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Re: Harvard architecture with 24 bit data bytes and 32 bit code bytes
- From: Joel Sherrill <joel dot sherrill at oarcorp dot com>
- To: Ned <Thomas dot Gill at csr dot com>
- Cc: "binutils at sourceware dot org" <binutils at sourceware dot org>
- Date: Wed, 27 Feb 2008 10:56:19 -0600
- Subject: Re: Harvard architecture with 24 bit data bytes and 32 bit code bytes
- References: <op.t66zf1jj34duuh@tg01pc02.europe.root.pri>
Ned wrote:
Hi there,
I'm beginning to hack a binutils port for our in-house DSP core. It's a
Harvard architecture, with different sized bytes in instruction and data
memory. Instruction memory has a smallest addressable unit of 32 bits,
while data memory has a smallest addressable unit of 24 bits.
Does anyone on the list know whether this is going to cause me a lot of
pain? Has anyone had to deal with this problem before?
I'm guessing my first problem will be that there's only one
OCTETS_PER_BYTE. I'll presumably have to look at the places where that's
used and add code to guess whether it should be using 3 or 4. Is there
likely to be anything else that trips me up? Any corner cases I should
watch out for?
The tic4x was only 32-bit word addressable. The binutils
port may be rusty but it is something to look at. It is certainly
possible other places may have assumptions that have crept in.
Thanks,
Ned.
--
Joel Sherrill, Ph.D. Director of Research & Development
joel.sherrill@OARcorp.com On-Line Applications Research
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