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MACHINE CODE ROUTINES GALORE!
BY MICHAEL NICHOLAS
Machine routines can be very useful where complex and lengthy
operations are required. The SAM has a superb basic, but is
limited to some extent by the speed at which routines are
executed. A Machine code routine can be over 8000 times quicker
than the same routine done in basic.
Now and again over the past few years, I have attempted to
program some routines in machine code, but haven't got many of
them to work, mainly because I havn't set the correct paremeters
and conditions for the routines to work in.
Here are some simple, yet useful routines which I have done in
the past few months.
Some detailed source is included, to show how they work and to
show you how simple they are.
The machine code routines have basic drivers to accompany them
and they are called by using the DEFined PROCedures. The defined
procedures can be merged into your programs.
CAPITALISING A STRING OR AN AREA IN MEMORY
COMMAND: CAP 0 : CAPITALISES THE STRING CALLED "SUBJECT$"
:
OR: CAP 1,MEMORY LOCATION,LENGTH OF AREA TO CAPIALISE
EXPLANATION
The "CAP" command can work in two modes, the first mode
capitalises the string SUBJECT$, this string should be filled
with the sentences/words you wish to put into upper case. The
"SUBJECT$"string musn't be more than 31000 bytes long, otherwise
the routine won't operate.
The second mode capitalises an area in memory which is specified
by you. The LOCATION can be anywhere you like and the characters
from this memory location are all put into uppercase. The
amount/LENGTH of memory you want to capitalise is determined by
you and can be upto 31000 bytes.
APPLICATIONS
Could be useful when searching memory for a word. The INSTR
command searches memory for a word specified by you, inside
another string, but the command only gives a result if the word
is exactly the same as the one it is looking for. i.e upper case
and lower case letters must be the same etc. If you capitalised
the string first then you wouldn't have this problem and so,
therefore, have a more successful search.
UNCAPITALISING A STRING OR AN AREA OF MEMORY
COMMAND: UNCAP 0 : Uncapitalises the string "SUBJECT$"
:
OR: UNCAP 1,MEMORY LOCATION,LENGTH OF AREA TO UNCAPITALISE
EXPLANATION
Works the same way as the CAP command, the applications are much
the same.
COUNTING THE WORDS IN A STRING OR AN AREA OF MEMORY
COMMAND: COUNT 0 : Counts the number of words in "SUBJECT$"
:
OR: COUNT 1,MEMORY LOCATION, LENGTH OF AREA TO COUNT
EXPLANATION
This little routine has it's own word counter and each time the
routine detects a space/character 32 and then a different
character, it adds one to it's counter.
At the end of the routine the defined procedure reads the
machine codes counter and gives the result in the variable
called "RESULT".
Again this routine has two modes of operation and that's either
searching the string "SUBJECT$" (MODE 0) or an area of memory
(MODE 1).
APPLICATIONS
Have you ever had to write an essay for school and it's said
something like 500 words minimum, well this routine could save
you from counting each and every word. I'm sure there are lots
of other applications but this routine was made specifically for
a word processor.
LAST CHARACTER IN A STRING OR AN AREA IN MEMORY
COMMAND: LAST 0 ( you guessed it!)
:
OR: LAST 1,MEMORY LOCATION,LENGTH OF MEMORY TO SEARCH
EXPLANATION
This routine is probably the fastest out of all the routines I
have written. It tells you the LAST character it detected during
the search through the whole area of memory or string contents
you specified.
It treats everything as a character except character 32.
The result is given in the variable "RESULT" when the routine
has finished it's search.
APPLICATIONS
Could prove useful where you have a word processor and you need
to know the last line to print or the number of pages to print.
NOTES:
Don't forget to type in LOADMC before using the routines. This
defined procedure puts the machine code routines into the memory
location PAGE*16384 - PAGE being a variable in LOAMDMC. You can
alter PAGE to your requirements if you wish, though make sure
you don't overwrite any ROM,RAM,SCREEN,DOS,MDOS,MBASIC pages.
The SAM basic command called LENGTH could prove very useful when
using these routines. It finds the location of a string in the
memory and can tell you the length of the entire string. The
USER manual doesn't explain this command very well so I shall
explain:
PRINT LENGTH (0,string$() : Where string$ is in the memory.
PRINT LENGTH (2,string$() : The length of the second part of
the dimenstion of STRING$.
PRINT LENGTH (1,string$) : The length of the first part of the
dimension of STRING$.
EXAMPLES:
Using length with the CAP command:
LET A$="hELLo evEryBOdY"
LET A=LENGTH (0,A$) ; FIND LOCATION
LET B=LENGTH (1,A$) ; FIND DIMENSIONS
LET C=LENGTH (2,A$) ;
CAP 1,A,(B*C) ; CAPITALISE
NB: USING LENGTH SAVES YOU FROM CREATING ANOTHER STRING
EXAMPLE2: Same as above example but without using LENGTH
This is more memory wasteful because another string
called SUBJECT$ is created.
LET A$="heLLo evEryBOdY" ; get the string you want
LET SUBJECT$=A$ ; Put it into SUBJECT$
CAP 0 ; Capitalise SUBJECT$
LET A$=SUBJECT$ ; Put capitalised version
of A$ back into A$.
Thats yer lot, I hope some other people can contribute to this
area in SAM programming. Who needs to buy uttilities when you
can make programs and tailor them to your own requirements!
----------------------------------------------------------------
THE WORM by John McCabe
A variation on the "CENTIPEDE" game, showing just how fast Sam
BASIC can run. I particularly like the way the worm turns in a
circle and not in the normal right angled way. Full instructions
are given in the program.
----------------------------------------------------------------
INVESTIGATIONS by Ron Fox
An unusual article with examples, on how a computer can be used
for problem solving. If anyone else has delved into this area of
computing I'm sure that both Ron and the mag would like to hear
from you.
----------------------------------------------------------------
CROSSWORD by D.A.Lorner
These are becoming a regular feature of the mag. This is no
easier than previous ones published, but it gave me an hour or 2
of pleasure. I like the option of having the answers built in.
which saves having to wait a month to find out if you were
right!!
----------------------------------------------------------------
D.T.P. FONT by Dave Ison
Dave has used the font designer published in Format and modified
to run on the Sam, to create a new headliner font for P.C.G's
D.T.P. package, and very nice it is too.
----------------------------------------------------------------
DIZZY MAPS by Bob Evans
This month there are no pokes or tips in Bobs section. This is
because I thought that I would let you see all the hard work
that Bob has put into mapping out the Dizzy games. I should
think that every Dizzy game ever produced is included.
----------------------------------------------------------------
DISC CHECK by Keith Pirie
This one only works with masterbasic installed, but it is well
worth it. It gives you an instant view of the current state of
your discs, and is very easy to use.
----------------------------------------------------------------
PRIMES by Mike Haine
Another unusual program which deals with prime numbers and their
frquency of occurence.
There is a nice program which shows graphically the differing
ressults given for different groups of numbers.
BLACKJACK by Gordon Henderson
A good version of PONTOON, which uses a nice set of cards and
plays well.
Gordon told me that there was a bug that occasionally gave the
same card twice, and he couldn't cure it. I think that I may
have done, but if after playing you still find it there, both
Gordon and I would like to hear from you with solutions.
What I did was to put the card count variable into the card
printing routine. This means that every time a card is dealt to
either you or the computer, the card count is updated. I think
this has cured the bug, but I may be wrong.
----------------------------------------------------------------
GALLERY by Noel Hathorn
An unusal gallery this issue, in as much as all the pictures
were done by the same person. I thought that they were 16 bit
"ports", but I am assured that Noel did them all from scratch.
----------------------------------------------------------------
MUSIC by John Hutchings
John has been playing with the sound machine, and come up with
these well known tunes (well all except number 2 which I
couldn't name).
They are stored on the disc in a compressed form so to use them
do the following:-
1) Load the tune from the menu
2) Press ESC and then "STOPM" plus return
3) Save the full code with SAVE "name" CODE 81920,49352
This will give you a standard Sound Machine file.
----------------------------------------------------------------
CONVERT by M.Nicholas
This is one of those programs that you think you will never use,
until you use it. It converts just about any imperial measure
into metric and vice versa.
It's menu driven and very quick and easy to use.
----------------------------------------------------------------
LEAPING LETTERS by Robin Smith
A couple of DEF PROCs to allow you to add the little extra to
your programs. It puts your message onto the screen either by
shooting the characters up the screen or dropping them down.
Use them as follows:-
LEAP X,Y,X1,A$
X AND Y ARE THE START POSITIONS OF YOUR MESSAGE IN PRINT
POSITIONS. X CAN BE UP TO 20, Y 0 TO 31
X1 IS THE ROW THAT YOU WANT YOUR MESSAGE TO FINISH ON
A$ IS YOUR MESSAGE
E.G. If you wanted the message "Hello Everyone" to come from
line 18 starting at position 3 along and end up on line 4 you
would put:-
LEAP 18,3,4,"Hello Everyone"
The PROC FALL works in the same way except that x1 will be lower
that x, because the message falls down the screen.
If the string is longer than the screen, it will automatically
be wrapped around to the start of the next line.
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