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/*
* Copyright (c) 2010, 2012 Richard Braun.
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include <kern/init.h>
#include <kern/macros.h>
#include <kern/param.h>
#include <kern/stdint.h>
#include <kern/string.h>
#include <machine/io.h>
#include <machine/pmap.h>
#include <machine/cga.h>
/*
* Screen dimensions.
*/
#define CGA_COLUMNS 80
#define CGA_LINES 25
/*
* Text mode mapped memory and size.
*/
#define CGA_MEMORY 0xb8000
#define CGA_MEMORY_SIZE (CGA_COLUMNS * CGA_LINES * 2)
/*
* I/O ports.
*/
#define CGA_MISC_OUTPUT_REGISTER_READ 0x3cc
#define CGA_MISC_OUTPUT_REGISTER_WRITE 0x3c2
#define CGA_CRTC_ADDRESS_REGISTER 0x3d4
#define CGA_CRTC_DATA_REGISTER 0x3d5
/*
* CRTC registers.
*/
#define CGA_CRTC_CURSOR_LOCATION_HIGH_REGISTER 0xe
#define CGA_CRTC_CURSOR_LOCATION_LOW_REGISTER 0xf
/*
* Foreground screen color.
*/
#define CGA_FOREGROUND_COLOR 0x7
/*
* Blank space 16 bits word.
*/
#define CGA_BLANK ((CGA_FOREGROUND_COLOR << 8) | ' ')
/*
* Number of spaces to display for a tabulation.
*/
#define CGA_TABULATION_SPACES 8
static uint8_t *cga_memory;
static uint16_t cga_cursor;
static uint16_t
cga_get_cursor_position(void)
{
uint16_t tmp;
io_write_byte(CGA_CRTC_ADDRESS_REGISTER,
CGA_CRTC_CURSOR_LOCATION_HIGH_REGISTER);
tmp = io_read_byte(CGA_CRTC_DATA_REGISTER) << 8;
io_write_byte(CGA_CRTC_ADDRESS_REGISTER,
CGA_CRTC_CURSOR_LOCATION_LOW_REGISTER);
tmp |= io_read_byte(CGA_CRTC_DATA_REGISTER);
return tmp;
}
static void
cga_set_cursor_position(uint16_t position)
{
io_write_byte(CGA_CRTC_ADDRESS_REGISTER,
CGA_CRTC_CURSOR_LOCATION_HIGH_REGISTER);
io_write_byte(CGA_CRTC_DATA_REGISTER, position >> 8);
io_write_byte(CGA_CRTC_ADDRESS_REGISTER,
CGA_CRTC_CURSOR_LOCATION_LOW_REGISTER);
io_write_byte(CGA_CRTC_DATA_REGISTER, position & 0xff);
}
static uint8_t
cga_get_cursor_column(void)
{
return cga_cursor % CGA_COLUMNS;
}
void __init
cga_setup(void)
{
uint8_t misc_output_register;
unsigned long va;
va = pmap_bootalloc(1);
pmap_kenter(va, CGA_MEMORY);
pmap_update(kernel_pmap, va, va + PAGE_SIZE);
cga_memory = (uint8_t *)va;
/*
* Check if the Input/Output Address Select bit is set.
*/
misc_output_register = io_read_byte(CGA_MISC_OUTPUT_REGISTER_READ);
if (!(misc_output_register & 0x1)) {
/*
* Set the I/O AS bit.
*/
misc_output_register |= 0x1;
/*
* Update the misc output register.
*/
io_write_byte(CGA_MISC_OUTPUT_REGISTER_WRITE, misc_output_register);
}
cga_cursor = cga_get_cursor_position();
}
static void
cga_scroll_lines(void)
{
uint16_t *last_line;
int i;
memmove(cga_memory, (uint16_t *)cga_memory + CGA_COLUMNS,
CGA_MEMORY_SIZE - (CGA_COLUMNS * 2));
last_line = (uint16_t *)cga_memory + (CGA_COLUMNS * (CGA_LINES - 1));
for(i = 0; i < CGA_COLUMNS; i++)
last_line[i] = CGA_BLANK;
}
void
cga_write_byte(uint8_t byte)
{
if (byte == '\r')
return;
else if (byte == '\n') {
cga_cursor += CGA_COLUMNS - cga_get_cursor_column();
if (cga_cursor >= (CGA_LINES * CGA_COLUMNS)) {
cga_scroll_lines();
cga_cursor -= CGA_COLUMNS;
}
cga_set_cursor_position(cga_cursor);
} else if (byte == '\b') {
if (cga_cursor > 0) {
cga_cursor--;
((uint16_t *)cga_memory)[cga_cursor] = CGA_BLANK;
cga_set_cursor_position(cga_cursor);
}
} else if (byte == '\t') {
int i;
for(i = 0; i < CGA_TABULATION_SPACES; i++)
cga_write_byte(' ');
} else {
if ((cga_cursor + 1) >= CGA_COLUMNS * CGA_LINES) {
cga_scroll_lines();
cga_cursor -= CGA_COLUMNS;
}
((uint16_t *)cga_memory)[cga_cursor] = ((CGA_FOREGROUND_COLOR << 8)
| byte);
cga_cursor++;
cga_set_cursor_position(cga_cursor);
}
}
void console_write_byte(char c) __alias("cga_write_byte");
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