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
_fp_udivmodti4(_FP_W_TYPE q[2],_FP_W_TYPE r[2],_FP_W_TYPE n1,_FP_W_TYPE n0,_FP_W_TYPE d1,_FP_W_TYPE d0)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