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1 | /******************************************************************************* |
2 | * | |
3 | * Module Name: utmath - Integer math support routines | |
4 | * | |
5 | ******************************************************************************/ | |
6 | ||
7 | /* | |
8 | * Copyright (C) 2000 - 2005, R. Byron Moore | |
9 | * All rights reserved. | |
10 | * | |
11 | * Redistribution and use in source and binary forms, with or without | |
12 | * modification, are permitted provided that the following conditions | |
13 | * are met: | |
14 | * 1. Redistributions of source code must retain the above copyright | |
15 | * notice, this list of conditions, and the following disclaimer, | |
16 | * without modification. | |
17 | * 2. Redistributions in binary form must reproduce at minimum a disclaimer | |
18 | * substantially similar to the "NO WARRANTY" disclaimer below | |
19 | * ("Disclaimer") and any redistribution must be conditioned upon | |
20 | * including a substantially similar Disclaimer requirement for further | |
21 | * binary redistribution. | |
22 | * 3. Neither the names of the above-listed copyright holders nor the names | |
23 | * of any contributors may be used to endorse or promote products derived | |
24 | * from this software without specific prior written permission. | |
25 | * | |
26 | * Alternatively, this software may be distributed under the terms of the | |
27 | * GNU General Public License ("GPL") version 2 as published by the Free | |
28 | * Software Foundation. | |
29 | * | |
30 | * NO WARRANTY | |
31 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
32 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
33 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR | |
34 | * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |
35 | * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
36 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
37 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
38 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
39 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING | |
40 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
41 | * POSSIBILITY OF SUCH DAMAGES. | |
42 | */ | |
43 | ||
44 | ||
45 | #include <acpi/acpi.h> | |
46 | ||
47 | ||
48 | #define _COMPONENT ACPI_UTILITIES | |
49 | ACPI_MODULE_NAME ("utmath") | |
50 | ||
51 | /* | |
52 | * Support for double-precision integer divide. This code is included here | |
53 | * in order to support kernel environments where the double-precision math | |
54 | * library is not available. | |
55 | */ | |
56 | ||
57 | #ifndef ACPI_USE_NATIVE_DIVIDE | |
58 | /******************************************************************************* | |
59 | * | |
60 | * FUNCTION: acpi_ut_short_divide | |
61 | * | |
62 | * PARAMETERS: Dividend - 64-bit dividend | |
63 | * Divisor - 32-bit divisor | |
64 | * out_quotient - Pointer to where the quotient is returned | |
65 | * out_remainder - Pointer to where the remainder is returned | |
66 | * | |
67 | * RETURN: Status (Checks for divide-by-zero) | |
68 | * | |
69 | * DESCRIPTION: Perform a short (maximum 64 bits divided by 32 bits) | |
70 | * divide and modulo. The result is a 64-bit quotient and a | |
71 | * 32-bit remainder. | |
72 | * | |
73 | ******************************************************************************/ | |
74 | ||
75 | acpi_status | |
76 | acpi_ut_short_divide ( | |
77 | acpi_integer dividend, | |
78 | u32 divisor, | |
79 | acpi_integer *out_quotient, | |
80 | u32 *out_remainder) | |
81 | { | |
82 | union uint64_overlay dividend_ovl; | |
83 | union uint64_overlay quotient; | |
84 | u32 remainder32; | |
85 | ||
86 | ||
87 | ACPI_FUNCTION_TRACE ("ut_short_divide"); | |
88 | ||
89 | ||
90 | /* Always check for a zero divisor */ | |
91 | ||
92 | if (divisor == 0) { | |
93 | ACPI_REPORT_ERROR (("acpi_ut_short_divide: Divide by zero\n")); | |
94 | return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO); | |
95 | } | |
96 | ||
97 | dividend_ovl.full = dividend; | |
98 | ||
99 | /* | |
100 | * The quotient is 64 bits, the remainder is always 32 bits, | |
101 | * and is generated by the second divide. | |
102 | */ | |
103 | ACPI_DIV_64_BY_32 (0, dividend_ovl.part.hi, divisor, | |
104 | quotient.part.hi, remainder32); | |
105 | ACPI_DIV_64_BY_32 (remainder32, dividend_ovl.part.lo, divisor, | |
106 | quotient.part.lo, remainder32); | |
107 | ||
108 | /* Return only what was requested */ | |
109 | ||
110 | if (out_quotient) { | |
111 | *out_quotient = quotient.full; | |
112 | } | |
113 | if (out_remainder) { | |
114 | *out_remainder = remainder32; | |
115 | } | |
116 | ||
117 | return_ACPI_STATUS (AE_OK); | |
118 | } | |
119 | ||
120 | ||
121 | /******************************************************************************* | |
122 | * | |
123 | * FUNCTION: acpi_ut_divide | |
124 | * | |
125 | * PARAMETERS: in_dividend - Dividend | |
126 | * in_divisor - Divisor | |
127 | * out_quotient - Pointer to where the quotient is returned | |
128 | * out_remainder - Pointer to where the remainder is returned | |
129 | * | |
130 | * RETURN: Status (Checks for divide-by-zero) | |
131 | * | |
132 | * DESCRIPTION: Perform a divide and modulo. | |
133 | * | |
134 | ******************************************************************************/ | |
135 | ||
136 | acpi_status | |
137 | acpi_ut_divide ( | |
138 | acpi_integer in_dividend, | |
139 | acpi_integer in_divisor, | |
140 | acpi_integer *out_quotient, | |
141 | acpi_integer *out_remainder) | |
142 | { | |
143 | union uint64_overlay dividend; | |
144 | union uint64_overlay divisor; | |
145 | union uint64_overlay quotient; | |
146 | union uint64_overlay remainder; | |
147 | union uint64_overlay normalized_dividend; | |
148 | union uint64_overlay normalized_divisor; | |
149 | u32 partial1; | |
150 | union uint64_overlay partial2; | |
151 | union uint64_overlay partial3; | |
152 | ||
153 | ||
154 | ACPI_FUNCTION_TRACE ("ut_divide"); | |
155 | ||
156 | ||
157 | /* Always check for a zero divisor */ | |
158 | ||
159 | if (in_divisor == 0) { | |
160 | ACPI_REPORT_ERROR (("acpi_ut_divide: Divide by zero\n")); | |
161 | return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO); | |
162 | } | |
163 | ||
164 | divisor.full = in_divisor; | |
165 | dividend.full = in_dividend; | |
166 | if (divisor.part.hi == 0) { | |
167 | /* | |
168 | * 1) Simplest case is where the divisor is 32 bits, we can | |
169 | * just do two divides | |
170 | */ | |
171 | remainder.part.hi = 0; | |
172 | ||
173 | /* | |
174 | * The quotient is 64 bits, the remainder is always 32 bits, | |
175 | * and is generated by the second divide. | |
176 | */ | |
177 | ACPI_DIV_64_BY_32 (0, dividend.part.hi, divisor.part.lo, | |
178 | quotient.part.hi, partial1); | |
179 | ACPI_DIV_64_BY_32 (partial1, dividend.part.lo, divisor.part.lo, | |
180 | quotient.part.lo, remainder.part.lo); | |
181 | } | |
182 | ||
183 | else { | |
184 | /* | |
185 | * 2) The general case where the divisor is a full 64 bits | |
186 | * is more difficult | |
187 | */ | |
188 | quotient.part.hi = 0; | |
189 | normalized_dividend = dividend; | |
190 | normalized_divisor = divisor; | |
191 | ||
192 | /* Normalize the operands (shift until the divisor is < 32 bits) */ | |
193 | ||
194 | do { | |
195 | ACPI_SHIFT_RIGHT_64 (normalized_divisor.part.hi, | |
196 | normalized_divisor.part.lo); | |
197 | ACPI_SHIFT_RIGHT_64 (normalized_dividend.part.hi, | |
198 | normalized_dividend.part.lo); | |
199 | ||
200 | } while (normalized_divisor.part.hi != 0); | |
201 | ||
202 | /* Partial divide */ | |
203 | ||
204 | ACPI_DIV_64_BY_32 (normalized_dividend.part.hi, | |
205 | normalized_dividend.part.lo, | |
206 | normalized_divisor.part.lo, | |
207 | quotient.part.lo, partial1); | |
208 | ||
209 | /* | |
210 | * The quotient is always 32 bits, and simply requires adjustment. | |
211 | * The 64-bit remainder must be generated. | |
212 | */ | |
213 | partial1 = quotient.part.lo * divisor.part.hi; | |
214 | partial2.full = (acpi_integer) quotient.part.lo * divisor.part.lo; | |
215 | partial3.full = (acpi_integer) partial2.part.hi + partial1; | |
216 | ||
217 | remainder.part.hi = partial3.part.lo; | |
218 | remainder.part.lo = partial2.part.lo; | |
219 | ||
220 | if (partial3.part.hi == 0) { | |
221 | if (partial3.part.lo >= dividend.part.hi) { | |
222 | if (partial3.part.lo == dividend.part.hi) { | |
223 | if (partial2.part.lo > dividend.part.lo) { | |
224 | quotient.part.lo--; | |
225 | remainder.full -= divisor.full; | |
226 | } | |
227 | } | |
228 | else { | |
229 | quotient.part.lo--; | |
230 | remainder.full -= divisor.full; | |
231 | } | |
232 | } | |
233 | ||
234 | remainder.full = remainder.full - dividend.full; | |
235 | remainder.part.hi = (u32) -((s32) remainder.part.hi); | |
236 | remainder.part.lo = (u32) -((s32) remainder.part.lo); | |
237 | ||
238 | if (remainder.part.lo) { | |
239 | remainder.part.hi--; | |
240 | } | |
241 | } | |
242 | } | |
243 | ||
244 | /* Return only what was requested */ | |
245 | ||
246 | if (out_quotient) { | |
247 | *out_quotient = quotient.full; | |
248 | } | |
249 | if (out_remainder) { | |
250 | *out_remainder = remainder.full; | |
251 | } | |
252 | ||
253 | return_ACPI_STATUS (AE_OK); | |
254 | } | |
255 | ||
256 | #else | |
257 | ||
258 | /******************************************************************************* | |
259 | * | |
260 | * FUNCTION: acpi_ut_short_divide, acpi_ut_divide | |
261 | * | |
44f6c012 RM |
262 | * PARAMETERS: See function headers above |
263 | * | |
1da177e4 LT |
264 | * DESCRIPTION: Native versions of the ut_divide functions. Use these if either |
265 | * 1) The target is a 64-bit platform and therefore 64-bit | |
266 | * integer math is supported directly by the machine. | |
267 | * 2) The target is a 32-bit or 16-bit platform, and the | |
268 | * double-precision integer math library is available to | |
269 | * perform the divide. | |
270 | * | |
271 | ******************************************************************************/ | |
272 | ||
273 | acpi_status | |
274 | acpi_ut_short_divide ( | |
275 | acpi_integer in_dividend, | |
276 | u32 divisor, | |
277 | acpi_integer *out_quotient, | |
278 | u32 *out_remainder) | |
279 | { | |
280 | ||
281 | ACPI_FUNCTION_TRACE ("ut_short_divide"); | |
282 | ||
283 | ||
284 | /* Always check for a zero divisor */ | |
285 | ||
286 | if (divisor == 0) { | |
287 | ACPI_REPORT_ERROR (("acpi_ut_short_divide: Divide by zero\n")); | |
288 | return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO); | |
289 | } | |
290 | ||
291 | /* Return only what was requested */ | |
292 | ||
293 | if (out_quotient) { | |
294 | *out_quotient = in_dividend / divisor; | |
295 | } | |
296 | if (out_remainder) { | |
297 | *out_remainder = (u32) in_dividend % divisor; | |
298 | } | |
299 | ||
300 | return_ACPI_STATUS (AE_OK); | |
301 | } | |
302 | ||
303 | acpi_status | |
304 | acpi_ut_divide ( | |
305 | acpi_integer in_dividend, | |
306 | acpi_integer in_divisor, | |
307 | acpi_integer *out_quotient, | |
308 | acpi_integer *out_remainder) | |
309 | { | |
310 | ACPI_FUNCTION_TRACE ("ut_divide"); | |
311 | ||
312 | ||
313 | /* Always check for a zero divisor */ | |
314 | ||
315 | if (in_divisor == 0) { | |
316 | ACPI_REPORT_ERROR (("acpi_ut_divide: Divide by zero\n")); | |
317 | return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO); | |
318 | } | |
319 | ||
320 | ||
321 | /* Return only what was requested */ | |
322 | ||
323 | if (out_quotient) { | |
324 | *out_quotient = in_dividend / in_divisor; | |
325 | } | |
326 | if (out_remainder) { | |
327 | *out_remainder = in_dividend % in_divisor; | |
328 | } | |
329 | ||
330 | return_ACPI_STATUS (AE_OK); | |
331 | } | |
332 | ||
333 | #endif | |
334 | ||
335 |