Tag Archives: OR’ing

FT_ISBITON

Posted on by vivaclipper 
FT_ISBITON()
 Determine the state of individual bits in a number

 Syntax

      FT_ISBITON( <nNumber>, <nBit> ) -> lResult

 Arguments

     <nNumber> is an integer for which a bit state needs to be checked.

     <nBit> is a number from 0 to 15 that indicates which bit to test.

 Returns

     .T. if the specified bit was on., .F. if off.

 Description

     This function is useful when dealing with binary integers.  It will
     come in very handy if you use the FT_INT86() function, because the
     CPU flags are returned as a series of bits.  Using this function, you
     can determine the state of each CPU flag.

 Examples

     if FT_ISBITON( nCPUFlags, 0 )
        Qout( "The carry flag was set." )
     endif

     if FT_ISBITON( nCPUFlags, 7 )
        Qout( "The sign flag was set." )
     endif

 Source: ISBITON.PRG

 Author: Ted Means

 

FT_ISBIT

Posted on by vivaclipper 
FT_ISBIT()
 Test the status of an individual bit

 Syntax

      FT_ISBIT( <cByte>, <nBitPos> ) -> lResult

 Arguments

     <cByte> is a character from CHR(0) to CHR(255)

     <nBitPos> is a number from 0 to 7 conforming to standard right-to-left
               bit-numbering convention and representing the position of the
               bit within the byte.

 Returns

     .T. if designated bit is set (1), .F. if not set (0), NIL if
      invalid parameters.

 Description

     Tests for status of any selected bit in the byte passed as a parameter.
     Byte must be presented in CHR() form, as a literal constant, or as the
     one-byte character result of an expression.

     This function is presented to illustrate that bit-wise operations
     are possible with Clipper code.  For greater speed, write .C or
     .ASM versions and use the Clipper Extend system.

 Examples

     This code tests whether bit 3 is set in the byte represented by
     CHR(107):

      lBitflag := FT_ISBIT(CHR(107), 3)
      ? lBitflag                  // result: .T.

      This code tests whether bit 5 is set in the byte represented by ASCII
      65 (letter 'A')

      ? FT_ISBIT('A', 5)          // result: .F.

     For a demonstration of Clipper bit manipulations, compile and
     link the program BITTEST.PRG in the Nanforum Toolkit source code.

 Source: ISBIT.PRG

 Author: Forest Belt, Computer Diagnostic Services, Inc.

See Also: FT_BITSET() FT_BITCLR()

 

FT_BITSET

Posted on by vivaclipper 
FT_BITSET()
 Set selected bit in a byte

 Syntax

      FT_BITSET( <cByte>, <nBitPos> ) -> cByte

 Arguments

     <cByte> is a character from CHR(0) to CHR(255).

     <nBitPos> is a number from 0 to 7 conforming to standard right-to-left
     bit numbering convention and representing the position of the bit
     within the byte.

 Returns

     Returns new byte, with designated bit set.  If parameters are faulty,
     returns NIL.

 Description

     In effect, ORs argument byte with a byte that has only the target bit
     set.  If bit is already set, it remains set.
     Note: Calls FT_ISBIT() which is also in this Library.

     This function is presented to illustrate that bit-wise operations
     are possible with Clipper code.  For greater speed, write .C or
     .ASM versions and use the Clipper Extend system.

 Examples

     This code would set bit 4 in a byte represented by CHR(107):

          cNewbyte := FT_BITSET( CHR(107), 4 )
          ? ASC( cNewbyte )             // result: 123
          ? cNewbyte                    // result: '{'

     This code would set bit 5 in the byte represented by the letter 'A'.

          ? FT_BITSET( 'A', 5 )         // result: 'a'
                                        // bit 5 set

     For a demonstration of Clipper bit manipulations, compile and
     link the program BITTEST.PRG in the Nanforum Toolkit source code.

 Source: BITSET.PRG

 Author: Forest Belt, Computer Diagnostic Services, Inc.

See Also: FT_BITCLR() FT_ISBIT()