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.
The functions support in-place computation allowing the source and destination pointers to reference the same memory buffer.
void arm_shift_q15 |
( |
const q15_t * |
pSrc, |
|
|
int8_t |
shiftBits, |
|
|
q15_t * |
pDst, |
|
|
uint32_t |
blockSize |
|
) |
| |
- 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 each vector |
- Returns
- none
- Scaling and Overflow Behavior
- The function uses saturating arithmetic. Results outside of the allowable Q15 range [0x8000 0x7FFF] are saturated.
void arm_shift_q31 |
( |
const q31_t * |
pSrc, |
|
|
int8_t |
shiftBits, |
|
|
q31_t * |
pDst, |
|
|
uint32_t |
blockSize |
|
) |
| |
- 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] are saturated.
void arm_shift_q7 |
( |
const q7_t * |
pSrc, |
|
|
int8_t |
shiftBits, |
|
|
q7_t * |
pDst, |
|
|
uint32_t |
blockSize |
|
) |
| |
- 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 each vector |
- Returns
- none
- onditions for optimum performance
- Input and output buffers should be aligned by 32-bit
- Scaling and Overflow Behavior
- The function uses saturating arithmetic. Results outside of the allowable Q7 range [0x80 0x7F] are saturated.