CMSIS DSP Software Library: Vector Shift

Functions

# Vector Shift
[Basic Math Functions]

## Functions

void | arm_shift_q31 (q31_t *pSrc, int8_t shiftBits, q31_t *pDst, uint32_t blockSize)
void | arm_shift_q15 (q15_t *pSrc, int8_t shiftBits, q15_t *pDst, uint32_t blockSize)
void | arm_shift_q7 (q7_t *pSrc, int8_t shiftBits, q7_t *pDst, uint32_t blockSize)

## 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:

         pDst[n] = pSrc[n] << shift,   0 <= n < blockSize.

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.

## Function Documentation

void arm_shift_q31 | ( | q31_t * | pSrc,
|  | int8_t | shiftBits,
|  | q31_t * | pDst,
|  | uint32_t | blockSize
| ) |  |

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

Parameters:

  [in] | *pSrc | points to the input vector
  [in] | shiftBits | number of bits to shift. A positive value shifts left; a negative value shifts right.
  [out] | *pDst | points to the output vector
  [in] | blockSize | number of samples in the vector

Returns:
  none.

Scaling and Overflow Behavior:

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

Definition at line 73 of file arm_shift_q31.c.

void arm_shift_q15 | ( | q15_t * | pSrc,
|  | int8_t | shiftBits,
|  | q15_t * | pDst,
|  | uint32_t | blockSize
| ) |  |

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

Parameters:

  [in] | *pSrc | points to the input vector
  [in] | shiftBits | number of bits to shift. A positive value shifts left; a negative value shifts right.
  [out] | *pDst | points to the output vector
  [in] | blockSize | number of samples in the vector

Returns:
  none.

Scaling and Overflow Behavior:

  The function uses saturating arithmetic. Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated.

Definition at line 58 of file arm_shift_q15.c.

void arm_shift_q7 | ( | q7_t * | pSrc,
|  | int8_t | shiftBits,
|  | q7_t * | pDst,
|  | uint32_t | blockSize
| ) |  |

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

Parameters:

  [in] | *pSrc | points to the input vector
  [in] | shiftBits | number of bits to shift. A positive value shifts left; a negative value shifts right.
  [out] | *pDst | points to the output vector
  [in] | blockSize | number of samples in the vector

Returns:
  none.

Scaling and Overflow Behavior:

  The function uses saturating arithmetic. Results outside of the allowable Q7 range [0x8 0x7F] will be saturated.

Definition at line 59 of file arm_shift_q7.c.

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