img_wave_horz.h64

TMS320C64x Image／Video Processing Library (V1.04)

;* ======================================================================== *;
;*  TEXAS INSTRUMENTS, INC.                                                 *;
;*                                                                          *;
;*  IMGLIB  DSP Image/Video Processing Library                              *;
;*                                                                          *;
;*      Release:        Revision 1.04b                                      *;
;*      CVS Revision:   1.11    Sun Sep 29 03:32:31 2002 (UTC)              *;
;*      Snapshot date:  23-Oct-2003                                         *;
;*                                                                          *;
;*  This library contains proprietary intellectual property of Texas        *;
;*  Instruments, Inc.  The library and its source code are protected by     *;
;*  various copyrights, and portions may also be protected by patents or    *;
;*  other legal protections.                                                *;
;*                                                                          *;
;*  This software is licensed for use with Texas Instruments TMS320         *;
;*  family DSPs.  This license was provided to you prior to installing      *;
;*  the software.  You may review this license by consulting the file       *;
;*  TI_license.PDF which accompanies the files in this library.             *;
;* ------------------------------------------------------------------------ *;
;*          Copyright (C) 2003 Texas Instruments, Incorporated.             *;
;*                          All Rights Reserved.                            *;
;* ======================================================================== *;
;* ======================================================================== *;
;*  Assembler compatibility shim for assembling 4.30 and later code on      *;
;*  tools prior to 4.30.                                                    *;
;* ======================================================================== *;
;* ======================================================================== *;
;*  End of assembler compatibility shim.                                    *;
;* ======================================================================== *;
* ========================================================================= *
*   TEXAS INSTRUMENTS, INC.                                                 *
*                                                                           *
*   NAME                                                                    *
*       IMG_wave_horz : 1D Wavelet Transform                                *
*                                                                           *
*   REVISION DATE                                                           *
*       21-Jan-1999                                                         *
*                                                                           *
*   USAGE                                                                   *
*       This routine is C-callable and can be called as:                    *
*                                                                           *
*           void IMG_wave_horz                                              *
*           (                                                               *
*               const short *restrict in_data,  /* Row of input pixels  */  *
*               const short *restrict qmf,      /* Low-pass QMF filter  */  *
*               const short *restrict mqmf,     /* High-pass QMF filter */  *
*               short       *restrict out_data, /* Row of output data   */  *
*               int                   cols      /* Length of input.     */  *
*           );                                                              *
*                                                                           *
*   DESCRIPTION                                                             *
*       This kernel performs a 1D Periodic Orthogonal Wavelet               *
*       decomposition.  This also performs athe row decomposition in a      *
*       2D wavelet transform.  An input signal x[n] is low pass and         *
*       high pass filtered and decimated by two.  This results in a         *
*       reference signal r1[n] which is the decimated output obtained       *
*       by dropping the odd samples of the low pass filtered output and     *
*       a detail signal d[n] obtained by dropping the odd samples of        *
*       the high-pass output.  A circular convolution algorithm is          *
*       implemented and hence the wavelet transform is periodic.  The       *
*       reference signal and the detail signal are half the size of the     *
*       original signal.  The reference signal may then be iterated         *
*       again to perform another scale of multi-resolution analysis.        *
*                                                                           *
*   TECHNIQUES                                                              *
*       The main idea in optimizing the code is to issue one set of         *
*       reads to the x array and to perform low-pass and high pass          *
*       filtering together and to perfrom the filtering operations          *
*       together to maximize the number of multiplies.  The last 6          *
*       elements of the low-pass filter and the first 6 elements of the     *
*       high pass filter use the same input This is used to                 *
*       appropraitely change the output pointer to the low pass filter      *
*       after 6 iterations.  However for the first six iterations           *
*       pointer wrap-around can occurr and hence this creates a             *
*       dependency.  Pre-reading those 6 values outside the array           *
*       prevents the checks that introduce this dependency.  In addtion     *
*       the input data is read as word wide quantities and the low-pass     *
*       and high-pass filter coefficients are stored in registers           *
*       allowing for the input loop to be completely unrolled.  Thus        *
*       the assembly code has only one loop.  A predication register is     *
*       used to reset the low-pass output pointer after three               *
*       iterations.  The merging of the loops in this fashion allows f      *
*                                                                           *
*   ASSUMPTIONS                                                             *
*       This kernel assumes that the # of filter taps for the qmf and       *
*       mqmf is 8.                                                          *
*                                                                           *
*       Both the filters are assumed to be double-word aligned and have     *
*       8 taps.                                                             *
*                                                                           *
*       The input line is assumed to be word aligned so that LDWs           *
*       may be performed.                                                   *
*                                                                           *
*       This code assumes that filter coefficients are maintained as        *
*       shorts in Q15 format.                                               *
*                                                                           *
*       It also assumes that input data is an array of shorts (16 bit)      *
*       (The input is assumed to be an array of shorts to allow for         *
*       re-using this kernel to perform Multi Resolution Analysis as        *
*       the output of this code will feedback again as input in the         *
*       next stage.)                                                        *
*                                                                           *
*       Since the transform is a dyadic wavelet cols should be a power      *
*       of 2. Cols must also be >=8.                                        *
*                                                                           *
*                                                                           *
*   MEMORY NOTE                                                             *
*       This code has no bank conflicts.                                    *
*                                                                           *
*       This code is ENDIAN Neutral.                                        *
*                                                                           *
*                                                                           *
*   NOTES                                                                   *
*       This code masks interrupts for nearly its entire duration.  As      *
*       a result, the code is interrupt tolerant but not                    *
*       interruptible.                                                      *
*                                                                           *
*       This code can implement the Daubechies D4 filterbank for            *
*       analysis with 4 vansishing moments.  The length of the analyzing    *
*       low-pass and high pass filters is 8 in that case.                   *
*                                                                           *
*   C CODE                                                                  *
*                                                                           *
*       This is the C equivalent of the assembly code without restrictions: *
*       Note that the assembly code is hand optimized and restrictions      *
*       apply as noted under "ASSUMPTIONS".                                 *
*                                                                           *