[Simh] Ferranti Pegasus Simulator

[Leo Broukhis]

Or, here is an implementation of 128-bit division:

Unsigned: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/builtins/
*udivmodti4*.c
Signed: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/builtins/
*divti3*.c
https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/builtins/*modti3*.c

Leo

On Fri, Jun 10, 2016 at 5:22 PM, Leo Broukhis <leob at mailcom.com> wrote:

> As a first step, you can try using https://gmplib.org/
>
> Leo
>
>
> On Sat, 11 Jun 2016 00:46:02 +0100, "Dave Wade" <dave.g4ugm at gmail.com>
> wrote:
>
>
>> Whilst its not a SIMH simulator, I hope you can help. I want to write an
>> emulator for the Pegasus. The Ferranti Pegasus was (there are none
>> operating
>> at present) a strange beast with two 18-bit instructions per 39-bit word.
>> Generally, it does 39-bit twos complement arithmetic. The multiply results
>> in a 77-bit result which I have no problems implementing.
>>
>> Where I am struggling is with the divide. I need to be able to divide a
>> 77-bit number by a 39-bit number and get a 39 bit quotient and a 39 bit
>> remainder. As the compiler I am using only does 64-bit numbers this is
>> proving challenging. Any one got a good article on how to do this?
>>
>> Dave Wade
>> G4UGM
>>
>
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