Add ARM Q15 filter library.

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Rob Riggs 2019-06-08 22:41:34 -05:00
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/* ----------------------------------------------------------------------
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
*
* $Date: 19. March 2015
* $Revision: V.1.4.5
*
* Project: CMSIS DSP Library
* Title: arm_fir_fast_q15.c
*
* Description: Q15 Fast FIR filter processing function.
*
* Target Processor: Cortex-M4/Cortex-M3
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* - Neither the name of ARM LIMITED nor the names of its contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* -------------------------------------------------------------------- */
#include "arm_math.h"
/**
* @ingroup groupFilters
*/
/**
* @addtogroup FIR
* @{
*/
/**
* @param[in] *S points to an instance of the Q15 FIR filter structure.
* @param[in] *pSrc points to the block of input data.
* @param[out] *pDst points to the block of output data.
* @param[in] blockSize number of samples to process per call.
* @return none.
*
* <b>Scaling and Overflow Behavior:</b>
* \par
* This fast version uses a 32-bit accumulator with 2.30 format.
* The accumulator maintains full precision of the intermediate multiplication results but provides only a single guard bit.
* Thus, if the accumulator result overflows it wraps around and distorts the result.
* In order to avoid overflows completely the input signal must be scaled down by log2(numTaps) bits.
* The 2.30 accumulator is then truncated to 2.15 format and saturated to yield the 1.15 result.
*
* \par
* Refer to the function <code>arm_fir_q15()</code> for a slower implementation of this function which uses 64-bit accumulation to avoid wrap around distortion. Both the slow and the fast versions use the same instance structure.
* Use the function <code>arm_fir_init_q15()</code> to initialize the filter structure.
*/
void arm_fir_fast_q15(
const arm_fir_instance_q15 * S,
q15_t * pSrc,
q15_t * pDst,
uint32_t blockSize)
{
q15_t *pState = S->pState; /* State pointer */
q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
q15_t *pStateCurnt; /* Points to the current sample of the state */
q31_t acc0, acc1, acc2, acc3; /* Accumulators */
q15_t *pb; /* Temporary pointer for coefficient buffer */
q15_t *px; /* Temporary q31 pointer for SIMD state buffer accesses */
q31_t x0, x1, x2, c0; /* Temporary variables to hold SIMD state and coefficient values */
uint32_t numTaps = S->numTaps; /* Number of taps in the filter */
uint32_t tapCnt, blkCnt; /* Loop counters */
/* S->pState points to state array which contains previous frame (numTaps - 1) samples */
/* pStateCurnt points to the location where the new input data should be written */
pStateCurnt = &(S->pState[(numTaps - 1u)]);
/* Apply loop unrolling and compute 4 output values simultaneously.
* The variables acc0 ... acc3 hold output values that are being computed:
*
* acc0 = b[numTaps-1] * x[n-numTaps-1] + b[numTaps-2] * x[n-numTaps-2] + b[numTaps-3] * x[n-numTaps-3] +...+ b[0] * x[0]
* acc1 = b[numTaps-1] * x[n-numTaps] + b[numTaps-2] * x[n-numTaps-1] + b[numTaps-3] * x[n-numTaps-2] +...+ b[0] * x[1]
* acc2 = b[numTaps-1] * x[n-numTaps+1] + b[numTaps-2] * x[n-numTaps] + b[numTaps-3] * x[n-numTaps-1] +...+ b[0] * x[2]
* acc3 = b[numTaps-1] * x[n-numTaps+2] + b[numTaps-2] * x[n-numTaps+1] + b[numTaps-3] * x[n-numTaps] +...+ b[0] * x[3]
*/
blkCnt = blockSize >> 2;
/* First part of the processing with loop unrolling. Compute 4 outputs at a time.
** a second loop below computes the remaining 1 to 3 samples. */
while(blkCnt > 0u)
{
/* Copy four new input samples into the state buffer.
** Use 32-bit SIMD to move the 16-bit data. Only requires two copies. */
*pStateCurnt++ = *pSrc++;
*pStateCurnt++ = *pSrc++;
*pStateCurnt++ = *pSrc++;
*pStateCurnt++ = *pSrc++;
/* Set all accumulators to zero */
acc0 = 0;
acc1 = 0;
acc2 = 0;
acc3 = 0;
/* Typecast q15_t pointer to q31_t pointer for state reading in q31_t */
px = pState;
/* Typecast q15_t pointer to q31_t pointer for coefficient reading in q31_t */
pb = pCoeffs;
/* Read the first two samples from the state buffer: x[n-N], x[n-N-1] */
x0 = *__SIMD32(px)++;
/* Read the third and forth samples from the state buffer: x[n-N-2], x[n-N-3] */
x2 = *__SIMD32(px)++;
/* Loop over the number of taps. Unroll by a factor of 4.
** Repeat until we've computed numTaps-(numTaps%4) coefficients. */
tapCnt = numTaps >> 2;
while(tapCnt > 0)
{
/* Read the first two coefficients using SIMD: b[N] and b[N-1] coefficients */
c0 = *__SIMD32(pb)++;
/* acc0 += b[N] * x[n-N] + b[N-1] * x[n-N-1] */
acc0 = __SMLAD(x0, c0, acc0);
/* acc2 += b[N] * x[n-N-2] + b[N-1] * x[n-N-3] */
acc2 = __SMLAD(x2, c0, acc2);
/* pack x[n-N-1] and x[n-N-2] */
#ifndef ARM_MATH_BIG_ENDIAN
x1 = __PKHBT(x2, x0, 0);
#else
x1 = __PKHBT(x0, x2, 0);
#endif
/* Read state x[n-N-4], x[n-N-5] */
x0 = _SIMD32_OFFSET(px);
/* acc1 += b[N] * x[n-N-1] + b[N-1] * x[n-N-2] */
acc1 = __SMLADX(x1, c0, acc1);
/* pack x[n-N-3] and x[n-N-4] */
#ifndef ARM_MATH_BIG_ENDIAN
x1 = __PKHBT(x0, x2, 0);
#else
x1 = __PKHBT(x2, x0, 0);
#endif
/* acc3 += b[N] * x[n-N-3] + b[N-1] * x[n-N-4] */
acc3 = __SMLADX(x1, c0, acc3);
/* Read coefficients b[N-2], b[N-3] */
c0 = *__SIMD32(pb)++;
/* acc0 += b[N-2] * x[n-N-2] + b[N-3] * x[n-N-3] */
acc0 = __SMLAD(x2, c0, acc0);
/* Read state x[n-N-6], x[n-N-7] with offset */
x2 = _SIMD32_OFFSET(px + 2u);
/* acc2 += b[N-2] * x[n-N-4] + b[N-3] * x[n-N-5] */
acc2 = __SMLAD(x0, c0, acc2);
/* acc1 += b[N-2] * x[n-N-3] + b[N-3] * x[n-N-4] */
acc1 = __SMLADX(x1, c0, acc1);
/* pack x[n-N-5] and x[n-N-6] */
#ifndef ARM_MATH_BIG_ENDIAN
x1 = __PKHBT(x2, x0, 0);
#else
x1 = __PKHBT(x0, x2, 0);
#endif
/* acc3 += b[N-2] * x[n-N-5] + b[N-3] * x[n-N-6] */
acc3 = __SMLADX(x1, c0, acc3);
/* Update state pointer for next state reading */
px += 4u;
/* Decrement tap count */
tapCnt--;
}
/* If the filter length is not a multiple of 4, compute the remaining filter taps.
** This is always be 2 taps since the filter length is even. */
if((numTaps & 0x3u) != 0u)
{
/* Read last two coefficients */
c0 = *__SIMD32(pb)++;
/* Perform the multiply-accumulates */
acc0 = __SMLAD(x0, c0, acc0);
acc2 = __SMLAD(x2, c0, acc2);
/* pack state variables */
#ifndef ARM_MATH_BIG_ENDIAN
x1 = __PKHBT(x2, x0, 0);
#else
x1 = __PKHBT(x0, x2, 0);
#endif
/* Read last state variables */
x0 = *__SIMD32(px);
/* Perform the multiply-accumulates */
acc1 = __SMLADX(x1, c0, acc1);
/* pack state variables */
#ifndef ARM_MATH_BIG_ENDIAN
x1 = __PKHBT(x0, x2, 0);
#else
x1 = __PKHBT(x2, x0, 0);
#endif
/* Perform the multiply-accumulates */
acc3 = __SMLADX(x1, c0, acc3);
}
/* The results in the 4 accumulators are in 2.30 format. Convert to 1.15 with saturation.
** Then store the 4 outputs in the destination buffer. */
#ifndef ARM_MATH_BIG_ENDIAN
*__SIMD32(pDst)++ =
__PKHBT(__SSAT((acc0 >> 15), 16), __SSAT((acc1 >> 15), 16), 16);
*__SIMD32(pDst)++ =
__PKHBT(__SSAT((acc2 >> 15), 16), __SSAT((acc3 >> 15), 16), 16);
#else
*__SIMD32(pDst)++ =
__PKHBT(__SSAT((acc1 >> 15), 16), __SSAT((acc0 >> 15), 16), 16);
*__SIMD32(pDst)++ =
__PKHBT(__SSAT((acc3 >> 15), 16), __SSAT((acc2 >> 15), 16), 16);
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
/* Advance the state pointer by 4 to process the next group of 4 samples */
pState = pState + 4u;
/* Decrement the loop counter */
blkCnt--;
}
/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
** No loop unrolling is used. */
blkCnt = blockSize % 0x4u;
while(blkCnt > 0u)
{
/* Copy two samples into state buffer */
*pStateCurnt++ = *pSrc++;
/* Set the accumulator to zero */
acc0 = 0;
/* Use SIMD to hold states and coefficients */
px = pState;
pb = pCoeffs;
tapCnt = numTaps >> 1u;
do
{
acc0 += (q31_t) * px++ * *pb++;
acc0 += (q31_t) * px++ * *pb++;
tapCnt--;
}
while(tapCnt > 0u);
/* The result is in 2.30 format. Convert to 1.15 with saturation.
** Then store the output in the destination buffer. */
*pDst++ = (q15_t) (__SSAT((acc0 >> 15), 16));
/* Advance state pointer by 1 for the next sample */
pState = pState + 1u;
/* Decrement the loop counter */
blkCnt--;
}
/* Processing is complete.
** Now copy the last numTaps - 1 samples to the satrt of the state buffer.
** This prepares the state buffer for the next function call. */
/* Points to the start of the state buffer */
pStateCurnt = S->pState;
/* Calculation of count for copying integer writes */
tapCnt = (numTaps - 1u) >> 2;
while(tapCnt > 0u)
{
*pStateCurnt++ = *pState++;
*pStateCurnt++ = *pState++;
*pStateCurnt++ = *pState++;
*pStateCurnt++ = *pState++;
tapCnt--;
}
/* Calculation of count for remaining q15_t data */
tapCnt = (numTaps - 1u) % 0x4u;
/* copy remaining data */
while(tapCnt > 0u)
{
*pStateCurnt++ = *pState++;
/* Decrement the loop counter */
tapCnt--;
}
}
/**
* @} end of FIR group
*/

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/* ----------------------------------------------------------------------
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
*
* $Date: 19. March 2015
* $Revision: V.1.4.5
*
* Project: CMSIS DSP Library
* Title: arm_fir_init_q15.c
*
* Description: Q15 FIR filter initialization function.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* - Neither the name of ARM LIMITED nor the names of its contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* ------------------------------------------------------------------- */
#include "arm_math.h"
/**
* @ingroup groupFilters
*/
/**
* @addtogroup FIR
* @{
*/
/**
* @param[in,out] *S points to an instance of the Q15 FIR filter structure.
* @param[in] numTaps Number of filter coefficients in the filter. Must be even and greater than or equal to 4.
* @param[in] *pCoeffs points to the filter coefficients buffer.
* @param[in] *pState points to the state buffer.
* @param[in] blockSize is number of samples processed per call.
* @return The function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if
* <code>numTaps</code> is not greater than or equal to 4 and even.
*
* <b>Description:</b>
* \par
* <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:
* <pre>
* {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}
* </pre>
* Note that <code>numTaps</code> must be even and greater than or equal to 4.
* To implement an odd length filter simply increase <code>numTaps</code> by 1 and set the last coefficient to zero.
* For example, to implement a filter with <code>numTaps=3</code> and coefficients
* <pre>
* {0.3, -0.8, 0.3}
* </pre>
* set <code>numTaps=4</code> and use the coefficients:
* <pre>
* {0.3, -0.8, 0.3, 0}.
* </pre>
* Similarly, to implement a two point filter
* <pre>
* {0.3, -0.3}
* </pre>
* set <code>numTaps=4</code> and use the coefficients:
* <pre>
* {0.3, -0.3, 0, 0}.
* </pre>
* \par
* <code>pState</code> points to the array of state variables.
* <code>pState</code> is of length <code>numTaps+blockSize</code>, when running on Cortex-M4 and Cortex-M3 and is of length <code>numTaps+blockSize-1</code>, when running on Cortex-M0 where <code>blockSize</code> is the number of input samples processed by each call to <code>arm_fir_q15()</code>.
*/
arm_status arm_fir_init_q15(
arm_fir_instance_q15 * S,
uint16_t numTaps,
q15_t * pCoeffs,
q15_t * pState,
uint32_t blockSize)
{
arm_status status;
#ifndef ARM_MATH_CM0_FAMILY
/* Run the below code for Cortex-M4 and Cortex-M3 */
/* The Number of filter coefficients in the filter must be even and at least 4 */
if(numTaps & 0x1u)
{
status = ARM_MATH_ARGUMENT_ERROR;
}
else
{
/* Assign filter taps */
S->numTaps = numTaps;
/* Assign coefficient pointer */
S->pCoeffs = pCoeffs;
/* Clear the state buffer. The size is always (blockSize + numTaps ) */
memset(pState, 0, (numTaps + (blockSize)) * sizeof(q15_t));
/* Assign state pointer */
S->pState = pState;
status = ARM_MATH_SUCCESS;
}
return (status);
#else
/* Run the below code for Cortex-M0 */
/* Assign filter taps */
S->numTaps = numTaps;
/* Assign coefficient pointer */
S->pCoeffs = pCoeffs;
/* Clear the state buffer. The size is always (blockSize + numTaps - 1) */
memset(pState, 0, (numTaps + (blockSize - 1u)) * sizeof(q15_t));
/* Assign state pointer */
S->pState = pState;
status = ARM_MATH_SUCCESS;
return (status);
#endif /* #ifndef ARM_MATH_CM0_FAMILY */
}
/**
* @} end of FIR group
*/

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/* ----------------------------------------------------------------------
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
*
* $Date: 19. March 2015
* $Revision: V.1.4.5
*
* Project: CMSIS DSP Library
* Title: arm_offset_q15.c
*
* Description: Q15 vector offset.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* - Neither the name of ARM LIMITED nor the names of its contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* -------------------------------------------------------------------- */
#include "arm_math.h"
/**
* @ingroup groupMath
*/
/**
* @addtogroup offset
* @{
*/
/**
* @brief Adds a constant offset to a Q15 vector.
* @param[in] *pSrc points to the input vector
* @param[in] offset is the offset to be added
* @param[out] *pDst points to the output vector
* @param[in] blockSize number of samples in the vector
* @return none.
*
* <b>Scaling and Overflow Behavior:</b>
* \par
* The function uses saturating arithmetic.
* Results outside of the allowable Q15 range [0x8000 0x7FFF] are saturated.
*/
void arm_offset_q15(
q15_t * pSrc,
q15_t offset,
q15_t * pDst,
uint32_t blockSize)
{
uint32_t blkCnt; /* loop counter */
#ifndef ARM_MATH_CM0_FAMILY
/* Run the below code for Cortex-M4 and Cortex-M3 */
q31_t offset_packed; /* Offset packed to 32 bit */
/*loop Unrolling */
blkCnt = blockSize >> 2u;
/* Offset is packed to 32 bit in order to use SIMD32 for addition */
offset_packed = __PKHBT(offset, offset, 16);
/* First part of the processing with loop unrolling. Compute 4 outputs at a time.
** a second loop below computes the remaining 1 to 3 samples. */
while(blkCnt > 0u)
{
/* C = A + offset */
/* Add offset and then store the results in the destination buffer, 2 samples at a time. */
*__SIMD32(pDst)++ = __QADD16(*__SIMD32(pSrc)++, offset_packed);
*__SIMD32(pDst)++ = __QADD16(*__SIMD32(pSrc)++, offset_packed);
/* Decrement the loop counter */
blkCnt--;
}
/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
** No loop unrolling is used. */
blkCnt = blockSize % 0x4u;
while(blkCnt > 0u)
{
/* C = A + offset */
/* Add offset and then store the results in the destination buffer. */
*pDst++ = (q15_t) __QADD16(*pSrc++, offset);
/* Decrement the loop counter */
blkCnt--;
}
#else
/* Run the below code for Cortex-M0 */
/* Initialize blkCnt with number of samples */
blkCnt = blockSize;
while(blkCnt > 0u)
{
/* C = A + offset */
/* Add offset and then store the results in the destination buffer. */
*pDst++ = (q15_t) __SSAT(((q31_t) * pSrc++ + offset), 16);
/* Decrement the loop counter */
blkCnt--;
}
#endif /* #ifndef ARM_MATH_CM0_FAMILY */
}
/**
* @} end of offset group
*/

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/* ----------------------------------------------------------------------------
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
*
* $Date: 19. March 2015
* $Revision: V.1.4.5
*
* Project: CMSIS DSP Library
* Title: arm_q15_to_float.c
*
* Description: Converts the elements of the Q15 vector to floating-point vector.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* - Neither the name of ARM LIMITED nor the names of its contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* ---------------------------------------------------------------------------- */
#include "arm_math.h"
/**
* @ingroup groupSupport
*/
/**
* @defgroup q15_to_x Convert 16-bit Integer value
*/
/**
* @addtogroup q15_to_x
* @{
*/
/**
* @brief Converts the elements of the Q15 vector to floating-point vector.
* @param[in] *pSrc points to the Q15 input vector
* @param[out] *pDst points to the floating-point output vector
* @param[in] blockSize length of the input vector
* @return none.
*
* \par Description:
*
* The equation used for the conversion process is:
*
* <pre>
* pDst[n] = (float32_t) pSrc[n] / 32768; 0 <= n < blockSize.
* </pre>
*
*/
void arm_q15_to_float(
q15_t * pSrc,
float32_t * pDst,
uint32_t blockSize)
{
q15_t *pIn = pSrc; /* Src pointer */
uint32_t blkCnt; /* loop counter */
#ifndef ARM_MATH_CM0_FAMILY
/* Run the below code for Cortex-M4 and Cortex-M3 */
/*loop Unrolling */
blkCnt = blockSize >> 2u;
/* First part of the processing with loop unrolling. Compute 4 outputs at a time.
** a second loop below computes the remaining 1 to 3 samples. */
while(blkCnt > 0u)
{
/* C = (float32_t) A / 32768 */
/* convert from q15 to float and then store the results in the destination buffer */
*pDst++ = ((float32_t) * pIn++ / 32768.0f);
*pDst++ = ((float32_t) * pIn++ / 32768.0f);
*pDst++ = ((float32_t) * pIn++ / 32768.0f);
*pDst++ = ((float32_t) * pIn++ / 32768.0f);
/* Decrement the loop counter */
blkCnt--;
}
/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
** No loop unrolling is used. */
blkCnt = blockSize % 0x4u;
#else
/* Run the below code for Cortex-M0 */
/* Loop over blockSize number of values */
blkCnt = blockSize;
#endif /* #ifndef ARM_MATH_CM0_FAMILY */
while(blkCnt > 0u)
{
/* C = (float32_t) A / 32768 */
/* convert from q15 to float and then store the results in the destination buffer */
*pDst++ = ((float32_t) * pIn++ / 32768.0f);
/* Decrement the loop counter */
blkCnt--;
}
}
/**
* @} end of q15_to_x group
*/