Diff: cmsis_dsp/TransformFunctions/arm_dct4_q15.c

Revision:

5:a912b042151f

Parent:

4:9cee975aadce

--- a/cmsis_dsp/TransformFunctions/arm_dct4_q15.c	Mon Jun 23 09:30:09 2014 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,394 +0,0 @@
-/* ----------------------------------------------------------------------    
-* Copyright (C) 2010-2013 ARM Limited. All rights reserved.    
-*    
-* $Date:        17. January 2013  
-* $Revision: 	V1.4.1  
-*    
-* Project: 	    CMSIS DSP Library    
-* Title:	    arm_dct4_q15.c    
-*    
-* Description:	Processing function of DCT4 & IDCT4 Q15.    
-*    
-* 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 Q15 DCT4/IDCT4.   
- * @param[in]       *S             points to an instance of the Q15 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:    
- * 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 dct4FormatsQ15Table.gif    
- */
-
-void arm_dct4_q15(
-  const arm_dct4_instance_q15 * S,
-  q15_t * pState,
-  q15_t * pInlineBuffer)
-{
-  uint32_t i;                                    /* Loop counter */
-  q15_t *weights = S->pTwiddle;                  /* Pointer to the Weights table */
-  q15_t *cosFact = S->pCosFactor;                /* Pointer to the cos factors table */
-  q15_t *pS1, *pS2, *pbuff;                      /* Temporary pointers for input buffer and pState buffer */
-  q15_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_q15(pInlineBuffer, cosFact, pInlineBuffer, S->N);
-  arm_shift_q15(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 = (uint32_t) 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 = (uint32_t) 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_q15(S->pRfft, pInlineBuffer, pState);
-
- /*----------------------------------------------------------------------    
-  *  Step3: Multiply the FFT output with the weights.    
-  *----------------------------------------------------------------------*/
-  arm_cmplx_mult_cmplx_q15(pState, weights, pState, S->N);
-
-  /* The output of complex multiplication is in 3.13 format.    
-   * Hence changing the format of N (i.e. 2*N elements) complex numbers to 1.15 format by shifting left by 2 bits. */
-  arm_shift_q15(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 = ((uint32_t) 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 = ((uint32_t) 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 = (uint32_t) 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++ = ((q15_t) (((q31_t) in * S->normalize) >> 15));
-
-    in = *pbuff;
-    *pbuff++ = ((q15_t) (((q31_t) in * S->normalize) >> 15));
-
-    in = *pbuff;
-    *pbuff++ = ((q15_t) (((q31_t) in * S->normalize) >> 15));
-
-    in = *pbuff;
-    *pbuff++ = ((q15_t) (((q31_t) in * S->normalize) >> 15));
-
-    /* Decrement the loop counter */
-    i--;
-  } while(i > 0u);
-
-
-#else
-
-  /* Run the below code for Cortex-M0 */
-
-  /* Initializing the loop counter to N/2 */
-  i = (uint32_t) 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 = (uint32_t) 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_q15(S->pRfft, pInlineBuffer, pState);
-
- /*----------------------------------------------------------------------    
-  *  Step3: Multiply the FFT output with the weights.    
-  *----------------------------------------------------------------------*/
-  arm_cmplx_mult_cmplx_q15(pState, weights, pState, S->N);
-
-  /* The output of complex multiplication is in 3.13 format.    
-   * Hence changing the format of N (i.e. 2*N elements) complex numbers to 1.15 format by shifting left by 2 bits. */
-  arm_shift_q15(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 */
-  i = ((uint32_t) S->N - 1u);
-
-  /* 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++;
-
-  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++;
-
-    /* Decrement the loop counter */
-    i--;
-  } while(i > 0u);
-
-   /*------------ Normalizing the output by multiplying with the normalizing factor ----------*/
-
-  /* Initializing the loop counter */
-  i = (uint32_t) 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++ = ((q15_t) (((q31_t) in * S->normalize) >> 15));
-
-    /* Decrement the loop counter */
-    i--;
-  } while(i > 0u);
-
-#endif /* #ifndef ARM_MATH_CM0_FAMILY */
-
-}
-
-/**    
-   * @} end of DCT4_IDCT4 group    
-   */