操作系统实验五、实现系统调用

#include "stdio.h" #define MAX_BUF_LEN 512 char buf[MAX_BUF_LEN]; void set_buf() { int bufpoint=0; while(1) { char c=get_the_char(); if(c=='\b') { if(bufpoint==0) continue; putch('\b'); putch(' '); putch('\b'); bufpoint--; } else if(c==10||c==13) { putch(10); buf[bufpoint]=0; bufpoint++; break; } else { putch(c); buf[bufpoint]=c; bufpoint++; } if(bufpoint==MAX_BUF_LEN-1) { buf[bufpoint]=0; break; } } } void putch(char c) { int position=get_cursor(); if(c==13) c=10; if(c==10) { int currow=position/80; position=80*currow; position+=80; } else { put_the_char(c,position); position++; } if(position>1999) { roll_screen(); position=1920; } set_curson(position); } int get_cursor() { int position; asm push ax asm push dx asm mov dx,3d4h asm mov al,0eh asm out dx,al asm mov dx,3d5h asm in al,dx asm mov ah,al asm mov dx,3d4h asm mov al,0fh asm out dx,al asm mov dx,3d5h asm in al,dx asm mov position,ax asm pop dx asm pop ax return position; } void set_curson(int position) { asm push ax asm push bx asm push dx asm mov bx,position asm mov dx,3d4h asm mov al,0eh asm out dx,al asm mov dx,3d5h asm mov al,bh asm out dx,al asm mov dx,3d4h asm mov al,0fh asm out dx,al asm mov dx,3d5h asm mov al,bl asm out dx,al asm pop dx asm pop bx asm pop ax } void put_the_char(char c,int position) { position*=2; asm push ax asm push cx asm push bx asm push ds asm push si asm mov cl,c asm mov ax,0b800h asm mov ds,ax asm mov bx,position asm mov si,bx asm mov byte ptr [si],cl asm pop si asm pop ds asm pop bx asm pop cx asm pop ax } void roll_screen() { asm push ax asm push ds asm push es asm push si asm push di asm push cx asm push bx asm mov ax,0xb800 asm mov ds,ax asm mov es,ax asm cld asm mov si,0xa0 asm mov di,0x00 asm mov cx,1920 asm rep movsw asm mov bx,3840 asm mov cx,80 last_row_cls: asm mov word ptr [bx],0x0720 asm add bx,2 asm loop last_row_cls asm pop bx asm pop cx asm pop di asm pop si asm pop es asm pop ds asm pop ax } void puts(char* str) { while(*str) { putch(*str); str++; } } char getch() { char c; char curchar; while(1) { curchar=get_the_char(); if(curchar==32||curchar==10||curchar==13) { putch(curchar); continue; } else { putch(curchar); c=curchar; break; } } return c; } char get_the_char() { char the_char; asm mov ah,0 asm int 16h asm mov the_char, al return the_char; } void gets(char* str) { char curchar; while(1) { curchar=get_the_char(); putch(curchar); if(curchar!=32&&curchar!=10&&curchar!=13) break; } (*str)=curchar; str++; while(1) { curchar=get_the_char(); putch(curchar); if(curchar!=10&&curchar!=13) { (*str)=curchar; str++; } else break; } (*str)=0; } void printfint(int num) { char buffer[8]; int point=0; if(num==0) { putch('0'); } else { while(num) { buffer[point]=(num%10)+'0'; num/=10; point++; } while(point) { putch(buffer[point-1]); point--; } } } void printf(char* format, ...) { int stackptr =(&format); int data; while(*format) { if((*format)=='%') { format++; stackptr+=2; asm push ax asm push bp asm mov ax,word ptr stackptr asm mov bp,ax asm mov ax,word ptr [bp] asm pop bp asm mov word ptr data,ax asm pop ax if((*format)=='c') { char c=(char )data; putch(c); } else if((*format)=='d') { printfint(data); } else if((*format)=='s') { char* s=(char* )data; puts(s); } else { format--; stackptr-=2; } } else { putch(*format); } format++; } } void scanf(char* format, ...) { int stackptr=(&format); int* data; char* temp; int pos; pos=0; set_buf(); while((*format)) { if((*format)=='%') { format++; stackptr+=2; asm push ax asm push bp asm mov ax,word ptr stackptr asm mov bp,ax asm mov ax,word ptr [bp] asm pop bp asm mov word ptr data,ax asm pop ax if((*format)=='c') { while(pos<MAX_BUF_LEN&&buf[pos]) { if(buf[pos]!=32&&buf[pos]!=10&&buf[pos]!=13) break; pos++; } temp=(char* )data; (*temp)=buf[pos]; pos++; } else if((*format)=='d') { int num=0; while(buf[pos]>'9'||buf[pos]<'0') { pos++; } while(buf[pos]>='0'&&buf[pos]<='9') { num=num*10+buf[pos]-'0'; pos++; } (*data)=num; } else if((*format)=='s') { while(buf[pos]==32||buf[pos]==10||buf[pos]==13) { pos++; } temp=(char* )data; while(pos<MAX_BUF_LEN&&buf[pos]!=0&&buf[pos]!=32&&buf[pos]!=10&&buf[pos]!=13) { (*temp)=buf[pos]; temp++; pos++; } (*temp)=0; } else { format--; stackptr-=2; } } format++; } }