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Diffstat (limited to 'platform/CMSIS/DSP_Lib/Source/TransformFunctions/arm_dct4_q31.c')
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1 files changed, 395 insertions, 0 deletions
diff --git a/platform/CMSIS/DSP_Lib/Source/TransformFunctions/arm_dct4_q31.c b/platform/CMSIS/DSP_Lib/Source/TransformFunctions/arm_dct4_q31.c new file mode 100644 index 0000000..6145791 --- /dev/null +++ b/platform/CMSIS/DSP_Lib/Source/TransformFunctions/arm_dct4_q31.c @@ -0,0 +1,395 @@ +/* ---------------------------------------------------------------------- +* Copyright (C) 2010-2014 ARM Limited. All rights reserved. +* +* $Date: 31. July 2014 +* $Revision: V1.4.4 +* +* Project: CMSIS DSP Library +* Title: arm_dct4_q31.c +* +* Description: Processing function of DCT4 & IDCT4 Q31. +* +* 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" + +/** + * @addtogroup DCT4_IDCT4 + * @{ + */ + +/** + * @brief Processing function for the Q31 DCT4/IDCT4. + * @param[in] *S points to an instance of the Q31 DCT4 structure. + * @param[in] *pState points to state buffer. + * @param[in,out] *pInlineBuffer points to the in-place input and output buffer. + * @return none. + * \par Input an output formats: + * Input samples need to be downscaled by 1 bit to avoid saturations in the Q31 DCT process, + * as the conversion from DCT2 to DCT4 involves one subtraction. + * Internally inputs are downscaled in the RFFT process function to avoid overflows. + * Number of bits downscaled, depends on the size of the transform. + * The input and output formats for different DCT sizes and number of bits to upscale are mentioned in the table below: + * + * \image html dct4FormatsQ31Table.gif + */ + +void arm_dct4_q31( + const arm_dct4_instance_q31 * S, + q31_t * pState, + q31_t * pInlineBuffer) +{ + uint16_t i; /* Loop counter */ + q31_t *weights = S->pTwiddle; /* Pointer to the Weights table */ + q31_t *cosFact = S->pCosFactor; /* Pointer to the cos factors table */ + q31_t *pS1, *pS2, *pbuff; /* Temporary pointers for input buffer and pState buffer */ + q31_t in; /* Temporary variable */ + + + /* DCT4 computation involves DCT2 (which is calculated using RFFT) + * along with some pre-processing and post-processing. + * Computational procedure is explained as follows: + * (a) Pre-processing involves multiplying input with cos factor, + * r(n) = 2 * u(n) * cos(pi*(2*n+1)/(4*n)) + * where, + * r(n) -- output of preprocessing + * u(n) -- input to preprocessing(actual Source buffer) + * (b) Calculation of DCT2 using FFT is divided into three steps: + * Step1: Re-ordering of even and odd elements of input. + * Step2: Calculating FFT of the re-ordered input. + * Step3: Taking the real part of the product of FFT output and weights. + * (c) Post-processing - DCT4 can be obtained from DCT2 output using the following equation: + * Y4(k) = Y2(k) - Y4(k-1) and Y4(-1) = Y4(0) + * where, + * Y4 -- DCT4 output, Y2 -- DCT2 output + * (d) Multiplying the output with the normalizing factor sqrt(2/N). + */ + + /*-------- Pre-processing ------------*/ + /* Multiplying input with cos factor i.e. r(n) = 2 * x(n) * cos(pi*(2*n+1)/(4*n)) */ + arm_mult_q31(pInlineBuffer, cosFact, pInlineBuffer, S->N); + arm_shift_q31(pInlineBuffer, 1, pInlineBuffer, S->N); + + /* ---------------------------------------------------------------- + * Step1: Re-ordering of even and odd elements as + * pState[i] = pInlineBuffer[2*i] and + * pState[N-i-1] = pInlineBuffer[2*i+1] where i = 0 to N/2 + ---------------------------------------------------------------------*/ + + /* pS1 initialized to pState */ + pS1 = pState; + + /* pS2 initialized to pState+N-1, so that it points to the end of the state buffer */ + pS2 = pState + (S->N - 1u); + + /* pbuff initialized to input buffer */ + pbuff = pInlineBuffer; + +#ifndef ARM_MATH_CM0_FAMILY + + /* Run the below code for Cortex-M4 and Cortex-M3 */ + + /* Initializing the loop counter to N/2 >> 2 for loop unrolling by 4 */ + i = S->Nby2 >> 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. */ + do + { + /* Re-ordering of even and odd elements */ + /* pState[i] = pInlineBuffer[2*i] */ + *pS1++ = *pbuff++; + /* pState[N-i-1] = pInlineBuffer[2*i+1] */ + *pS2-- = *pbuff++; + + *pS1++ = *pbuff++; + *pS2-- = *pbuff++; + + *pS1++ = *pbuff++; + *pS2-- = *pbuff++; + + *pS1++ = *pbuff++; + *pS2-- = *pbuff++; + + /* Decrement the loop counter */ + i--; + } while(i > 0u); + + /* pbuff initialized to input buffer */ + pbuff = pInlineBuffer; + + /* pS1 initialized to pState */ + pS1 = pState; + + /* Initializing the loop counter to N/4 instead of N for loop unrolling */ + i = S->N >> 2u; + + /* Processing with loop unrolling 4 times as N is always multiple of 4. + * Compute 4 outputs at a time */ + do + { + /* Writing the re-ordered output back to inplace input buffer */ + *pbuff++ = *pS1++; + *pbuff++ = *pS1++; + *pbuff++ = *pS1++; + *pbuff++ = *pS1++; + + /* Decrement the loop counter */ + i--; + } while(i > 0u); + + + /* --------------------------------------------------------- + * Step2: Calculate RFFT for N-point input + * ---------------------------------------------------------- */ + /* pInlineBuffer is real input of length N , pState is the complex output of length 2N */ + arm_rfft_q31(S->pRfft, pInlineBuffer, pState); + + /*---------------------------------------------------------------------- + * Step3: Multiply the FFT output with the weights. + *----------------------------------------------------------------------*/ + arm_cmplx_mult_cmplx_q31(pState, weights, pState, S->N); + + /* The output of complex multiplication is in 3.29 format. + * Hence changing the format of N (i.e. 2*N elements) complex numbers to 1.31 format by shifting left by 2 bits. */ + arm_shift_q31(pState, 2, pState, S->N * 2); + + /* ----------- Post-processing ---------- */ + /* DCT-IV can be obtained from DCT-II by the equation, + * Y4(k) = Y2(k) - Y4(k-1) and Y4(-1) = Y4(0) + * Hence, Y4(0) = Y2(0)/2 */ + /* Getting only real part from the output and Converting to DCT-IV */ + + /* Initializing the loop counter to N >> 2 for loop unrolling by 4 */ + i = (S->N - 1u) >> 2u; + + /* pbuff initialized to input buffer. */ + pbuff = pInlineBuffer; + + /* pS1 initialized to pState */ + pS1 = pState; + + /* Calculating Y4(0) from Y2(0) using Y4(0) = Y2(0)/2 */ + in = *pS1++ >> 1u; + /* input buffer acts as inplace, so output values are stored in the input itself. */ + *pbuff++ = in; + + /* pState pointer is incremented twice as the real values are located alternatively in the array */ + pS1++; + + /* 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. */ + do + { + /* Calculating Y4(1) to Y4(N-1) from Y2 using equation Y4(k) = Y2(k) - Y4(k-1) */ + /* pState pointer (pS1) is incremented twice as the real values are located alternatively in the array */ + in = *pS1++ - in; + *pbuff++ = in; + /* points to the next real value */ + pS1++; + + in = *pS1++ - in; + *pbuff++ = in; + pS1++; + + in = *pS1++ - in; + *pbuff++ = in; + pS1++; + + in = *pS1++ - in; + *pbuff++ = in; + pS1++; + + /* Decrement the loop counter */ + i--; + } while(i > 0u); + + /* If the blockSize is not a multiple of 4, compute any remaining output samples here. + ** No loop unrolling is used. */ + i = (S->N - 1u) % 0x4u; + + while(i > 0u) + { + /* Calculating Y4(1) to Y4(N-1) from Y2 using equation Y4(k) = Y2(k) - Y4(k-1) */ + /* pState pointer (pS1) is incremented twice as the real values are located alternatively in the array */ + in = *pS1++ - in; + *pbuff++ = in; + /* points to the next real value */ + pS1++; + + /* Decrement the loop counter */ + i--; + } + + + /*------------ Normalizing the output by multiplying with the normalizing factor ----------*/ + + /* Initializing the loop counter to N/4 instead of N for loop unrolling */ + i = S->N >> 2u; + + /* pbuff initialized to the pInlineBuffer(now contains the output values) */ + pbuff = pInlineBuffer; + + /* Processing with loop unrolling 4 times as N is always multiple of 4. Compute 4 outputs at a time */ + do + { + /* Multiplying pInlineBuffer with the normalizing factor sqrt(2/N) */ + in = *pbuff; + *pbuff++ = ((q31_t) (((q63_t) in * S->normalize) >> 31)); + + in = *pbuff; + *pbuff++ = ((q31_t) (((q63_t) in * S->normalize) >> 31)); + + in = *pbuff; + *pbuff++ = ((q31_t) (((q63_t) in * S->normalize) >> 31)); + + in = *pbuff; + *pbuff++ = ((q31_t) (((q63_t) in * S->normalize) >> 31)); + + /* Decrement the loop counter */ + i--; + } while(i > 0u); + + +#else + + /* Run the below code for Cortex-M0 */ + + /* Initializing the loop counter to N/2 */ + i = S->Nby2; + + do + { + /* Re-ordering of even and odd elements */ + /* pState[i] = pInlineBuffer[2*i] */ + *pS1++ = *pbuff++; + /* pState[N-i-1] = pInlineBuffer[2*i+1] */ + *pS2-- = *pbuff++; + + /* Decrement the loop counter */ + i--; + } while(i > 0u); + + /* pbuff initialized to input buffer */ + pbuff = pInlineBuffer; + + /* pS1 initialized to pState */ + pS1 = pState; + + /* Initializing the loop counter */ + i = S->N; + + do + { + /* Writing the re-ordered output back to inplace input buffer */ + *pbuff++ = *pS1++; + + /* Decrement the loop counter */ + i--; + } while(i > 0u); + + + /* --------------------------------------------------------- + * Step2: Calculate RFFT for N-point input + * ---------------------------------------------------------- */ + /* pInlineBuffer is real input of length N , pState is the complex output of length 2N */ + arm_rfft_q31(S->pRfft, pInlineBuffer, pState); + + /*---------------------------------------------------------------------- + * Step3: Multiply the FFT output with the weights. + *----------------------------------------------------------------------*/ + arm_cmplx_mult_cmplx_q31(pState, weights, pState, S->N); + + /* The output of complex multiplication is in 3.29 format. + * Hence changing the format of N (i.e. 2*N elements) complex numbers to 1.31 format by shifting left by 2 bits. */ + arm_shift_q31(pState, 2, pState, S->N * 2); + + /* ----------- Post-processing ---------- */ + /* DCT-IV can be obtained from DCT-II by the equation, + * Y4(k) = Y2(k) - Y4(k-1) and Y4(-1) = Y4(0) + * Hence, Y4(0) = Y2(0)/2 */ + /* Getting only real part from the output and Converting to DCT-IV */ + + /* pbuff initialized to input buffer. */ + pbuff = pInlineBuffer; + + /* pS1 initialized to pState */ + pS1 = pState; + + /* Calculating Y4(0) from Y2(0) using Y4(0) = Y2(0)/2 */ + in = *pS1++ >> 1u; + /* input buffer acts as inplace, so output values are stored in the input itself. */ + *pbuff++ = in; + + /* pState pointer is incremented twice as the real values are located alternatively in the array */ + pS1++; + + /* Initializing the loop counter */ + i = (S->N - 1u); + + while(i > 0u) + { + /* Calculating Y4(1) to Y4(N-1) from Y2 using equation Y4(k) = Y2(k) - Y4(k-1) */ + /* pState pointer (pS1) is incremented twice as the real values are located alternatively in the array */ + in = *pS1++ - in; + *pbuff++ = in; + /* points to the next real value */ + pS1++; + + /* Decrement the loop counter */ + i--; + } + + + /*------------ Normalizing the output by multiplying with the normalizing factor ----------*/ + + /* Initializing the loop counter */ + i = S->N; + + /* pbuff initialized to the pInlineBuffer(now contains the output values) */ + pbuff = pInlineBuffer; + + do + { + /* Multiplying pInlineBuffer with the normalizing factor sqrt(2/N) */ + in = *pbuff; + *pbuff++ = ((q31_t) (((q63_t) in * S->normalize) >> 31)); + + /* Decrement the loop counter */ + i--; + } while(i > 0u); + +#endif /* #ifndef ARM_MATH_CM0_FAMILY */ + +} + +/** + * @} end of DCT4_IDCT4 group + */ |