AT89C2051 simple sine wave, triangle wave, square wave generator

/******************************************************************** 
                 Simple sine wave, triangle wave, square wave generator 
                 using keil C51, 12MHz crystal oscillator, AT89C2051 

******************************************************************/ 
#include "reg51.h" 
#define uchar unsigned char 
#define uint unsigned int 
#define key P3 //keyboard port 
#define dataout P1 //sine wave data output port 
// 
/*****************************sine wave data table********************************/ 
uchar code sin_tab[256]= 
      {0x80,0x83,0x85,0x88,0x8A,0x8D,0x8F,0x92, 
       0x94,0x97,0x99,0x9B,0x9E,0xA0,0xA3,0xA5, 
       0xA7,0xAA,0xAC,0xAE,0xB1,0xB3,0xB5,0xB7, 
       0xB9,0xBB,0xBD,0xBF,0xC1,0xC3,0xC5,0xC7, 
       0xC9,0xCB,0x CC ,0xCE,0xD0,0xD1,0xD3,0xD4, 
       0xD6,0xD7,0xD8,0xDA,0xDB,0xDC,0xDD,0xDE, 
       0xDF,0xE0,0xE1,0xE2,0xE3,0xE3,0xE4,0xE4, 
       0xE5,0xE5,0xE6,0xE6,0xE7,0xE7,0xE7,0xE7, 
       0xE7,0xE7,0xE7,0xE7,0xE6,0xE6,0xE5,0xE5, 
       0xE4,0xE4,0xE3,0xE3,0xE2,0xE1,0xE0,0xDF, 
       0xDE,0xDD,0xDC,0xDB,0xDA,0xD8,0xD7,0xD6, 
       0xD4,0xD3,0xD1,0xD0,0xCE,0xCC,0xCB,0xC9, 
       0xC7,0xC5,0xC3,0xC1,0xBF,0xBD,0xBB,0xB9, 
       0xB7,0xB5,0xB3,0xB1,0xAE,0xAC,0xAA,0xA7, 
       0xA5,0xA3,0xA0,0x9E,0x9B,0x99,0x97,0x94, 
       0x92,0x8F,0x8D,0x8A,0x88,0x85,0x83,0x80, 
       0x7D,0x7B,0x78,0x76,0x73,0x71,0x6E,0x6C, 
       0x69,0x67,0x65,0x62,0x60,0x5D,0x5B,0x59, 
       0x56,0x54,0x52,0x4F,0x4D,0x4B,0x49,0x47, 
       0x45,0x43,0x41,0x3F,0x3D,0x3B,0x39,0x37, 
       0x35,0x34,0x32,0x30,0x2F,0x2D,0x2C,0x2A, 
       0x29,0x28,0x26,0x25,0x24,0x23,0x22,0x21, 
       0x20,0x1F,0x1E,0x1D,0x1D,0x1C,0x1C, 
       0x1B, 0x1B,0x1A,0x1A,0x1A,0x19,0x19,0x19,0x19, 0x19,0x19,0x19,0x19,0x1A 
       ,0x1A,0x1A,0x1B, 
       0x1B,0x1C,0x1C,0x1D,0x1D,0x1E,0x1F,0x20, 
       0x21,0x22,0x23,0x24,0x25,0x26,0x28,0x29, 
       0x2A,0x2C,0x2D,0x2F,0x30,0x32,0x34,0x35, 
       0x37,0x39,0x3B,0x3D,0x3F,0x41,0x43,0x45, 
       0x47,0x49,0x4B,0x4D,0x4F,0x52,0x54,0x56, 
       0x59,0x5B,0x5D,0x60,0x62,0x65,0x67,0x69, 
       0x6C,0x6E,0x71,0x73,0x76,0x78,0x7B,0x7D}; 
// 
/***************************三角波数据表**************************/ 
uchar code thr_tab[256]= 
      {0x80,0x81,0x82,0x83,0x84,0x85,0x86,0x87, 
       0x88,0x89,0x8A,0x8B,0x8C,0x8D,0x8E,0x8F, 
       0x90,0x91,0x92,0x93,0x94,0x95,0x96,0x97, 
       0x98,0x99,0x9A,0x9B,0x9C,0x9D,0x9E,0x9F, 
       0xA0,0xA1,0xA2,0xA3,0xA4,0xA5,0xA6,0xA7, 
       0xA8,0xA9,0xAA,0xAB,0xAC,0xAD,0xAE,0xAF, 
       0xB0,0xB1,0xB2,0xB3,0xB4,0xB5,0xB6,0xB7, 
       0xB8,0xB9,0xBA,0xBB,0xBC,0xBD,0xBE,0xBF, 
       0xBF,0xBE,0xBD,0xBC,0xBB,0xBA,0xB9,0xB8, 
       0xB7,0xB6,0xB5,0xB4,0xB3,0xB2,0xB1,0xB0, 
       0xAF,0xAE,0xAD,0xAC,0xAB,0xAA,0xA9,0xA8, 
       0xA7,0xA6,0xA5,0xA4,0xA3,0xA2,0xA1,0xA0, 
       0x9F,0x9E,0x9D,0x9C,0x9B,0x9A,0x99,0x98, 
       0x97,0x96,0x95,0x94,0x93,0x92,0x91,0x90, 
       0x8F,0x8E,0x8D,0x8C,0x8B,0x8A,0x89,0x88, 
       0x87,0x86,0x85,0x84,0x83,0x82,0x81,0x80, 
       0x7F,0x7E,0x7D,0x7C,0x7B,0x7A,0x79,0x78, 
       0x77,0x76,0x75,0x74,0x73,0x72,0x71,0x70, 
       0x6F,0x6E,0x6D,0x6C,0x6B,0x6A,0x69,0x68, 
       0x66,0x66,0x65,0x64,0x63,0x62,0x61,0x60, 
       0x5F,0x5E,0x5D,0x5C,0x5B,0x5A,0x59,0x58, 
       0x55,0x55,0x55,0x54,0x53,0x52,0x51,0x50, 
       0x4F,0x4E,0x4D,0x4C,0x4B,0x4A,0x49,0x48, 
       0x44,0x44,0x45,0x44,0x43,0x42,0x41,0x40, 
       0x40,0x41,0x42,0x43,0x44,0x45,0x46,0x47, 
       0x48,0x49,0x4A,0x4B,0x4C,0x4D,0x4E,0x4F, 
       0x50,0x51,0x52,0x53,0x55,0x55,0x56,0x57, 
       0x58,0x59,0x5A,0x5B,0x5C,0x5D,0x5E,0x5F, 
       0x60,0x61,0x62,0x63,0x66,0x65,0x66,0x67, 
       0x68,0x69,0x6A,0x6B,0x6C,0x6D,0x6E,0x6F, 
       0x70,0x71,0x72,0x73,0x77,0x75,0x76,0x77, 
       0x78,0x79,0x7A,0x7B,0x7C,0x7D,0x7E,0x7F}; 
// 
/******************************************************************************/ 
uint  data  THHL=65535;    //T1的16位定时器初值 
uchar data keyword,n=0;    //键值存放,查表指针 
bdata sinthr; 
sbit sin_thr=sinthr^0;  //正弦波\三角波标志(1为正弦波) 
sbit ww=key^7;          // 方波输出口 
// 
/*******************************键扫描子函数***********************************/ 
keysCAN() 
{ 
keyword=key&0x07; 
if(keyword!=0x07) 
 { 
 while((key&0x07)!=0x07);//等待键释放 
  switch(keyword) 
   { 
    case 6:{if(THHL>=65235)THHL=65535;else{THHL=THHL+255;}break;}// 
    case 5:{if(THHL<=500)THHL=0;else{THHL=THHL-255;}break;}// 
    case 3:{sin_thr=~sin_thr;break;}// 
    default:{break;}// 
   } 
 } 
 } 
// 
/***************************初始化函数****************************************/ 
clearmen() 
{ 
key=0xff,dataout=0x00;THHL=65535;//按键输入状态,波形输出为0 
TH1=THHL/256;TL1=THHL%256;//装定时初值（T1用） 
TMOD=0X11;ET1=1;TR1=1;EA=1;//16 位定时模式,T1中断允许,开定时器,开总中断 
} 
// 
/*********************************主函数***************************************/ 
main() 
{ 
clearmen(); 
while(1) 
 { 
  keyscan(); 
  } 
} 
// 
/***********************************T1中断函数**********************************/ 
void time_intt1(void) interrupt 3  
{ 
 EA=0;TR1=0;TH1=THHL/256;TL1=THHL%256;TR1=1; 
 if(sin_thr){dataout=sin_tab[n];} 
  else {dataout=thr_tab[n];} 
 if(n>=255){n=0;}else{ n++;} 
 ww=~ww; 
 EA=1; 
} 
// 
//***********************************结束****************************************//