAB (\t) char. */
#define WHITE   0x0007                 /* White on Black background colour.   */
#define BLANK   (WHITE | (' '<<8))     /* Blank character.                    */

/*
 * This is imported from i8042.c to provide flow control
 */
extern volatile boolean bScrollLock;

/*-------------------------------------------------------------------------+
| Global Variables
+--------------------------------------------------------------------------*/
/* Physical address of start of video text memory. */
static unsigned16 *videoRam    = (unsigned16 *)VGA_FB;
/* Pointer for current output position in display. */
static unsigned16 *videoRamPtr = (unsigned16 *)VGA_FB;
static unsigned8  videoRows = VGA_NUM_ROWS; /* Number of rows in display.    */
static unsigned8  videoCols = VGA_NUM_COLS; /* Number of columns in display. */
static unsigned8  cursRow   = 0;       /* Current cursor row.           */
static unsigned8  cursCol   = 0;       /* Current cursor column.        */


/*-------------------------------------------------------------------------+
|         Function: setHardwareCursorPos
|      Description: Set hardware video cursor at given offset into video RAM. 
| Global Variables: None.
|        Arguments: videoCursor - Offset into video memory.
|          Returns: Nothing. 
+--------------------------------------------------------------------------*/
static inline void
setHardwareCursorPos(unsigned16 videoCursor)
{
        VGA_WRITE_CRTC(0x0e, (videoCursor >> 8) & 0xff);
        VGA_WRITE_CRTC(0x0f, videoCursor & 0xff);
} /* setHardwareCursorPos */


/*-------------------------------------------------------------------------+
|         Function: updateVideoRamPtr
|      Description: Updates value of global variable "videoRamPtr" based on
|                   current window's cursor position. 
| Global Variables: videoRamPtr, cursRow, cursCol.
|        Arguments: None.
|          Returns: Nothing. 
+--------------------------------------------------------------------------*/
static inline void
updateVideoRamPtr(void)
{
        videoRamPtr = videoRam + cursRow * videoCols + cursCol;
} /* updateVideoRamPtr */


/*-------------------------------------------------------------------------+
|         Function: scrollUp
|      Description: Scrolls display up n lines.
| Global Variables: None.
|        Arguments: lines - number of lines to scroll.
|          Returns: Nothing. 
+--------------------------------------------------------------------------*/
static void
scrollUp(unsigned8 lines)
{
        /* Number of blank display cells on bottom of window. */
        unsigned16 blankCount;

       /* Source and destination pointers for memory copy operations. */
        unsigned16 *ptrDst, *ptrSrc;

        if(lines<videoRows)  /* Move window's contents up. */
        {
                /*
                 * Number of non-blank cells on upper part
                 * of display (total - blank).
                 */
                unsigned16 nonBlankCount;

                blankCount = lines * videoCols;
                nonBlankCount = DISPLAY_CELL_COUNT - blankCount;
                ptrSrc = videoRam + blankCount;
                ptrDst = videoRam; 

                while(nonBlankCount--)
                {
                        *ptrDst++ = *ptrSrc++;
                }
        }
        else
        {
                /* 
                 * Clear the whole display.
                 */
                blankCount = DISPLAY_CELL_COUNT;
                ptrDst = videoRam;
        }

        /* Fill bottom with blanks. */
        while (blankCount-->0)
        {
                *ptrDst++ = BLANK;
        }
} /* scrollUp */


/*-------------------------------------------------------------------------+
|         Function: printCHAR
|      Description: Print printable character to display.
| Global Variables: videoRamPtr, cursRow, cursCol.
|        Arguments: c - character to write to display.
|          Returns: Nothing. 
+--------------------------------------------------------------------------*/
static void
printCHAR(char c)
{
        *videoRamPtr++ = (c<<8) | WHITE;
        cursCol++;
        if(cursCol==videoCols)
        {
                cursCol = 0;
                cursRow++;
                if(cursRow==videoRows)
                {
                        cursRow--;
                        scrollUp(1);
                        videoRamPtr -= videoCols;
                }
        }
} /* printCHAR */

/*-------------------------------------------------------------------------+
|         Function: printBS
|      Description: Print BS (BackSpace - '\b') character to display.
| Global Variables: videoRamPtr, cursRow, cursCol.
|        Arguments: None.
|          Returns: Nothing. 
+--------------------------------------------------------------------------*/
static inline void
printBS(void)
{
        /* Move cursor back one cell. */
        if(cursCol>0)
        {
                cursCol--;
        }
        else if(cursRow>0)
        {
                cursRow--;
                cursCol = videoCols - 1;
        }
        else
        {
                return;
        }

        /* Write a whitespace. */
        *(--videoRamPtr) = BLANK;
} /* printBS */


/*-------------------------------------------------------------------------+
|         Function: printHT
|      Description: Print HT (Horizontal Tab - '\t') character to display.
| Global Variables: cursCol.
|        Arguments: None.
|          Returns: Nothing. 
+--------------------------------------------------------------------------*/
static inline void
printHT(void)
{
        do
        {
                printCHAR(' ');
        }
        while (cursCol % TABSIZE);
} /* printHT */


/*-------------------------------------------------------------------------+
|         Function: printLF
|      Description: Print LF (Line Feed  - '\n') character to display.
| Global Variables: cursRow.
|        Arguments: None.
|          Returns: Nothing. 
+--------------------------------------------------------------------------*/
static inline void
printLF(void)
{
        cursRow++;
        if(cursRow==videoRows)
        {
                cursRow--;
                scrollUp(1);
        }
        updateVideoRamPtr();
} /* printLF */


/*-------------------------------------------------------------------------+
|         Function: printCR
|      Description: Print CR (Carriage Return - '\r') to display.
| Global Variables: cursCol.
|        Arguments: None.
|          Returns: Nothing. 
+--------------------------------------------------------------------------*/
static inline void
printCR(void)
{
        cursCol = 0;
        updateVideoRamPtr();
} /* printCR */

/*
 *  Console Device Driver Entry Points
 */
void
vga_write(
        int   minor, 
        char cChar)
{
        switch (cChar)
        {
                case '\b':
                        printBS();
                        break;
                case '\t':
                        printHT();
                        break;
                case '\n':
                        printLF();
                        break;
                case '\r':
                        printCR();
                        break;
                default:
                        printCHAR(cChar);
                        break;
        }

        setHardwareCursorPos(videoRamPtr - videoRam);
} /* vga_write */

/* 
 *  vga_write_support
 *
 *  Console Termios output entry point.
 *
 */
int vga_write_support(
        int   minor, 
        const char *buf, 
        int   len
)
{
        int nwrite = 0;

        while(bScrollLock)
        {
                /*
                 * The Scroll lock on the keyboard is active
                 */
                /*
                 * Yield while we wait
                 */
                rtems_task_wake_after(RTEMS_YIELD_PROCESSOR);
        }

        /*
         * Write each byte in the string to the display
         */
        while (nwrite<len)
        {
                /*
                 * transmit character
                 */
                vga_write(minor, *buf++);
                nwrite++;
        }

        /*
         * return the number of bytes written.
         */
        return nwrite;
}

boolean vga_probe(int minor)
{
        unsigned8 ucMiscIn;

        /*
         * Check for presence of VGA adaptor
         */
        inport_byte(0x3cc, ucMiscIn);
        if(ucMiscIn!=0xff)
        {
                /*
                 * VGA device is present
                 */
                return(TRUE);
        }
        return(FALSE);
}

void vga_init(int minor)
{
        scrollUp(videoRows);     /* Clear entire screen         */
        setHardwareCursorPos(0); /* Cursor at upper left corner */
        /*
         * Enable the cursor
         */
        VGA_WRITE_CRTC(0x0a, 0x0e);     /* Crt cursor start */
}