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[/] [openrisc/] [tags/] [gnu-dev/] [fsf-gcc-snapshot-1-mar-12/] [or1k-gcc/] [libgcc/] [config/] [spu/] [divv2df3.c] - Rev 783
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/* Copyright (C) 2009 Free Software Foundation, Inc. This file is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This file is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. Under Section 7 of GPL version 3, you are granted additional permissions described in the GCC Runtime Library Exception, version 3.1, as published by the Free Software Foundation. You should have received a copy of the GNU General Public License and a copy of the GCC Runtime Library Exception along with this program; see the files COPYING3 and COPYING.RUNTIME respectively. If not, see <http://www.gnu.org/licenses/>. */ #include <spu_intrinsics.h> vector double __divv2df3 (vector double a_in, vector double b_in); /* __divv2df3 divides the vector dividend a by the vector divisor b and returns the resulting vector quotient. Maximum error about 0.5 ulp over entire double range including denorms, compared to true result in round-to-nearest rounding mode. Handles Inf or NaN operands and results correctly. */ vector double __divv2df3 (vector double a_in, vector double b_in) { /* Variables */ vec_int4 exp, exp_bias; vec_uint4 no_underflow, overflow; vec_float4 mant_bf, inv_bf; vec_ullong2 exp_a, exp_b; vec_ullong2 a_nan, a_zero, a_inf, a_denorm, a_denorm0; vec_ullong2 b_nan, b_zero, b_inf, b_denorm, b_denorm0; vec_ullong2 nan; vec_uint4 a_exp, b_exp; vec_ullong2 a_mant_0, b_mant_0; vec_ullong2 a_exp_1s, b_exp_1s; vec_ullong2 sign_exp_mask; vec_double2 a, b; vec_double2 mant_a, mant_b, inv_b, q0, q1, q2, mult; /* Constants */ vec_uint4 exp_mask_u32 = spu_splats((unsigned int)0x7FF00000); vec_uchar16 splat_hi = (vec_uchar16){0,1,2,3, 0,1,2,3, 8, 9,10,11, 8,9,10,11}; vec_uchar16 swap_32 = (vec_uchar16){4,5,6,7, 0,1,2,3, 12,13,14,15, 8,9,10,11}; vec_ullong2 exp_mask = spu_splats(0x7FF0000000000000ULL); vec_ullong2 sign_mask = spu_splats(0x8000000000000000ULL); vec_float4 onef = spu_splats(1.0f); vec_double2 one = spu_splats(1.0); vec_double2 exp_53 = (vec_double2)spu_splats(0x0350000000000000ULL); sign_exp_mask = spu_or(sign_mask, exp_mask); /* Extract the floating point components from each of the operands including * exponent and mantissa. */ a_exp = (vec_uint4)spu_and((vec_uint4)a_in, exp_mask_u32); a_exp = spu_shuffle(a_exp, a_exp, splat_hi); b_exp = (vec_uint4)spu_and((vec_uint4)b_in, exp_mask_u32); b_exp = spu_shuffle(b_exp, b_exp, splat_hi); a_mant_0 = (vec_ullong2)spu_cmpeq((vec_uint4)spu_andc((vec_ullong2)a_in, sign_exp_mask), 0); a_mant_0 = spu_and(a_mant_0, spu_shuffle(a_mant_0, a_mant_0, swap_32)); b_mant_0 = (vec_ullong2)spu_cmpeq((vec_uint4)spu_andc((vec_ullong2)b_in, sign_exp_mask), 0); b_mant_0 = spu_and(b_mant_0, spu_shuffle(b_mant_0, b_mant_0, swap_32)); a_exp_1s = (vec_ullong2)spu_cmpeq(a_exp, exp_mask_u32); b_exp_1s = (vec_ullong2)spu_cmpeq(b_exp, exp_mask_u32); /* Identify all possible special values that must be accomodated including: * +-denorm, +-0, +-infinity, and NaNs. */ a_denorm0= (vec_ullong2)spu_cmpeq(a_exp, 0); a_nan = spu_andc(a_exp_1s, a_mant_0); a_zero = spu_and (a_denorm0, a_mant_0); a_inf = spu_and (a_exp_1s, a_mant_0); a_denorm = spu_andc(a_denorm0, a_zero); b_denorm0= (vec_ullong2)spu_cmpeq(b_exp, 0); b_nan = spu_andc(b_exp_1s, b_mant_0); b_zero = spu_and (b_denorm0, b_mant_0); b_inf = spu_and (b_exp_1s, b_mant_0); b_denorm = spu_andc(b_denorm0, b_zero); /* Scale denorm inputs to into normalized numbers by conditionally scaling the * input parameters. */ a = spu_sub(spu_or(a_in, exp_53), spu_sel(exp_53, a_in, sign_mask)); a = spu_sel(a_in, a, a_denorm); b = spu_sub(spu_or(b_in, exp_53), spu_sel(exp_53, b_in, sign_mask)); b = spu_sel(b_in, b, b_denorm); /* Extract the divisor and dividend exponent and force parameters into the signed * range [1.0,2.0) or [-1.0,2.0). */ exp_a = spu_and((vec_ullong2)a, exp_mask); exp_b = spu_and((vec_ullong2)b, exp_mask); mant_a = spu_sel(a, one, (vec_ullong2)exp_mask); mant_b = spu_sel(b, one, (vec_ullong2)exp_mask); /* Approximate the single reciprocal of b by using * the single precision reciprocal estimate followed by one * single precision iteration of Newton-Raphson. */ mant_bf = spu_roundtf(mant_b); inv_bf = spu_re(mant_bf); inv_bf = spu_madd(spu_nmsub(mant_bf, inv_bf, onef), inv_bf, inv_bf); /* Perform 2 more Newton-Raphson iterations in double precision. The * result (q1) is in the range (0.5, 2.0). */ inv_b = spu_extend(inv_bf); inv_b = spu_madd(spu_nmsub(mant_b, inv_b, one), inv_b, inv_b); q0 = spu_mul(mant_a, inv_b); q1 = spu_madd(spu_nmsub(mant_b, q0, mant_a), inv_b, q0); /* Determine the exponent correction factor that must be applied * to q1 by taking into account the exponent of the normalized inputs * and the scale factors that were applied to normalize them. */ exp = spu_rlmaska(spu_sub((vec_int4)exp_a, (vec_int4)exp_b), -20); exp = spu_add(exp, (vec_int4)spu_add(spu_and((vec_int4)a_denorm, -0x34), spu_and((vec_int4)b_denorm, 0x34))); /* Bias the quotient exponent depending on the sign of the exponent correction * factor so that a single multiplier will ensure the entire double precision * domain (including denorms) can be achieved. * * exp bias q1 adjust exp * ===== ======== ========== * positive 2^+65 -65 * negative 2^-64 +64 */ exp_bias = spu_xor(spu_rlmaska(exp, -31), 64); exp = spu_sub(exp, exp_bias); q1 = spu_sel(q1, (vec_double2)spu_add((vec_int4)q1, spu_sl(exp_bias, 20)), exp_mask); /* Compute a multiplier (mult) to applied to the quotient (q1) to produce the * expected result. On overflow, clamp the multiplier to the maximum non-infinite * number in case the rounding mode is not round-to-nearest. */ exp = spu_add(exp, 0x3FF); no_underflow = spu_cmpgt(exp, 0); overflow = spu_cmpgt(exp, 0x7FE); exp = spu_and(spu_sl(exp, 20), (vec_int4)no_underflow); exp = spu_and(exp, (vec_int4)exp_mask); mult = spu_sel((vec_double2)exp, (vec_double2)(spu_add((vec_uint4)exp_mask, -1)), (vec_ullong2)overflow); /* Handle special value conditions. These include: * * 1) IF either operand is a NaN OR both operands are 0 or INFINITY THEN a NaN * results. * 2) ELSE IF the dividend is an INFINITY OR the divisor is 0 THEN a INFINITY results. * 3) ELSE IF the dividend is 0 OR the divisor is INFINITY THEN a 0 results. */ mult = spu_andc(mult, (vec_double2)spu_or(a_zero, b_inf)); mult = spu_sel(mult, (vec_double2)exp_mask, spu_or(a_inf, b_zero)); nan = spu_or(a_nan, b_nan); nan = spu_or(nan, spu_and(a_zero, b_zero)); nan = spu_or(nan, spu_and(a_inf, b_inf)); mult = spu_or(mult, (vec_double2)nan); /* Scale the final quotient */ q2 = spu_mul(q1, mult); return (q2); } /* We use the same function for vector and scalar division. Provide the scalar entry point as an alias. */ double __divdf3 (double a, double b) __attribute__ ((__alias__ ("__divv2df3"))); /* Some toolchain builds used the __fast_divdf3 name for this helper function. Provide this as another alternate entry point for compatibility. */ double __fast_divdf3 (double a, double b) __attribute__ ((__alias__ ("__divv2df3")));