/* ======================================================================== */
/* TEXAS INSTRUMENTS, INC. */
/* */
/* DSPLIB DSP Signal Processing Library */
/* */
/* Release: Version 1.02 */
/* CVS Revision: 1.4 Fri Mar 22 02:10:54 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. */
/* ======================================================================== */
/* ======================================================================== */
/* TEXAS INSTRUMENTS, INC. */
/* */
/* NAME */
/* DSP_recip16 */
/* */
/* */
/* REVISION DATE */
/* 20-Jul-2001 */
/* */
/* USAGE */
/* This routine is C-callable and can be called as: */
/* */
/* void DSP_recip16 (short *x, short *rfrac, short *rexp, short nx); */
/* */
/* x[nx] = Pointer to input vector of size nx */
/* rfrac[nx] = Pointer to output vector of size nx to */
/* contain the fractional part of the reciprocal */
/* rexp[nx] = Pointer to output vector of size nx to */
/* contain the exponent part of the reciprocal */
/* nx = Number of elements in input vector */
/* */
/* (See the C compiler reference guide.) */
/* */
/* DESCRIPTION */
/* This program performs a reciprocal on a vector of Q15 numbers. */
/* The result is stored in two parts: a Q15 part and an exponent */
/* (power of two) of the fraction. */
/* First, the input is loaded, then its absolute value is taken, */
/* then it is normalized, then divided using a loop of conditional */
/* subtracts, and finally it is negated if the original input was */
/* negative. */
/* */
/* void DSP_recip16 (short *x, short *rfrac, short *rexp, short nx) */
/* { */
/* int i,j,a,b; */
/* short neg, normal; */
/* */
/* for(i = nx; i > 0; i--) */
/* { */
/* a = *(x++); */
/* if(a < 0) // take absolute value // */
/* { */
/* a = -a; */
/* neg = 1; */
/* } */
/* else */
/* neg = 0; */
/* normal = _norm(a); // normalize // */
/* a = a << normal; */
/* *(rexp++) = normal - 15; // store exponent // */
/* b = 0x80000000; // dividend = 1 // */
/* for(j = 15; j > 0; j--) */
/* b = _subc(b,a); // divide // */
/* b = b & 0x7FFF; // clear remainder // */
/* if(neg) b = -b; // if negative, negate // */
/* *(rfrac++) = b; // store fraction // */
/* } */
/* } */
/* */
/* ASSUMPTIONS */
/* This code is endian neutral */
/* x and rfrac are Q15 format */
/* output is accurate up to the least significant bit of rfrac, but */
/* note that this bit could carry over and change rexp too */
/* */
/* MEMORY NOTE */
/* There are no memory bank hits in this procedure */
/* */
/* NOTE */
/* fully interruptible */
/* */
/* TECHNIQUES */
/* The conditional subtract instruction, SUBC, is used for division */
/* SUBC is used once for every bit of quotient needed (15). */
/* 2 stages of prolog and epilog collapsed */
/* split 2 live-too-longs (A_neg and B_norm) */
/* */
/* CYCLES */
/* 8 * nx + 14 */
/* */
/* ------------------------------------------------------------------------ */
/* Copyright (c) 2002 Texas Instruments, Incorporated. */
/* All Rights Reserved. */
/* ======================================================================== */
#ifndef DSP_RECIP16_H_
#define DSP_RECIP16_H_ 1
void DSP_recip16 (short *x, short *rfrac, short *rexp, short nx);
#endif
/* ======================================================================== */
/* End of file: dsp_recip16.h */
/* ------------------------------------------------------------------------ */
/* Copyright (c) 2002 Texas Instruments, Incorporated. */
/* All Rights Reserved. */
/* ======================================================================== */