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From: Paul Koning <paulkoning@comcast.net>
To: joel@rtems.org
Cc: ElijaxApps <elijaxapps@gmail.com>, Newlib <newlib@sourceware.org>
Subject: Re: Help porting newlib to a new CPU architecture (sorta)
Date: Tue, 6 Jul 2021 19:50:00 -0400	[thread overview]
Message-ID: <9F9C0A22-1CCA-47F8-8C19-F44ED4B47A8F@comcast.net> (raw)
In-Reply-To: <CAF9ehCXPuRAr7yj9fZsLbZ2uHOZFUuVLvCYQVfftrZB+h7WiMQ@mail.gmail.com>



> On Jul 6, 2021, at 6:00 PM, Joel Sherrill <joel@rtems.org> wrote:
> 
> I think you might get some ideas from the old m6809 port of gcc
> 
> http://vectrexc.malban.de/documentation/gcc-6809-documentation
> 
> That was an 8 bit CPU with only 64k memory space if I remember everything
> correctly.

pdp11 also has 64k of address space, and the current gcc still supports it.

> I think given an add with carry, gcc can be taught to use 8 bit operations
> in sequence on larger types. I recall seeing this on the h8 or avr.

pdp11 also, for 32 or 64 bit integers given 16 bit arithmetic.  You don't actually need add with carry, but having one makes the code more compact.  I think gcc core will do that flavor if the target code doesn't teach it the more efficient way (which is easy to do).

	paul


  reply	other threads:[~2021-07-06 23:50 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-06 21:08 ElijaxApps
2021-07-06 22:00 ` Joel Sherrill
2021-07-06 23:50   ` Paul Koning [this message]
2021-07-07  0:29     ` ElijaxApps
2021-07-07 15:09   ` Grant Edwards
  -- strict thread matches above, loose matches on Subject: below --
2021-07-06  0:49 ElijaxApps
2021-07-06  4:35 ` Mike Frysinger
2021-07-06 13:05   ` Paul Koning
2021-07-07 20:32     ` ElijaxApps
2021-07-07 20:56       ` Orlando Arias
2021-07-06 14:02   ` Brian Inglis
2021-07-06 14:35     ` Orlando Arias
2021-07-06 18:08       ` Brian Inglis
2021-07-06 19:04         ` Orlando Arias
2021-07-06 20:01           ` Hans-Bernhard Bröker
2021-07-06 20:46             ` Orlando Arias
2021-07-07  5:45               ` Brian Inglis
2021-07-07 13:58                 ` Orlando Arias
2021-07-07 15:18                   ` Dave Nadler
2021-07-07 18:43               ` Hans-Bernhard Bröker
2021-07-07 20:23                 ` Orlando Arias

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