不随操作系统版本而改变的API

20_day/bootpack.h

@@ -30,6 +30,8 @@ void asm_inthandler27(void);
 void asm_inthandler2c(void);
 unsigned int memtest_sub(unsigned int start, unsigned int end);
 void farjmp(int eip, int cs);
+void farcall(int eip, int cs);
+void asm_cons_putchar(void);
 
 /* fifo.c */
 struct FIFO32 {

20_day/console.c

@@ -16,6 +16,7 @@ void console_task(struct SHEET *sheet, unsigned int memtotal)
 	cons.cur_x = 8;
 	cons.cur_y = 28;
 	cons.cur_c = -1;
+	*((int *) 0x0fec) = (int) &cons;
 
 	fifo32_init(&task->fifo, 128, fifobuf, task);
 	timer = timer_alloc();
@@ -255,7 +256,7 @@ void cmd_hlt(struct CONSOLE *cons, int *fat)
 		p = (char *) memman_alloc_4k(memman, finfo->size);
 		file_loadfile(finfo->clustno, finfo->size, p, fat, (char *) (ADR_DISKIMG + 0x003e00));
 		set_segmdesc(gdt + 1003, finfo->size - 1, (int) p, AR_CODE32_ER);
-		farjmp(0, 1003 * 8);
+		farcall(0, 1003 * 8);
 		memman_free_4k(memman, (int) p, finfo->size);
 	} else {
 		/*没有找到文件的情况*/

20_day/dsctbl.c

@@ -27,6 +27,7 @@ void init_gdtidt(void)
 	set_gatedesc(idt + 0x21, (int) asm_inthandler21, 2 * 8, AR_INTGATE32);
 	set_gatedesc(idt + 0x27, (int) asm_inthandler27, 2 * 8, AR_INTGATE32);
 	set_gatedesc(idt + 0x2c, (int) asm_inthandler2c, 2 * 8, AR_INTGATE32);
+	set_gatedesc(idt + 0x40, (int) asm_cons_putchar, 2 * 8, AR_INTGATE32);
 
 	return;
 }

20_day/hlt.nas

@@ -1,5 +1,12 @@
 [BITS 32]
-		CLI
-fin:
-		HLT
-		JMP		fin
+		MOV		AL,'h'
+		INT  0x40
+		MOV		AL,'e'
+		INT  0x40
+		MOV		AL,'l'
+		INT  0x40
+		MOV		AL,'l'
+		INT  0x40
+		MOV		AL,'o'
+		INT  0x40
+		RETF

20_day/naskfunc.nas

@@ -16,9 +16,11 @@
 		GLOBAL	_asm_inthandler20, _asm_inthandler21
 		GLOBAL	_asm_inthandler27, _asm_inthandler2c
 		GLOBAL	_memtest_sub
-		GLOBAL	_farjmp
+		GLOBAL	_farjmp, _farcall
+		GLOBAL	_asm_cons_putchar
 		EXTERN	_inthandler20, _inthandler21
 		EXTERN	_inthandler27, _inthandler2c
+		EXTERN	_cons_putchar
 
 [SECTION .text]
 
@@ -209,4 +211,18 @@ mts_fin:
 
 _farjmp:		; void farjmp(int eip, int cs);
 		JMP    FAR [ESP+4]    ; eip, cs
-		RET
+		RET
+
+_farcall:		; void farcall(int eip, int cs);
+		CALL		FAR [ESP+4]     ; eip, cs
+		RET
+
+_asm_cons_putchar:
+		STI
+		PUSH		1
+		AND			EAX,0xff ; 将AH和EAX的高位置0，将EAX置为已存入字符编码的状态
+		PUSH    EAX
+		PUSH		DWORD [0x0fec] ; 读取内存并PUSH该值
+		CALL		_cons_putchar
+		ADD			ESP,12   ; 将栈中的数据丢弃
+		IRETD