Re: [PATCH] Use read_memory_unsigned_integer when reading to CORE_ADDR

[Daniel Jacobowitz <drow at mvista dot com>]

On Sun, Oct 06, 2002 at 02:52:57AM -0400, Klee Dienes wrote:
> Perhaps something along the lines of the following?
> 
> {
>   unsigned char buf[sizeof (CORE_ADDR)];
>   if (target_read_memory (memaddr, buf, TYPE_LENGTH 
> (builtin_type_void_data_ptr)) != 0)
> 	error ("Unable to determine lower bound of array.");
>   *lower_bound = extract_typed_address (buf, 
> builtin_type_void_data_ptr);
> }
> 
> That's a bit verbose, and it's not clear to me if sizeof (CORE_ADDR) is 
> guaranteed to be large enough to contain a raw target pointer, but I 
> can't really think of any better alternatives.

Might want to use alloca (TYPE_LENGTH (builtin_type_void_data_ptr)).

> Aside from the intimidating comments in findvar.c, this would seem a 
> good candidate for extract_address ... though a similar modification 
> would have to be made to it to handle the sign-extension as well.
> 
> Or alternately, I could just leave well-enough alone, and be careful to 
> truncate CORE_ADDRs to 32 bits in our target xfer_memory code (or the 
> MIPS code could sign-extend it in the same place).

Well, I think a general read_memory_typed_address (returning CORE_ADDR,
and honoroing POINTER_TO_ADDRESS) would be the way to go here.


> 
> On Saturday, October 5, 2002, at 10:57 PM, Daniel Jacobowitz wrote:
> >
> >Well, I'm a little concerned about this.  MIPS generally wants the
> >result to be sign extended; the MIPS 32-bit ABIs map onto the lowest
> >and highest 2G segments of the 64-bit address space, not the low 4G
> >segment.  Isn't there an appropriate function somewhere to read a 
> >CORE_ADDR?
> >
> >Answer: Yes, there is, but it has the same problem.  You're just
> >extending current practice, so I don't see a problem with your patch.
> >
> >Andrew, is my understanding right?  Is there some reason this isn't a
> >problem?
> 
> 

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer