Diff: src/Cortex-M4-M3/TransformFunctions/arm_rfft_q15.c

Revision:

0:1014af42efd9

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Cortex-M4-M3/TransformFunctions/arm_rfft_q15.c	Thu Mar 10 15:07:50 2011 +0000
@@ -0,0 +1,292 @@
+/* ----------------------------------------------------------------------  
+* Copyright (C) 2010 ARM Limited. All rights reserved.  
+*  
+* $Date:        29. November 2010  
+* $Revision: 	V1.0.3  
+*  
+* Project: 	    CMSIS DSP Library  
+* Title:	    arm_rfft_q15.c  
+*  
+* Description:	RFFT & RIFFT Q15 process function  
+*  
+*  
+* Target Processor: Cortex-M4/Cortex-M3
+*  
+* Version 1.0.3 2010/11/29 
+*    Re-organized the CMSIS folders and updated documentation.  
+*   
+* Version 1.0.2 2010/11/11  
+*    Documentation updated.   
+*  
+* Version 1.0.1 2010/10/05   
+*    Production release and review comments incorporated.  
+*  
+* Version 1.0.0 2010/09/20   
+*    Production release and review comments incorporated  
+*  
+* Version 0.0.7  2010/06/10   
+*    Misra-C changes done  
+* -------------------------------------------------------------------- */ 
+ 
+ 
+#include "arm_math.h" 
+ 
+/*--------------------------------------------------------------------  
+*		Internal functions prototypes  
+--------------------------------------------------------------------*/ 
+ 
+void arm_split_rfft_q15( 
+  q15_t * pSrc, 
+  uint32_t fftLen, 
+  q15_t * pATable, 
+  q15_t * pBTable, 
+  q15_t * pDst, 
+  uint32_t modifier); 
+ 
+void arm_split_rifft_q15( 
+  q15_t * pSrc, 
+  uint32_t fftLen, 
+  q15_t * pATable, 
+  q15_t * pBTable, 
+  q15_t * pDst, 
+  uint32_t modifier); 
+ 
+/**  
+ * @addtogroup RFFT_RIFFT  
+ * @{  
+ */ 
+ 
+/**  
+ * @brief Processing function for the Q15 RFFT/RIFFT. 
+ * @param[in]  *S    points to an instance of the Q15 RFFT/RIFFT structure. 
+ * @param[in]  *pSrc points to the input buffer. 
+ * @param[out] *pDst points to the output buffer. 
+ * @return none. 
+ *  
+ * \par Input an output formats: 
+ * \par  
+ * Internally input is downscaled by 2 for every stage to avoid saturations inside CFFT/CIFFT process.  
+ * Hence the output format is different for different RFFT sizes.  
+ * The input and output formats for different RFFT sizes and number of bits to upscale are mentioned in the tables below for RFFT and RIFFT: 
+ * \par  
+ * \image html RFFTQ15.gif "Input and Output Formats for Q15 RFFT"  
+ * \par  
+ * \image html RIFFTQ15.gif "Input and Output Formats for Q15 RIFFT"  
+ */ 
+ 
+void arm_rfft_q15( 
+  const arm_rfft_instance_q15 * S, 
+  q15_t * pSrc, 
+  q15_t * pDst) 
+{ 
+  const arm_cfft_radix4_instance_q15 *S_CFFT = S->pCfft; 
+ 
+  /* Calculation of RIFFT of input */ 
+  if(S->ifftFlagR == 1u) 
+  { 
+    /*  Real IFFT core process */ 
+    arm_split_rifft_q15(pSrc, S->fftLenBy2, S->pTwiddleAReal, 
+                        S->pTwiddleBReal, pDst, S->twidCoefRModifier); 
+ 
+    /* Complex readix-4 IFFT process */ 
+    arm_radix4_butterfly_inverse_q15(pDst, S_CFFT->fftLen, 
+                                     S_CFFT->pTwiddle, 
+                                     S_CFFT->twidCoefModifier); 
+ 
+    /* Bit reversal process */ 
+    if(S->bitReverseFlagR == 1u) 
+    { 
+      arm_bitreversal_q15(pDst, S_CFFT->fftLen, 
+                          S_CFFT->bitRevFactor, S_CFFT->pBitRevTable); 
+    } 
+  } 
+  else 
+  { 
+    /* Calculation of RFFT of input */ 
+ 
+    /* Complex readix-4 FFT process */ 
+    arm_radix4_butterfly_q15(pSrc, S_CFFT->fftLen, 
+                             S_CFFT->pTwiddle, S_CFFT->twidCoefModifier); 
+ 
+    /* Bit reversal process */ 
+    if(S->bitReverseFlagR == 1u) 
+    { 
+      arm_bitreversal_q15(pSrc, S_CFFT->fftLen, 
+                          S_CFFT->bitRevFactor, S_CFFT->pBitRevTable); 
+    } 
+ 
+    arm_split_rfft_q15(pSrc, S->fftLenBy2, S->pTwiddleAReal, 
+                       S->pTwiddleBReal, pDst, S->twidCoefRModifier); 
+  } 
+ 
+} 
+ 
+  /**  
+   * @} end of RFFT_RIFFT group  
+   */ 
+ 
+/**  
+ * @brief  Core Real FFT process  
+ * @param  *pSrc 				points to the input buffer. 
+ * @param  fftLen  				length of FFT. 
+ * @param  *pATable 			points to the A twiddle Coef buffer.  
+ * @param  *pBTable 			points to the B twiddle Coef buffer. 
+ * @param  *pDst 				points to the output buffer. 
+ * @param  modifier 	        twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table. 
+ * @return none.  
+ * The function implements a Real FFT  
+ */ 
+ 
+void arm_split_rfft_q15( 
+  q15_t * pSrc, 
+  uint32_t fftLen, 
+  q15_t * pATable, 
+  q15_t * pBTable, 
+  q15_t * pDst, 
+  uint32_t modifier) 
+{ 
+  uint32_t i;                                    /* Loop Counter */ 
+  q31_t outR, outI;                              /* Temporary variables for output */ 
+  q15_t *pCoefA, *pCoefB;                        /* Temporary pointers for twiddle factors */ 
+  q15_t *pSrc1, *pSrc2; 
+ 
+ 
+  pSrc[2u * fftLen] = pSrc[0]; 
+  pSrc[(2u * fftLen) + 1u] = pSrc[1]; 
+ 
+  pCoefA = &pATable[modifier * 2u]; 
+  pCoefB = &pBTable[modifier * 2u]; 
+ 
+  pSrc1 = &pSrc[2]; 
+  pSrc2 = &pSrc[(2u * fftLen) - 2u]; 
+ 
+  i = 1u; 
+ 
+  while(i < fftLen) 
+  { 
+    /*  
+       outR = (pSrc[2 * i] * pATable[2 * i] - pSrc[2 * i + 1] * pATable[2 * i + 1]  
+       + pSrc[2 * n - 2 * i] * pBTable[2 * i] +  
+       pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1]);  
+     */ 
+ 
+    /* outI = (pIn[2 * i + 1] * pATable[2 * i] + pIn[2 * i] * pATable[2 * i + 1] +  
+       pIn[2 * n - 2 * i] * pBTable[2 * i + 1] -  
+       pIn[2 * n - 2 * i + 1] * pBTable[2 * i]); */ 
+ 
+    /* pSrc[2 * i] * pATable[2 * i] - pSrc[2 * i + 1] * pATable[2 * i + 1] */ 
+    outR = __SMUSD(*__SIMD32(pSrc1), *__SIMD32(pCoefA)); 
+ 
+    /* pSrc[2 * n - 2 * i] * pBTable[2 * i] +  
+       pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1]) */ 
+    outR = __SMLAD(*__SIMD32(pSrc2), *__SIMD32(pCoefB), outR) >> 15u; 
+ 
+    /* pIn[2 * n - 2 * i] * pBTable[2 * i + 1] -  
+       pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */ 
+    outI = __SMUSDX(*__SIMD32(pSrc2)--, *__SIMD32(pCoefB)); 
+ 
+    /* (pIn[2 * i + 1] * pATable[2 * i] + pIn[2 * i] * pATable[2 * i + 1] */ 
+    outI = __SMLADX(*__SIMD32(pSrc1)++, *__SIMD32(pCoefA), outI); 
+ 
+    /* write output */ 
+    pDst[2u * i] = (q15_t) outR; 
+    pDst[(2u * i) + 1u] = outI >> 15u; 
+ 
+    /* write complex conjugate output */ 
+    pDst[(4u * fftLen) - (2u * i)] = (q15_t) outR; 
+    pDst[((4u * fftLen) - (2u * i)) + 1u] = -(outI >> 15u); 
+ 
+    /* update coefficient pointer */ 
+    pCoefB = pCoefB + (2u * modifier); 
+    pCoefA = pCoefA + (2u * modifier); 
+ 
+    i++; 
+ 
+  } 
+ 
+  pDst[2u * fftLen] = pSrc[0] - pSrc[1]; 
+  pDst[(2u * fftLen) + 1u] = 0; 
+ 
+  pDst[0] = pSrc[0] + pSrc[1]; 
+  pDst[1] = 0; 
+ 
+} 
+ 
+ 
+/**  
+ * @brief  Core Real IFFT process  
+ * @param[in]   *pSrc 				points to the input buffer.  
+ * @param[in]   fftLen  		    length of FFT. 
+ * @param[in]   *pATable 			points to the twiddle Coef A buffer. 
+ * @param[in]   *pBTable 			points to the twiddle Coef B buffer.  
+ * @param[out]  *pDst 				points to the output buffer. 
+ * @param[in]   modifier 	        twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table. 
+ * @return none.  
+ * The function implements a Real IFFT  
+ */ 
+ 
+void arm_split_rifft_q15( 
+  q15_t * pSrc, 
+  uint32_t fftLen, 
+  q15_t * pATable, 
+  q15_t * pBTable, 
+  q15_t * pDst, 
+  uint32_t modifier) 
+{ 
+  uint32_t i;                                    /* Loop Counter */ 
+  q31_t outR, outI;                              /* Temporary variables for output */ 
+  q15_t *pCoefA, *pCoefB;                        /* Temporary pointers for twiddle factors */ 
+  q15_t *pSrc1, *pSrc2; 
+  q15_t *pDst1 = &pDst[0]; 
+ 
+  pCoefA = &pATable[0]; 
+  pCoefB = &pBTable[0]; 
+ 
+  pSrc1 = &pSrc[0]; 
+  pSrc2 = &pSrc[2u * fftLen]; 
+ 
+  i = fftLen; 
+ 
+  while(i > 0u) 
+  { 
+ 
+    /*  
+       outR = (pIn[2 * i] * pATable[2 * i] + pIn[2 * i + 1] * pATable[2 * i + 1] +  
+       pIn[2 * n - 2 * i] * pBTable[2 * i] -  
+       pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1]);  
+ 
+       outI = (pIn[2 * i + 1] * pATable[2 * i] - pIn[2 * i] * pATable[2 * i + 1] -  
+       pIn[2 * n - 2 * i] * pBTable[2 * i + 1] -  
+       pIn[2 * n - 2 * i + 1] * pBTable[2 * i]);  
+ 
+     */ 
+ 
+    /* pIn[2 * n - 2 * i] * pBTable[2 * i] -  
+       pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1]) */ 
+    outR = __SMUSD(*__SIMD32(pSrc2), *__SIMD32(pCoefB)); 
+ 
+    /* pIn[2 * i] * pATable[2 * i] + pIn[2 * i + 1] * pATable[2 * i + 1] +  
+       pIn[2 * n - 2 * i] * pBTable[2 * i] */ 
+    outR = __SMLAD(*__SIMD32(pSrc1), *__SIMD32(pCoefA), outR) >> 15u; 
+ 
+    /*  
+       -pIn[2 * n - 2 * i] * pBTable[2 * i + 1] +  
+       pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */ 
+    outI = __SMUADX(*__SIMD32(pSrc2)--, *__SIMD32(pCoefB)); 
+ 
+    /* pIn[2 * i + 1] * pATable[2 * i] - pIn[2 * i] * pATable[2 * i + 1] */ 
+    outI = __SMLSDX(*__SIMD32(pCoefA), *__SIMD32(pSrc1)++, -outI); 
+ 
+    /* write output */ 
+    *__SIMD32(pDst1)++ = 
+      (q31_t) ((outI << 1u) & 0xFFFF0000) | (outR & 0x0000FFFF); 
+ 
+    /* update coefficient pointer */ 
+    pCoefB = pCoefB + (2u * modifier); 
+    pCoefA = pCoefA + (2u * modifier); 
+ 
+    i--; 
+ 
+  } 
+ 
+}