Hi.
While porting Realtek's 8196c code to OpenWrt,
I came up with a need for an inline asm macro that mimics
instructions that manipulate lexra's CP0 registers.
The instructions are
MFLXC0 reg,cp0reg
where cp0reg = 0 (ESTATUS), 1 (ECAUSE) or 2 (INTVEC),
to read ESTATUS, ECAUSE or INTVEC into reg, and
MTLXC0 reg,cp0reg
where cp0reg = 0 (ESTATUS) or 2 (INTVEC),
to write reg into ESTATUS or INTVEC.
For MFLXC0, the base opcode is 0x40600000, and the
reg and cp0reg are encoded as 0x40600000 | (reg << 16) | (cp0reg << 11).
For MTLXC0, the base opcode is 0x40e00000.
Let's say I want an inline macro that read the ECAUSE register.
I came up with the following.
#define read_lxc0_ecause() \
({ int __res; \
__asm__ __volatile__( \
".word 0x40600800 | (%0 << 16)\n\t" \
: "=r" (__res)); \
__res; \
})
If I just write "read_lxc0_ecause();", and assume $2 is
assigned to %0 by gcc, then I have
#APP
.word 0x40600800 | ($2 << 16)
#NOAPP
sw $2,8($fp)
which clearly will not survive through an as stage.
I would want
.word 0x40600800 | (2 << 16)
instead of
.word 0x40600800 | ($2 << 16)
Is there anyway to convert the assigned $2 into 2
(or equivalent integer constant) before it is pass to the as stage?
Any help would be appreciated, including a pointer to proper ML
that this question should be redirected to.
Thanks in advance.
--- shinoda
_______________________________________________
openwrt-devel mailing list
openwrt-devel@lists.openwrt.org
https://lists.openwrt.org/mailman/listinfo/openwrt-devel
