Arrays in c programming

Electro nS said:

the index of 8 is 7 here . because K[0]=1 , k[1] =2 ..... k[8]=9.

you might need to check the libraries of C that search for an item inside an array and tells you at what index it is . but problem if there is more than one !!

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#define ARRAY_SIZE 9
const int k[]={1,2,3,4,5,6,7,8,9}

int FindIndex(int *vals, int size, int search)
{
    int i;

    for ( i = 0; i < size ; i++)
        if ( vals[i] == search )
            return i;

    return -1;
}

yannoo95170 said:

This can be to make using a very simple loop on the entire array and return the first index that contain the search value
(and return -1 if the value is not in this array)

Code:

#define ARRAY_SIZE 9
const int k[]={1,2,3,4,5,6,7,8,9}

int FindIndex(int *vals, int size, int search)
{
    int i;

    for ( i = 0; i < size ; i++)
        if ( vals[i] == search )
            return i;

    return -1;
}

In your specific example, a call to FindIndex(k, ARRAY_SIZE, 8) should logically return 7
(if the array have more than one occurence of the search value, this fonction always return the lowest index that contain this value and if the value is not in the array, the fonction return -1)

But this is a "true" C example, so I don't think that this can coded as this on a FPGA language ...
=> I implement/test the same thing but using the verilog syntax tomorow (with the print of the result of course)

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john120 said:

can you plz help me on the codes for this index searching:I am thinking that it is better that I find the index which correspond to a number which has been read by the processor then
that index is multiplied by 0.1 and then added to the starting number which is 8

for example
const double hi_limit[]={1234900,1234100,1234000,1231500,1230090,1228900,122600};
const double lo_limit[]={1235900,1234800,1231900,1231800,1230300,1230100,122800};

the index of those bold number will be 2 then jean=jean+0.1*2 ;as jean has been initialized equals 7.0 the output will be 7.2%


meanwhile what is needed is to find that index 2 (how may I search it inside array);in those two arrays no number appearing twice.

And also the comparison has to be made inside the FindIndex function because I need to see whether the value read is in a given boundary and the calculate jean and then print its final value.
Thanks.

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I declared the function FindIndex and coded,but when I call it it says:Attempt to create a pointer to a constant

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john120 said:

can you plz help me on the codes for this index searching:I am thinking that it is better that I find the index which correspond to a number which has been read by the processor then
that index is multiplied by 0.1 and then added to the starting number which is 8

for example
const double hi_limit[]={1234900,1234100,1234000,1231500,1230090,1228900,122600};
const double lo_limit[]={1235900,1234800,1231900,1231800,1230300,1230100,122800};

the index of those bold number will be 2 then jean=jean+0.1*2 ;as jean has been initialized equals 7.0 the output will be 7.2%


meanwhile what is needed is to find that index 2 (how may I search it inside array);in those two arrays no number appearing twice.

And also the comparison has to be made inside the FindIndex function because I need to see whether the value read is in a given boundary and the calculate jean and then print its final value.
Thanks.

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john120 said:

The given codes does not give me the index of a number in the array,help to solve the issue plz.

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yannoo95170 said:

Can you please post your array please ?
(I don't understand why this can to work with somes datas and not with others ...)
[note that this code return **the first** index when the search value is contained between the high and low limits arrays ...]

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yannoo95170 said:

Why this ?

Code:

for ( i =0; i <size ; i++)
while((value1<= j[i])&&(k[i]<=value1))

You don't want to make this ?

Code:

for ( i =0; i <size ; i++)
if ( ((value1<= j[i]) &&( k[i] <=value1)) || ((value1<= k[i]) &&( j[i] <=value1))  )

(cf. use if instead while + test if value1 is **between** k and j with no assumption than k is always <= j )

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yannoo95170 said:

Ok, so you want everything into the main() for to begin, right ?

if yes, this is something like this :

Code:

#include <16F877A.h>
#DEVICE ADC=10
#fuses HS,NOWDT,NOPROTECT,NOLVP,NOBROWNOUT
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#include "lcd.c"
//#define ARRAY_SIZE 7
#define ARRAY_SIZE 9

int i, found;
int value;

int j[]={1,2,3,4,5,6,7,8,9};

void main(void)
{

   set_tris_c(0xff);
   set_tris_b(0x00);
   lcd_init();
   delay_us(200);

   while(1)
   {
      set_timer1(0);
      setup_timer_1(t1_external | T1_DIV_BY_1);
      delay_ms(1000);
      setup_timer_1(T1_DISABLED);
      value=get_timer1();
      delay_ms(20);

      for ( i = 0, found = -1 ; i < ARRAY_SIZE ; i++)
        if ( j[i] == value )
        {
           printf(lcd_putc,"j[%d] is %d", i, value);
           found = 1;
        }

      if ( found == -1 )
         printf(lcd_put, "cannot found the %d value :(", value);   

      delay_ms(1000);

   } // end while(1)

} // end main()

PS : please, respond me about what platform you use for to transfert the code from your computer to the FGPA board
(I haven't already find how to make this from my Linux box to a SPARTAN FPGA board :sad: )

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yannoo95170 said:

I have see this at https://iroi.seu.edu.cn/books/asics/book2/ch11/CH11.02.htm :
There are no multidimensional arrays in Verilog, but we may declare a memory data type as an array of registers

You have to use something like this :

Code:

module declarations_5;
reg [31:0] VideoRam [7:0]; // An 8-word by 32-bit wide memory.
initial begin 
VideoRam[1] = 'bxz; // We must specify an index for a memory.
VideoRam[2] = 1; 
VideoRam[7] = VideoRam[VideoRam[2]]; // Need 2 clock cycles for this.
VideoRam[8] = 1; // Careful! the compiler won't complain about this!
// Verify what we entered:
$display("VideoRam[0] is %b",VideoRam[0]);
$display("VideoRam[1] is %b",VideoRam[1]);
$display("VideoRam[2] is %b",VideoRam[2]);
$display("VideoRam[7] is %b",VideoRam[7]);
end 
endmodule 
VideoRam[0] is xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
VideoRam[1] is xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxz
VideoRam[2] is 00000000000000000000000000000001
VideoRam[7] is xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxz

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I have a verilog source that work well when emulated on my linux box :

Code:

module between;
 
  reg clock;
  integer idx;
  integer search = 8;
  reg [31:0] limits [8:0];
  

initial 
  begin 

    clock = 0; idx = 0;
    limits[0] = 1;
    limits[1] = 2;
    limits[2] = 3;
    limits[3] = 4;
    limits[4] = 5;
    limits[5] = 6;
    limits[6] = 7;
    limits[7] = 8;
    limits[8] = 9;
    #1000 $finish;
  end 

always  #10 clock = ~ clock;

always 
  begin @ (negedge clock);

    if (idx == 9)
      	idx = 0;
    else      
	idx = idx + 1;

    if ( limits[idx] == search) 
    	$display("time = ",$time," limits[", idx, "]=", search);
  end 
endmodule

=> this search the value 8 (cf. the line "integer search = 8") into the array limits[] declared at the line "reg [31:0] limits [8:0];"

This give this at output when emulated on my Linux box

Code:

yannoo@Ubuntoo:~/dev/FPGA$ make
iverilog -o between_fpga between.vl
vvp between_fpga
time =                  140 limits[          7]=          8
time =                  320 limits[          7]=          8
time =                  500 limits[          7]=          8
time =                  680 limits[          7]=          8
time =                  860 limits[          7]=          8

(I don't know how to handle only one occurence, so I have employ "#1000 $finish;" for to be sure that this test stop a day)
[note than the array begin at 0, not at 1]

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I have found how to finish as soon as possible :

Code:

   if ( limits[idx] == search)
    begin
    	$display("time = ",$time," limits[", idx, "]=", search);
        $finish;
    end

=> now, I have only to found how to handle the nesting of multiples modules between them for to have the equivalent of fonctions

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This version exit at the first index that contain the searched value or display a message such as the value isn't found at the end

Code:

module between;
 
  reg clock;
  integer idx;
  integer search = 11;
  reg [31:0] limits [8:0];
  

initial 
  begin 

    clock = 0; idx = 0;
    limits[0] = 1;
    limits[1] = 2;
    limits[2] = 3;
    limits[3] = 4;
    limits[4] = 5;
    limits[5] = 6;
    limits[6] = 7;
    limits[7] = 8;
    limits[8] = 9;
    #1000 $finish;

  end 

always  #10 clock = ~ clock;

always 
  begin @ (negedge clock);

    if ( limits[idx] == search)
    begin
    	$display("time = ",$time," limits[", idx, "]=", search);
        $finish;
    end
    else

    if (idx == 9)
    begin
      	$display("Cannot found the value ", search, " into the array");
        $finish;
    end
    else      
	idx = idx + 1;
  end 
endmodule

With search = 8

Code:

time =                  160 limits[          7]=          8

And if I modify the value of search with 11 :

Code:

integer search = 11;

Code:

Cannot found the value          11 into the array

But in first view, you want a true C source (not a verilog source), so my last post with the linux source seem to more adapted for you

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