about summary refs log tree commit diff
path: root/sysdeps/wordsize-32/divdi3.c
blob: 4998ebc1c6bab5faad6d7e952f54dde2f127c669 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
/* 64-bit multiplication and division
   Copyright (C) 1989, 1992-2023 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <endian.h>
#include <stdlib.h>
#include <bits/wordsize.h>

#if __WORDSIZE != 32
#error This is for 32-bit targets only
#endif

typedef unsigned int UQItype	__attribute__ ((mode (QI)));
typedef          int SItype	__attribute__ ((mode (SI)));
typedef unsigned int USItype	__attribute__ ((mode (SI)));
typedef          int DItype	__attribute__ ((mode (DI)));
typedef unsigned int UDItype	__attribute__ ((mode (DI)));
#define Wtype SItype
#define HWtype SItype
#define DWtype DItype
#define UWtype USItype
#define UHWtype USItype
#define UDWtype UDItype
#define W_TYPE_SIZE 32

#include <stdlib/longlong.h>

#if __BYTE_ORDER == __BIG_ENDIAN
struct DWstruct { Wtype high, low;};
#elif __BYTE_ORDER == __LITTLE_ENDIAN
struct DWstruct { Wtype low, high;};
#else
#error Unhandled endianity
#endif
typedef union { struct DWstruct s; DWtype ll; } DWunion;

/* Prototypes of exported functions.  */
extern DWtype __divdi3 (DWtype u, DWtype v);
extern DWtype __moddi3 (DWtype u, DWtype v);
extern UDWtype __udivdi3 (UDWtype u, UDWtype v);
extern UDWtype __umoddi3 (UDWtype u, UDWtype v);

static UDWtype
__udivmoddi4 (UDWtype n, UDWtype d, UDWtype *rp)
{
  DWunion ww;
  DWunion nn, dd;
  DWunion rr;
  UWtype d0, d1, n0, n1, n2;
  UWtype q0, q1;
  UWtype b, bm;

  nn.ll = n;
  dd.ll = d;

  d0 = dd.s.low;
  d1 = dd.s.high;
  n0 = nn.s.low;
  n1 = nn.s.high;

#if !UDIV_NEEDS_NORMALIZATION
  if (d1 == 0)
    {
      if (d0 > n1)
	{
	  /* 0q = nn / 0D */

	  udiv_qrnnd (q0, n0, n1, n0, d0);
	  q1 = 0;

	  /* Remainder in n0.  */
	}
      else
	{
	  /* qq = NN / 0d */

	  if (d0 == 0)
	    d0 = 1 / d0;	/* Divide intentionally by zero.  */

	  udiv_qrnnd (q1, n1, 0, n1, d0);
	  udiv_qrnnd (q0, n0, n1, n0, d0);

	  /* Remainder in n0.  */
	}

      if (rp != 0)
	{
	  rr.s.low = n0;
	  rr.s.high = 0;
	  *rp = rr.ll;
	}
    }

#else /* UDIV_NEEDS_NORMALIZATION */

  if (d1 == 0)
    {
      if (d0 > n1)
	{
	  /* 0q = nn / 0D */

	  count_leading_zeros (bm, d0);

	  if (bm != 0)
	    {
	      /* Normalize, i.e. make the most significant bit of the
		 denominator set.  */

	      d0 = d0 << bm;
	      n1 = (n1 << bm) | (n0 >> (W_TYPE_SIZE - bm));
	      n0 = n0 << bm;
	    }

	  udiv_qrnnd (q0, n0, n1, n0, d0);
	  q1 = 0;

	  /* Remainder in n0 >> bm.  */
	}
      else
	{
	  /* qq = NN / 0d */

	  if (d0 == 0)
	    d0 = 1 / d0;	/* Divide intentionally by zero.  */

	  count_leading_zeros (bm, d0);

	  if (bm == 0)
	    {
	      /* From (n1 >= d0) /\ (the most significant bit of d0 is set),
		 conclude (the most significant bit of n1 is set) /\ (the
		 leading quotient digit q1 = 1).

		 This special case is necessary, not an optimization.
		 (Shifts counts of W_TYPE_SIZE are undefined.)  */

	      n1 -= d0;
	      q1 = 1;
	    }
	  else
	    {
	      /* Normalize.  */

	      b = W_TYPE_SIZE - bm;

	      d0 = d0 << bm;
	      n2 = n1 >> b;
	      n1 = (n1 << bm) | (n0 >> b);
	      n0 = n0 << bm;

	      udiv_qrnnd (q1, n1, n2, n1, d0);
	    }

	  /* n1 != d0...  */

	  udiv_qrnnd (q0, n0, n1, n0, d0);

	  /* Remainder in n0 >> bm.  */
	}

      if (rp != 0)
	{
	  rr.s.low = n0 >> bm;
	  rr.s.high = 0;
	  *rp = rr.ll;
	}
    }
#endif /* UDIV_NEEDS_NORMALIZATION */

  else
    {
      if (d1 > n1)
	{
	  /* 00 = nn / DD */

	  q0 = 0;
	  q1 = 0;

	  /* Remainder in n1n0.  */
	  if (rp != 0)
	    {
	      rr.s.low = n0;
	      rr.s.high = n1;
	      *rp = rr.ll;
	    }
	}
      else
	{
	  /* 0q = NN / dd */

	  count_leading_zeros (bm, d1);
	  if (bm == 0)
	    {
	      /* From (n1 >= d1) /\ (the most significant bit of d1 is set),
		 conclude (the most significant bit of n1 is set) /\ (the
		 quotient digit q0 = 0 or 1).

		 This special case is necessary, not an optimization.  */

	      /* The condition on the next line takes advantage of that
		 n1 >= d1 (true due to program flow).  */
	      if (n1 > d1 || n0 >= d0)
		{
		  q0 = 1;
		  sub_ddmmss (n1, n0, n1, n0, d1, d0);
		}
	      else
		q0 = 0;

	      q1 = 0;

	      if (rp != 0)
		{
		  rr.s.low = n0;
		  rr.s.high = n1;
		  *rp = rr.ll;
		}
	    }
	  else
	    {
	      UWtype m1, m0;
	      /* Normalize.  */

	      b = W_TYPE_SIZE - bm;

	      d1 = (d1 << bm) | (d0 >> b);
	      d0 = d0 << bm;
	      n2 = n1 >> b;
	      n1 = (n1 << bm) | (n0 >> b);
	      n0 = n0 << bm;

	      udiv_qrnnd (q0, n1, n2, n1, d1);
	      umul_ppmm (m1, m0, q0, d0);

	      if (m1 > n1 || (m1 == n1 && m0 > n0))
		{
		  q0--;
		  sub_ddmmss (m1, m0, m1, m0, d1, d0);
		}

	      q1 = 0;

	      /* Remainder in (n1n0 - m1m0) >> bm.  */
	      if (rp != 0)
		{
		  sub_ddmmss (n1, n0, n1, n0, m1, m0);
		  rr.s.low = (n1 << b) | (n0 >> bm);
		  rr.s.high = n1 >> bm;
		  *rp = rr.ll;
		}
	    }
	}
    }

  ww.s.low = q0;
  ww.s.high = q1;
  return ww.ll;
}

DWtype
__divdi3 (DWtype u, DWtype v)
{
  Wtype c = 0;
  DWtype w;

  if (u < 0)
    {
      c = ~c;
      u = -u;
    }
  if (v < 0)
    {
      c = ~c;
      v = -v;
    }
  w = __udivmoddi4 (u, v, NULL);
  if (c)
    w = -w;
  return w;
}
strong_alias (__divdi3, __divdi3_internal)

DWtype
__moddi3 (DWtype u, DWtype v)
{
  Wtype c = 0;
  DWtype w;

  if (u < 0)
    {
      c = ~c;
      u = -u;
    }
  if (v < 0)
    v = -v;
  __udivmoddi4 (u, v, (UDWtype *) &w);
  if (c)
    w = -w;
  return w;
}
strong_alias (__moddi3, __moddi3_internal)

UDWtype
__udivdi3 (UDWtype u, UDWtype v)
{
  return __udivmoddi4 (u, v, NULL);
}
strong_alias (__udivdi3, __udivdi3_internal)

UDWtype
__umoddi3 (UDWtype u, UDWtype v)
{
  UDWtype w;

  __udivmoddi4 (u, v, &w);
  return w;
}
strong_alias (__umoddi3, __umoddi3_internal)

/* We declare these with compat_symbol so that they are not visible at
   link time.  Programs must use the functions from libgcc.  */
#ifdef SHARED
# include <shlib-compat.h>
compat_symbol (libc, __divdi3, __divdi3, GLIBC_2_0);
compat_symbol (libc, __moddi3, __moddi3, GLIBC_2_0);
compat_symbol (libc, __udivdi3, __udivdi3, GLIBC_2_0);
compat_symbol (libc, __umoddi3, __umoddi3, GLIBC_2_0);
#endif