eduOS/arch/x86/kernel/vga.c
2016-01-10 21:50:24 +01:00

235 lines
5.9 KiB
C

/*
* Copyright (c) 2010, Stefan Lankes, RWTH Aachen University
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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.
* * 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 COPYRIGHT HOLDERS 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 REGENTS 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.
*/
#include <eduos/string.h>
#include <asm/io.h>
#include <asm/vga.h>
/*
* These define our textpointer, our background and foreground
* colors (attributes), and x and y cursor coordinates
*/
static unsigned short *textmemptr;
static int attrib = 0x0F;
static int csr_x = 0, csr_y = 0;
inline static unsigned short *memsetw(unsigned short *dest, unsigned short val, size_t count)
{
size_t i;
if (BUILTIN_EXPECT(!dest, 0))
return dest;
for (i = 0; i < count; i++)
dest[i] = val;
return dest;
}
/* Scrolls the screen */
static void scroll(void)
{
unsigned blank, temp;
/*
* A blank is defined as a space... we need to give it
* backcolor too
*/
blank = 0x20 | (attrib << 8);
/* Row 25 is the end, this means we need to scroll up */
if (csr_y >= 25) {
/*
* Move the current text chunk that makes up the screen
*
* back in the buffer by one line
*/
temp = csr_y - 25 + 1;
memcpy(textmemptr, textmemptr + temp * 80,
(25 - temp) * 80 * 2);
/*
* Finally, we set the chunk of memory that occupies
* the last line of text to our 'blank' character
*/
memsetw(textmemptr + (25 - temp) * 80, blank, 80);
csr_y = 25 - 1;
}
}
/*
* Updates the hardware cursor: the little blinking line
* on the screen under the last character pressed!
*/
static void move_csr(void)
{
unsigned temp;
/*
* The equation for finding the index in a linear
* chunk of memory can be represented by:
* Index = [(y * width) + x] */
temp = csr_y * 80 + csr_x;
/*
* This sends a command to indicies 14 and 15 in the
* CRT Control Register of the VGA controller. These
* are the high and low bytes of the index that show
* where the hardware cursor is to be 'blinking'. To
* learn more, you should look up some VGA specific
* programming documents. A great start to graphics:
* http://www.brackeen.com/home/vga
*/
outportb(0x3D4, 14);
outportb(0x3D5, temp >> 8);
outportb(0x3D4, 15);
outportb(0x3D5, temp);
}
/* Clears the screen */
void vga_clear(void)
{
unsigned blank;
int i;
/*
* Again, we need the 'short' that will be used to
* represent a space with color
*/
blank = 0x20 | (attrib << 8);
/*
* Fills the entire screen with spaces in our current
* color
**/
for (i = 0; i < 25; i++)
memsetw(textmemptr + i * 80, blank, 80);
/*
* Update out virtual cursor, and then move the
* hardware cursor
*/
csr_x = 0;
csr_y = 0;
move_csr();
}
/* Puts a single character on the screen */
int vga_putchar(unsigned char c)
{
unsigned short *where;
unsigned att = attrib << 8;
/* Handle a backspace by moving the cursor back one space */
if (c == 0x08) {
if (csr_x != 0)
csr_x--;
}
/*
* Handles a tab by incrementing the cursor's x, but only
* to a point that will make it divisible by 8
*/
else if (c == 0x09) {
csr_x = (csr_x + 8) & ~(8 - 1);
}
/*
* Handles a 'Carriage Return', which simply brings the
* cursor back to the margin
*/
else if (c == '\r') {
csr_x = 0;
}
/*
* We handle our newlines the way DOS and BIOS do: we
* treat it as if a 'CR' was there also, so we bring the
* cursor to the margin and increment the 'y' value
*/
else if (c == '\n') {
csr_x = 0;
csr_y++;
}
/*
* Any character greater than and including the space is a
* printable character. The equation for finding the index
* in a linear chunk of memory can be represented by:
* Index = [(y * width) + x]
*/
else if (c >= ' ') {
where = textmemptr + (csr_y * 80 + csr_x);
*where = c | att; /* Character AND attributes: color */
csr_x++;
}
/*
* If the cursor has reached the edge of the screen's width, we
* insert a new line in there
*/
if (csr_x >= 80) {
csr_x = 0;
csr_y++;
}
/* Scroll the screen if needed, and finally move the cursor */
scroll();
move_csr();
return (int) c;
}
/* Uses the routine above to output a string... */
int vga_puts(const char *text)
{
size_t i;
for (i = 0; i < strlen(text); i++)
vga_putchar(text[i]);
return i-1;
}
/* Sets the forecolor and backcolor we will use */
//void settextcolor(unsigned char forecolor, unsigned char backcolor)
//{
/*
* Top 4 bytes are the background, bottom 4 bytes
* are the foreground color
*/
// attrib = (backcolor << 4) | (forecolor & 0x0F);
//}
/* Sets our text-mode VGA pointer, then clears the screen for us */
void vga_init(void)
{
textmemptr = (unsigned short *)VIDEO_MEM_ADDR;
vga_clear();
}