os/kernel/syscall.c

#include <kernel/tty.h>
#include <kernel/keyboard.h>
#include <debugging.h>

static void print(char* buffer) 
{
    terminal_writestring(buffer);
}

static void* memcpy(void* restrict dstptr, const void* restrict srcptr, size_t size) {
	unsigned char* dst = (unsigned char*) dstptr;
	const unsigned char* src = (const unsigned char*) srcptr;
	for (size_t i = 0; i < size; i++)
		dst[i] = src[i];
	return dstptr;
}

static void input(char* buffer)
{
    while (true) {
        for (int i = 0; i < keyboard_buffer_top; i++) {
            buffer[i] = keyboard_buffer[i];
            if (keyboard_buffer[i] == '\n') {
                buffer[keyboard_buffer_top] = 0;
                keyboard_buffer_top = 0;
                return;
            }
        }
        asm("hlt");
    }
}

void _syscall(uint32_t a, uint32_t b, uint32_t c, uint32_t d)
{
    switch (d) {
        case 0x00:
            print((char*) a);
            break;
        case 0x01:
            input((char*) a);
            break;
    }
}