12864绘图操控

#include "12864.h"

void delayms(unsigned int n)
{
 unsigned char i;
 for(;n>0;n--)
 for(i=0;i<100;i++);
}

void checkBusy(void)
{
 rs=0;
 rw=1;
 en=1;
 dataPort=0xff;
 while(dataPort & 0x80);
 en=0;
}

void writeCommand(unsigned char cmd)
{
 checkBusy();
 rs=0;
 rw=0;
 en=1;
 dataPort=cmd;
 _nop_();
 en=0;
}

void writeData(unsigned char adata)
{
 checkBusy();
 rs=1;
 rw=0;
 en=1;
 dataPort=adata;
 _nop_();
 en=0;
} 

unsigned char readData(void)
{
 unsigned char RData;
 dataPort=0xff;
 checkBusy();
 rs=1;
 rw=1;
 en=0;
 en=1;
 RData=dataPort;
 en=0;
 return RData;
}

void ClrGDRAM(void)
{
unsigned char x,y;
for(y=0;y<64;y++)
     for(x=0;x<16;x++)