如何在我的“内核”中实现 newlin(\n)？

Question

我正在尝试为我的“内核/终端”创建换行符（\n）字符支持， 我正在学习以下链接https://wiki.osdev.org/Bare_Bones

作者建议如下 向终端驱动程序添加对换行符的支持 “在 terminal_putchar 中检查 c == '\n' 并增加 terminal_row 并重置 terminal_column。”

***除非绝对必要，否则请不要分享任何代码。我想自己实现这个，只是让我知道我的错误。

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
 
/* Check if the compiler thinks you are targeting the wrong operating system. */
#if defined(__linux__)
#error "You are not using a cross-compiler, you will most certainly run into trouble"
#endif
 
/* This tutorial will only work for the 32-bit ix86 targets. */
#if !defined(__i386__)
#error "This tutorial needs to be compiled with a ix86-elf compiler"
#endif
 
/* Hardware text mode color constants. */
enum vga_color {
    VGA_COLOR_BLACK = 0,
    VGA_COLOR_BLUE = 1,
    VGA_COLOR_GREEN = 2,
    VGA_COLOR_CYAN = 3,
    VGA_COLOR_RED = 4,
    VGA_COLOR_MAGENTA = 5,
    VGA_COLOR_BROWN = 6,
    VGA_COLOR_LIGHT_GREY = 7,
    VGA_COLOR_DARK_GREY = 8,
    VGA_COLOR_LIGHT_BLUE = 9,
    VGA_COLOR_LIGHT_GREEN = 10,
    VGA_COLOR_LIGHT_CYAN = 11,
    VGA_COLOR_LIGHT_RED = 12,
    VGA_COLOR_LIGHT_MAGENTA = 13,
    VGA_COLOR_LIGHT_BROWN = 14,
    VGA_COLOR_WHITE = 15,
};
 
static inline uint8_t vga_entry_color(enum vga_color fg, enum vga_color bg) 
{
    return fg | bg << 4;
}
 
static inline uint16_t vga_entry(unsigned char uc, uint8_t color) 
{
    return (uint16_t) uc | (uint16_t) color << 8;
}
 
size_t strlen(const char* str) 
{
    size_t len = 0;
    while (str[len])
        len++;
    return len;
}
 
static const size_t VGA_WIDTH = 80;
static const size_t VGA_HEIGHT = 25;
 
size_t terminal_row;
size_t terminal_column;
uint8_t terminal_color;
uint16_t* terminal_buffer;
 
void terminal_initialize(void) 
{
    terminal_row = 0;
    terminal_column = 0;
    terminal_color = vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);
    terminal_buffer = (uint16_t*) 0xB8000;
    for (size_t y = 0; y < VGA_HEIGHT; y++) {
        for (size_t x = 0; x < VGA_WIDTH; x++) {
            const size_t index = y * VGA_WIDTH + x;
            terminal_buffer[index] = vga_entry(' ', terminal_color);
        }
    }
}
 
void terminal_setcolor(uint8_t color) 
{
    terminal_color = color;
}
 
void terminal_putentryat(char c, uint8_t color, size_t x, size_t y) 
{
    const size_t index = y * VGA_WIDTH + x;
    terminal_buffer[index] = vga_entry(c, color);
}
 
void terminal_putchar(char c) 
{
    terminal_putentryat(c, terminal_color, terminal_column, terminal_row);
    if (++terminal_column == VGA_WIDTH) {
        terminal_column = 0;
        if (++terminal_row == VGA_HEIGHT)
            terminal_row = 0;
        if(c == '\n')
        {
            terminal_row = terminal_row + 1;
            terminal_column = 0;
        }
    }
}
 
void terminal_write(const char* data, size_t size) 
{
    for (size_t i = 0; i < size; i++)
        terminal_putchar(data[i]);
}
 
void terminal_writestring(const char* data) 
{
    terminal_write(data, strlen(data));
}
 
void kernel_main(void) 
{
    /* Initialize terminal interface */
    terminal_initialize();
 
    /* Newline support is left as an exercise. */
    terminal_writestring("Hello, kernel World!\n");
}

Answer 1

检查换行符的代码位于检查 WIDTH 和 HEIGHT 的块内。

你只需要在'\n'检查它之前关闭那个块。

if (++terminal_column == VGA_WIDTH) {
        terminal_column = 0;
        if (++terminal_row == VGA_HEIGHT)
            terminal_row = 0;
       }
       else if(c == '\n')
        {
            terminal_row = terminal_row + 1;
            terminal_column = 0;
        }

但这有一个小问题，因为它不会在遇到 \n 时检查 HEIGHT。 下面的代码也解决了这个问题。

if (++terminal_column == VGA_WIDTH) {
        terminal_column = 0;
       ++terminal_row;
       }
       else if(c == '\n')
        {
            terminal_row = terminal_row + 1;
            terminal_column = 0;
        }
       if(terminal_row==VGA_HEIGHT){
           terminal_row=0;
        }

希望它有效。