lib_bits.h

st7 单片机模拟I2C软件包 对没有I2C总线的单片机需要I2C功能非常有用

/************************* (c) 2003  STMicroelectronics ***********************

PROJECT  : EVALUATION BOARD - ST7
COMPILERS : COSMIC AND METROWERKS 
MODULE  :  lib_bits.h
REVISION DATE : 12/06/03
AUTHOR : Micro Controller Division Application Team      

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    THE SOFTWARE INCLUDED IN THIS FILE IS FOR GUIDANCE ONLY. STMicroelectronics 
    SHALL NOT BE HELD LIABLE FOR ANY DIRECT, INDIRECT OR CONSEQUENTIAL 
    DAMAGES WITH RESPECT TO ANY CLAIMS ARISING FROM USE OF THIS SOFTWARE.

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DESCRIPTION : Bit handling macro command.

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PUBLIC MACROS :

  SetBit, ClrBit  - set/clear a selected bit in a byte variable.
  ChgBit          - invert the selected bit value (0->1 or 1->0).
  AffBit          - set with a chosen value a selected bit in a byte variable.
  MskBit          - select some bits in a byte variable and copy them in
                    another byte variable.
  ValBit          - return the logic value of a selected bit in a byte
                    variable.

  BitSet, BitClr  - set/clear a defined bit in the hardware register map.
  BitVal          - return the logic value of a defined bit.

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MODIFICATIONS :

  26/03/98 - V2.0 - Update for the ST72251.

******************************************************************************/

/* PREPROCESSING SYSTEM DECLARATIONS *****************************************/
/* MODEL => #define system_define value                                      */
#ifndef LIB_BITS_H
#define LIB_BITS_H

/* MACRO FUNCTION DECLARATIONS ***********************************************/
/* MODEL => #define macro_name macro                                         */

/*-----------------------------------------------------------------------------
Method : I
Description : Handle the bit from the character variables. 
Comments :    The different parameters of commands are
              - VAR : Name of the character variable where the bit is located.
              - Place : Bit position in the variable (7 6 5 4 3 2 1 0)
              - Value : Can be 0 (reset bit) or not 0 (set bit)
              The "MskBit" command allows to select some bits in a source
              variables and copy it in a destination var (return the value).
              The "ValBit" command returns the value of a bit in a char 
              variable: the bit is reseted if it returns 0 else the bit is set.
              This method generates not an optimised code yet.
-----------------------------------------------------------------------------*/ 
#define SetBit(VAR,Place)         ( VAR |= (1<<Place) )
#define ClrBit(VAR,Place)         ( VAR &= ((1<<Place)^255) )
#define ChgBit(VAR,Place)         ( VAR ^= (1<<Place) )
#define AffBit(VAR,Place,Value)   ((Value) ? \
                                   (VAR |= (1<<Place)) : \
                                   (VAR &= ((1<<Place)^255)))
#define MskBit(Dest,Msk,Src)      ( Dest = (Msk & Src) | ((~Msk) & Dest) )
#define ValBit(VAR,Place)         (VAR & (1<<Place))

/*-----------------------------------------------------------------------------
Method : II
Description : Handle directly the bit. 
Comments :    The idea is to handle directly with the bit name. For that, it is
              necessary to have RAM area descriptions (example: HW register...)
              and the following command line for each area.
              This method generates the most optimized code.
-----------------------------------------------------------------------------*/
#define AREA 0x00     /* The area of bits begins at address 0x10. */                   
#define BitClr(BIT)  ( *((unsigned char *) (AREA+BIT/8)) &= (~(1<<(7-BIT%8))) )
#define BitSet(BIT)  ( *((unsigned char *) (AREA+BIT/8)) |=   (1<<(7-BIT%8))  )
#define BitVal(BIT)  ( *((unsigned char *) (AREA+BIT/8)) & (1<<(7-BIT%8)) ) 

#endif

/************** (c) 2003  STMicroelectronics ***************** END OF FILE ***/