Калькулятор на МК

#define LCD_CMD_WR     0x0000
#define LCD_DATA_WR    0x0100
#define LCD_BUSY_RD    0x0200
#define LCD_DATA_RD    0x0300
 
#define E_PIN_MASK     0x0400
                     
//LCD Commands        
#define LCD_CLS        0x01
#define LCD_HOME       0x02
#define LCD_SETMODE    0x04
#define LCD_SETVISIBLE 0x08
#define LCD_SHIFT      0x10
#define LCD_SETFUNCTION    0x20
#define LCD_SETCGADDR      0x40
#define LCD_SETDDADDR      0x80
 
 
#define G_MASK  0x78000000
#define G_SHIFT 27

void init_system()
 { MEMMAP = 1;
   SCS_bit.GPIO0M = 0; 
   PINSEL0 = 0;
   PINSEL1 = 0; 
   IODIR =  0xFF07FF; 
   IOCLR = 0xFFFFFFFF;
 }

...
for (row=0; row < KEYP_NUM_ROWS; row++)
    { // Drive appropriate row low and read columns:
 
      IOSET = (~(1 << row)) & 0xFF;
      IOCLR = (1 << row) & 0xFF;
      for (wait=0; wait<10; ++wait)
         nop();
      tmp = (IOPIN & G_MASK) >> G_SHIFT;
    
      // See if any column is active (low):
      for (col=0; col<KEYP_NUM_COLS; ++col)
         if ((tmp & (1<<col)) == 0)
          { idx = (row*KEYP_NUM_COLS) + col;
            key = keycodes[idx]; 
 
            IOSET = idx << 16;
 
            IOCLR = (~(idx <<16)) & 0xFF0000;
            goto DONE;
          }
    }
   DONE:
 
   // Disable Port Drive and return.
 
   IODIR =  0xFF0700;
   return key;

void wrdata (BYTE data)
// Write a Character to the LCD Display. 
 { IODIR =  0xFF07FF;
   IOCLR = (~(LCD_DATA_WR | data)) & 0x7FF;
   IOSET = LCD_DATA_WR | data;
    
   // Toggle Pin 'E' to send the command.
   IOSET = E_PIN_MASK;
   nop(); 
   nop();
   nop();
   nop();
   IOCLR = E_PIN_MASK;
   
   lcd_wait();
 }