Paul Gilmartin <[email protected]> wrote:
> Me too. A comparison:
>
> Assembler H:
>
>
> PAGE 2
> LOC OBJECT CODE ADDR1 ADDR2 STMT SOURCE STATEMENT
> ASM H V 02 10.13 09/09/10
> 000000 1 NEGDISP CSECT
> FFFFF000 2 USING -4096,R1
> 000000 4132 1FFC FFFFFC 3 LA R3,-4(R2)
> 4 *
> 000004 0000 0000 00000 5 LA R3,-4(,R2)
> IEV034 *** ERROR *** ADDRESSABILITY ERROR
> 6 *
> 7 YREGS
>
> HLASM:
>
>
> Page 3
> Active Usings: None
> Loc Object Code Addr1 Addr2 Stmt Source Statement
> HLASM R6.0 2010/09/09 10.14
> 000000 00000 00008 1 NEGDISP CSECT
> R:1 FFF000 2 USING -4096,R1
> 000000 4132 1FFC FFFFFC 3 LA R3,-4(R2)
> 4 *
> 000004 4130 2FFC FFFFFC 5 LA R3,-4(,R2)
> 6 *
> 7 YREGS
>
> Tachyon:
>
>
> PAGE 5
> Active USINGs: None
>
> Loc Object Code Addr1 Addr2 Stmt Source Statement
> X390 2.3.05 2010/09/09 10.11
>
> 000000 00000 00008 1 NEGDISP CSECT
> 000000 2 USING -4096,R1
> ** TXA111E Operand 1 is invalid.
> ** TXA301I Record 2 in .m1/src_Rolltest/NEGDISP.s
> 000000 FFFFC 3 LA R3,-4(R2)
> ** TXA317E Addressability error in operand 2.
> ** TXA301I Record 3 in .m1/src_Rolltest/NEGDISP.s
> 4 *
> 000004 FFFFC 5 LA R3,-4(,R2)
> ** TXA316E Invalid displacement in operand 2.
> ** TXA301I Record 5 in .m1/src_Rolltest/NEGDISP.s
> 6 *
> 7 YREGS
>
> In my view, the only correct one is Assembler H.
>
> -- gil
>
And, to add to the list, here's what DASM generates:
DASM V1.85.05 2010/09/09 13:54
00000000 00000000 00000008 1 NEGDISP CSECT
2 USING -4096,R1
** DASM305E Operand 1 does not refer to location within reference control
section
** DASM435I Record 2 in negdisp.asm
00000000 0000 0000 00000000 3 LA R3,-4(R2)
** DASM028E Invalid displacement
** DASM435I Record 3 in negdisp.asm
00000004 0000 0000 00000000 4 LA R3,-4(,R2)
** DASM028E Invalid displacement
** DASM435I Record 4 in negdisp.asm
I wonder why HLASM allows the negative displacement?
The HLASM documentation (HLASM V1R6 Language Reference manual)
for an "Ordinary USING" indicates:
base
specifies a base address, which can be a relocatable
or an absolute expression. The value of the expression
must lie between 0 and 2**31-1.
and -4096 doesn't lie in that range...
Furthermore, this same document describes the valid
values used for displacements in an "Explicit Address"
(see page 85), where it says:
Explicit address:
An explicit address is specified by coding two absolute
expressions as follows:
* The first is an absolute expression for the
displacement, whose value must lie in the range 0
through 4095 (4095 is the maximum value that can be
represented by the 12 binary bits available for the
displacement in the object code), or in the range
-524,288 to 524,287 for long-displacement
instructions.
...
and, -4 is not in the range 0 through 4095.
Even if you assume the assembler is simply
wrapping-around and treating -4 as X'FFFFFFFC',
X'FFFFFFFC' is not in the range 0 through 4095
either.
So - I think an argument can be made that both
Tachyon and Dignus are correct in diagnosing
a displacement of '-4' as being invalid.
Or, perhaps, the HLASM documentation needs to
be updated?
- Dave Rivers -
--
[email protected] Work: (919) 676-0847
Get your mainframe programming tools at http://www.dignus.com
