Stuck on difficult string conversion (C inside) to integer problem

[Pigi_102]

Stucked on studid string conversion ( C inside )

Hi all,
I'm facing a stupid problem on converting from string to integer.


I have a string ( like "123" ) and need to interpreter his value, char by char reading backword and looking up his display value in an array ( to lit a 7 segment display by using a 4094 driver.

I already have a code working in C on my linux machine, and a working code for a really old Pic C compiler, but translating in CCS it does not work.

Here some snippet:

char digit[10]=
{
0b01111110,   // 0
0b00010010,   // 1
0b10111100,   // 2
0b10110110,   // 3
0b11010010,   // 4
0b11100110,   // 5
0b11001110,   // 6
0b00110010,   // 7
0b11111110,   // 8
0b11110010    // 9
} ;

void display(char * content, int howmany){

char Bytem;
char p[2];

    while ( (howmany+1) > 0 ) {                         // for every byte in buffer
           p[0] = content[howmany--];                    // read from last char in string backword 
           p[1] = '\0';
           Bytem = digit[atoi(p)];  
/* here the 4094 routine */
   }

void main () {
   while ( 1 )
     display ( "123", 3);
     display ( "456", 3);
// and so on
   } 
}

In the previous code I had:

int i=0;

    while ( (howmany+1) > 0 ) {                         
           i = (char) content[howmany--] - 0x80;
           Bytem = digit[i];  
/* here the 4094 routine */
   }

and was working, but in CCS it does not.

In linux the code is almost the same :

    while ( (howmany+1) > 0 ) {                         
           i = (char) content[howmany--] - '0';
           Bytem = digit[i];

Can you help me understand what I'm doing wrong ?

Thanks

Pigi

 

[betwixt]

Re: Stucked on studid string conversion ( C inside )

I can't see why it shouldn't work but it isn't the most efficient way to program it.

Try changing removing 'howmany' from the declaration and function call and use "howmany = sizeof(content)" instead, it will let you use any length of string without specifying it explicitly.
Also, if the characters are 0-9, change "bytem = digit[atoi(p)]" to "bytem = digit[content[howmany] - '0'];"

Brian.

 

[xenos]

Re: Stucked on studid string conversion ( C inside )

Try this:

[COLOR="#FF0000"]unsigned char [/COLOR]digit[10]=
{
0b01111110,   // 0
0b00010010,   // 1
0b10111100,   // 2
0b10110110,   // 3
0b11010010,   // 4
0b11100110,   // 5
0b11001110,   // 6
0b00110010,   // 7
0b11111110,   // 8
0b11110010    // 9
} ;

void display(char * content, int howmany){
[COLOR="#FF0000"]unsigned char Bytem;[/COLOR]
    while ([COLOR="#FF0000"]howmany[/COLOR]) {                         // for every byte in buffer
           [COLOR="#FF0000"]Bytem = digit[content[[SIZE=3]--howmany[/SIZE]] - '0']; [/COLOR] 
           /* here the 4094 routine */
   }
}

void main () {
[COLOR="#FF0000"]   char x[4] = "123";
[/COLOR]   while ( 1 ){
     [COLOR="#FF0000"]display ( x, 3);//or display(x,strlen(x)) or display(x,sizeof(x))[/COLOR]
// and so on
    } 
}

You read the '\0' (NUL) character initialy because you have used post decrement.
So in stead of accessing 3 digits, you access 4 (and the first is an invalid one).
Maybe the code that follows do the trick.

Initially you could replace:

content[howmany--]

with

content[--howmany]

and check if this alone do the trick.
The other red indications are speed optimizations or compiler compatibility hints.

 

[Pigi_102]

Re: Stucked on studid string conversion ( C inside )

I have tried the suggestion but they ( they are basically the same ) don't work too.

Now my code is:

while ( howmany  ) {           // per ogni byte del buffer

   Bytem=digit[content[--howmanyi] - '0'];

but still no display....

Before you ask, the display code works, as if I do:

while ( howmany ){

   Bytem=digit[howmany];

I get a nice "0" "1" "2" on display.

I'm starting to suspect that the problem could be in some differences in variable dimension or even endianess.

Pigi

 

[xenos]

Re: Stucked on studid string conversion ( C inside )

What is the mC?

Why don't you debug the code and see what values are used?
I noticed that you rewrite fragment of code here. Maybe some detail that you omit do the problem.

Test the above and see if it works displaying the first digit 3 times

while ( howmany  ) {           // per ogni byte del buffer
   Bytem = digit[content[0]];
   howmany--;
   //
   display segments here
}

 

[Pigi_102]

Re: Stucked on studid string conversion ( C inside )

The compiler is CCS. The micro is a pic 16F84 ( which unfortunally doesn't has icd capabilities ).

If I'm not wrong, being content a char* , if for example content is "123", content[0] is "1" ( in decimal should be 49 ).
Byetm = digit[49] would give unpredictable results ( or a core dump if possible ).

Am I right ?

Pigi

 

[xenos]

Re: Stucked on studid string conversion ( C inside )

Yes, subtract '0', sorry.

I suspect that because of limited capabilities the "123" you have problem or to the "123" (may be rom array that pointer cannot handle, or the double array usage digits[content[]].

 

[milan.rajik]

Re: Stucked on studid string conversion ( C inside )

Please zip and post the complete CCS C project with latest code. I will test it in my hardware and reply.

 

[Pigi_102]

Re: Stucked on studid string conversion ( C inside )

I' m sure, at the moment, that it was a compiler bug.
I have upgraded from 4 to 5 and the same code is now working.

Thanks everyone for the help.

Pigi