NIBHEX 411
*                         REVBIT$ entry point
REVBIT  CD1EX             
        D1=C              
        R0=C              string header
        GOSBVL #0BD38 =POP1S 
        C=0    W          
        C=A    A          nib length of string
        CSRB              byte length
        D=C    A          byte counter
r500C7  D=D-1  A          decrement
        GOC    r500E8     last byte done if D[A]=0
***********************************************
* This is the heart of REVBIT$ - reverses the bit order
        P=     7          
        A=DAT1 B          get the byte
r500D1  A=A+A  X          shift the bit to least significant position of A[XS]
        C=A    XS         move to C[XS]
        CSRB              and shift it to C[B] most significant bit
        P=P-1             do it once for each bit and C[B] is in reverse order
        GONC   r500D1     next bit unless carry
        DAT1=C B          - store the reversed byte, we are done with this one
        D1=D1+ 2          advance to next byte
        GONC   r500C7     and go reverse it
r500E8  C=R0              get header address
        D1=C              
        P=     0          
        GOVLNG #0F23C     =EXPR