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
9 void
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 }
193
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