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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 _LOG2D2_H_ #define _LOG2D2_H_ 1 #include /* * FUNCTION * vector double _log2d2(vector double x) * * DESCRIPTION * The function _log2d2 computes log base 2 of the input x for each * of the double word elements of x. The log2 is decomposed * into two parts, log2 of the exponent and log2 of the * fraction. The log2 of the fraction is approximated * using a 21st order polynomial of the form: * * __20_ * \ * log(x) = x * (1 + \ (Ci * x^i)) * / * /____ * i=0 * * for x in the range 0-1. */ #define LOG_C00 #define LOG_C01 #define LOG_C02 static __inline vector double _log2d2(vector double vx) { vec_int4 addval; vec_ullong2 exp_mask = spu_splats(0x7FF0000000000000ULL); vec_double2 vy, vxw; vec_double2 v1 = spu_splats(1.0); vec_double2 x2, x4, x8, x10, p1, p2; /* Extract the fraction component of input by forcing * its exponent so that input is in the range [1.0, 2.0) * and then subtract 1.0 to force it in the range * [0.0, 1.0). */ vxw = spu_sub(spu_sel(vx, v1, exp_mask), v1); /* Compute the log2 of the exponent as exp - 1023. */ addval = spu_add(spu_rlmask((vec_int4)vx, -20), -1023); /* Compute the log2 of the fractional component using a 21st * order polynomial. The polynomial is evaluated in two halves * to improve efficiency. */ p1 = spu_madd(spu_splats(3.61276447184348752E-05), vxw, spu_splats(-4.16662127033480827E-04)); p2 = spu_madd(spu_splats(-1.43988260692073185E-01), vxw, spu_splats(1.60245637034704267E-01)); p1 = spu_madd(vxw, p1, spu_splats(2.28193656337578229E-03)); p2 = spu_madd(vxw, p2, spu_splats(-1.80329036970820794E-01)); p1 = spu_madd(vxw, p1, spu_splats(-7.93793829370930689E-03)); p2 = spu_madd(vxw, p2, spu_splats(2.06098446037376922E-01)); p1 = spu_madd(vxw, p1, spu_splats(1.98461565426430164E-02)); p2 = spu_madd(vxw, p2, spu_splats(-2.40449108727688962E-01)); p1 = spu_madd(vxw, p1, spu_splats(-3.84093543662501949E-02)); p2 = spu_madd(vxw, p2, spu_splats(2.88539004851839364E-01)); p1 = spu_madd(vxw, p1, spu_splats(6.08335872067172597E-02)); p2 = spu_madd(vxw, p2, spu_splats(-3.60673760117245982E-01)); p1 = spu_madd(vxw, p1, spu_splats(-8.27937055456904317E-02)); p2 = spu_madd(vxw, p2, spu_splats(4.80898346961226595E-01)); p1 = spu_madd(vxw, p1, spu_splats(1.01392360727236079E-01)); p2 = spu_madd(vxw, p2, spu_splats(-7.21347520444469934E-01)); p1 = spu_madd(vxw, p1, spu_splats(-1.16530490533844182E-01)); p2 = spu_madd(vxw, p2, spu_splats(0.44269504088896339E+00)); p1 = spu_madd(vxw, p1, spu_splats(1.30009193360025350E-01)); x2 = spu_mul(vxw, vxw); x4 = spu_mul(x2, x2); x8 = spu_mul(x4, x4); x10 = spu_mul(x8, x2); vy = spu_madd(spu_madd(x10, p1, p2), vxw, vxw); /* Add the log2(exponent) and the log2(fraction) to * compute the final result. */ vy = spu_add(vy, spu_extend(spu_convtf(addval, 0))); vxw = spu_extend(spu_convtf(addval, 20)); return(vy); } #endif /* _LOG2D2_H_ */ #endif /* __SPU__ */