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Array Accessing - [SOLVED]

 
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carl



Joined: 06 Feb 2008
Posts: 240
Location: Chester

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Array Accessing - [SOLVED]
PostPosted: Tue Aug 14, 2012 7:51 am     Reply with quote
Sorry to bother you all again,
but I have a question regarding arrays and look-up tables.

If I had an array [46] [2]

And to access it you would say:
I want what is in row [35] and column [2].
so X = [35] [2] returns what is in that location from the array. In this case = 6.
This is the normal way of doing it.

But is there any way to 'match' the information in the array to a variable rather than accessing the row/column??

so my array is below
Code:
unsigned int32 max_val[46][2] = {
{0,0},          //row0
{64,33},                       
{100,16},
{128,11},
{152,8},
{180,6},         //row5
{256,6},
{360,5},
{512,4},
{600,4},
{720,3},       //row 10
{800,3},
{1000,3},
{1024,3},
{1440,3},
{1500,2},      //row 15
{2000,2},
{2048,2},
{2880,2},
{3600,2},
{4096,2},      //row 20
{0X3FF,33},                       
{0X7FF,16},
{0XFFF,11},
{0X1FFF,8},
{0X3FFF,6},     //row25
{0X7FFF,6},
{0XFFFF,5},
{0X1FFFF,4},
{0X3FFFF,4},
{0X7FFFF,3},    //row 30
{0XFFFFF,33},                       
{0X1FFFFF,16},
{0X3FFFFF,11},
{0X7FFFFF,8},
{0XFFFFFF,6},   //row35
{0X11DF,6},
{0X23BF,5},
{0X477F,4},
{0X8EFF,4},
{0X11DFF,3},    //row 40
{0X14F27,3},
{0X23BFF,3},
{0X3245F,3},
{0X477FF,3},
{0X8E,2},      //row 45
};


Now if I read a value (which will always be incorporated in the array above) from somewhere else (eeprom or other hardware), and lets say the value is val = 0X477FF.

Is it possible to search the array, to find when 'val' = 'the value in the first array' - so that I can then return the value from the second array - in this case '3' would be returned.

Any help appreciated
Carl

Last edited by carl on Wed Aug 15, 2012 3:12 am; edited 1 time in total
carl



Joined: 06 Feb 2008
Posts: 240
Location: Chester

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PostPosted: Tue Aug 14, 2012 9:07 am     Reply with quote
Tried using switch case as below but got this error message:
Quote:
Constant out of the valid range 131071 is not less than 65536


so I presume that a switch case can only work on 16bit variables.
I need 32 bit - so this method is not going to work.
Code:
extern unsigned int32 load_max_result;

unsigned int32 get_max(void){
switch (load_max_result){

case 64:    return 0;                   
case 100:   return 76;   
case 128:    return 0;                   
case 152:   return 76;   
case 180:    return 0;                   
case 256:   return 76;   
case 360:    return 0;                   
case 512:   return 76; 
case 600:    return 0;                   
case 720:   return 76;   
case 800:    return 0;                   
case 1000:   return 76; 
case 1024:    return 0;                   
case 1440:   return 76;   
case 1500:    return 0;                   
case 2000:   return 76; 
case 2048:    return 0;                   
case 2880:   return 76;   
case 3600:    return 0;                   
case 4096:   return 76; 
case 0x3FF:    return 0;                   
case 0x7FF:   return 76;   
case 0xFFF:    return 0;                   
case 0x1FFF:   return 76; 
case 0x3FFF:    return 0;                   
case 0X7FFF:   return 76;   
case 0XFFFF:    return 0;                   
case 0X1FFFF:   return 76; 
case 0X3FFFF:    return 0;                   
case 0X7FFFF:   return 76;   
case 0XFFFFF:    return 0;                   
case 0X1FFFFF:   return 76; 
case 0X3FFFFF:    return 0;                   
case 0X7FFFFF:   return 76;   
case 0XFFFFFF:    return 0;                   
case 0X11DF:   return 76;   
case 0X23BF:   return 76; 
case 0X477F:    return 0;                   
case 0X8EFF:   return 76;   
case 0X11DFF:    return 0;                   
case 0X14F27:   return 76; 
case 0X23BFF:    return 0;                   
case 0X3245F:   return 76;   
case 0X477FF:    return 0;                   
case 0X8E:   return 76;
      }
}


Any THoughts?
carl



Joined: 06 Feb 2008
Posts: 240
Location: Chester

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PostPosted: Tue Aug 14, 2012 1:57 pm     Reply with quote
Anyone?

The only other way I can think of if loads of nested IF's - but I dont like this plan....
Ttelmah



Joined: 11 Mar 2010
Posts: 19539

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PostPosted: Tue Aug 14, 2012 2:22 pm     Reply with quote
Just search the array. Not exactly 'rocket science'.....
Code:

int8 find(int32 valtofind) {
   int8 count;
   for (count=0;count<46;count++) {
      if (max_val[count][0]==valtofind) return(max_val[count][1]);
   }
   return(0); //put what you want here - error did not find the value;
}

This is really a 'C 101' question, nothing to do with CCS as such.

Best Wishes
asmboy



Joined: 20 Nov 2007
Posts: 2128
Location: albany ny

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PostPosted: Tue Aug 14, 2012 2:23 pm     Reply with quote
your exposition is not totally clear to me.

there are ways to index - as you seem to desire with TWO arrays

where each is loaded with constants

as in
int32 a[48]
int 8 b[48]

then searching with comparisons ( especially if the arrays are SORTED from hi to lo or vice versa ) funny but, i just wrote some code like that this morning to add to a project.

here is an excerpt


Code:

int16 omult=0;
const unsigned int16 fcor[8]={2700,3143,3883,5191,5333,5491,5571,5659,};
const unsigned int32 gfreq[8]={250000,200000,150000,100000,96000,92000,90000,80000,};
.... later

for (j=0; j<8; j++) {  if (infreq>=gfreq[j]) { omult=fcor[j];  break;  }}
// the version i actually wrote has 72 elements but this is the idea
carl



Joined: 06 Feb 2008
Posts: 240
Location: Chester

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PostPosted: Wed Aug 15, 2012 3:12 am     Reply with quote
Thanks
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