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 Post subject: Some questions on MUMPS V1
PostPosted: Thu Nov 01, 2012 3:00 pm 
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Joined: Mon Nov 01, 2010 3:33 pm
Posts: 104
Location: Australia
Real Name: Ray Newman
Began Programming in MUMPS: 01 Jul 1976
I have been asked the following by Peter Otis.

Have few questions regarding some enhancement to MV1:

1. Long Variable / Tag / Routine / Global names:

In a earlier discussion you mention that to implement it would be a complete rewrite. If we would find a skilled C programmer would you provide hints to help him to do the work?

2. Multiple database file mounted
Are they any implication that would make it difficult to implement it?

3. Did you try to compile your MV1 on Android? Any intention to to it?


1. Problems with changing the size of Variable / Tag / Routine / Global names

The size is currently NOT a counted size, it is fixed at 8 and zero filled.

These are described as a var_u as:
typedef union __attribute__ ((__packed__)) VAR_U // get at this two ways
{ chr_q var_qu; // variable name (quadword)
u_char var_cu[8]; // variable name (as char[])
} var_u; // variable name union

They are accessed both as a quad word and as a character string.

The size is hardcoded as 8 in many places (loops, bcopy etc).

Other structures which include a name, put the name first and rely on a fixed size.

Tables of names rely on fixed size to index directly.

Because of these problems, I feel that increasing the size is basically a
re-write of at least half the system. Although I would provide assistance,
I would also keep the current version alive as I believe the bugs introduced
would be legion. Besides, I see no purpose to longer names.

2. Multiple database files mounted

This should be just a matter of adding the code to mount files as the run time
code is all there. Again, I haven't done it as I don't have a use for it.
I would prefer to add DDP but network and security programming can get a bit

3. Did you try to compile your MV1 on Android?

I haven't tried as I don't have an Android device. I will try eventually.
It should work as it works fine on the Raspberry Pi which is linux on ARM as
Android is. Again, why would one want MUMPS on a phone/tablet; I always thought of it as a server language. (Yes, the Pi is a *small* server).

Ray Newman

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