remove unnecessary class members

[koloboxer]

There were two class members in gps_l1_ca_telemetry_decoder_gs class

1. d_bits_per_preamble
2. d_samples_per_preamble

which were initialized from GPS_CA_PREAMBLE_LENGTH_BITS and never changed its value. It seemed not necessary, so I replaced them by just GPS_CA_PREAMBLE_LENGTH_BITS which is more readable: you can check the value of this const in IDE directly.

[vladisslav2011]

Could you choose 'next' branch instead of 'main' as a target of your PR?

[jwmelto]

in my opinion, this is not a desirable change. There is much duplicate code in the various decoders; I would think the preferred direction is towards greater abstraction, not more constellation/algorithm-unique duplication.

As far as I can tell, the motivation behind this is to make the IDE experience "nicer"? I believe that is misguided. Understanding the code should not depend upon knowing the precise value of the preamble values.

[koloboxer]

@jwmelto , two reasons actually. First of all it does not make sense to have three variables for the same entity. d_bits_per_preamble and d_samples_per_preamble is the number of bits in the preamble, which is 8, and it is already defined by a constant GPS_CA_PREAMBLE_LENGTH_BITS. There is no sense to introduce two new class members for storing a value, which is not being changed in the process of calculation.

Just as an example... You have the constant M_PI in math.h. I hope that when writing your code, you do not introduce a new variable

double my_pi = M_PI;

And if you do, I hope that at least you do not do it twice))

double my_pi_1 = M_PI;
double my_pi_2 = M_PI;

And the second reason is indeed the comfort in IDE, when you do not have to search the initialization of variables d_bits_per_preamble and d_samples_per_preamble just to find out that this is GPS_CA_PREAMBLE_LENGTH_BITS.

I do believe that these two class members exist only because of historical reasons.