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carl
Joined: 06 Feb 2008
Posts: 240
Location: Chester
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| Array Accessing - [SOLVED] |
 Posted: Tue Aug 14, 2012 7:51 am |
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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 |
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carl
Joined: 06 Feb 2008
Posts: 240
Location: Chester
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| Posted: Tue Aug 14, 2012 9:07 am |
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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? |
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carl
Joined: 06 Feb 2008
Posts: 240
Location: Chester
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| Posted: Tue Aug 14, 2012 1:57 pm |
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Anyone?
The only other way I can think of if loads of nested IF's - but I dont like this plan.... |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19347
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| Posted: Tue Aug 14, 2012 2:22 pm |
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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;
}
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This is really a 'C 101' question, nothing to do with CCS as such.
Best Wishes |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Tue Aug 14, 2012 2:23 pm |
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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
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carl
Joined: 06 Feb 2008
Posts: 240
Location: Chester
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| Posted: Wed Aug 15, 2012 3:12 am |
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| Thanks |
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