Vector Shift

Functions
void	zdsp_shift_q7 (const q7_t *src, int8_t shift_bits, q7_t *dst, uint32_t block_size)
	Shifts the elements of a Q7 vector a specified number of bits.
void	zdsp_shift_q15 (const q15_t *src, int8_t shift_bits, q15_t *dst, uint32_t block_size)
	Shifts the elements of a Q15 vector a specified number of bits.
void	zdsp_shift_q31 (const q31_t *src, int8_t shift_bits, q31_t *dst, uint32_t block_size)
	Shifts the elements of a Q31 vector a specified number of bits.

Detailed Description

Shifts the elements of a fixed-point vector by a specified number of bits. There are separate functions for Q7, Q15, and Q31 data types. The underlying algorithm used is:

    dst[n] = src[n] << shift,   0 <= n < block_size.

If shift is positive then the elements of the vector are shifted to the left. If shift is negative then the elements of the vector are shifted to the right.

The functions support in-place computation allowing the source and destination pointers to reference the same memory buffer.

Function Documentation

zdsp_shift_q15()

void zdsp_shift_q15	(	const q15_t *	src,
		int8_t	shift_bits,
		q15_t *	dst,
		uint32_t	block_size )

#include <zephyr/dsp/basicmath.h>

Shifts the elements of a Q15 vector a specified number of bits.

Precondition

Scaling and Overflow Behavior The function uses saturating arithmetic. Results outside of the allowable Q15 range [0x8000 0x7FFF] are saturated.

Parameters

[in]	src	points to the input vector
[in]	shift_bits	number of bits to shift. A positive value shifts left; a negative value shifts right.
[out]	dst	points to the output vector
[in]	block_size	number of samples in the vector

zdsp_shift_q31()

void zdsp_shift_q31	(	const q31_t *	src,
		int8_t	shift_bits,
		q31_t *	dst,
		uint32_t	block_size )

#include <zephyr/dsp/basicmath.h>

Shifts the elements of a Q31 vector a specified number of bits.

Scaling and Overflow Behavior

The function uses saturating arithmetic. Results outside of the allowable Q31 range [0x80000000 0x7FFFFFFF] are saturated.

Parameters

[in]	src	points to the input vector
[in]	shift_bits	number of bits to shift. A positive value shifts left; a negative value shifts right.
[out]	dst	points to the output vector
[in]	block_size	number of samples in the vector

zdsp_shift_q7()

void zdsp_shift_q7	(	const q7_t *	src,
		int8_t	shift_bits,
		q7_t *	dst,
		uint32_t	block_size )

#include <zephyr/dsp/basicmath.h>

Shifts the elements of a Q7 vector a specified number of bits.

Scaling and Overflow Behavior

The function uses saturating arithmetic. Results outside of the allowable Q7 range [0x80 0x7F] are saturated.

Parameters

[in]	src	points to the input vector
[in]	shift_bits	number of bits to shift. A positive value shifts left; a negative value shifts right.
[out]	dst	points to the output vector
[in]	block_size	number of samples in the vector