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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 "regs.h"
#include "vbe.h"
#include "vga.h"
static u16
int10_cursor_for_page (u8 page)
{
return *(volatile u16 *)(MUBIOS_BDA_BASE + BDA_CURSOR_BASE + 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_teletype (u8 character)
{
volatile u8 *bda = (volatile u8 *)MUBIOS_BDA_BASE;
u8 page = bda[BDA_VIDEO_PAGE];
volatile u16 *video = int10_video_for_page (page);
u16 cursor = int10_cursor_for_page (page);
u16 row = cursor >> 8;
u16 column = cursor & 0xFFu;
u16 position;
u16 cell;
u16 blank;
/* AH=0Eh uses the active page, as in SeaVGABIOS. BEL has no text effect. */
if (character == 0x07u)
return;
if (character == 0x0Du)
column = 0u;
else if (character == 0x0Au)
++row;
else if (character == 0x08u)
{
/* A text-mode backspace moves left without erasing or crossing a row. */
if (column != 0u)
--column;
}
else
{
position = (u16)(row * VGA_COLUMNS + column);
/* Mode 03h has 2000 visible cells per page. */
if (position >= VGA_TEXT_CELLS)
return;
video[position] = (u16)((video[position] & 0xFF00u) | character);
++column;
if (column >= VGA_COLUMNS)
{
column = 0u;
++row;
}
}
/* Passing the last row scrolls the active page, retaining text attributes.
*/
if (row >= VGA_ROWS)
{
blank = (u16)((video[(VGA_ROWS - 1u) * VGA_COLUMNS] & 0xFF00u) | 0x20u);
for (cell = 0; cell < (VGA_ROWS - 1u) * VGA_COLUMNS; ++cell)
video[cell] = video[cell + VGA_COLUMNS];
for (; cell < VGA_TEXT_CELLS; ++cell)
video[cell] = blank;
row = VGA_ROWS - 1u;
}
vga_set_cursor_position (page, (u16)((row << 8) | column));
}
void
int10_service (struct bios_regs *regs)
{
volatile u8 *bda = (volatile u8 *)MUBIOS_BDA_BASE;
volatile u16 *video;
u8 function = (u8)(regs->eax >> 8);
u8 page = (u8)(regs->ebx >> 8);
u16 cursor;
u16 position;
u16 count;
u32 font_address;
if (function == 0x4Fu)
{
vbe_service (regs);
return;
}
if (function == 0x00u)
{
/* Bit 7 preserves video memory; the remaining bits select mode 03h. */
if (((u8)regs->eax & 0x7Fu) == 0x03u)
vga_text_mode_set ((u8)regs->eax & 0x80u);
return;
}
if (function == 0x01u)
{
vga_set_cursor_shape ((u16)regs->ecx);
return;
}
if (function == 0x05u)
{
vga_set_active_page ((u8)regs->eax);
return;
}
if (function == 0x0Fu)
{
regs->eax = (regs->eax & 0xFFFF0000u)
| ((u32)bda[BDA_VIDEO_COLUMNS] << 8) | bda[BDA_VIDEO_MODE]
| (bda[BDA_VIDEO_CTL] & 0x80u);
regs->ebx = (regs->ebx & 0xFFFF00FFu) | ((u32)bda[BDA_VIDEO_PAGE] << 8);
return;
}
/* AH=11h/AL=30h reports the current font (BH=1) or ROM 8x16 font (BH=6). */
if (function == 0x11u && (u8)regs->eax == 0x30u)
{
if (page == 0x01u || page == 0x06u)
{
font_address = (u32)vga_font_8x16;
regs->es = (u16)(font_address >> 4);
regs->ebp = (regs->ebp & 0xFFFF0000u) | (font_address & 0x0Fu);
}
regs->ecx = (regs->ecx & 0xFFFF0000u)
| *(volatile u16 *)(bda + BDA_VIDEO_HEIGHT);
regs->edx = (regs->edx & 0xFFFFFF00u) | bda[BDA_VIDEO_ROWS];
return;
}
if (function == 0x0Eu)
{
int10_teletype ((u8)regs->eax);
return;
}
/* The mode 03h INT 10h interface provides page numbers 0 through 7. */
if (page >= VGA_PAGE_COUNT)
return;
if (function == 0x02u)
{
vga_set_cursor_position (page, (u16)regs->edx);
return;
}
if (function == 0x03u)
{
regs->edx = (regs->edx & 0xFFFF0000u) | int10_cursor_for_page (page);
regs->ecx = (regs->ecx & 0xFFFF0000u)
| *(volatile u16 *)(bda + BDA_CURSOR_SHAPE);
return;
}
if (function != 0x09u)
return;
cursor = int10_cursor_for_page (page);
position = (u16)((cursor >> 8) * VGA_COLUMNS + (cursor & 0xFFu));
video = int10_video_for_page (page);
count = (u16)regs->ecx;
/* Repeated character/attribute output stays within the visible page and
does not change either the BDA or hardware cursor. */
while (count != 0u && position < VGA_TEXT_CELLS)
{
video[position] = (u16)((u8)regs->eax | ((u16)(u8)regs->ebx << 8));
++position;
--count;
}
}
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