udivmodti4.c (3531B)
1// SPDX-License-Identifier: GPL-2.0 2/* This has so very few changes over libgcc2's __udivmoddi4 it isn't funny. */ 3 4#include <math-emu/soft-fp.h> 5 6#undef count_leading_zeros 7#define count_leading_zeros __FP_CLZ 8 9void 10_fp_udivmodti4(_FP_W_TYPE q[2], _FP_W_TYPE r[2], 11 _FP_W_TYPE n1, _FP_W_TYPE n0, 12 _FP_W_TYPE d1, _FP_W_TYPE d0) 13{ 14 _FP_W_TYPE q0, q1, r0, r1; 15 _FP_I_TYPE b, bm; 16 17 if (d1 == 0) 18 { 19#if !UDIV_NEEDS_NORMALIZATION 20 if (d0 > n1) 21 { 22 /* 0q = nn / 0D */ 23 24 udiv_qrnnd (q0, n0, n1, n0, d0); 25 q1 = 0; 26 27 /* Remainder in n0. */ 28 } 29 else 30 { 31 /* qq = NN / 0d */ 32 33 if (d0 == 0) 34 d0 = 1 / d0; /* Divide intentionally by zero. */ 35 36 udiv_qrnnd (q1, n1, 0, n1, d0); 37 udiv_qrnnd (q0, n0, n1, n0, d0); 38 39 /* Remainder in n0. */ 40 } 41 42 r0 = n0; 43 r1 = 0; 44 45#else /* UDIV_NEEDS_NORMALIZATION */ 46 47 if (d0 > n1) 48 { 49 /* 0q = nn / 0D */ 50 51 count_leading_zeros (bm, d0); 52 53 if (bm != 0) 54 { 55 /* Normalize, i.e. make the most significant bit of the 56 denominator set. */ 57 58 d0 = d0 << bm; 59 n1 = (n1 << bm) | (n0 >> (_FP_W_TYPE_SIZE - bm)); 60 n0 = n0 << bm; 61 } 62 63 udiv_qrnnd (q0, n0, n1, n0, d0); 64 q1 = 0; 65 66 /* Remainder in n0 >> bm. */ 67 } 68 else 69 { 70 /* qq = NN / 0d */ 71 72 if (d0 == 0) 73 d0 = 1 / d0; /* Divide intentionally by zero. */ 74 75 count_leading_zeros (bm, d0); 76 77 if (bm == 0) 78 { 79 /* From (n1 >= d0) /\ (the most significant bit of d0 is set), 80 conclude (the most significant bit of n1 is set) /\ (the 81 leading quotient digit q1 = 1). 82 83 This special case is necessary, not an optimization. 84 (Shifts counts of SI_TYPE_SIZE are undefined.) */ 85 86 n1 -= d0; 87 q1 = 1; 88 } 89 else 90 { 91 _FP_W_TYPE n2; 92 93 /* Normalize. */ 94 95 b = _FP_W_TYPE_SIZE - bm; 96 97 d0 = d0 << bm; 98 n2 = n1 >> b; 99 n1 = (n1 << bm) | (n0 >> b); 100 n0 = n0 << bm; 101 102 udiv_qrnnd (q1, n1, n2, n1, d0); 103 } 104 105 /* n1 != d0... */ 106 107 udiv_qrnnd (q0, n0, n1, n0, d0); 108 109 /* Remainder in n0 >> bm. */ 110 } 111 112 r0 = n0 >> bm; 113 r1 = 0; 114#endif /* UDIV_NEEDS_NORMALIZATION */ 115 } 116 else 117 { 118 if (d1 > n1) 119 { 120 /* 00 = nn / DD */ 121 122 q0 = 0; 123 q1 = 0; 124 125 /* Remainder in n1n0. */ 126 r0 = n0; 127 r1 = n1; 128 } 129 else 130 { 131 /* 0q = NN / dd */ 132 133 count_leading_zeros (bm, d1); 134 if (bm == 0) 135 { 136 /* From (n1 >= d1) /\ (the most significant bit of d1 is set), 137 conclude (the most significant bit of n1 is set) /\ (the 138 quotient digit q0 = 0 or 1). 139 140 This special case is necessary, not an optimization. */ 141 142 /* The condition on the next line takes advantage of that 143 n1 >= d1 (true due to program flow). */ 144 if (n1 > d1 || n0 >= d0) 145 { 146 q0 = 1; 147 sub_ddmmss (n1, n0, n1, n0, d1, d0); 148 } 149 else 150 q0 = 0; 151 152 q1 = 0; 153 154 r0 = n0; 155 r1 = n1; 156 } 157 else 158 { 159 _FP_W_TYPE m1, m0, n2; 160 161 /* Normalize. */ 162 163 b = _FP_W_TYPE_SIZE - bm; 164 165 d1 = (d1 << bm) | (d0 >> b); 166 d0 = d0 << bm; 167 n2 = n1 >> b; 168 n1 = (n1 << bm) | (n0 >> b); 169 n0 = n0 << bm; 170 171 udiv_qrnnd (q0, n1, n2, n1, d1); 172 umul_ppmm (m1, m0, q0, d0); 173 174 if (m1 > n1 || (m1 == n1 && m0 > n0)) 175 { 176 q0--; 177 sub_ddmmss (m1, m0, m1, m0, d1, d0); 178 } 179 180 q1 = 0; 181 182 /* Remainder in (n1n0 - m1m0) >> bm. */ 183 sub_ddmmss (n1, n0, n1, n0, m1, m0); 184 r0 = (n1 << b) | (n0 >> bm); 185 r1 = n1 >> bm; 186 } 187 } 188 } 189 190 q[0] = q0; q[1] = q1; 191 r[0] = r0, r[1] = r1; 192}