Re: Assembly macro with parameters

[Fabrizio Fazzino <fabrizio@fazzino.it>]

After three months I still have the same problem...

Suppose I want to generate my own opcode, let's say 0xC4000000,
inside a C program. Suppose this value is NOT a constant in
the macro I want to write since it will contain three
variable fields for the rd,rs,rt registers, so I need to calculate
the opcode at least at compilation time (at runtime is NOT
required).

Daniel suggested using .word and writing the function by hand,
but which is the syntax I have to use?

#define myopcode(rs,rt,rd) { \
   int opcode_number = 0xC4000000 | (rs<<21) | (rt<<16) | (rd<<11); \
   char opcode_string[20]; \
   sprintf(opcode_string, ".word 0x%X", opcode_number); \
   asm(opcode_string); \
}

This doesn't work since "argument of 'asm' is not a constant string"...
Furthermore I do NOT have the possibility to link the string library
so I should find another solution.

Is there any common solution to write an instruction "completely
by hand" ?

Many thanks in advance,

	Fabrizio Fazzino



Daniel Jacobowitz wrote:
> On Fri, Apr 08, 2005 at 06:47:58PM +0200, Fabrizio Fazzino wrote:
> 
>>Ralf Baechle wrote:
>>
>>>Fabrizio Fazzino wrote:
>>>
>>>>It works, but I need a way to set the values of the parameters
>>>>at runtime; so I've tried the following macro:
>>>>
>>>>	#define fzmin(rd, rs, rt) asm("lwc1 $rt, rd<<11($rs)");
>>>
>>>Which will leave the assembler entirely unimpressed ;-)
>>
>>I thought that the compiler was able to substitute also the
>>values inside strings... Is there any way to force it to do so?
> 
> You should probably be using .word then, and generating the instruction
> completely by hand.
> 


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    Fabrizio Fazzino - fabrizio@fazzino.it
      Fazzino.IT - http://www.fazzino.it
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