《30天自制操作系统》第五天

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_screen(char *vram, int x, int y);

#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

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();
    }
}

void init_palette(void)
{
    static unsigned char table_rgb[16 * 3] = {
        0x00, 0x00, 0x00,    /*  0:黒 */
        0xff, 0x00, 0x00,    /*  1:明るい赤 */
        0x00, 0xff, 0x00,    /*  2:明るい緑 */
        0xff, 0xff, 0x00,    /*  3:明るい黄色 */
        0x00, 0x00, 0xff,    /*  4:明るい青 */
        0xff, 0x00, 0xff,    /*  5:明るい紫 */
        0x00, 0xff, 0xff,    /*  6:明るい水色 */
        0xff, 0xff, 0xff,    /*  7:白 */
        0xc6, 0xc6, 0xc6,    /*  8:明るい灰色 */
        0x84, 0x00, 0x00,    /*  9:暗い赤 */
        0x00, 0x84, 0x00,    /* 10:暗い緑 */
        0x84, 0x84, 0x00,    /* 11:暗い黄色 */
        0x00, 0x00, 0x84,    /* 12:暗い青 */
        0x84, 0x00, 0x84,    /* 13:暗い紫 */
        0x00, 0x84, 0x84,    /* 14:暗い水色 */
        0x84, 0x84, 0x84    /* 15:暗い灰色 */
    };
    set_palette(0, 15, table_rgb);
    return;

    /* static char 命令は、データにしか使えないけどDB命令相当 */
}

void set_palette(int start, int end, unsigned char *rgb)
{
    int i, eflags;
    eflags = io_load_eflags();    /* 割り込み許可フラグの値を記録する */
    io_cli();                     /* 許可フラグを0にして割り込み禁止にする */
    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);    /* 割り込み許可フラグを元に戻す */
    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_screen(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;
}

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;
}

void HariMain(void)
{
    struct BOOTINFO *binfo = (struct BOOTINFO *) 0x0ff0;
    static char font_A[16] = {
        0x00, 0x18, 0x18, 0x18, 0x18, 0x24, 0x24, 0x24,
        0x24, 0x7e, 0x42, 0x42, 0x42, 0xe7, 0x00, 0x00
    };

    init_palette();
    init_screen(binfo->vram, binfo->scrnx, binfo->scrny);
    putfont8(binfo->vram, binfo->scrnx, 10, 10, COL8_FFFFFF, font_A);

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