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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.
*/
#include "bios.h"
#include "regs.h"
#define BIOS_ZF 0x0040u
#define BDA_KBD_HEAD 0x041Au
#define BDA_KBD_TAIL 0x041Cu
#define BDA_KBD_BUFFER 0x041Eu
#define BDA_KBD_BUFFER_END 0x043Eu
static u8
scancode_to_ascii (u8 scancode)
{
switch (scancode)
{
case 0x1Eu:
return 'a';
case 0x30u:
return 'b';
case 0x2Eu:
return 'c';
case 0x20u:
return 'd';
case 0x12u:
return 'e';
case 0x21u:
return 'f';
case 0x22u:
return 'g';
case 0x23u:
return 'h';
case 0x17u:
return 'i';
case 0x24u:
return 'j';
case 0x25u:
return 'k';
case 0x26u:
return 'l';
case 0x32u:
return 'm';
case 0x31u:
return 'n';
case 0x18u:
return 'o';
case 0x19u:
return 'p';
case 0x10u:
return 'q';
case 0x13u:
return 'r';
case 0x1Fu:
return 's';
case 0x14u:
return 't';
case 0x16u:
return 'u';
case 0x2Fu:
return 'v';
case 0x11u:
return 'w';
case 0x2Du:
return 'x';
case 0x15u:
return 'y';
case 0x2Cu:
return 'z';
case 0x39u:
return ' ';
case 0x1Cu:
return '\r';
default:
return 0;
}
}
void
int16_service (struct bios_regs *regs)
{
volatile u16 *head;
volatile u16 *tail;
volatile u16 *buffer;
u8 function;
u16 position;
u16 value;
u8 scancode;
u8 ascii;
function = (u8)(regs->eax >> 8);
if (function != 0x00u && function != 0x01u)
{
regs->eax = 0;
regs->flags |= BIOS_ZF;
return;
}
head = (volatile u16 *)BDA_KBD_HEAD;
tail = (volatile u16 *)BDA_KBD_TAIL;
buffer = (volatile u16 *)BDA_KBD_BUFFER;
if (*head == *tail)
{
regs->eax = 0;
regs->flags |= BIOS_ZF;
return;
}
position = *head;
value = buffer[(position - BDA_KBD_BUFFER) >> 1];
scancode = (u8)(value >> 8);
ascii = scancode_to_ascii (scancode);
regs->eax = ((u32)scancode << 8) | ascii;
regs->flags &= (u16)~BIOS_ZF;
if (function == 0x00u)
{
position += 2;
if (position >= BDA_KBD_BUFFER_END)
position = BDA_KBD_BUFFER;
*head = position;
}
}
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