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| /* (C)Copyright 2007,2008, */ |
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| /* -------------------------------------------------------------- */ |
| /* PROLOG END TAG zYx */ |
| #ifdef __SPU__ |
| |
| #ifndef _EXPM1F4_H_ |
| #define _EXPM1F4_H_ 1 |
| |
| #include <spu_intrinsics.h> |
| |
| #include "expf4.h" |
| #include "divf4.h" |
| |
| |
| #define EXPM1F4_P0 0.0000000000000000000000000e-00 |
| #define EXPM1F4_P1 9.9999999999999988897769754e-01 |
| #define EXPM1F4_P2 -6.5597409827762467697531701e-04 |
| #define EXPM1F4_P3 2.3800889637330315679042414e-02 |
| #define EXPM1F4_P4 -1.0914929910143700584950963e-05 |
| |
| #define EXPM1F4_Q0 1.0000000000000000000000000e-00 |
| #define EXPM1F4_Q1 -5.0065597410018825019761834e-01 |
| #define EXPM1F4_Q2 1.0746220997195164714721471e-01 |
| #define EXPM1F4_Q3 -1.1966024153043854083566799e-02 |
| #define EXPM1F4_Q4 5.9997727954467768105711878e-04 |
| |
| |
| /* |
| * FUNCTION |
| * vector float _expm1f4(vector float x) |
| * |
| * _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 float _expm1f4(vector float x) |
| { |
| vector float onef = spu_splats(1.0f); |
| vector float rangelo = spu_splats(-0.4f); |
| vector float rangehi = spu_splats(0.35f); |
| vector unsigned int use_exp; |
| vector float pr, qr; |
| vector float eresult; |
| vector float rresult; |
| vector float result; |
| |
| use_exp = spu_or(spu_cmpgt(x, rangehi), spu_cmpgt(rangelo, x)); |
| |
| /* |
| * Calculate directly using exp(x) - 1 |
| */ |
| eresult = spu_sub(_expf4(x), onef); |
| |
| /* |
| * For x in [-0.5,0.5], 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((float)EXPM1F4_P4), spu_splats((float)EXPM1F4_P3)); |
| qr = spu_madd(x, spu_splats((float)EXPM1F4_Q4), spu_splats((float)EXPM1F4_Q3)); |
| pr = spu_madd(pr, x, spu_splats((float)EXPM1F4_P2)); |
| qr = spu_madd(qr, x, spu_splats((float)EXPM1F4_Q2)); |
| pr = spu_madd(pr, x, spu_splats((float)EXPM1F4_P1)); |
| qr = spu_madd(qr, x, spu_splats((float)EXPM1F4_Q1)); |
| pr = spu_madd(pr, x, spu_splats((float)EXPM1F4_P0)); |
| qr = spu_madd(qr, x, spu_splats((float)EXPM1F4_Q0)); |
| rresult = _divf4(pr, qr); |
| |
| /* |
| * Select either direct calculation or rational approximation. |
| */ |
| result = spu_sel(rresult, eresult, use_exp); |
| |
| return result; |
| } |
| |
| #endif /* _EXPM1F4_H_ */ |
| #endif /* __SPU__ */ |