File f32_to_i16u32_core.h¶

FileList > f32_to_i16u32 > f32_to_i16u32_core.h

Go to the source code of this file

Scale-and-saturate float to Q15-in-uint32 converter. More...

• #include "clib_common.h"
• #include "dp_state.h"
• #include "jm_perf.h"
• #include <math.h>

Classes¶

Public Functions¶

Macros¶

Detailed Description¶

Converts a float to a saturated int16, then zero-extends the 16-bit two's complement bit pattern into the lower 16 bits of a uint32 (upper 16 bits are always zero). This is the wire format expected by the CIC filter's integer input path, which exploits the upper bits as headroom for the bit-growth that naturally occurs through an integrator cascade.

input +1.0 → int16 32767 → uint32 0x00007FFF input -1.0 → int16 -32768 → uint32 0x00008000

The default scale of 32768.0 maps [-1, +1] float to Q15 range. A sticky clipped flag is raised on saturation and cleared only by reset().

Lifecycle: create -> (step / steps / reset)* -> destroy

>>> from doppler.cvt import F32ToI16U32
>>> import numpy as np
>>> obj = F32ToI16U32(scale=32768.0)
>>> hex(obj.step(-1.0))
'0x8000'
>>> hex(obj.step(1.0))
'0x7fff'
>>> obj.step(0.0)
0
>>> x = np.array([-1.0, 0.0, 1.0], dtype=np.float32)
>>> obj.steps(x).tolist()
[32768, 0, 32767]

Public Functions Documentation¶

function f32_to_i16u32_create¶

Create a f32_to_i16u32 instance.

f32_to_i16u32_state_t * f32_to_i16u32_create (
    float scale
) 

Stores scale and initialises the sticky clipped flag to 0.

Parameters:

• scale Multiply factor applied before quantisation and saturation (default: 32768.0f). Use 32768.0 to convert normalised [-1, +1] samples to Q15 packed into a uint32.

Returns:

Heap-allocated state, or NULL on allocation failure.

Note:

Caller must call f32_to_i16u32_destroy() when done.

function f32_to_i16u32_destroy¶

Destroy a f32_to_i16u32 instance and release all memory.

void f32_to_i16u32_destroy (
    f32_to_i16u32_state_t * state
) 

Parameters:

• state May be NULL.

function f32_to_i16u32_get_state¶

void f32_to_i16u32_get_state (
    const f32_to_i16u32_state_t * state,
    void * blob
) 

function f32_to_i16u32_reset¶

Reset f32_to_i16u32 to its post-create state.

void f32_to_i16u32_reset (
    f32_to_i16u32_state_t * state
) 

Clears the sticky clipped flag. The scale is preserved.

Parameters:

• state Must be non-NULL.

function f32_to_i16u32_set_state¶

int f32_to_i16u32_set_state (
    f32_to_i16u32_state_t * state,
    const void * blob
) 

function f32_to_i16u32_state_bytes¶

size_t f32_to_i16u32_state_bytes (
    const f32_to_i16u32_state_t * state
) 

function f32_to_i16u32_step¶

Process one input sample.

JM_FORCEINLINE  JM_HOT uint32_t f32_to_i16u32_step (
    f32_to_i16u32_state_t * state,
    float x
) 

Computes round(x * scale), saturates to [-32768, 32767], then zero-extends the int16 bit pattern into the lower 16 bits of a uint32. The clipped flag is set if saturation occurred.

Parameters:

• state Must be non-NULL.
• x Normalised float input sample.

Returns:

Q15 value packed into the lower 16 bits of a uint32.

function f32_to_i16u32_steps¶

Process a block of float samples to Q15-in-uint32.

void f32_to_i16u32_steps (
    f32_to_i16u32_state_t * state,
    const float * input,
    uint32_t * output,
    size_t n
) 

Applies step() to every element. The clipped flag is updated cumulatively across the block. Accepts an optional pre-allocated output array; allocates a fresh one when output is NULL.

Parameters:

• state Must be non-NULL.
• input Input float32 array; must contain at least n elements.
• output Output uint32 array; must contain at least n elements.
• n Number of samples to process.

>>> from doppler.cvt import F32ToI16U32
>>> import numpy as np
>>> F32ToI16U32().steps(np.array([0.0, 0.5], dtype=np.float32)).tolist()
[0, 16384]

Macro Definition Documentation¶

define F32_TO_I16U32_STATE_MAGIC¶

#define F32_TO_I16U32_STATE_MAGIC `DP_FOURCC ('F','U','3','2')`

define F32_TO_I16U32_STATE_VERSION¶

#define F32_TO_I16U32_STATE_VERSION `1u`

The documentation for this class was generated from the following file native/inc/f32_to_i16u32/f32_to_i16u32_core.h