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| /* (C)Copyright 2007,2008, */ |
| /* International Business Machines Corporation */ |
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| /* -------------------------------------------------------------- */ |
| /* PROLOG END TAG zYx */ |
| #ifdef __SPU__ |
| |
| #ifndef _EXPM1D2_H_ |
| #define _EXPM1D2_H_ 1 |
| |
| #include <spu_intrinsics.h> |
| |
| #include "expd2.h" |
| #include "divd2.h" |
| |
| #define EXPM1_P0 0.0000000000000000000000000e+00 |
| #define EXPM1_P1 1.0000000000000000000000000e+00 |
| #define EXPM1_P2 9.7234232565378004697204117e-04 |
| #define EXPM1_P3 3.3328278237299953368211192e-02 |
| #define EXPM1_P4 3.1156225044634678993365345e-05 |
| #define EXPM1_P5 2.1352206553343212164751408e-04 |
| #define EXPM1_P6 1.6975135794626144795757452e-07 |
| #define EXPM1_P7 2.7686287801334994383131629e-07 |
| #define EXPM1_P8 1.1186114936216450015354379e-10 |
| |
| #define EXPM1_Q0 1.0000000000000000000000000e+00 |
| #define EXPM1_Q1 -4.9902765767434620336473472e-01 |
| #define EXPM1_Q2 1.1617544040780639069687652e-01 |
| #define EXPM1_Q3 -1.6551954366467523660499950e-02 |
| #define EXPM1_Q4 1.5864115838972218334307351e-03 |
| #define EXPM1_Q5 -1.0534540477401370666288988e-04 |
| #define EXPM1_Q6 4.7650003993592160620959043e-06 |
| #define EXPM1_Q7 -1.3529198871087017840776265e-07 |
| #define EXPM1_Q8 1.8635779407675460757658020e-09 |
| |
| /* |
| * FUNCTION |
| * vector double _expm1d2(vector double x) |
| * |
| * DESCRIPTION |
| * _expm1d2 computes the exponential - 1 for each element |
| * of the input vector x. |
| * |
| * This function is intended to return accurate values, even |
| * where exp(x) - 1 would normally produce bad results due to |
| * floating-point cancellation errors. |
| * |
| */ |
| |
| static __inline vector double _expm1d2(vector double x) |
| { |
| vector double oned = spu_splats(1.0); |
| vector double range = spu_splats(1.0625); |
| vector unsigned long long use_exp; |
| vector double pr, qr; |
| vector double eresult; |
| vector double rresult; |
| vector double result; |
| |
| /* Compiler Bug. Replace xbug with x when spu_cmp*() doesn't |
| * modify it's arguments! */ |
| volatile vector double xbug = x; |
| use_exp = spu_cmpabsgt(xbug, range); |
| |
| /* |
| * Calculate directly using exp(x) - 1 |
| */ |
| eresult = spu_sub(_expd2(x), oned); |
| |
| /* |
| * For x in [-1.0625,1.0625], use a rational approximation. |
| * The madd's are interleaved to reduce dependency stalls. Looks |
| * like gcc is smart enough to do this on it's own... but why |
| * take the chance. |
| */ |
| pr = spu_madd(x, spu_splats(EXPM1_P8), spu_splats(EXPM1_P7)); |
| qr = spu_madd(x, spu_splats(EXPM1_Q8), spu_splats(EXPM1_Q7)); |
| pr = spu_madd(pr, x, spu_splats(EXPM1_P6)); |
| qr = spu_madd(qr, x, spu_splats(EXPM1_Q6)); |
| pr = spu_madd(pr, x, spu_splats(EXPM1_P5)); |
| qr = spu_madd(qr, x, spu_splats(EXPM1_Q5)); |
| pr = spu_madd(pr, x, spu_splats(EXPM1_P4)); |
| qr = spu_madd(qr, x, spu_splats(EXPM1_Q4)); |
| pr = spu_madd(pr, x, spu_splats(EXPM1_P3)); |
| qr = spu_madd(qr, x, spu_splats(EXPM1_Q3)); |
| pr = spu_madd(pr, x, spu_splats(EXPM1_P2)); |
| qr = spu_madd(qr, x, spu_splats(EXPM1_Q2)); |
| pr = spu_madd(pr, x, spu_splats(EXPM1_P1)); |
| qr = spu_madd(qr, x, spu_splats(EXPM1_Q1)); |
| pr = spu_madd(pr, x, spu_splats(EXPM1_P0)); |
| qr = spu_madd(qr, x, spu_splats(EXPM1_Q0)); |
| rresult = _divd2(pr, qr); |
| |
| /* |
| * Select either direct calculation or rational approximation. |
| */ |
| result = spu_sel(rresult, eresult, use_exp); |
| |
| return result; |
| } |
| |
| #endif /* _EXPM1D2_H_ */ |
| #endif /* __SPU__ */ |