File i8_to_f32_core.h¶

FileList > i8_to_f32 > i8_to_f32_core.h

int8-to-float converter with configurable inverse scale. More...

#include "clib_common.h"
#include "jm_perf.h"

Classes¶

Type	Name
struct	i8_to_f32_state_t I8ToF32 state.

Public Functions¶

Type	Name
i8_to_f32_state_t *	i8_to_f32_create (float scale) Create a i8_to_f32 instance.
void	i8_to_f32_destroy (i8_to_f32_state_t * state) Destroy a i8_to_f32 instance and release all memory.
void	i8_to_f32_reset (i8_to_f32_state_t * state) Reset I8ToF32 to its post-create state.
JM_FORCEINLINE JM_HOT float	i8_to_f32_step (const i8_to_f32_state_t * state, int8_t x) Process one input sample.
void	i8_to_f32_steps (i8_to_f32_state_t * state, const int8_t * input, float * output, size_t n) Process a block of int8 samples to float32.

Detailed Description¶

Multiplies each signed int8 sample by 1/scale and returns a float32. The default scale of 128.0 maps the full int8 range [-128, 127] to [-1.0, ~+1.0), which is the natural inverse of an 8-bit ADC path. This converter is used in the 8-bit IQ sample pipeline (e.g., RTL-SDR signed-8 I/Q streams) where samples arrive as int8 and must be converted to normalised complex floats. The inverse scale is pre-computed at construction time.

Lifecycle: create -> [step / steps / reset]* -> destroy

>>> from doppler.cvt import I8ToF32
>>> import numpy as np
>>> obj = I8ToF32(scale=128.0)
>>> float(obj.step(-128))
-1.0
>>> float(obj.step(0))
0.0
>>> x = np.array([-128, 0, 127], dtype=np.int8)
>>> [round(v, 7) for v in obj.steps(x).tolist()]
[-1.0, 0.0, 0.9921875]

Public Functions Documentation¶

function i8_to_f32_create¶

Create a i8_to_f32 instance.

i8_to_f32_state_t * i8_to_f32_create (
    float scale
)

Pre-computes iscale = 1.0f / scale.

Parameters:

scale Denominator scale; 1/scale is applied to each sample (default: 128.0f). Use 128.0 to recover normalised floats from a signed 8-bit stream.

Returns:

Heap-allocated state, or NULL on allocation failure.

Note:

Caller must call i8_to_f32_destroy() when done.

function i8_to_f32_destroy¶

Destroy a i8_to_f32 instance and release all memory.

void i8_to_f32_destroy (
    i8_to_f32_state_t * state
)

Parameters:

state May be NULL.

function i8_to_f32_reset¶

Reset I8ToF32 to its post-create state.

void i8_to_f32_reset (
    i8_to_f32_state_t * state
)

No mutable state exists beyond the immutable iscale; reset is a no-op provided for lifecycle symmetry with other converters.

Parameters:

state Must be non-NULL.

function i8_to_f32_step¶

Process one input sample.

JM_FORCEINLINE  JM_HOT float i8_to_f32_step (
    const i8_to_f32_state_t * state,
    int8_t x
)

Returns ``(float)x * iscale.

Parameters:

state Must be non-NULL.
x Signed int8 input sample.

Returns:

Scaled float32 output.

function i8_to_f32_steps¶

Process a block of int8 samples to float32.

void i8_to_f32_steps (
    i8_to_f32_state_t * state,
    const int8_t * input,
    float * output,
    size_t n
)

Applies step() to every element. Accepts an optional pre-allocated output array; allocates a fresh one when output is NULL.

Parameters:

state Must be non-NULL.
input Input int8 array; must contain at least n elements.
output Output float32 array; must contain at least n elements.
n Number of samples to process.

>>> from doppler.cvt import I8ToF32
>>> import numpy as np
>>> I8ToF32().steps(np.array([0, 64, -128], dtype=np.int8)).tolist()
[0.0, 0.5, -1.0]

The documentation for this class was generated from the following file native/inc/i8_to_f32/i8_to_f32_core.h