Vector ScaleBasic Math Functions

Functions

void arm_scale_f32 (float32_t *pSrc, float32_t scale, float32_t *pDst, uint32_t blockSize)
 Multiplies a floating-point vector by a scalar.
 
void arm_scale_q15 (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 (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 (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

void arm_scale_f32 ( float32_t *  pSrc,
float32_t  scale,
float32_t *  pDst,
uint32_t  blockSize 
)
Parameters
[in]*pSrcpoints to the input vector
[in]scalescale factor to be applied
[out]*pDstpoints to the output vector
[in]blockSizenumber of samples in the vector
Returns
none.

References blockSize.

Referenced by arm_dct4_f32(), and main().

void arm_scale_q15 ( q15_t *  pSrc,
q15_t  scaleFract,
int8_t  shift,
q15_t *  pDst,
uint32_t  blockSize 
)
Parameters
[in]*pSrcpoints to the input vector
[in]scaleFractfractional portion of the scale value
[in]shiftnumber of bits to shift the result by
[out]*pDstpoints to the output vector
[in]blockSizenumber of samples in the vector
Returns
none.

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.

References __PKHBT, __SIMD32, and blockSize.

void arm_scale_q31 ( q31_t *  pSrc,
q31_t  scaleFract,
int8_t  shift,
q31_t *  pDst,
uint32_t  blockSize 
)
Parameters
[in]*pSrcpoints to the input vector
[in]scaleFractfractional portion of the scale value
[in]shiftnumber of bits to shift the result by
[out]*pDstpoints to the output vector
[in]blockSizenumber of samples in the vector
Returns
none.

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.

References blockSize.

Referenced by main().

void arm_scale_q7 ( q7_t *  pSrc,
q7_t  scaleFract,
int8_t  shift,
q7_t *  pDst,
uint32_t  blockSize 
)
Parameters
[in]*pSrcpoints to the input vector
[in]scaleFractfractional portion of the scale value
[in]shiftnumber of bits to shift the result by
[out]*pDstpoints to the output vector
[in]blockSizenumber of samples in the vector
Returns
none.

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.

References __PACKq7, __SIMD32, and blockSize.