;* ======================================================================== *;
;* TEXAS INSTRUMENTS, INC. *;
;* *;
;* DSPLIB DSP Signal Processing Library *;
;* *;
;* Release: Version 1.02 *;
;* CVS Revision: 1.8 Fri Mar 29 20:22:54 2002 (UTC) *;
;* Snapshot date: 18-Apr-2002 *;
;* *;
;* 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) 2002 Texas Instruments, Incorporated. *;
;* All Rights Reserved. *;
;* ======================================================================== *;
* ========================================================================= *
* NAME *
* DSP_bexp -- Block exponent of a vector *
* *
* REVISION DATE *
* 28-Jan-2002 *
* *
* USAGE *
* This routine has the following C prototype: *
* *
* int DSP_bexp *
* ( *
* const int *x, /* Input Data */ *
* unsigned nx /* Number of elements */ *
* ); *
* *
* The DSP_bexp routine accepts a list of 'num' input points and *
* performs the determination of the block exponent. It returns *
* the minimum number of "redundant sign bits" observed on the *
* block of data. *
* *
* DESCRIPTION *
* The DSP_bexp function, performs a determination of the block *
* exponent of the vector of elements and returns the maximum *
* exponent. This information can then be used to re-normalize *
* the vector. This operation is useful when auto-scaling is *
* required as in a FFT. The DSP_bexp operation returns the *
* minimum norm of the vector. The minimum norm corresponds to *
* the maximum exponent. *
* *
* C CODE *
* The following is a general C code description of the algorithm *
* without restrictions. This implementation may have restrictions *
* as noted under 'ASSUMPTIONS' below. *
* *
* int DSP_bexp(const int *x, short nx) *
* { *
* int i; *
* int mask, mag; *
* *
* mask = 0; *
* *
* /* ---------------------------------------------------- */ *
* /* Merge the absolute values of all the elements */ *
* /* together. The leftmost bit-change on this mask */ *
* /* gives us the magnitude we desire. */ *
* /* ---------------------------------------------------- */ *
* for (i = 0; i < nx; i++) *
* mask |= x[i] ^ (x[i] >> 31); *
* *
* /* ---------------------------------------------------- */ *
* /* Find the magnitude of the mask. */ *
* /* ---------------------------------------------------- */ *
* for (mag = 0; (1 << mag) < mask; mag++) *
* ; *
* *
* return 31 - mag; *
* } *
* *
* ASSUMPTIONS *
* nx >= 6. *
* nx % 2 == 0. *
* *
* NOTES *
* This code is interrupt tolerant, but not interruptible. It masks *
* interrupts for its entire duration with branch delay slots. *
* *
* This code is ENDIAN NEUTRAL. *
* *
* SOURCE *
* DSPLIB. *
* *
* CYCLES *
* cycles = nx + 17, including 6 cycle function call overhead. *
* For nx = 32, cycles = 49. *
* *
* CODESIZE *
* 128 bytes. *
* ------------------------------------------------------------------------- *
* Copyright (c) 2002 Texas Instruments, Incorporated. *
* All Rights Reserved. *
* ========================================================================= *
.global _DSP_bexp
* ========================================================================= *
* End of file: dsp_bexp.h62 *
* ------------------------------------------------------------------------- *
* Copyright (c) 2002 Texas Instruments, Incorporated. *
* All Rights Reserved. *
* ========================================================================= *