/* ======================================================================= */
/* DSP_fft16x16.h -- 16x16 Mixed Radix FFT                                 */
/*                   Serial ASM Implementation                             */
/*                                                                         */
/* Rev 0.0.1                                                               */
/*                                                                         */
/* Copyright (C) 2011 Texas Instruments Incorporated - http://www.ti.com/  */ 
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/* ======================================================================= */

#ifndef DSP_FFT16X16_H_
#define DSP_FFT16X16_H_ 1

#ifndef __TI_COMPILER_VERSION__           // for non TI compiler
#include "assert.h"                       // intrinsics prototypes
#include "C6xSimulator.h"                 // intrinsics prototypes
#include "C6xSimulator_type_modifiers.h"  // define/undefine typing keywords
#endif

/** @ingroup FFT */
/* @{ */

/** @defgroup DSP_fft16x16 */
/** @ingroup DSP_fft16x16 */
/* @{ */

/**
 *      This routine computes a complex forward mixed radix FFT with
 *      rounding and digit reversal. Input data x[ ], output data y[ ],
 *      and coefficients w[ ] are 16-bit. The output is returned in the 
 *      separate array y[ ] in normal order. Each complex value is stored 
 *      with interleaved real and imaginary parts. The code uses a special 
 *      ordering of FFT coefficients (also called twiddle factors) and
 *      memory accesses to improve performance in the presence of cache.
 *
 *          @param  ptr_w   =  input twiddle factors    
 *          @param  npoints =  number of points         
 *          @param  ptr_x   =  transformed data reversed
 *          @param  ptr_y   =  linear transformed data  
 *
 * @par Algorithm:
 * DSP_fft16x16_cn.c is the natural C equivalent of the optimized intrinsic C
 * code without restrictions. Note that the intrinsic C code is optimized and
 * restrictions may apply.  
 * 
 * @par Assumptions:
 *     In-place computation is not allowed. <BR>                            
 *     Size of FFT, nx, must be power of 2 and 16<=nx<=65536. <BR>                                 
 *     The arrays for the complex input data x[], complex output data y[]
 *        and twiddle factor w[] must be double word aligned. <BR>
 *     The input and output data are complex, with the real/imaginary 
 *        components stored in adjacent locations in the array.  The real
 *        components are stored at even array indices, and the imaginary 
 *        components are stored at odd array indices. <BR>                    
 *     All data are in short precision or Q.15 format. Allowed maximum absolute 
 *        value of input is 2^(16 - (log2(nx)-ceil[log4(nx)-1])). <BR>                    
 *
 * @par Implementation Notes:
 * @b Endian Support: 
 *    The intrinsic optimized C code supports both big and little endian modes. <BR> 
 *    The linear assembly code supports little endian mode only. <BR> 
 * @b Interruptibility: The code is interruptible. <BR>
 *
 */

void DSP_fft16x16 (
    const short * restrict ptr_w,
    int npoints,
    short * restrict ptr_x,
    short * restrict ptr_y
);

#endif

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/*  End of file:  DSP_fft16x16.h                                            */
/* ------------------------------------------------------------------------ */
/*            Copyright (c) 2011 Texas Instruments, Incorporated.           */
/*                           All Rights Reserved.                           */
/* ======================================================================== */