《30天自制操作系统》05_day_学习笔记

//bootpack.c  完整代码
#include <stdio.h>

void io_hlt(void);
void io_cli(void);
void io_out8(int port, int data);
int io_load_eflags(void);
void io_store_eflags(int eflags);

void init_palette(void);
void set_palette(int start, int end, unsigned char *rgb);
void boxfill8(unsigned char *vram, int xsize, unsigned char c, int x0, int y0, int x1, int y1);
void init_screen8(char *vram, int x, int y);
void putfont8(char *vram, int xsize, int x, int y, char c, char *font);
void putfonts8_asc(char *vram, int xsize, int x, int y, char c, unsigned char *s);
void init_mouse_cursor8(char *mouse, char bc);
void putblock8_8(char *vram, int vxsize, int pxsize,
    int pysize, int px0, int py0, char *buf, int bxsize);

#define COL8_000000        0
#define COL8_FF0000        1
#define COL8_00FF00        2
#define COL8_FFFF00        3
#define COL8_0000FF        4
#define COL8_FF00FF        5
#define COL8_00FFFF        6
#define COL8_FFFFFF        7
#define COL8_C6C6C6        8
#define COL8_840000        9
#define COL8_008400        10
#define COL8_848400        11
#define COL8_000084        12
#define COL8_840084        13
#define COL8_008484        14
#define COL8_848484        15

//接受启动信息写成结构体的形式  P89.接着从asmhead.nas中读取启动信息数据（启动地址和内容）
//注意在第一天中，我们已经把asmhead.nas中的信息写到了镜像中。每次系统启动时，首先载入镜像，然后读到asmhead.nas中的内容启动
struct BOOTINFO {  
    char cyls, leds, vmode, reserve;
    short scrnx, scrny;
    char *vram;
};

struct SEGMENT_DESCRIPTOR {  //GDT的内容；8字节
    short limit_low, base_low;
    char base_mid, access_right;
    char limit_high, base_high;
};

struct GATE_DESCRIPTOR {    //IDT的内容，8字节
    short offset_low, selector;
    char dw_count, access_right;
    short offset_high;
};

void init_gdtidt(void);
void set_segmdesc(struct SEGMENT_DESCRIPTOR *sd, unsigned int limit, int base, int ar);
void set_gatedesc(struct GATE_DESCRIPTOR *gd, int offset, int selector, int ar);
void load_gdtr(int limit, int addr);
void load_idtr(int limit, int addr);

void HariMain(void)
{
    struct BOOTINFO *binfo = (struct BOOTINFO *) 0x0ff0;
    char s[40], mcursor[256];
    int mx, my;

    init_gdtidt();
    init_palette();
    init_screen8(binfo->vram, binfo->scrnx, binfo->scrny);  //所谓的使用箭头记号->
    mx = (binfo->scrnx - 16) / 2;   /* 启动信息结构体BOOTINFO 从asmhead.nas中读取启动信息数据*/
    my = (binfo->scrny - 28 - 16) / 2;

    init_mouse_cursor8(mcursor, COL8_008484); //初始化并显示鼠标指针
    putblock8_8(binfo->vram, binfo->scrnx, 16, 16, mx, my, mcursor, 16);

    sprintf(s, "(%d, %d)", mx, my);  //显示变量，先把内容放到字符串s中
    putfonts8_asc(binfo->vram, binfo->scrnx, 0, 0, COL8_FFFFFF, s); //接着把字符串s显示出来

    for (;;) {
        io_hlt();
    }
}

void init_palette(void)
{
    static unsigned char table_rgb[16 * 3] = {
        0x00, 0x00, 0x00,    
        0xff, 0x00, 0x00,    
        0x00, 0xff, 0x00,    
        0xff, 0xff, 0x00,    
        0x00, 0x00, 0xff,    
        0xff, 0x00, 0xff,    
        0x00, 0xff, 0xff,    
        0xff, 0xff, 0xff,    
        0xc6, 0xc6, 0xc6,    
        0x84, 0x00, 0x00,    
        0x00, 0x84, 0x00,    
        0x84, 0x84, 0x00,    
        0x00, 0x00, 0x84,    
        0x84, 0x00, 0x84,    
        0x00, 0x84, 0x84,    
        0x84, 0x84, 0x84    
    };
    set_palette(0, 15, table_rgb);
    return;
}

void set_palette(int start, int end, unsigned char *rgb)
{
    int i, eflags;
    eflags = io_load_eflags();
    io_cli();                     
    io_out8(0x03c8, start);
    for (i = start; i <= end; i++) {
        io_out8(0x03c9, rgb[0] / 4);
        io_out8(0x03c9, rgb[1] / 4);
        io_out8(0x03c9, rgb[2] / 4);
        rgb += 3;
    }
    io_store_eflags(eflags);
    return;
}

void boxfill8(unsigned char *vram, int xsize, unsigned char c, int x0, int y0, int x1, int y1)
{
    int x, y;
    for (y = y0; y <= y1; y++) {
        for (x = x0; x <= x1; x++)
            vram[y * xsize + x] = c;
    }
    return;
}

void init_screen8(char *vram, int x, int y)
{
    boxfill8(vram, x, COL8_008484,  0,     0,      x -  1, y - 29);
    boxfill8(vram, x, COL8_C6C6C6,  0,     y - 28, x -  1, y - 28);
    boxfill8(vram, x, COL8_FFFFFF,  0,     y - 27, x -  1, y - 27);
    boxfill8(vram, x, COL8_C6C6C6,  0,     y - 26, x -  1, y -  1);

    boxfill8(vram, x, COL8_FFFFFF,  3,     y - 24, 59,     y - 24);
    boxfill8(vram, x, COL8_FFFFFF,  2,     y - 24,  2,     y -  4);
    boxfill8(vram, x, COL8_848484,  3,     y -  4, 59,     y -  4);
    boxfill8(vram, x, COL8_848484, 59,     y - 23, 59,     y -  5);
    boxfill8(vram, x, COL8_000000,  2,     y -  3, 59,     y -  3);
    boxfill8(vram, x, COL8_000000, 60,     y - 24, 60,     y -  3);

    boxfill8(vram, x, COL8_848484, x - 47, y - 24, x -  4, y - 24);
    boxfill8(vram, x, COL8_848484, x - 47, y - 23, x - 47, y -  4);
    boxfill8(vram, x, COL8_FFFFFF, x - 47, y -  3, x -  4, y -  3);
    boxfill8(vram, x, COL8_FFFFFF, x -  3, y - 24, x -  3, y -  3);
    return;
}

//输出，显示字符
void putfont8(char *vram, int xsize, int x, int y, char c, char *font)
{
    int i;
    char *p, d /* data */;
    for (i = 0; i < 16; i++) {
        p = vram + (y + i) * xsize + x;
        d = font[i];
        if ((d & 0x80) != 0) { p[0] = c; }
        if ((d & 0x40) != 0) { p[1] = c; }
        if ((d & 0x20) != 0) { p[2] = c; }
        if ((d & 0x10) != 0) { p[3] = c; }
        if ((d & 0x08) != 0) { p[4] = c; }
        if ((d & 0x04) != 0) { p[5] = c; }
        if ((d & 0x02) != 0) { p[6] = c; }
        if ((d & 0x01) != 0) { p[7] = c; }
    }
    return;
}

//输出，显示字符串
void putfonts8_asc(char *vram, int xsize, int x, int y, char c, unsigned char *s)
{
    extern char hankaku[4096];
    for (; *s != 0x00; s++) {
        putfont8(vram, xsize, x, y, c, hankaku + *s * 16);
        x += 8;
    }
    return;
}

void init_mouse_cursor8(char *mouse, char bc)
/* 准备，初始化鼠标指针 16*16=512字符（字节）*/
{
    static char cursor[16][16] = {
        "**************..",
        "*OOOOOOOOOOO*...",
        "*OOOOOOOOOO*....",
        "*OOOOOOOOO*.....",
        "*OOOOOOOO*......",
        "*OOOOOOO*.......",
        "*OOOOOOO*.......",
        "*OOOOOOOO*......",
        "*OOOO**OOO*.....",
        "*OOO*..*OOO*....",
        "*OO*....*OOO*...",
        "*O*......*OOO*..",
        "**........*OOO*.",
        "*..........*OOO*",
        "............*OO*",
        ".............***"
    };
    int x, y;

    for (y = 0; y < 16; y++) {
        for (x = 0; x < 16; x++) {
            if (cursor[y][x] == '*') {
                mouse[y * 16 + x] = COL8_000000;
            }
            if (cursor[y][x] == 'O') {
                mouse[y * 16 + x] = COL8_FFFFFF;
            }
            if (cursor[y][x] == '.') {
                mouse[y * 16 + x] = bc;
            }
        }
    }
    return;
}
//这里显示鼠标指针；
void putblock8_8(char *vram, int vxsize, int pxsize,
    int pysize, int px0, int py0, char *buf, int bxsize)
{
    int x, y;
    for (y = 0; y < pysize; y++) {
        for (x = 0; x < pxsize; x++) {
            vram[(py0 + y) * vxsize + (px0 + x)] = buf[y * bxsize + x];
        }
    }
    return;
}

void init_gdtidt(void)   //GDT和IDT的初始化
{
    struct SEGMENT_DESCRIPTOR *gdt = (struct SEGMENT_DESCRIPTOR *) 0x00270000;
    struct GATE_DESCRIPTOR    *idt = (struct GATE_DESCRIPTOR    *) 0x0026f800;
    int i;

    /* GDT初始化 */
    for (i = 0; i < 8192; i++) {    //i每次加一；但是gdt指向8字节的结构体；结果地址增加了8
        set_segmdesc(gdt + i, 0, 0, 0);    //gdt*（地址）每次+8
    }
    set_segmdesc(gdt + 1, 0xffffffff, 0x00000000, 0x4092);  //段号为1；大小4G 表示CPU管理的全部内存
    set_segmdesc(gdt + 2, 0x0007ffff, 0x00280000, 0x409a);  //段号位2； 大小512K  为bootpack.hrb准备
    load_gdtr(0xffff, 0x00270000);  //GDT    0x270000-0x27ffff  借助汇编语言的力量给寄存器GDTR赋值

    /* IDT初始化  */
    for (i = 0; i < 256; i++) {    //和上面一样
        set_gatedesc(idt + i, 0, 0, 0);
    }                               //IDT    0x26f800-0x26ffff
    load_idtr(0x7ff, 0x0026f800);    //向寄存器IDTR赋值

    return;
}

void set_segmdesc(struct SEGMENT_DESCRIPTOR *sd, unsigned int limit, int base, int ar)
{
    if (limit > 0xfffff) {
        ar |= 0x8000; /* G_bit = 1 */
        limit /= 0x1000;
    }
    sd->limit_low    = limit & 0xffff;
    sd->base_low     = base & 0xffff;
    sd->base_mid     = (base >> 16) & 0xff;
    sd->access_right = ar & 0xff;
    sd->limit_high   = ((limit >> 16) & 0x0f) | ((ar >> 8) & 0xf0);
    sd->base_high    = (base >> 24) & 0xff;
    return;
}

void set_gatedesc(struct GATE_DESCRIPTOR *gd, int offset, int selector, int ar)
{
    gd->offset_low   = offset & 0xffff;
    gd->selector     = selector;
    gd->dw_count     = (ar >> 8) & 0xff;
    gd->access_right = ar & 0xff;
    gd->offset_high  = (offset >> 16) & 0xffff;
    return;
}

harib02a:

　　P89 这里做的就是数值写入asmhead.nas中，然后取值；
　　而不是将这些数值直接写入程序bootpack.c中

//bootpack.c节选
void HariMain(void)
{
    char *vram;
    int xsize, ysize;
    short *binfo_scrnx, *binfo_scrny;
    int *binfo_vram;

    init_palette();
    binfo_scrnx = (short *) 0x0ff4;
    binfo_scrny = (short *) 0x0ff6;
    binfo_vram = (int *) 0x0ff8;
    xsize = *binfo_scrnx;
    ysize = *binfo_scrny;
    vram = (char *) *binfo_vram;

    init_screen(vram, xsize, ysize);
    for (;;) {
        io_hlt();
    }
}

harib02b:
　　这次使用的是结构体的方法重新写一遍，实现的内容是一样的
　　只是实现方法在这里使用了结构体的写法。如下：

//bootpack.c节选
//接受启动信息写成结构体的形式 P89.接着从asmhead.nas中读取启动信息数据（启动地址和内容）
//注意在第一天中，我们已经把asmhead.nas中的信息写到了镜像中。每次系统启动时，首先载入镜像，然后读到asmhead.nas中的内容启动
struct BOOTINFO {
    char cyls, leds, vmode, reserve;
    short scrnx, scrny;
    char *vram;
};
void HariMain(void)
{
    char *vram;
    int xsize, ysize;
    struct BOOTINFO *binfo;

    init_palette();
    binfo = (struct BOOTINFO *) 0x0ff0;
    xsize = (*binfo).scrnx;
    ysize = (*binfo).scrny;
    vram = (*binfo).vram;

    init_screen(vram, xsize, ysize);

    for (;;) {
        io_hlt();
    }
}

harib02c:
　　这一步在结构体的基础上，引入了箭头记号的C变成的方式
　　eg::xsize = (*binfo).scrnx  可以写成  xsize = binfo -> scrnx
　　进一步改进了程序，但实现的内容任然不变

void HariMain(void)
{
    struct BOOTINFO *binfo = (struct BOOTINFO *) 0x0ff0;

    init_palette();
    init_screen(binfo->vram, binfo->scrnx, binfo->scrny);

    for (;;) {
        io_hlt();
    }
}

harib02d:
　　P92 显示字符；
　　原理：字符使用8*16的像素点阵来表示，
　　1个字符是16个字节
　　建立了font结构体数组，用来表示像素点阵字符
　　函数purfont8()用来将像素点阵字符输出

//字符显示函数
void putfont8(char *vram, int xsize, int x, int y, char c, char *font)
{
    int i;
    char *p, d /* data */;
    for (i = 0; i < 16; i++) {
        p = vram + (y + i) * xsize + x;
        d = font[i];
        if ((d & 0x80) != 0) { p[0] = c; }
        if ((d & 0x40) != 0) { p[1] = c; }
        if ((d & 0x20) != 0) { p[2] = c; }
        if ((d & 0x10) != 0) { p[3] = c; }
        if ((d & 0x08) != 0) { p[4] = c; }
        if ((d & 0x04) != 0) { p[5] = c; }
        if ((d & 0x02) != 0) { p[6] = c; }
        if ((d & 0x01) != 0) { p[7] = c; }
    }
    return;
}

harib02e:
　　P94 增加了字体的显示； 这里使用了OSASK的字体数据；
　　原理：相应了字体显示的像素点阵存储在hankaku.txt中。
　　每一个字体字符都有一个编号。直接查找调用即可
　　方法：用OSASK的专用编译器makefont.exe将hankaku.txt编译成hankaku.bin
　　再由连接器bin2obj.exer将hankaku.bin加上必须的接口信息和bootpack.obj链接
　　生成目标文件

//显示ABC  123
void HariMain(void)
{
    struct BOOTINFO *binfo = (struct BOOTINFO *) 0x0ff0;
    extern char hankaku[4096];

    init_palette();
    init_screen(binfo->vram, binfo->scrnx, binfo->scrny);
    putfont8(binfo->vram, binfo->scrnx, 10, 0, COL8_FFFFFF, hankaku + 'A' * 16);
    putfont8(binfo->vram, binfo->scrnx, 16, 8, COL8_FFFFFF, hankaku + 'B' * 16);
    putfont8(binfo->vram, binfo->scrnx, 24, 8, COL8_FFFFFF, hankaku + 'C' * 16);
    putfont8(binfo->vram, binfo->scrnx, 40, 8, COL8_FFFFFF, hankaku + '1' * 16);
    putfont8(binfo->vram, binfo->scrnx, 48, 8, COL8_FFFFFF, hankaku + '2' * 16);
    putfont8(binfo->vram, binfo->scrnx, 56, 8, COL8_FFFFFF, hankaku + '3' * 16);
    for (;;) {
        io_hlt();
    }
}

harib02f:
　　接着笔者干脆写了一个函数用来专门显示字符串；putfonts8_asc();

//字符串显示函数
void putfonts8_asc(char *vram, int xsize, int x, int y, char c, unsigned char *s)
{
    extern char hankaku[4096];
    for (; *s != 0x00; s++) {
        putfont8(vram, xsize, x, y, c, hankaku + *s * 16);
        x += 8;
    }
    return;
}

harib02g:
　　P98 显示变量的值；虽然我们不能用prinft()函数；但是我们可以使用sprintf()函数
　　sprintf()将输出的内容写在内存中间。这个函数只对内存进行操作，可以应用于所有的操作系统
　　笔者还附带的介绍了一下sprintf（）的使用方法和格式；

    sprintf(s, "scrnx = %d", binfo->scrnx);
    putfonts8_asc(binfo->vram, binfo->scrnx, 16, 64, COL8_FFFFFF, s);

harib02h:
　　P100 鼠标指针的显示。大小设定为16*16的字符数组的大小
　　内存空间：16*16=256字节；程序写在了init_mouse_cursor8中。
　　显示的原理和上面字符显示的原理一样；将buf中的数据复制到VARM中去就可以了
　　接下来笔者写了一个显示的函数putblock8_8()；教材100面有函数详细的介绍。

//bootpack.c 节选
void init_mouse_cursor8(char *mouse, char bc)
/* 准备，初始化鼠标指针 16*16=512字符（字节）*/
{
    static char cursor[16][16] = {
        "**************..",
        "*OOOOOOOOOOO*...",
        "*OOOOOOOOOO*....",
        "*OOOOOOOOO*.....",
        "*OOOOOOOO*......",
        "*OOOOOOO*.......",
        "*OOOOOOO*.......",
        "*OOOOOOOO*......",
        "*OOOO**OOO*.....",
        "*OOO*..*OOO*....",
        "*OO*....*OOO*...",
        "*O*......*OOO*..",
        "**........*OOO*.",
        "*..........*OOO*",
        "............*OO*",
        ".............***"
    };
    int x, y;

    for (y = 0; y < 16; y++) {
        for (x = 0; x < 16; x++) {
            if (cursor[y][x] == '*') {
                mouse[y * 16 + x] = COL8_000000;
            }
            if (cursor[y][x] == 'O') {
                mouse[y * 16 + x] = COL8_FFFFFF;
            }
            if (cursor[y][x] == '.') {
                mouse[y * 16 + x] = bc;
            }
        }
    }
    return;
}
//这里显示鼠标指针；
void putblock8_8(char *vram, int vxsize, int pxsize,
    int pysize, int px0, int py0, char *buf, int bxsize)
{
    int x, y;
    for (y = 0; y < pysize; y++) {
        for (x = 0; x < pxsize; x++) {
            vram[(py0 + y) * vxsize + (px0 + x)] = buf[y * bxsize + x];
        }
    }
    return;
}

harib02i:
　　P101 怎么才能让鼠标动起来？我们先来看看什么事GDT和IDT
　　这两个东西是CPU有关的设定（大家暂时不用深究什么是设定，先往下看）
　　接下来要用汇编语言（有回到汇编语言了）来对CPU做一些鼠标的设定
　　接下来笔者讲了操作系统分段的概念，关于分段、分页。学过操作系统的都应该知道，不再赘述
　　GDT：全局段号记录表，存放在内存中的。把需要查找的地址和相应的段号对应起来，便于寻址和查找；
　　　　　 寄存器GDTR用来存储该段内存的起始地址和有效的设定个数
　　IDT：中断记录表；中断号为0-255；每一个中断号对应一个函数调用，
　　　　   这些函数就是用来处理操作系统中的中断的，中断发生后，调用通过IDT调用相应的中断函数即可

//bootpack.c节选
struct SEGMENT_DESCRIPTOR {  //GDT的内容；8字节
    short limit_low, base_low;
    char base_mid, access_right;
    char limit_high, base_high;
};

struct GATE_DESCRIPTOR {   //IDT的内容，8字节
    short offset_low, selector;
    char dw_count, access_right;
    short offset_high;
};
...................
void init_gdtidt(void)   //GDT和IDT的初始化
{
    struct SEGMENT_DESCRIPTOR *gdt = (struct SEGMENT_DESCRIPTOR *) 0x00270000;
    struct GATE_DESCRIPTOR    *idt = (struct GATE_DESCRIPTOR    *) 0x0026f800;
    int i;

    /* GDT初始化 */
    for (i = 0; i < 8192; i++) {    //i每次加一；但是gdt指向8字节的结构体；结果地址增加了8
        set_segmdesc(gdt + i, 0, 0, 0);    //gdt*（地址）每次+8
    }
    set_segmdesc(gdt + 1, 0xffffffff, 0x00000000, 0x4092);  //段号为1；大小4G 表示CPU管理的全部内存
    set_segmdesc(gdt + 2, 0x0007ffff, 0x00280000, 0x409a);  //段号位2； 大小512K  为bootpack.hrb准备
    load_gdtr(0xffff, 0x00270000);  //GDT    0x270000-0x27ffff  借助汇编语言的力量给寄存器GDTR赋值

    /* IDT初始化  */
    for (i = 0; i < 256; i++) {    //和上面一样
        set_gatedesc(idt + i, 0, 0, 0);
    }                               //IDT    0x26f800-0x26ffff
    load_idtr(0x7ff, 0x0026f800);    //向寄存器IDTR赋值

    return;
}