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
|
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is the Netscape Portable Runtime (NSPR).
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1998-2000
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#include "primpl.h"
static PRInt64 ll_zero = LL_INIT( 0x00000000,0x00000000 );
static PRInt64 ll_maxint = LL_INIT( 0x7fffffff, 0xffffffff );
static PRInt64 ll_minint = LL_INIT( 0x80000000, 0x00000000 );
static PRUint64 ll_maxuint = LL_INIT( 0xffffffff, 0xffffffff );
PR_IMPLEMENT(PRInt64) LL_Zero(void) { return ll_zero; }
PR_IMPLEMENT(PRInt64) LL_MaxInt(void) { return ll_maxint; }
PR_IMPLEMENT(PRInt64) LL_MinInt(void) { return ll_minint; }
PR_IMPLEMENT(PRUint64) LL_MaxUint(void) { return ll_maxuint; }
#ifndef HAVE_LONG_LONG
/*
** Divide 64-bit a by 32-bit b, which must be normalized so its high bit is 1.
*/
static void norm_udivmod32(PRUint32 *qp, PRUint32 *rp, PRUint64 a, PRUint32 b)
{
PRUint32 d1, d0, q1, q0;
PRUint32 r1, r0, m;
d1 = _hi16(b);
d0 = _lo16(b);
r1 = a.hi % d1;
q1 = a.hi / d1;
m = q1 * d0;
r1 = (r1 << 16) | _hi16(a.lo);
if (r1 < m) {
q1--, r1 += b;
if (r1 >= b /* i.e., we didn't get a carry when adding to r1 */
&& r1 < m) {
q1--, r1 += b;
}
}
r1 -= m;
r0 = r1 % d1;
q0 = r1 / d1;
m = q0 * d0;
r0 = (r0 << 16) | _lo16(a.lo);
if (r0 < m) {
q0--, r0 += b;
if (r0 >= b
&& r0 < m) {
q0--, r0 += b;
}
}
*qp = (q1 << 16) | q0;
*rp = r0 - m;
}
static PRUint32 CountLeadingZeros(PRUint32 a)
{
PRUint32 t;
PRUint32 r = 32;
if ((t = a >> 16) != 0)
r -= 16, a = t;
if ((t = a >> 8) != 0)
r -= 8, a = t;
if ((t = a >> 4) != 0)
r -= 4, a = t;
if ((t = a >> 2) != 0)
r -= 2, a = t;
if ((t = a >> 1) != 0)
r -= 1, a = t;
if (a & 1)
r--;
return r;
}
PR_IMPLEMENT(void) ll_udivmod(PRUint64 *qp, PRUint64 *rp, PRUint64 a, PRUint64 b)
{
PRUint32 n0, n1, n2;
PRUint32 q0, q1;
PRUint32 rsh, lsh;
n0 = a.lo;
n1 = a.hi;
if (b.hi == 0) {
if (b.lo > n1) {
/* (0 q0) = (n1 n0) / (0 D0) */
lsh = CountLeadingZeros(b.lo);
if (lsh) {
/*
* Normalize, i.e. make the most significant bit of the
* denominator be set.
*/
b.lo = b.lo << lsh;
n1 = (n1 << lsh) | (n0 >> (32 - lsh));
n0 = n0 << lsh;
}
a.lo = n0, a.hi = n1;
norm_udivmod32(&q0, &n0, a, b.lo);
q1 = 0;
/* remainder is in n0 >> lsh */
} else {
/* (q1 q0) = (n1 n0) / (0 d0) */
if (b.lo == 0) /* user wants to divide by zero! */
b.lo = 1 / b.lo; /* so go ahead and crash */
lsh = CountLeadingZeros(b.lo);
if (lsh == 0) {
/*
* From (n1 >= b.lo)
* && (the most significant bit of b.lo is set),
* conclude that
* (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 32 are undefined).
*/
n1 -= b.lo;
q1 = 1;
} else {
/*
* Normalize.
*/
rsh = 32 - lsh;
b.lo = b.lo << lsh;
n2 = n1 >> rsh;
n1 = (n1 << lsh) | (n0 >> rsh);
n0 = n0 << lsh;
a.lo = n1, a.hi = n2;
norm_udivmod32(&q1, &n1, a, b.lo);
}
/* n1 != b.lo... */
a.lo = n0, a.hi = n1;
norm_udivmod32(&q0, &n0, a, b.lo);
/* remainder in n0 >> lsh */
}
if (rp) {
rp->lo = n0 >> lsh;
rp->hi = 0;
}
} else {
if (b.hi > n1) {
/* (0 0) = (n1 n0) / (D1 d0) */
q0 = 0;
q1 = 0;
/* remainder in (n1 n0) */
if (rp) {
rp->lo = n0;
rp->hi = n1;
}
} else {
/* (0 q0) = (n1 n0) / (d1 d0) */
lsh = CountLeadingZeros(b.hi);
if (lsh == 0) {
/*
* From (n1 >= b.hi)
* && (the most significant bit of b.hi is set),
* conclude that
* (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 >= b.hi (true due to control flow).
*/
if (n1 > b.hi || n0 >= b.lo) {
q0 = 1;
a.lo = n0, a.hi = n1;
LL_SUB(a, a, b);
} else {
q0 = 0;
}
q1 = 0;
if (rp) {
rp->lo = n0;
rp->hi = n1;
}
} else {
PRInt64 m;
/*
* Normalize.
*/
rsh = 32 - lsh;
b.hi = (b.hi << lsh) | (b.lo >> rsh);
b.lo = b.lo << lsh;
n2 = n1 >> rsh;
n1 = (n1 << lsh) | (n0 >> rsh);
n0 = n0 << lsh;
a.lo = n1, a.hi = n2;
norm_udivmod32(&q0, &n1, a, b.hi);
LL_MUL32(m, q0, b.lo);
if ((m.hi > n1) || ((m.hi == n1) && (m.lo > n0))) {
q0--;
LL_SUB(m, m, b);
}
q1 = 0;
/* Remainder is ((n1 n0) - (m1 m0)) >> lsh */
if (rp) {
a.lo = n0, a.hi = n1;
LL_SUB(a, a, m);
rp->lo = (a.hi << rsh) | (a.lo >> lsh);
rp->hi = a.hi >> lsh;
}
}
}
}
if (qp) {
qp->lo = q0;
qp->hi = q1;
}
}
#endif /* !HAVE_LONG_LONG */
|
