HP 3000 Manuals

System Debug Reference Manual

func bitx 

Bit extract.  Extracts a range of bits from an expression.

Syntax 

      bitx (source position length)

Formal Declaration 

      bitx:any (source:any position:s16 length:u16)

Parameters 

source           The value from which to extract a range of bits.  Its
                 type is restricted to the INT and PTR classes.

position         This parameter specifies the starting bit position
                 (positive value), or the ending bit position (negative
                 value) of the extraction.  Regardless of the size of the
                 source value, bit positions are always numbered from
                 left to right.  The leftmost bit of the source is bit 0.

length           The number of bits to extract.

This function is sensitive to the type of the source parameter.  If a S32
or U32 value is passed, the format of the word (start/end positions) is
as follows:

                          1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +---------------------------------------------------------------+
     |                                                               |
     +---------------------------------------------------------------+

If a S16 or U16 value is passed, the format of the word (start/end
positions) is as follows:

                          1 1 1 1 1 1
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
     +-------------------------------+
     |                               |
     +-------------------------------+

Examples 

This is a 32-bit word containing the bit pattern for the hex value
4015381c:

                          1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +---------------------------------------------------------------+
     |0 1 0 0 0 0 0 0 0 0 0 1 0 1 0 1 0 0 1 1 1 0 0 0 0 0 0 1 1 1 0 0|
     +---------------------------------------------------------------+

     $nmdebug > var xx:u32 4015381c 
     $nmdebug > wl bitx(xx,#10,5) 
     $a

Extract five bits starting at position 10 (this yields the bit pattern
01010).

     $nmdebug > wl bitx(xx,-#14,5) 
     $a

Extract five bits ending at position 14 (this yields the bit pattern
01010).  This is the same field of bits as in the previous example.

Limitations, Restrictions 

If the specified bit range extends past the bounds of a 32-bit word, the
function is undefined and an error status is set.

MPE/iX 5.0 Documentation