Vector Scale

Functions
void	arm_scale_f16 (const float16_t *pSrc, float16_t scale, float16_t *pDst, uint32_t blockSize)
	Multiplies a floating-point vector by a scalar.
void	arm_scale_f32 (const float32_t *pSrc, float32_t scale, float32_t *pDst, uint32_t blockSize)
	Multiplies a floating-point vector by a scalar.
void	arm_scale_f64 (const float64_t *pSrc, float64_t scale, float64_t *pDst, uint32_t blockSize)
	Multiplies a floating-point vector by a scalar.
void	arm_scale_q15 (const q15_t *pSrc, q15_t scaleFract, int8_t shift, q15_t *pDst, uint32_t blockSize)
	Multiplies a Q15 vector by a scalar.
void	arm_scale_q31 (const q31_t *pSrc, q31_t scaleFract, int8_t shift, q31_t *pDst, uint32_t blockSize)
	Multiplies a Q31 vector by a scalar.
void	arm_scale_q7 (const q7_t *pSrc, q7_t scaleFract, int8_t shift, q7_t *pDst, uint32_t blockSize)
	Multiplies a Q7 vector by a scalar.

Description

Multiply a vector by a scalar value. For floating-point data, the algorithm used is:

    pDst[n] = pSrc[n] * scale,   0 <= n < blockSize.

In the fixed-point Q7, Q15, and Q31 functions, scale is represented by a fractional multiplication scaleFract and an arithmetic shift shift. The shift allows the gain of the scaling operation to exceed 1.0. The algorithm used with fixed-point data is:

    pDst[n] = (pSrc[n] * scaleFract) << shift,   0 <= n < blockSize.

The overall scale factor applied to the fixed-point data is

    scale = scaleFract * 2^shift.

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

Function Documentation

arm_scale_f16()

void arm_scale_f16	(	const float16_t *	pSrc,
		float16_t	scale,
		float16_t *	pDst,
		uint32_t	blockSize
	)

Multiplies a floating-point vector by a scalar.

Parameters

[in]	pSrc	points to the input vector
[in]	scale	scale factor to be applied
[out]	pDst	points to the output vector
[in]	blockSize	number of samples in each vector

arm_scale_f32()

void arm_scale_f32	(	const float32_t *	pSrc,
		float32_t	scale,
		float32_t *	pDst,
		uint32_t	blockSize
	)

Multiplies a floating-point vector by a scalar.

Parameters

[in]	pSrc	points to the input vector
[in]	scale	scale factor to be applied
[out]	pDst	points to the output vector
[in]	blockSize	number of samples in each vector

arm_scale_f64()

void arm_scale_f64	(	const float64_t *	pSrc,
		float64_t	scale,
		float64_t *	pDst,
		uint32_t	blockSize
	)

Multiplies a floating-point vector by a scalar.

Parameters

[in]	pSrc	points to the input vector
[in]	scale	scale factor to be applied
[out]	pDst	points to the output vector
[in]	blockSize	number of samples in each vector

arm_scale_q15()

void arm_scale_q15	(	const q15_t *	pSrc,
		q15_t	scaleFract,
		int8_t	shift,
		q15_t *	pDst,
		uint32_t	blockSize
	)

Multiplies a Q15 vector by a scalar.

Parameters

[in]	pSrc	points to the input vector
[in]	scaleFract	fractional portion of the scale value
[in]	shift	number of bits to shift the result by
[out]	pDst	points to the output vector
[in]	blockSize	number of samples in each vector

Scaling and Overflow Behavior

The input data *pSrc and scaleFract are in 1.15 format. These are multiplied to yield a 2.30 intermediate result and this is shifted with saturation to 1.15 format.

arm_scale_q31()

void arm_scale_q31	(	const q31_t *	pSrc,
		q31_t	scaleFract,
		int8_t	shift,
		q31_t *	pDst,
		uint32_t	blockSize
	)

Multiplies a Q31 vector by a scalar.

Parameters

[in]	pSrc	points to the input vector
[in]	scaleFract	fractional portion of the scale value
[in]	shift	number of bits to shift the result by
[out]	pDst	points to the output vector
[in]	blockSize	number of samples in each vector

Scaling and Overflow Behavior

The input data *pSrc and scaleFract are in 1.31 format. These are multiplied to yield a 2.62 intermediate result and this is shifted with saturation to 1.31 format. There is an intermediate shift by 32 to go from the 2.62 to 1.31 format. The shift argument is applied on the 1.31 result and not to the intermediate 2.62 format.

arm_scale_q7()

void arm_scale_q7	(	const q7_t *	pSrc,
		q7_t	scaleFract,
		int8_t	shift,
		q7_t *	pDst,
		uint32_t	blockSize
	)

Multiplies a Q7 vector by a scalar.

Parameters

[in]	pSrc	points to the input vector
[in]	scaleFract	fractional portion of the scale value
[in]	shift	number of bits to shift the result by
[out]	pDst	points to the output vector
[in]	blockSize	number of samples in each vector

Scaling and Overflow Behavior

The input data *pSrc and scaleFract are in 1.7 format. These are multiplied to yield a 2.14 intermediate result and this is shifted with saturation to 1.7 format.