bits2.lst

Embedded C 这本书的范例光碟程式

C51 COMPILER V6.21  BITS2                                                                  01/23/2002 17:16:48 PAGE 1   


C51 COMPILER V6.21, COMPILATION OF MODULE BITS2
OBJECT MODULE PLACED IN bits2.OBJ
COMPILER INVOKED BY: C:\KEIL\C51\BIN\C51.EXE bits2.c BROWSE DEBUG OBJECTEXTEND

stmt level    source

   1          /*------------------------------------------------------------------*-
   2          
   3             Bits2.C (v1.00)
   4          
   5            ------------------------------------------------------------------
   6          
   7             Reading and writing individual port pins.
   8          
   9             NOTE: Both pins on the same port
  10          
  11             --- Generic version ---
  12          
  13             COPYRIGHT
  14             ---------
  15          
  16             This code is associated with the book:
  17          
  18             EMBEDDED C by Michael J. Pont 
  19             [Pearson Education, 2002: ISBN: 0-201-79523-X].
  20          
  21             This code is copyright (c) 2001 by Michael J. Pont.
  22           
  23             See book for copyright details and other information.
  24          
  25          -*------------------------------------------------------------------*/
  26          
  27          #include <reg52.H>  
  28          
  29          // Function prototypes
  30          void Write_Bit_P1(const unsigned char, const bit);
  31          bit Read_Bit_P1(const unsigned char);
  32          
  33          /* ............................................................... */
  34          
  35          void main (void)
  36             {
  37   1         bit x;
  38   1         
  39   1         while(1) 
  40   1           {
  41   2           x = Read_Bit_P1(0);   // Read Port 1, Pin 0
  42   2           Write_Bit_P1(1,x);    // Write to Port 1, Pin 1
  43   2           }
  44   1         }
  45          
  46          /* --------------------------------------------------------------- */
  47          
  48          void Write_Bit_P1(const unsigned char PIN, const bit VALUE)
  49             {
  50   1         unsigned char p = 0x01;  // 00000001
  51   1      
  52   1         // Left shift appropriate number of places
  53   1         p <<= PIN;  
  54   1         
  55   1         // If we want 1 output at this pin
C51 COMPILER V6.21  BITS2                                                                  01/23/2002 17:16:48 PAGE 2   

  56   1         if (VALUE == 1)
  57   1            {
  58   2            P1 |= p;  // Bitwise OR
  59   2            return;
  60   2            }
  61   1         
  62   1         // If we want 0 output at this pin
  63   1         p = ~p;  // Complement
  64   1         P1 &= p; // Bitwise AND  
  65   1         }
  66          
  67          /* --------------------------------------------------------------- */
  68          
  69          bit Read_Bit_P1(const unsigned char PIN)
  70             {
  71   1         unsigned char p = 0x01;  // 00000001
  72   1      
  73   1         // Left shift appropriate number of places
  74   1         p <<= PIN;  
  75   1         
  76   1         // Write a 1 to the pin (to set up for reading)
  77   1         Write_Bit_P1(PIN, 1);
  78   1      
  79   1         // Read the pin (bitwise AND) and return
  80   1         return (P1 & p); 
  81   1         }
  82          
  83          /*------------------------------------------------------------------*-
  84            ---- END OF FILE -------------------------------------------------
  85          -*------------------------------------------------------------------*/


MODULE INFORMATION:   STATIC OVERLAYABLE
   CODE SIZE        =     68    ----
   CONSTANT SIZE    =   ----    ----
   XDATA SIZE       =   ----    ----
   PDATA SIZE       =   ----    ----
   DATA SIZE        =   ----    ----
   IDATA SIZE       =   ----    ----
   BIT SIZE         =   ----       2
END OF MODULE INFORMATION.


C51 COMPILATION COMPLETE.  0 WARNING(S),  0 ERROR(S)