mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-28 05:51:04 +00:00
135 lines
4.5 KiB
C
135 lines
4.5 KiB
C
/*
|
|
(C) Copyright 2001,2006,
|
|
International Business Machines Corporation,
|
|
Sony Computer Entertainment, Incorporated,
|
|
Toshiba 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 names of the copyright holders nor the names of their
|
|
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.
|
|
*/
|
|
#ifndef _SQRT_H_
|
|
#define _SQRT_H_ 1
|
|
|
|
/*
|
|
* FUNCTION
|
|
* double _sqrt(double in)
|
|
*
|
|
* DESCRIPTION
|
|
* _sqrt computes the square root of the input "in" and returns the
|
|
* result.
|
|
*/
|
|
#include <spu_intrinsics.h>
|
|
#include "headers/vec_literal.h"
|
|
#include "headers/dom_chkd_less_than.h"
|
|
|
|
static __inline double _sqrt(double in)
|
|
{
|
|
vec_int4 bias_exp;
|
|
vec_uint4 exp;
|
|
vec_float4 fx, fg, fy, fd, fe, fy2, fhalf;
|
|
vec_ullong2 nochange;
|
|
vec_ullong2 mask = VEC_SPLAT_U64(0x7FE0000000000000ULL);
|
|
vec_double2 x, dx, de, dd, dy, dg, dy2, dhalf;
|
|
vec_double2 denorm, neg;
|
|
vec_double2 vc = { 0.0, 0.0 };
|
|
|
|
fhalf = VEC_SPLAT_F32(0.5f);
|
|
dhalf = VEC_SPLAT_F64(0.5);
|
|
|
|
/* Coerce the input, in, into the argument reduced space [0.5, 2.0).
|
|
*/
|
|
x = spu_promote(in, 0);
|
|
dx = spu_sel(x, dhalf, mask);
|
|
|
|
/* Compute an initial single precision guess for the square root (fg)
|
|
* and half reciprocal (fy2).
|
|
*/
|
|
fx = spu_roundtf(dx);
|
|
|
|
fy2 = spu_rsqrte(fx);
|
|
fy = spu_mul(fy2, fhalf);
|
|
fg = spu_mul(fy2, fx); /* 12-bit approximation to sqrt(cx) */
|
|
|
|
/* Perform one single precision Newton-Raphson iteration to improve
|
|
* accuracy to about 22 bits.
|
|
*/
|
|
fe = spu_nmsub(fy, fg, fhalf);
|
|
fd = spu_nmsub(fg, fg, fx);
|
|
|
|
fy = spu_madd(fy2, fe, fy);
|
|
fg = spu_madd(fy, fd, fg); /* 22-bit approximation */
|
|
|
|
dy = spu_extend(fy);
|
|
dg = spu_extend(fg);
|
|
|
|
/* Perform two double precision Newton-Raphson iteration to improve
|
|
* accuracy to about 44 and 88 bits repectively.
|
|
*/
|
|
dy2 = spu_add(dy, dy);
|
|
de = spu_nmsub(dy, dg, dhalf);
|
|
dd = spu_nmsub(dg, dg, dx);
|
|
dy = spu_madd(dy2, de, dy);
|
|
dg = spu_madd(dy, dd, dg); /* 44 bit approximation */
|
|
|
|
dd = spu_nmsub(dg, dg, dx);
|
|
dg = spu_madd(dy, dd, dg); /* full double precision approximation */
|
|
|
|
|
|
/* Compute the expected exponent assuming that it is not a special value.
|
|
* See special value handling below.
|
|
*/
|
|
bias_exp = spu_rlmaska(spu_sub((vec_int4)spu_and((vec_ullong2)x, mask),
|
|
(vec_int4)VEC_SPLAT_U64(0x3FE0000000000000ULL)), -1);
|
|
dg = (vec_double2)spu_add((vec_int4)dg, bias_exp);
|
|
|
|
|
|
/* Handle special inputs. These include:
|
|
*
|
|
* input output
|
|
* ========= =========
|
|
* -0 -0
|
|
* +infinity +infinity
|
|
* NaN NaN
|
|
* <0 NaN
|
|
* denorm zero
|
|
*/
|
|
exp = (vec_uint4)spu_and((vec_ullong2)x, VEC_SPLAT_U64(0xFFF0000000000000ULL));
|
|
exp = spu_shuffle(exp, exp, VEC_LITERAL(vec_uchar16, 0,1,2,3,0,1,2,3, 8,9,10,11,8,9,10,11));
|
|
|
|
neg = (vec_double2)spu_rlmaska((vec_int4)exp, -31);
|
|
denorm = (vec_double2)spu_rlmask(spu_cmpeq(spu_sl(exp, 1), 0), VEC_LITERAL(vec_int4, -1,0,-1,0));
|
|
|
|
nochange = (vec_ullong2)spu_cmpeq(exp, 0x7FF00000);
|
|
|
|
dg = spu_sel(spu_andc(spu_or(dg, neg), denorm), x, nochange);
|
|
|
|
#ifndef _IEEE_LIBM
|
|
dom_chkd_less_than(spu_splats(in), vc);
|
|
#endif
|
|
return (spu_extract(dg, 0));
|
|
}
|
|
#endif /* _SQRT_H_ */
|