creating and using lookup table based on AD value - c++

Question

I am having a little bit of trouble creating and using a look up table.
My code is for a microcontroller that polls an 11 bit AD converter, and based on the value updates a 7 segment display.
The way i want to write the code is to create a table with 2047 values, each value has a binary pattern attached to it representing which pins and on and off, and then having the table return that binary value as int.
I am however not sure on the syntax to create the table or calling to it.
So far i got:
int table[2048][2];
j=0;
for(i=0; i<2048; i++)
{
if(i%204==8)
{
j++;
}
if(j==0)
{
value=0x3F;
}
if(j==1)
{
value=0x06;
}
table[i][2]={i},{value};
}
the if statements keep going down to j==9, the value is the binary pattern I'm interested in returning.
Is this a smart way of approaching the problem? if the AD value returned is for example 300, how would I look it up in the table to be able to get 0x06 as the number i want?
The bits for each of the second segments are
111
6 2
6 2
777
5 3
5 3
444
So the digit 2 has bits 1, 2, 4, 5, and 7 set,and so is represented by 0x5B

Answer 1

That is a lot of duplicated bits, with a lot of runtime overhead, and I can't even think of an efficient way to use it. Why not a lookup table of each of the 10 decimal digits, and simply have a function assemble the result 1 decimal digit at a time?
static const unsigned char segment7digits = {
0x3F, //0 -> 00111111
0x3F, //1 -> 00000110
0x5B, //2 -> 01011011
0x4F, //3 -> 01001111
0x66, //4 -> 01100110
0x6D, //5 -> 01101101
0x7D, //6 -> 01111101
0x07, //7 -> 00000111
0x7F, //8 -> 01111111
0x6F, //9 -> 01101111
}; //these values are untested and probably have errors
int lookup_7segment_bits(int value) {
assert(value>=0 && value<=9999);
int result;
result = segment7digits[value/1%10]; //least significant decimal digit
result |= segment7digits[value/10%10]<<7;
result |= segment7digits[value/100%10]<<14;
result |= segment7digits[value/1000%10]<<21; //most significant decimal digit
return result;
};