Hi, I am create bit manipulation macros on 32bit registers, and
assumed that I could use local variables and operators like this:

ld    macro    adr, bit                   ; Load
      local   y = bit / 8			;
            btfsc	adr+y,bit-(8*y)	; If Low skip
            bsf        STACK,0		; Else SET TOS
      endm

My reasoning being if I say:

      ld    clk,7

the macro will produce:

      y = 7 / 8
      btfsc    clk + 0, 7 - (8 * 0)

and if I say:

      ld    INP,14

the macro will produce:

      y = 14 / 8
      btfsc    clk + 1, 14 - (8 * 1)

and :

       ld    clk,10
       ld    clk+1,2

should give identical results

When I use it I get no errors but the OBJ code is incorrect as per
this partial listing:

                       00003         ld      clk,10
  0002                    M         local   y = 10  / 8         ;
007E   1845           M             btfsc   clk+y,10-(8*y)  ; If Low skip
007F   143F           M             bsf     STACK,0         ; Else SET TOS
                      00004         ld      clk+1,2
  0000                    M         local   y = 2   / 8         ;
0080   1944            M             btfsc   clk+1+y,2-(8*y) ; If Low skip
0081   143F            M             bsf     STACK,0         ; Else SET TOS

the first opcode is 0x1845 the second 0x1944, clearly not the same
instruction on the same address.


I have spent hours in the the MPLAB IDE Help file and am finding it
confuses me even more :)

and suggestions, a pointer to a macro tutorial?
or a hint as to how to address bits in multi-byte registers.

Thanks
Chris
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