File i32_to_f32_core.h¶

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int32-to-float converter with configurable inverse scale. More...

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

Classes¶

Public Functions¶

Detailed Description¶

Multiplies each int32 sample by 1/scale and returns a float32 result. The default scale of 2147483648.0 (2^31) maps the full int32 range [-2147483648, 2147483647] to [-1.0, ~+1.0), recovering the normalised float representation from a 32-bit fixed-point stream. Note: float32 has 23 mantissa bits, so int32 values beyond ±16777217 will be rounded to the nearest representable float. Use I32ToF32 when only the magnitude matters or the source is genuinely 32-bit fixed-point. The inverse scale is pre-computed at construction time.

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

>>> from doppler.cvt import I32ToF32
>>> import numpy as np
>>> obj = I32ToF32(scale=2147483648.0)
>>> float(obj.step(-2147483648))
-1.0
>>> float(obj.step(0))
0.0
>>> x = np.array([-2147483648, 0, 2147483647], dtype=np.int32)
>>> obj.steps(x).tolist()
[-1.0, 0.0, 1.0]

Public Functions Documentation¶

function i32_to_f32_create¶

Create a i32_to_f32 instance.

i32_to_f32_state_t * i32_to_f32_create (
    float scale
) 

Pre-computes iscale = 1.0f / scale. Any non-zero finite float is a valid scale.

Parameters:

• scale Denominator scale; 1/scale is applied to each sample (default: 2147483648.0f). Use 2^31 to recover normalised floats from a full-range int32 stream.

Returns:

Heap-allocated state, or NULL on allocation failure.

Note:

Caller must call i32_to_f32_destroy() when done.

function i32_to_f32_destroy¶

Destroy a i32_to_f32 instance and release all memory.

void i32_to_f32_destroy (
    i32_to_f32_state_t * state
) 

Parameters:

• state May be NULL.

function i32_to_f32_reset¶

No-op reset, provided only for lifecycle symmetry.

void i32_to_f32_reset (
    i32_to_f32_state_t * state
) 

No mutable state exists beyond the immutable iscale, so there is nothing to clear; the method exists so every converter in the module presents the same create / step / reset / destroy lifecycle.

Parameters:

• state Must be non-NULL.

>>> from doppler.cvt import I32ToF32
>>> c = I32ToF32()
>>> c.reset()           # stateless converter -> reset is a no-op
>>> round(c.step(-2**31), 4)
-1.0

function i32_to_f32_step¶

Convert one signed int32 sample to a normalised float via 1/scale .

JM_FORCEINLINE  JM_HOT float i32_to_f32_step (
    const i32_to_f32_state_t * state,
    int32_t x
) 

Returns `(float)x \* iscale, a single multiply on the hot path. At the default scale of 2^31 the full int32 range recovers[-1.0, ~+1.0)`. Note that float32 carries only 23 mantissa bits, so int32 magnitudes beyond 2^24 are rounded to the nearest representable float.

Parameters:

• state Must be non-NULL.
• x Signed int32 code, normally a full-range fixed-point sample.

Returns:

Normalised float, x / scale.

>>> from doppler.cvt import I32ToF32
>>> c = I32ToF32(scale=2147483648.0)  # 2**31: int32 -> [-1, 1)
>>> round(c.step(2**30), 4)            # quarter-scale code -> 0.5
0.5
>>> round(c.step(-2**31), 4)           # full-negative code -> -1.0
-1.0

function i32_to_f32_steps¶

Process a block of int32 samples to float32.

void i32_to_f32_steps (
    i32_to_f32_state_t * state,
    const int32_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 int32 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 I32ToF32
>>> import numpy as np
>>> I32ToF32().steps(
...     np.array([0, 2**30, -2**31], dtype=np.int32)).tolist()
[0.0, 0.5, -1.0]

The documentation for this class was generated from the following file native/inc/i32_to_f32/i32_to_f32_core.h