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| /* PROLOG END TAG zYx */ |
| #ifdef __SPU__ |
| #ifndef _HYPOTF4_H_ |
| #define _HYPOTF4_H_ 1 |
| |
| #include <spu_intrinsics.h> |
| |
| #include "sqrtf4.h" |
| |
| /* |
| * FUNCTION |
| * vector float _hypotf4(vector float x, vector float y) |
| * |
| * DESCRIPTION |
| * The function hypotf4 returns a float vector in which each element is |
| * the square root of the sum of the squares of the corresponding |
| * elements of x and y. In other words, each element is sqrt(x^2 + y^2). |
| * |
| * The purpose of this function is to avoid overflow during |
| * intermediate calculations, and therefore it is slower than |
| * simply calcualting sqrt(x^2 + y^2). |
| * |
| * This function is performed by factoring out the larger of the 2 |
| * input exponents and moving this factor outside of the sqrt calculation. |
| * This will minimize the possibility of over/underflow when the square |
| * of the values are calculated. Think of it as normalizing the larger |
| * input to the range [1,2). |
| * |
| * |
| * Special Cases: |
| * - hypot(x, +/-0) returns |x| |
| * - hypot(+/- infinity, y) returns +infinity |
| * - hypot(+/- infinity, NaN) returns +infinity |
| * |
| */ |
| |
| |
| static __inline vector float _hypotf4(vector float x, vector float y) |
| { |
| vector unsigned int emask = spu_splats(0x7F800000u); |
| vector unsigned int mmask = spu_splats(0x007FFFFFu); |
| vector signed int bias = spu_splats(0x3F800000); |
| vector float inf = (vec_float4)spu_splats(0x7F800000); |
| vector float onef = spu_splats(1.0f); |
| vector float sbit = spu_splats(-0.0f); |
| vector float max, max_e, max_m; |
| vector float min, min_e, min_m; |
| vector unsigned int xgty; |
| vector float sum; |
| vector float result; |
| |
| /* Only need absolute values for this function */ |
| x = spu_andc(x, sbit); |
| y = spu_andc(y, sbit); |
| xgty = spu_cmpgt(x,y); |
| |
| max = spu_sel(y,x,xgty); |
| min = spu_sel(x,y,xgty); |
| |
| /* Extract exponents and mantissas */ |
| max_e = (vec_float4)spu_and((vec_uint4)max, emask); |
| max_m = (vec_float4)spu_and((vec_uint4)max, mmask); |
| min_e = (vec_float4)spu_and((vec_uint4)min, emask); |
| min_m = (vec_float4)spu_and((vec_uint4)min, mmask); |
| |
| /* Adjust the exponent of the smaller of the 2 input values by |
| * subtracting max_exp from min_exp. |
| */ |
| vec_int4 min_e_int = spu_sub((vec_int4)min_e, (vec_int4)max_e); |
| min_e = (vec_float4)spu_add(min_e_int, bias); |
| |
| /* If the new min exponent is too small, just set it to 0. It |
| * wouldn't contribute to the final result in either case. |
| */ |
| min_e = spu_sel(min_e, sbit, spu_cmpgt(sbit, min_e)); |
| |
| /* Combine new exponents with original mantissas */ |
| max = spu_or(onef, max_m); |
| min = spu_or(min_e, min_m); |
| |
| sum = _sqrtf4(spu_madd(max, max, spu_mul(min, min))); |
| sum = spu_mul(max_e, sum); |
| |
| /* Special case: x = +/- infinity */ |
| result = spu_sel(sum, inf, spu_cmpeq(x, inf)); |
| |
| return result; |
| } |
| |
| #endif /* _HYPOTF4_H_ */ |
| #endif /* __SPU__ */ |