Not so stuck anymore...

[Gabriel]

hi all...

I have these 3 functions which depend on each other.
I have a long data string coming to my pic through a gsm module
(SE T290A).
I got communication with the module done, previous to these functions.

My programs works fine until this point.

The problem is that when I give the command to receive a text message,
I get a pretty long string, that varies in size.

This string contains miscellaneous data, phone#, date, time, actual text msg, etc.

M pic is supposed to find the "actual text message", which is a command
I send via sms, as in, a sms I type on another phone.... pretty basic concept... I'm sure you guys know the drill.

Below is an example of received text msg.

[Ttelmah]

Several comments.

First strstr, looks for a string, in a string. As in your previous question, a _string_, needs to be 'null terminated'. There is no guarantee that your circular buffer, will contain a null termination (there is nothing to put this there), so the strstr function, will end up searching through the whole of memory, if it does not find a match....
You need to declare your buffer one character larger than you use (so if the buffer is 69 charcaters, declare a 70 character buffer space), and then load the extra character with a 'null' character, so strstr, will find this and stop searching.

Then, strstr, is going to take quite a long time, if the buffer is large. Why not 'break' out, from your test sequence, as soon as a match is found?.

Then, strstr, does not return true/false. It returns the location in the first string, where the second is found. Your tests need to bear this in mind.

Now, you are doing a lot of repeated work, that is unnecessary, searching the whole buffer, for the entire sequence. Instead simplify your searching. Effectively, search through the buffer, till 'L' is found. Then from this location, see if you have the next two characters 'ed'. If so, then look just in the next three characters, for '1 0' etc.. The actual amount of processing time being spent searching the entire buffer, will be enormous....

Best Wishes

[Gabriel]

hi Ttelmah

This is my first attempt at using strstr...i guess it shows hahah
I was under the impression that strstr returned a null character if the string was not found... i build my function to work based on this...
I guess i was wrong.... in anycase this was a last desperate attempt..

Just trying to get a "shorter" way of doing this... if you can believe that hahah

My buffer size is 70... thus my ISR loops at 69...i get this...


I tried doing it this way since i dont really know a SHORT way of finding continuos characters in a buffer... exept with ifs...

The more continuos characters.. the more ifs.... and it doesent really solve much of my problem if my commands are not exactly the same size and have alot of repeated letters.... so i think....


got any suggestions?

any sort of help is much apreciated
_________________
CCS PCM 5.078 & CCS PCH 5.093

[Gabriel]

forgot to mention....

Time is not really an issue in my situation...for my circuit that is.

I got 2 or 3 seconds to spare....even 5

g
_________________
CCS PCM 5.078 & CCS PCH 5.093

[Ttelmah]

Lets start with the simplest bit. Have you added the null terminator to the input buffer?. This is the 'killer' for the code at present. Without it, the search will walk through memory, till it either hits a '0' there by accident, or finds the string you are searching for. Remember that your search string, is itself in memory (you have copied it there, to do the search), so without the terminator, the 'odds' are that all the tests will always return a non zero value....

Now, you can save a lot of work, by not searching the whole lot every time.
Simply 'walk' through the buffer yourself, looking for the letter 'L'.
Then check if the rest of the message is present, using strncmp, from this location.
The advantage here is that you don't have to keep going through the whole buffer each time.

Alternatively, and better really, forget about searching the buffer at all. Use a state machine, on the incoming data.
Start in 'state0'. In this, check for a '*', and when it is seen, advance to state1.
In state1, check for the letter 'L'. If it is seen, advance to state2.
In state2, check for 'e'. If it is seen, advance to state3, if not, go back to state1, and check again.
In state3, check for 'd'. If it is seen, advance to state4. If not, go back to state1, and try again.

Similarly, then look for 1,2,3 & 4, then for the space, and finally the 0 or 1.
There only needs to be seven tests, and on any individual character, there will normally only be a single test used....

Best Wishes

[Gabriel]

hi

[Ttelmah]

You need to learn more C.
In C, the _name_ of an array, is a shortcut notation, for the pointer to the first element. Strncmp, can be used to compare 'n' characters from anywhere in two arrays, by just giving it the required pointers and count.
All the string functions, have source code available to you. Also they are described in any C book.
The first line of the 'help' parameters sectio, tells you everything:

"s1 and s2 are pointers to an array of characters (or the name of an array)."

Since the search functions return pointers, you can use the value returned as the point you want to search _from_.

Best Wishes

[mkuang]

I think this:

[Gabriel]

so...

i got it working... pretty neatly i think... im still open for suggestions.
it can be optimized i think...and would love to hear your thoughts

[PCM programmer]

[Gabriel]

Mkuang:

I'm using "LED1 1" means LED#1 ON...
and "LED1 0" means LED#1 OFF...

g
_________________
CCS PCM 5.078 & CCS PCH 5.093

[Gabriel]

I have to send via rs232 the following command

[PCM programmer]

[Gabriel]

PCM programmer

nice tutorial..

like it. thank you

g
_________________
CCS PCM 5.078 & CCS PCH 5.093