二状态进程模型

#define SCHEDULE_QUEUE_LEN 9
#define NEW 0
#define RUNNING 1
struct PCB
{
	int ip, cs, es, ds, ss, di, si, bp, sp, ax, bx, cx, dx, flags, pid;
} q[SCHEDULE_QUEUE_LEN], *qb = q, *qe = q + 1;
int statues[SCHEDULE_QUEUE_LEN] = {RUNNING, NEW}, pidStack[SCHEDULE_QUEUE_LEN], *top = pidStack;
void schedule()
{
	do
		if (++qb == q + SCHEDULE_QUEUE_LEN)
			qb = q;
	while (statues[qb->pid] != RUNNING);
	if (++qe == q + SCHEDULE_QUEUE_LEN)
		qe = q;
}

statues[pid] = NEW, *++top = pid;

#define SCREEN_WIDTH 80
#define SCREEN_HEIGHT 25
#define BUF_LEN (SCREEN_WIDTH * SCREEN_HEIGHT)
#define PROGRAM_NUM 4
#define SCHEDULE_QUEUE_LEN 5
#define NEW 0
#define RUNNING 1
struct PCB
{
	int ip, cs, es, ds, ss, di, si, bp, sp, ax, bx, cx, dx, flags, pid;
} q[SCHEDULE_QUEUE_LEN], *qb = q, *qe = q + 1;
int statues[SCHEDULE_QUEUE_LEN] = {RUNNING, NEW}, pidStack[SCHEDULE_QUEUE_LEN], *top = pidStack;
void schedule()
{
	do
		if (++qb == q + SCHEDULE_QUEUE_LEN)
			qb = q;
	while (statues[qb->pid] != RUNNING);
	if (++qe == q + SCHEDULE_QUEUE_LEN)
		qe = q;
}
const struct
{
	const char *name, *size, *command;
	int address;
} prg[PROGRAM_NUM] =
	{{"prg1", "    156 bytes", "prg1", 1},
	 {"prg2", "    158 bytes", "prg2", 2},
	 {"prg3", "    168 bytes", "prg3", 3},
	 {"prg4", "    174 bytes", "prg4", 4}};
void loadProgram(int PrgSectorOffset, int UserPrgOffset)
{
	asm("int 0x13"
		:
		: "a"(2 << 8 | 1), "b"(UserPrgOffset), "c"(PrgSectorOffset), "d"(1 << 8));
}
void call(int UserPrgOffset)
{
	asm("call bx"
		:
		: "b"(UserPrgOffset));
}
void prgCall(int i)
{
	loadProgram(prg[i].address, 0x0a100 + i * 0x100), call(0x0a100 + i * 0x100);
}
int getCursor()
{
	int p;
	asm("int 0x10"
		: "=d"(p)
		: "a"(0x0300), "b"(0));
	return p;
}
void setCursor(int pos)
{
	asm("int 0x10"
		:
		: "a"(0x0200), "b"(0), "d"(pos));
}
void pageUP(int p)
{
	asm("push bx\n"
		"mov bh,0\n"
		"int 0x10\n"
		"pop bx\n"
		:
		: "a"(1536 + p), "c"(0), "d"(0x184F));
}
void putC(int ch, int color)
{
	asm("int 0x10"
		:
		: "a"(9 << 8 | ch), "b"(color), "c"(1));
}
int getch()
{
	int ch;
	asm("getch_loop:\n"
		"mov ah, 0x01\n"
		"int 0x16\n"
		"jz getch_loop\n"
		"mov ah, 0x00\n"
		"int 0x16\n"
		"xor ah, ah\n"
		: "=a"(ch)
		:);
	return ch;
}
void putchar(char c)
{
	int cur = getCursor(), curX = cur >> 8, curY = cur - (curX << 8);
	if (c == '\r' || c == '\n')
	{
		if (++curX >= SCREEN_HEIGHT)
			--curX, pageUP(1);
		return setCursor(curX << 8);
	}
	putC(c, 0x07);
	if (++curY >= SCREEN_WIDTH)
		putchar('\n');
	else
		setCursor(curX << 8 | curY);
}
void gets(char *s)
{
	for (;; ++s)
	{
		putchar(*s = getch());
		if (*s == '\r' || *s == '\n')
			break;
	}
	*s = 0;
}
void printf(const char *s)
{
	for (; *s; ++s)
		putchar(*s);
}
int strcmp(const char *s1, const char *s2)
{
	while (*s1 && (*s1 == *s2))
		++s1, ++s2;
	return (int)*s1 - (int)*s2;
}
void terminal()
{
	char str[BUF_LEN] = "$ ";
	printf(str), gets(str);
	const char
		*CLEAR_COM = "clear",
		*HELP_COM = "help",
		*EXEC_COM = "exec",
		*EXECPRO_COM = "execpro",
		*EXIT_COM = "exit",
		*KILL_COM = "kill",
		*LS_COM = "ls",
		*PS_COM = "ps";
	if (!strcmp(str, CLEAR_COM))
		pageUP(SCREEN_HEIGHT), setCursor(0);
	else if (!strcmp(str, HELP_COM))
	{
		const char
			*HELP_INFO =
				"WuK-shell v0.0.3\n"
				"These shell commands are defined internally.\n"
				"Command         Description\n"
				"clear        -- Clean the screen\n"
				"help         -- Show this list\n"
				"exec         -- Execute all the user programs\n"
				"execpro      -- Execute all the user programs by mutiprocess\n"
				"exit         -- Exit OS\n"
				"kill         -- kill process\n"
				"ls           -- Show existing programs\n"
				"prg[num]     -- Execute the num-th program\n"
				"ps           -- Show running programs with their pid\n";
		printf(HELP_INFO);
	}
	else if (!strcmp(str, EXEC_COM))
		for (int i = 0; i < PROGRAM_NUM; ++i)
			prgCall(i);
	else if (!strcmp(str, EXECPRO_COM))
		for (int i = 0; i < PROGRAM_NUM; ++i)
		{
			if (top == pidStack)
				for (int j = 1; j < SCHEDULE_QUEUE_LEN; ++j)
					*++top = j;

			qe->flags = 512;
			qe->ip = 0x000;
			qe->sp = qe->ip - 8;
			qe->ss = qe->es = qe->ds = qe->cs = 0xa100 + i * 0x100;

			loadProgram(prg[i].address, 0x0a100 + i * 0x100);
			statues[qe->pid = *(top--)] = RUNNING;
			if (++qe == q + SCHEDULE_QUEUE_LEN)
				qe = q;
		}
	else if (!strcmp(str, EXIT_COM))
		return pageUP(SCREEN_HEIGHT);
	else if (!strcmp(str, KILL_COM))
	{
		const char *INFO = "Input the pid to kill: ";
		printf(INFO);
		gets(str);
		int pid = str[0] - '0';
		if (pid <= 0)
		{
			const char *INFO = "Can not kill process 0.\n";
			printf(INFO);
		}
		else if (pid >= SCHEDULE_QUEUE_LEN || statues[pid] != RUNNING)
		{
			const char *INFO = "Invalid pid.\n";
			printf(INFO);
		}
		else
			statues[pid] = NEW, *++top = pid;
	}
	else if (!strcmp(str, LS_COM))
		for (int i = 0; i < PROGRAM_NUM; ++i)
			printf(prg[i].name), printf(prg[i].size), putchar('\n');
	else if (!strcmp(str, PS_COM))
	{
		const char
			*INFO = "pid statues\n",
			*RUNNING_INFO = "   RUNNING\n",
			*NEW_INFO = "   NEW\n";
		printf(INFO);
		for (int i = 0; i < SCHEDULE_QUEUE_LEN; ++i)
		{
			putchar('0' + i);
			printf(statues[i] == RUNNING ? RUNNING_INFO : NEW_INFO);
		}
	}
	else
		for (int i = 0;; ++i)
		{
			if (i == PROGRAM_NUM)
			{
				printf(str);
				const char
					*COMM_NOT_FOUND =
						" : command not found, type \'help\' for available commands list.\n";
				printf(COMM_NOT_FOUND);
				break;
			}
			if (!strcmp(str, prg[i].command))
			{
				asm("int 33" ::"a"(i << 8));
				break;
			}
		}
	terminal();
}