diff options
author | Clyne Sullivan <clyne@bitgloo.com> | 2025-01-29 21:34:25 -0500 |
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committer | Clyne Sullivan <clyne@bitgloo.com> | 2025-01-29 21:34:25 -0500 |
commit | 5b81bc8ccbd342b8566d88fc9f17a73aec03b5b6 (patch) | |
tree | cc57486912cfa74c6440d8b97c28f451ec787d78 /Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_logsumexp_f16.c |
initial commit
Diffstat (limited to 'Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_logsumexp_f16.c')
-rw-r--r-- | Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_logsumexp_f16.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_logsumexp_f16.c b/Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_logsumexp_f16.c new file mode 100644 index 0000000..84d4843 --- /dev/null +++ b/Drivers/CMSIS/DSP/Source/StatisticsFunctions/arm_logsumexp_f16.c @@ -0,0 +1,172 @@ +/* ---------------------------------------------------------------------- + * Project: CMSIS DSP Library + * Title: arm_logsumexp_f16.c + * Description: LogSumExp + * + * $Date: 23 April 2021 + * $Revision: V1.9.0 + * + * Target Processor: Cortex-M and Cortex-A cores + * -------------------------------------------------------------------- */ +/* + * Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved. + * + * SPDX-License-Identifier: Apache-2.0 + * + * Licensed under the Apache License, Version 2.0 (the License); you may + * not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an AS IS BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#include "dsp/statistics_functions_f16.h" + +#if defined(ARM_FLOAT16_SUPPORTED) + +#include <limits.h> +#include <math.h> + + +/** + * @addtogroup LogSumExp + * @{ + */ + + +/** + * @brief Computation of the LogSumExp + * + * In probabilistic computations, the dynamic of the probability values can be very + * wide because they come from gaussian functions. + * To avoid underflow and overflow issues, the values are represented by their log. + * In this representation, multiplying the original exp values is easy : their logs are added. + * But adding the original exp values is requiring some special handling and it is the + * goal of the LogSumExp function. + * + * If the values are x1...xn, the function is computing: + * + * ln(exp(x1) + ... + exp(xn)) and the computation is done in such a way that + * rounding issues are minimised. + * + * The max xm of the values is extracted and the function is computing: + * xm + ln(exp(x1 - xm) + ... + exp(xn - xm)) + * + * @param[in] *in Pointer to an array of input values. + * @param[in] blockSize Number of samples in the input array. + * @return LogSumExp + * + */ + +#if defined(ARM_MATH_MVE_FLOAT16) && !defined(ARM_MATH_AUTOVECTORIZE) + +#include "arm_helium_utils.h" +#include "arm_vec_math_f16.h" + +float16_t arm_logsumexp_f16(const float16_t *in, uint32_t blockSize) +{ + float16_t maxVal; + const float16_t *pIn; + int32_t blkCnt; + _Float16 accum=0.0f16; + _Float16 tmp; + + + arm_max_no_idx_f16((float16_t *) in, blockSize, &maxVal); + + + blkCnt = blockSize; + pIn = in; + + + f16x8_t vSum = vdupq_n_f16(0.0f16); + blkCnt = blockSize >> 3; + while(blkCnt > 0) + { + f16x8_t vecIn = vld1q(pIn); + f16x8_t vecExp; + + vecExp = vexpq_f16(vsubq_n_f16(vecIn, maxVal)); + + vSum = vaddq_f16(vSum, vecExp); + + /* + * Decrement the blockSize loop counter + * Advance vector source and destination pointers + */ + pIn += 8; + blkCnt --; + } + + /* sum + log */ + accum = vecAddAcrossF16Mve(vSum); + + blkCnt = blockSize & 0x7; + while(blkCnt > 0) + { + tmp = *pIn++; + accum += (_Float16)expf((float32_t)((_Float16)tmp - (_Float16)maxVal)); + blkCnt--; + + } + + accum = (_Float16)maxVal + (_Float16)logf((float32_t)accum); + + return (accum); +} + +#else +float16_t arm_logsumexp_f16(const float16_t *in, uint32_t blockSize) +{ + _Float16 maxVal; + _Float16 tmp; + const float16_t *pIn; + uint32_t blkCnt; + _Float16 accum; + + pIn = in; + blkCnt = blockSize; + + maxVal = *pIn++; + blkCnt--; + + while(blkCnt > 0) + { + tmp = *pIn++; + + if (tmp > maxVal) + { + maxVal = tmp; + } + blkCnt--; + + } + + blkCnt = blockSize; + pIn = in; + accum = 0; + while(blkCnt > 0) + { + tmp = *pIn++; + accum += (_Float16)expf((float32_t)((_Float16)tmp - (_Float16)maxVal)); + blkCnt--; + + } + accum = (_Float16)maxVal + (_Float16)logf((float32_t)accum); + + return(accum); +} +#endif /* defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE) */ + +/** + * @} end of LogSumExp group + */ + +#endif /* #if defined(ARM_FLOAT16_SUPPORTED) */ + |