How Can I add a 8bits offset for MIPS?

How Can I add a 8bits offset for MIPS?

[Liu]

hi all
MIPS have only 16bits offset, I need a 8bits offset now. How can I make it?
I know very few about bfd, please tell me more details, thanks.

-Liu

Re: How Can I add a 8bits offset for MIPS?

[Richard Sandiford]

Liu <proljc@gmail.com> writes:
> hi all
> MIPS have only 16bits offset, I need a 8bits offset now. How can I make it?
> I know very few about bfd, please tell me more details, thanks.

Support for Loongson 3A was recently added to binutils and some of
its instructions also need non-16-bit-offsets.  See:

#define OP_SH_OFFSET_A		6
#define OP_MASK_OFFSET_A	0xff
#define OP_SH_OFFSET_B		3
#define OP_MASK_OFFSET_B	0xff
#define OP_SH_OFFSET_C		6
#define OP_MASK_OFFSET_C	0x1ff

in include/opcode/mips.h, and the way they're handled in the rest
of the codebase.  OFFSET_A is an 8-bit offset in bits 6-13,
OFFSET_B is an 8-bit offset in bits 3-10.  The associated mips-opc.c
operand strings are "+a" and "+b".

If your offsets are in the same bit positions as either A or B,
then you could use them directly.  If not, you could add an
OFFSET_D (and "+d") along the same lines.

Richard

Re: How Can I add a 8bits offset for MIPS?

[Liu]

On Thursday, March 31, 2011, Richard Sandiford
<rdsandiford@googlemail.com> wrote:
> Liu <proljc@gmail.com> writes:
>> hi all
>> MIPS have only 16bits offset, I need a 8bits offset now. How can I make it?
>> I know very few about bfd, please tell me more details, thanks.
>
> Support for Loongson 3A was recently added to binutils and some of
> its instructions also need non-16-bit-offsets.  See:
>
> #define OP_SH_OFFSET_A          6
> #define OP_MASK_OFFSET_A        0xff
> #define OP_SH_OFFSET_B          3
> #define OP_MASK_OFFSET_B        0xff
> #define OP_SH_OFFSET_C          6
> #define OP_MASK_OFFSET_C        0x1ff
>
> in include/opcode/mips.h, and the way they're handled in the rest
> of the codebase.  OFFSET_A is an 8-bit offset in bits 6-13,
> OFFSET_B is an 8-bit offset in bits 3-10.  The associated mips-opc.c
> operand strings are "+a" and "+b".
>
> If your offsets are in the same bit positions as either A or B,
> then you could use them directly.  If not, you could add an
> OFFSET_D (and "+d") along the same lines.
>
> Richard
>

Thank you! Richard
I thought I need to modify BFD.
For now, I get that I need to ask MingJie Xing. He is a nice man, too.
thank you again Richard.

-Liu