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| /* PROLOG END TAG zYx */ |
| #ifdef __SPU__ |
| #ifndef _NEXTAFTERD2_H_ |
| #define _NEXTAFTERD2_H_ 1 |
| |
| #include <spu_intrinsics.h> |
| |
| /* |
| * FUNCTION |
| * vector double _nextafterd2(vector double x, vector double y) |
| * |
| * DESCRIPTION |
| * The nextafterf4 function returns a vector containing the next representable |
| * floating-point number after the element of x, in the direction of the |
| * corresponding element y. |
| * |
| * Special Cases: |
| * - nextafter(NaN, y) = NaN |
| * - nextafter(x, NaN) = NaN |
| * - x = largest finite value, y = infinity, result is undefined |
| * - x = largest finite negative value, y = -infinity, result is undefined |
| * - x != y, and result = 0, considered an underflow |
| * |
| */ |
| |
| static __inline vector double _nextafterd2(vector double x, vector double y) |
| { |
| vec_double2 n1ulp = (vec_double2)spu_splats(0x8000000000000001ull); |
| vector unsigned char mov_carry = {0x80,0x80,0x80, 7, 0x80,0x80,0x80,0x80, |
| 0x80,0x80,0x80,15, 0x80,0x80,0x80,0x80}; |
| vec_double2 zerod = spu_splats(0.0); |
| vec_llong2 one = spu_splats(1ll); |
| vec_ullong2 xlt0, xgty, xeqy, xeq0; |
| vec_llong2 xllong; |
| vec_int4 carry; |
| vec_llong2 delta, deltap1; |
| vec_double2 result; |
| |
| /* Compiler Bug. Replace xtmp/ytmp with x/y when spu_cmpgt(x,y) doesn't change x/y!*/ |
| volatile vec_double2 xtmp = x; |
| volatile vec_double2 ytmp = y; |
| |
| /* |
| * The idea here is to treat x as a signed long long value, which allows us to |
| * add or subtact one to/from it to get the next representable value. |
| */ |
| |
| xeq0 = spu_cmpeq(xtmp, zerod); |
| xlt0 = spu_cmpgt(zerod, xtmp); |
| xeqy = spu_cmpeq(xtmp, ytmp); |
| xgty = spu_cmpgt(xtmp, ytmp); |
| |
| /* If x = -0.0, set x = 0.0 */ |
| x = spu_andc(x, (vec_double2)xeq0); |
| |
| xllong = (vec_llong2)x; |
| |
| /* Determine value to add to x */ |
| delta = (vec_llong2)spu_xor(xgty, xlt0); |
| |
| //deltap1 = delta + one; |
| carry = spu_genc((vec_int4)delta, (vec_int4)one); |
| carry = spu_shuffle(carry, carry, mov_carry); |
| deltap1 = (vec_llong2)spu_addx((vec_int4)delta, (vec_int4)one, (vec_int4)carry); |
| |
| delta = spu_sel(deltap1, delta, (vec_ullong2)delta); |
| |
| //xllong = xllong + delta; |
| carry = spu_genc((vec_int4)xllong, (vec_int4)delta); |
| carry = spu_shuffle(carry, carry, mov_carry); |
| xllong = (vec_llong2)spu_addx((vec_int4)xllong, (vec_int4)delta, (vec_int4)carry); |
| |
| /* Fix the case of x = 0, and answer should be -1 ulp */ |
| result = spu_sel((vec_double2)xllong, n1ulp, spu_and((vec_ullong2)delta, xeq0)); |
| |
| /* |
| * Special Cases |
| */ |
| |
| /* x = y */ |
| result = spu_sel(result, y, xeqy); |
| |
| return result; |
| } |
| |
| #endif /* _NEXTAFTERD2_H_ */ |
| #endif /* __SPU__ */ |