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1da177e4 LT |
1 | /******************************************************************************* |
2 | * | |
3 | * Module Name: utmath - Integer math support routines | |
4 | * | |
5 | ******************************************************************************/ | |
6 | ||
7 | /* | |
4a90c7e8 | 8 | * Copyright (C) 2000 - 2006, R. Byron Moore |
1da177e4 LT |
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 | ||
1da177e4 LT |
44 | #include <acpi/acpi.h> |
45 | ||
1da177e4 | 46 | #define _COMPONENT ACPI_UTILITIES |
4be44fcd | 47 | ACPI_MODULE_NAME("utmath") |
1da177e4 LT |
48 | |
49 | /* | |
50 | * Support for double-precision integer divide. This code is included here | |
51 | * in order to support kernel environments where the double-precision math | |
52 | * library is not available. | |
53 | */ | |
1da177e4 LT |
54 | #ifndef ACPI_USE_NATIVE_DIVIDE |
55 | /******************************************************************************* | |
56 | * | |
57 | * FUNCTION: acpi_ut_short_divide | |
58 | * | |
59 | * PARAMETERS: Dividend - 64-bit dividend | |
60 | * Divisor - 32-bit divisor | |
61 | * out_quotient - Pointer to where the quotient is returned | |
62 | * out_remainder - Pointer to where the remainder is returned | |
63 | * | |
64 | * RETURN: Status (Checks for divide-by-zero) | |
65 | * | |
66 | * DESCRIPTION: Perform a short (maximum 64 bits divided by 32 bits) | |
67 | * divide and modulo. The result is a 64-bit quotient and a | |
68 | * 32-bit remainder. | |
69 | * | |
70 | ******************************************************************************/ | |
1da177e4 | 71 | acpi_status |
4be44fcd LB |
72 | acpi_ut_short_divide(acpi_integer dividend, |
73 | u32 divisor, | |
74 | acpi_integer * out_quotient, u32 * out_remainder) | |
1da177e4 | 75 | { |
4be44fcd LB |
76 | union uint64_overlay dividend_ovl; |
77 | union uint64_overlay quotient; | |
78 | u32 remainder32; | |
1da177e4 | 79 | |
4be44fcd | 80 | ACPI_FUNCTION_TRACE("ut_short_divide"); |
1da177e4 LT |
81 | |
82 | /* Always check for a zero divisor */ | |
83 | ||
84 | if (divisor == 0) { | |
b8e4d893 | 85 | ACPI_ERROR((AE_INFO, "Divide by zero")); |
4be44fcd | 86 | return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
1da177e4 LT |
87 | } |
88 | ||
89 | dividend_ovl.full = dividend; | |
90 | ||
91 | /* | |
92 | * The quotient is 64 bits, the remainder is always 32 bits, | |
93 | * and is generated by the second divide. | |
94 | */ | |
4be44fcd | 95 | ACPI_DIV_64_BY_32(0, dividend_ovl.part.hi, divisor, |
1da177e4 | 96 | quotient.part.hi, remainder32); |
4be44fcd | 97 | ACPI_DIV_64_BY_32(remainder32, dividend_ovl.part.lo, divisor, |
1da177e4 LT |
98 | quotient.part.lo, remainder32); |
99 | ||
100 | /* Return only what was requested */ | |
101 | ||
102 | if (out_quotient) { | |
103 | *out_quotient = quotient.full; | |
104 | } | |
105 | if (out_remainder) { | |
106 | *out_remainder = remainder32; | |
107 | } | |
108 | ||
4be44fcd | 109 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
110 | } |
111 | ||
1da177e4 LT |
112 | /******************************************************************************* |
113 | * | |
114 | * FUNCTION: acpi_ut_divide | |
115 | * | |
116 | * PARAMETERS: in_dividend - Dividend | |
117 | * in_divisor - Divisor | |
118 | * out_quotient - Pointer to where the quotient is returned | |
119 | * out_remainder - Pointer to where the remainder is returned | |
120 | * | |
121 | * RETURN: Status (Checks for divide-by-zero) | |
122 | * | |
123 | * DESCRIPTION: Perform a divide and modulo. | |
124 | * | |
125 | ******************************************************************************/ | |
126 | ||
127 | acpi_status | |
4be44fcd LB |
128 | acpi_ut_divide(acpi_integer in_dividend, |
129 | acpi_integer in_divisor, | |
130 | acpi_integer * out_quotient, acpi_integer * out_remainder) | |
1da177e4 | 131 | { |
4be44fcd LB |
132 | union uint64_overlay dividend; |
133 | union uint64_overlay divisor; | |
134 | union uint64_overlay quotient; | |
135 | union uint64_overlay remainder; | |
136 | union uint64_overlay normalized_dividend; | |
137 | union uint64_overlay normalized_divisor; | |
138 | u32 partial1; | |
139 | union uint64_overlay partial2; | |
140 | union uint64_overlay partial3; | |
141 | ||
142 | ACPI_FUNCTION_TRACE("ut_divide"); | |
1da177e4 LT |
143 | |
144 | /* Always check for a zero divisor */ | |
145 | ||
146 | if (in_divisor == 0) { | |
b8e4d893 | 147 | ACPI_ERROR((AE_INFO, "Divide by zero")); |
4be44fcd | 148 | return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
1da177e4 LT |
149 | } |
150 | ||
4be44fcd | 151 | divisor.full = in_divisor; |
1da177e4 LT |
152 | dividend.full = in_dividend; |
153 | if (divisor.part.hi == 0) { | |
154 | /* | |
155 | * 1) Simplest case is where the divisor is 32 bits, we can | |
156 | * just do two divides | |
157 | */ | |
158 | remainder.part.hi = 0; | |
159 | ||
160 | /* | |
161 | * The quotient is 64 bits, the remainder is always 32 bits, | |
162 | * and is generated by the second divide. | |
163 | */ | |
4be44fcd | 164 | ACPI_DIV_64_BY_32(0, dividend.part.hi, divisor.part.lo, |
1da177e4 | 165 | quotient.part.hi, partial1); |
4be44fcd | 166 | ACPI_DIV_64_BY_32(partial1, dividend.part.lo, divisor.part.lo, |
1da177e4 LT |
167 | quotient.part.lo, remainder.part.lo); |
168 | } | |
169 | ||
170 | else { | |
171 | /* | |
172 | * 2) The general case where the divisor is a full 64 bits | |
173 | * is more difficult | |
174 | */ | |
4be44fcd | 175 | quotient.part.hi = 0; |
1da177e4 LT |
176 | normalized_dividend = dividend; |
177 | normalized_divisor = divisor; | |
178 | ||
179 | /* Normalize the operands (shift until the divisor is < 32 bits) */ | |
180 | ||
181 | do { | |
4be44fcd LB |
182 | ACPI_SHIFT_RIGHT_64(normalized_divisor.part.hi, |
183 | normalized_divisor.part.lo); | |
184 | ACPI_SHIFT_RIGHT_64(normalized_dividend.part.hi, | |
185 | normalized_dividend.part.lo); | |
1da177e4 LT |
186 | |
187 | } while (normalized_divisor.part.hi != 0); | |
188 | ||
189 | /* Partial divide */ | |
190 | ||
4be44fcd | 191 | ACPI_DIV_64_BY_32(normalized_dividend.part.hi, |
1da177e4 LT |
192 | normalized_dividend.part.lo, |
193 | normalized_divisor.part.lo, | |
194 | quotient.part.lo, partial1); | |
195 | ||
196 | /* | |
197 | * The quotient is always 32 bits, and simply requires adjustment. | |
198 | * The 64-bit remainder must be generated. | |
199 | */ | |
4be44fcd LB |
200 | partial1 = quotient.part.lo * divisor.part.hi; |
201 | partial2.full = | |
202 | (acpi_integer) quotient.part.lo * divisor.part.lo; | |
1da177e4 LT |
203 | partial3.full = (acpi_integer) partial2.part.hi + partial1; |
204 | ||
205 | remainder.part.hi = partial3.part.lo; | |
206 | remainder.part.lo = partial2.part.lo; | |
207 | ||
208 | if (partial3.part.hi == 0) { | |
209 | if (partial3.part.lo >= dividend.part.hi) { | |
210 | if (partial3.part.lo == dividend.part.hi) { | |
211 | if (partial2.part.lo > dividend.part.lo) { | |
212 | quotient.part.lo--; | |
213 | remainder.full -= divisor.full; | |
214 | } | |
4be44fcd | 215 | } else { |
1da177e4 LT |
216 | quotient.part.lo--; |
217 | remainder.full -= divisor.full; | |
218 | } | |
219 | } | |
220 | ||
4be44fcd LB |
221 | remainder.full = remainder.full - dividend.full; |
222 | remainder.part.hi = (u32) - ((s32) remainder.part.hi); | |
223 | remainder.part.lo = (u32) - ((s32) remainder.part.lo); | |
1da177e4 LT |
224 | |
225 | if (remainder.part.lo) { | |
226 | remainder.part.hi--; | |
227 | } | |
228 | } | |
229 | } | |
230 | ||
231 | /* Return only what was requested */ | |
232 | ||
233 | if (out_quotient) { | |
234 | *out_quotient = quotient.full; | |
235 | } | |
236 | if (out_remainder) { | |
237 | *out_remainder = remainder.full; | |
238 | } | |
239 | ||
4be44fcd | 240 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
241 | } |
242 | ||
243 | #else | |
1da177e4 LT |
244 | /******************************************************************************* |
245 | * | |
246 | * FUNCTION: acpi_ut_short_divide, acpi_ut_divide | |
247 | * | |
44f6c012 RM |
248 | * PARAMETERS: See function headers above |
249 | * | |
1da177e4 LT |
250 | * DESCRIPTION: Native versions of the ut_divide functions. Use these if either |
251 | * 1) The target is a 64-bit platform and therefore 64-bit | |
252 | * integer math is supported directly by the machine. | |
253 | * 2) The target is a 32-bit or 16-bit platform, and the | |
254 | * double-precision integer math library is available to | |
255 | * perform the divide. | |
256 | * | |
257 | ******************************************************************************/ | |
1da177e4 | 258 | acpi_status |
4be44fcd LB |
259 | acpi_ut_short_divide(acpi_integer in_dividend, |
260 | u32 divisor, | |
261 | acpi_integer * out_quotient, u32 * out_remainder) | |
1da177e4 LT |
262 | { |
263 | ||
4be44fcd | 264 | ACPI_FUNCTION_TRACE("ut_short_divide"); |
1da177e4 LT |
265 | |
266 | /* Always check for a zero divisor */ | |
267 | ||
268 | if (divisor == 0) { | |
b8e4d893 | 269 | ACPI_ERROR((AE_INFO, "Divide by zero")); |
4be44fcd | 270 | return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
1da177e4 LT |
271 | } |
272 | ||
273 | /* Return only what was requested */ | |
274 | ||
275 | if (out_quotient) { | |
276 | *out_quotient = in_dividend / divisor; | |
277 | } | |
278 | if (out_remainder) { | |
279 | *out_remainder = (u32) in_dividend % divisor; | |
280 | } | |
281 | ||
4be44fcd | 282 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
283 | } |
284 | ||
285 | acpi_status | |
4be44fcd LB |
286 | acpi_ut_divide(acpi_integer in_dividend, |
287 | acpi_integer in_divisor, | |
288 | acpi_integer * out_quotient, acpi_integer * out_remainder) | |
1da177e4 | 289 | { |
4be44fcd | 290 | ACPI_FUNCTION_TRACE("ut_divide"); |
1da177e4 LT |
291 | |
292 | /* Always check for a zero divisor */ | |
293 | ||
294 | if (in_divisor == 0) { | |
b8e4d893 | 295 | ACPI_ERROR((AE_INFO, "Divide by zero")); |
4be44fcd | 296 | return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
1da177e4 LT |
297 | } |
298 | ||
1da177e4 LT |
299 | /* Return only what was requested */ |
300 | ||
301 | if (out_quotient) { | |
302 | *out_quotient = in_dividend / in_divisor; | |
303 | } | |
304 | if (out_remainder) { | |
305 | *out_remainder = in_dividend % in_divisor; | |
306 | } | |
307 | ||
4be44fcd | 308 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
309 | } |
310 | ||
311 | #endif |