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/*
RCC-Project
Copyright (C) 2026 Richard Qin
This file is part of RCC-Project.
RCC-Project 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.
RCC-Project 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
RCC-Project; see the file COPYING. If not see
<http://www.gnu.org/licenses/>.
*/
#include "bios.h"
#include "regs.h"
#define VGA_TEXT_BASE 0x000B8000u
#define BDA_CURSOR 0x00000450u
#define BDA_CURSOR_SHAPE 0x00000460u
#define VGA_PAGE_SIZE 0x00001000u
static volatile u16 *
int10_cursor_for_page (u8 page)
{
return (volatile u16 *)(BDA_CURSOR + ((u32)page * 2u));
}
static volatile u16 *
int10_video_for_page (u8 page)
{
return (volatile u16 *)(VGA_TEXT_BASE + ((u32)page * VGA_PAGE_SIZE));
}
static void
int10_newline (volatile u16 *cursor)
{
u16 row;
row = (u16)(*cursor / 80u);
*cursor = (u16)((row + 1u) * 80u);
}
void
int10_service (struct bios_regs *regs)
{
volatile u16 *cursor;
volatile u16 *video;
u8 function;
u8 page;
u8 character;
u8 attribute;
u16 position;
u16 count;
function = (u8)(regs->eax >> 8);
page = (u8)(regs->ebx >> 8);
if (function == 0x02u)
{
cursor = int10_cursor_for_page (page);
position = (u16)(((u8)(regs->edx >> 8) * 80u) + (u8)regs->edx);
*cursor = position;
return;
}
if (function == 0x03u)
{
cursor = int10_cursor_for_page (page);
position = *cursor;
regs->edx = (regs->edx & 0xFFFF0000u) | ((u32)(position / 80u) << 8)
| (u32)(position % 80u);
regs->ecx = (regs->ecx & 0xFFFF0000u) | 0x0607u;
return;
}
if (function != 0x09u && function != 0x0Eu)
return;
cursor = int10_cursor_for_page (page);
video = int10_video_for_page (page);
character = (u8)regs->eax;
attribute = (u8)regs->ebx;
position = *cursor;
if (function == 0x09u)
{
count = (u16)regs->ecx;
while (count != 0u)
{
if (position >= 2000u)
position = 0;
video[position] = (u16)character | ((u16)attribute << 8);
position++;
count--;
}
return;
}
if (character == 0x0Du)
{
*cursor = (u16)((position / 80u) * 80u);
return;
}
if (character == 0x0Au)
{
int10_newline (cursor);
return;
}
if (character == 0x08u)
{
if (position != 0u)
{
position--;
video[position] = (u16)(0x20u | ((u16)attribute << 8));
*cursor = position;
}
return;
}
if (position >= 2000u)
position = 0;
video[position] = (u16)character | ((u16)attribute << 8);
*cursor = (u16)(position + 1u);
}
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