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[M16C-dev] Pointer size in GCC


From: Grant Edwards
Subject: [M16C-dev] Pointer size in GCC
Date: Sun, 19 Oct 2003 21:53:03 -0500
User-agent: Mutt/1.4i

All the info I can find leads me to believe that all pointers
in GCC are the same size.  That means that an M16C port of GCC
would have to use one of two memory models:

 1) A single, 64KB space containing all text and data.
 
    I doubt this is going to be very useful for most
    applications. 

 2) A model where _all_ pointers are 32-bits.  

    This will result in lousy performance and bloated data
    structures.

IMO, the only practical solution would be to default to 24-bit
pointers for pointers to functions, and 16-bit pointers for
pointers to data.  This is assuming that most real-world M16C
applications have:

 1) Less that 64K of "data" (including peripheral registers).

 2) Code that isn't located in the bottom 64KB.

Ideally, one would allow for "far" pointers to data as well in
the case where one wants to use RAM that isn't in the "near"
area.

-- 
Grant Edwards
address@hidden




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