图形模式下读写屏幕象点

#include "dos.h" int rtv5f(row,col,color,xor) int row,col,color,xor; { int bp,i,j,k; long int ix,k46=65536L; unsigned char far *ptr; static unsigned char x[8]={128,64,32,16,8,4,2,1}; unsigned char t,a,b,c,d; if (col<0||col>1023||row<0||row>767) return(0); ptr=(unsigned char far *)0xA0000000; bp=col%8; ix=(long)row*128L+(long)(col/8); k=ix/k46; ix=ix-(long)k*k46; a=k; outportb(0x03C4,0x0E); outportb(0x03C5,a^0x02); t=x[bp]; if (color<0) xor=1; if (xor!=0) { outportb(0x03CE,5); outportb(0x03CF,0); outportb(0x03CE,4); outportb(0x03CF,0); a=*(ptr+ix)&t; if (a!=0) a=1; outportb(0x03CE,4); outportb(0x03CF,1); b=*(ptr+ix)&t; if (b!=0) b=2; outportb(0x03CE,4); outportb(0x03CF,2); c=*(ptr+ix)&t; if (c!=0) c=4; outportb(0x03CE,4); outportb(0x03CF,3); d=*(ptr+ix)&t; if (d!=0) d=8; a=a|b|c|d; } if (color<0) { color=(int)a; return(color);} outportb(0x03CE,5); outportb(0x03CF,2); color=color%127; outportb(0x03CE,8); outportb(0x03CF,t); outportb(0x03C4,2); outportb(0x03C5,255); if (xor!=0) { t=*(ptr+ix); t=a^color; *(ptr+ix)=t;} else { t=*(ptr+ix); *(ptr+ix)=color;} outportb(0x03CE,8); outportb(0x03CF,255); outportb(0x03CE,5); outportb(0x03CF,0); return(color); }