/* --------------------------------------------------------------  */
/* (C)Copyright 2006,2008,                                         */
/* International Business Machines Corporation                     */
/* All Rights Reserved.                                            */
/*                                                                 */
/* Redistribution and use in source and binary forms, with or      */
/* without modification, are permitted provided that the           */
/* following conditions are met:                                   */
/*                                                                 */
/* - Redistributions of source code must retain the above copyright*/
/*   notice, this list of conditions and the following disclaimer. */
/*                                                                 */
/* - Redistributions in binary form must reproduce the above       */
/*   copyright notice, this list of conditions and the following   */
/*   disclaimer in the documentation and/or other materials        */
/*   provided with the distribution.                               */
/*                                                                 */
/* - Neither the name of IBM Corporation nor the names of its      */
/*   contributors may be used to endorse or promote products       */
/*   derived from this software without specific prior written     */
/*   permission.                                                   */
/*                                                                 */
/* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND          */
/* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,     */
/* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF        */
/* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE        */
/* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR            */
/* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,    */
/* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT    */
/* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;    */
/* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)        */
/* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN       */
/* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR    */
/* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,  */
/* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.              */
/* --------------------------------------------------------------  */
/* PROLOG END TAG zYx                                              */
#ifdef __SPU__

#ifndef _LOGBF4_H_
#define _LOGBF4_H_ 1

#include <spu_intrinsics.h>
#include <vec_types.h>

/*
 * FUNCTION
 *	vector float _logbf4(vector float x)
 *
 * DESCRIPTION
 *  The _logbf4 function returns a vector float that contains the exponent
 *  of the corresponding elements of the input vector x. The exponent is
 *  defined by:
 *    x = frac * FLT_RADIX^exp, with frac in [1, FLT_RADIX).
 *
 *  Special Cases:
 *    x = 0,  result is undefined.
 *    x = NaN, result is NaN.
 *    x = infinity, +infinity is returned.
 *
 */
static __inline vector float
_logbf4(vector float x)
{
    vec_uint4  lzero = (vector unsigned int) { 0, 0, 0, 0 };
    vec_uint4  exp_mask = (vector unsigned int) { 0xFF, 0xFF, 0xFF, 0xFF };
    vec_int4   exp_shift = (vector signed int) { -23, -23, -23, -23 };
    vec_int4   exp_bias = (vector signed int) { -127, -127, -127, -127 };
    vec_uint4  sign_mask = (vector unsigned int) { 0x80000000, 0x80000000, 0x80000000, 0x80000000 };
    vec_uint4  linf = (vector unsigned int) { 0x7F800000, 0x7F800000, 0x7F800000, 0x7F800000 };
    vec_uint4  lminf = (vector unsigned int) { 0xFF800000, 0xFF800000, 0xFF800000, 0xFF800000 };
    vec_uint4  exp;
    vec_uint4  xabs;
    vec_float4 exp_unbias;

    xabs = spu_andc((vec_uint4)x, sign_mask);

    exp = spu_and(spu_rlmask((vec_uint4)x, exp_shift), exp_mask);
    exp_unbias = spu_convtf(spu_add((vec_int4)exp, exp_bias), 0);

    /* Zero */
    exp_unbias = spu_sel(exp_unbias, (vec_float4)lminf, (vec_uint4)spu_cmpeq(xabs, lzero));

    /* NaN */
    exp_unbias = spu_sel(exp_unbias, x, (vec_uint4)spu_cmpgt(xabs, linf));

    /* Infinite */
    exp_unbias = spu_sel(exp_unbias, (vec_float4)linf, (vec_uint4)spu_cmpeq(xabs, linf));

    return (exp_unbias);
}

#endif /* _LOGBF4_H_ */

#endif /* __SPU__ */
