File syn_lut.h¶

FileList > src > syntropic > util > syn_lut.h

Lookup table with linear interpolation. More...

#include <stddef.h>
#include <stdint.h>

Classes¶

Type	Name
struct	SYN_LUT_Entry Lookup table entry (x, y pair).

Public Static Functions¶

Type	Name
int32_t	syn_lut_forward (const SYN_LUT_Entry * table, size_t count, int32_t x) Look up y for a given x, with linear interpolation.
int32_t	syn_lut_reverse (const SYN_LUT_Entry * table, size_t count, int32_t y) Look up x for a given y, with linear interpolation.

Detailed Description¶

For calibration curves, thermistor tables, transfer functions, etc. The table is a const array of (x, y) pairs, sorted by ascending x. Lookups interpolate linearly between the two nearest entries.

Header-only — integer math, no floating point.

** **

static const SYN_LUT_Entry thermistor_table[] = {
    {   0, 3300 },  // 0°C → 3300 ADC counts
    {  25, 2048 },
    {  50, 1200 },
    { 100,  400 },
};

int32_t temp = syn_lut_lookup(thermistor_table, 4, adc_value);
// Returns interpolated x for a given y

int32_t adc = syn_lut_forward(thermistor_table, 4, 37);
// Returns interpolated y for a given x (37°C)

Public Static Functions Documentation¶

function syn_lut_forward¶

Look up y for a given x, with linear interpolation.

static inline int32_t syn_lut_forward (
    const SYN_LUT_Entry * table,
    size_t count,
    int32_t x
)

Table must be sorted by ascending x. Values outside the table range are clamped to the nearest endpoint.

Parameters:

table Array of (x, y) entries.
count Number of entries.
x Input value.

Returns:

Interpolated y.

function syn_lut_reverse¶

Look up x for a given y, with linear interpolation.

static inline int32_t syn_lut_reverse (
    const SYN_LUT_Entry * table,
    size_t count,
    int32_t y
)

The y column can be monotonically increasing OR decreasing. Values outside the table range are clamped.

Parameters:

table Array of (x, y) entries, sorted by ascending x.
count Number of entries.
y Input value (in the y domain).

Returns:

Interpolated x.

The documentation for this class was generated from the following file src/syntropic/util/syn_lut.h