Strange input of function in C++ - c++

Question

What is done by (1L<<16u) in following code?
and What is the role of this pointer(&mode_absolute_pos_el.tracking) as an input to a function?
if (command_axis2.cif_mode_state == STATUS__DONE)
{
delta_position = absolute_position - turret_pos.elevation_16bit_pm180deg;
delta_position = MathRange_PlusMinusHalfRange32Bit(delta_position, 1L<<16u);
mode_absolute_pos_el.speed_setpoint = MathTracking_Main(&mode_absolute_pos_el.tracking, delta_position, 0L);
}
This is the complete function as one requested for the complete one:
static int16_t TwinX_AbsPos_Calc_El(int16_t absolute_position)
{
uint16_t position_reached = NO;
int32_t delta_position = 0L;
if (command_axis2.cif_mode_state == STATUS__DONE)
{
delta_position = absolute_position - turret_pos.elevation_16bit_pm180deg;
delta_position = MathRange_PlusMinusHalfRange32Bit(delta_position, 1L<<16u);
mode_absolute_pos_el.speed_setpoint = MathTracking_Main(&mode_absolute_pos_el.tracking, delta_position, 0L);
/* verify that absolute position is reached with tolerance: +/- CUSTOMER_ABSOLUTE_POS_ERROR
* for more than MODE_ABSOLUTE_POS_OK_DELAY_IN_MS:
* bai: That has to be here because otherwise position_reached is always "Yes" because delta_position == 0L */
if ((delta_position < TwinX_MODE_ABSOLUTE_POS_ERROR) && (delta_position > (-1 * TwinX_MODE_ABSOLUTE_POS_ERROR)))
{
position_reached = YES;
}
mode_absolute_pos_el.absolute_pos_reached = MathDebounce_Status(&mode_absolute_pos_el.debounce, position_reached);
}
else
{
mode_absolute_pos_el.speed_setpoint = 0;
MathTracking_SetStartCondition(&mode_absolute_pos_el.tracking, turret_speed.elev_speed_max16bit);
}
return mode_absolute_pos_el.speed_setpoint;
}
And below you can see the MATH_DEBOUNCE :
typedef struct
{
bool_t debounced_status; /* debounced status ZERO / ONE */
uint32_t debounce_counter; /* counter */
uint32_t threshold_for_zero; /* threshold to set debounced status to ZERO */
uint32_t threshold_for_one; /* threshold to set debounced status to ONE */
uint32_t step_down_size; /* step size to count down. used for underclock */
}MATH_DEBOUNCE_t;
void MathDebounce_Init(MATH_DEBOUNCE_t *const debounce_p,
bool_t initial_status,
uint16_t debounce_delay,
uint16_t underclock);
void MathDebounce_ResetStatus(MATH_DEBOUNCE_t *const debounce_p, bool_t reset_status);
bool_t MathDebounce_Status(MATH_DEBOUNCE_t *const debounce_p, bool_t status);

Answer 1

1 << 16 is 2^16. << is a left binary shift operator.
Lets look at how to get 2^3, imagine that you have 1 which in binary form looks like this 0b0001. One point about binary system is that powers of 2 have only one bit in their binary representation, so 2^3 = 8 looks like 0b1000. It's a very fast way to get a power of 2.
Passing pointer to function is usually a way to get more then one output from it. Like when return value is something like error code and actual output of the function is passed through the pointer you pass to it.
But it's hard to tell what exactly it does because you didn't provide the code of the function.