76 lines
2.9 KiB
C
76 lines
2.9 KiB
C
/* scalbnf4 computes x * 2^exp. This function is computed without
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the assistence of any floating point operations and as such does
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not set any floating point exceptions.
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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_SCALBNF4_H___
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#define ___SIMD_MATH_SCALBNF4_H___
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#include <simdmath.h>
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#include <spu_intrinsics.h>
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static inline vector float
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_scalbnf4(vector float x, vector signed int n)
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{
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vec_int4 x_exp;
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vec_uint4 zero, overflow;
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vec_uint4 exp_mask = spu_splats((unsigned int)0x7F800000);
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vec_float4 out;
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/* Extract exponent from x. If the exponent is 0, then
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* x is either 0 or a denorm and x*2^exp is a zero.
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*/
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x_exp = spu_and(spu_rlmask((vec_int4)x, -23), 0xFF);
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zero = spu_cmpeq(x_exp, 0);
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/* Compute the expected exponent and determine if the
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* result is within range.
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*/
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x_exp = spu_add(n, x_exp);
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zero = spu_orc(zero, spu_cmpgt(x_exp, 0));
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// overflow = spu_rlmask(spu_cmpgt(x_exp, 255), -1);
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overflow = spu_cmpgt(x_exp, 255);
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/* Merge the expect exponent with x's mantissa. Zero the
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* result if underflow and force to max if overflow.
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*/
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out = spu_sel(x, (vec_float4)spu_rl(x_exp, 23), exp_mask);
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out = spu_andc(out, (vec_float4)zero);
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out = spu_or(out, (vec_float4)overflow);
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// add sign bit
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out = spu_sel(out, x, spu_splats((unsigned int)0x80000000));
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return out;
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}
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#endif
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