keyin.c

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/*
WKern - A Bare Metal OS / Kernel I am maKing (For Fun)
Copyright (C) 2025  Wdboyes13
 
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
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 <https://www.gnu.org/licenses/>.
*/

 
#include <global.h>
#include <io/kio.h>

unsigned char scancode_to_ascii(unsigned char scancode) {
    static const unsigned char Keymap[256] = {
        0,   27,  '1', '2', '3', '4', '5',  '6', // 0x00 - 0x07
        '7', '8', '9', '0', '-', '=', '\b', '\t', 'q',  'w', 'e', 'r',  't',
        'y', 'u', 'i', 'o', 'p', '[', ']',  '\n', 0,    'a', 's', // 0x10 - 0x17
        'd', 'f', 'g', 'h', 'j', 'K', 'l',  ';',  '\'', '`', 0,   '\\', 'z',
        'x', 'c', 'v', // 0x18 - 0x1F
        'b', 'n', 'm', ',', '.', '/', 0,    '*',  0,    ' ', 0,   0,    0,
        0,   0,   0, // 0x20 - 0x27
        0,   0,   0,   0,   0,   0,   0,    0,    0,    0,   0,   0,    0,
        0,   0,   0,   0,   0,   0,   0,    0,    0,    0,   0,   0,    0,
        0,   0,   0,   0,   0,   0,   0,    0,    0,    0,   0,   0,    0,
        0,   0,   0,   0,   0,   0,   0,    0,    0,    0,   0,   0,    0,
        0,   0,   0,   0,   0,   0,   0,    0,    0,    0,   0,   0,    0,
        0,   0,   0,   0,   0,   0,   0,    0,    0,    0,   0,   0,    0,
        0,   0,   0,   0,   0,   0,   0,    0,    0,    0,   0,   0,    0,
        0,   0,   0,   0,   0,   0,   0,    0,    0,    0,   0,   0,    0,
        0,   0,   0,   0,   0,   0,   0,    0,    0,    0,   0,   0,    0,
        0,   0,   0,   0,   0,   0,   0,    0,    0,    0,   0,   0,    0,
        0,   0,   0,   0,   0,   0,   0,    0,    0,    0,   0,   0,    0,
        0,   0,   0,   0,   0,   0,   0,    0,    0,    0,   0,   0,    0,
        0,   0,   0,   0,   0,   0,   0,    0,    0,    0,   0,   0,    0,
        0,   0,   0,   0,   0,   0,   0,    0,    0,    0,   0,   0,    0,
        0,   0,   0,   0,   0,   0,   0,    0,    0,    0,
    };
 
    return Keymap[scancode];
}

volatile char Keybuf[256];
volatile int buf_head = 0;
volatile int buf_tail = 0;

unsigned char Keytoshift(unsigned char ascii) {
    if (ascii >= 'a' && ascii <= 'z') {
        return ascii - 32; // 'a' to 'A'
    }
 
    switch (ascii) {
    case '1':
        return '!';
    case '2':
        return '@';
    case '3':
        return '#';
    case '4':
        return '$';
    case '5':
        return '%';
    case '6':
        return '^';
    case '7':
        return '&';
    case '8':
        return '*';
    case '9':
        return '(';
    case '0':
        return ')';
    case '-':
        return '_';
    case '=':
        return '+';
    case '[':
        return '{';
    case ']':
        return '}';
    case '\\':
        return '|';
    case ';':
        return ':';
    case '\'':
        return '"';
    case ',':
        return '<';
    case '.':
        return '>';
    case '/':
        return '?';
    case '`':
        return '~';
    default:
        return ascii; // default if no shift mapping exists
    }
}

void Irq1HandlerC(void) {
    unsigned char sc = Inb(0x60);
 
    if (!(sc & 0x80)) { // Key press (not release)
        if (sc == 0x3A) {
            capson = !capson;
            return;
        }
 
        if (sc == 0x2A || sc == 0x36) {
            shift = 1;
            return;
        }
 
        unsigned char ascii = scancode_to_ascii(sc);
 
        if (shift) {
            ascii = Keytoshift(ascii);
        }
        if (capson && ascii >= 'a' && ascii <= 'z') {
            ascii -= 32;
        }
        if (ascii == 0 || ascii > 127) {
            return;
        }
        Keybuf[buf_head++] = ascii;
        if (buf_head == 256) {
            buf_head = 0;
        }
    } else {
        // Key release
        if (sc == 0xAA || sc == 0xB6) {
            shift = 0;
        }
    }
}

char Kgetkey() {
    while (buf_tail == buf_head) {
        ; // wait for Key
    }
    char ch = Keybuf[buf_tail++];
    if (buf_tail == 256) {
        buf_tail = 0;
    }
    return ch;
}

void Kgetstr(char *str, int length) {
    int i = 0;
 
    while (i < length - 1) {
        unsigned char Key = 0;
        while (!(Key = Kgetkey())) {
            ;
        }
 
        if (Key == '\n') {
            str[i] = '\0';
            Kputchar('\n');
            return;
        }
 
        if (Key == '\b' || Key == 0x7F) { // 0x7F is DEL on some layouts
            if (i > 0) {
                i--;
                str[i] = '\0';
                KputcharBackspace();
            }
            continue;
        }
        str[i++] = Key;
        Kputchar(Key);
    }
 
    str[length - 1] = '\0';
}

void Kflush() {
    while (Inb(0x64) & 0x01) {
        Inb(0x60);
    }
}