95 lines
3.6 KiB
C
95 lines
3.6 KiB
C
/* fmodf4 - for each of four float slots, compute remainder of x/y defined as x - truncated_integer(x/y) * y.
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Copyright (C) 2006, 2007 Sony Computer Entertainment Inc.
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All rights reserved.
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Redistribution and use in source and binary forms,
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with or without modification, are permitted provided that the
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following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the name of the Sony Computer Entertainment Inc nor the names
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of its contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef ___SIMD_MATH_FMODF4_H___
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#define ___SIMD_MATH_FMODF4_H___
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#include <simdmath.h>
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#include <spu_intrinsics.h>
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#include <simdmath/divf4.h>
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#include <simdmath/fabsf4.h>
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#include <simdmath/copysignf4.h>
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//
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// This returns an accurate result when |divf4(x,y)| < 2^20 and |x| < 2^128, and otherwise returns zero.
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// If x == 0, the result is 0.
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// If x != 0 and y == 0, the result is undefined.
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static inline vector float
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_fmodf4 (vector float x, vector float y)
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{
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vec_float4 q, xabs, yabs, qabs, xabs2;
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vec_int4 qi0, qi1, qi2;
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vec_float4 i0, i1, i2, r1, r2, i;
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vec_uint4 inrange;
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// Find i = truncated_integer(|x/y|)
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// If |divf4(x,y)| < 2^20, the quotient is at most off by 1.0.
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// Thus i is either the truncated quotient, one less, or one greater.
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q = _divf4( x, y );
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xabs = _fabsf4( x );
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yabs = _fabsf4( y );
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qabs = _fabsf4( q );
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xabs2 = spu_add( xabs, xabs );
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inrange = spu_cmpabsgt( (vec_float4)spu_splats(0x49800000), q );
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inrange = spu_and( inrange, spu_cmpabsgt( (vec_float4)spu_splats(0x7f800000), x ) );
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qi1 = spu_convts( qabs, 0 );
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qi0 = spu_add( qi1, -1 );
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qi2 = spu_add( qi1, 1 );
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i0 = spu_convtf( qi0, 0 );
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i1 = spu_convtf( qi1, 0 );
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i2 = spu_convtf( qi2, 0 );
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// Correct i will be the largest one such that |x| - i*|y| >= 0. Can test instead as
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// 2*|x| - i*|y| >= |x|:
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//
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// With exact inputs, the negative-multiply-subtract gives the exact result rounded towards zero.
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// Thus |x| - i*|y| may be < 0 but still round to zero. However, if 2*|x| - i*|y| < |x|, the computed
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// answer will be rounded down to < |x|. 2*|x| can be represented exactly provided |x| < 2^128.
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r1 = spu_nmsub( i1, yabs, xabs2 );
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r2 = spu_nmsub( i2, yabs, xabs2 );
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i = i0;
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i = spu_sel( i1, i, spu_cmpgt( xabs, r1 ) );
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i = spu_sel( i2, i, spu_cmpgt( xabs, r2 ) );
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i = _copysignf4( i, q );
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return spu_sel( spu_splats(0.0f), spu_nmsub( i, y, x ), inrange );
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}
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#endif
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