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1da177e4 LT |
1 | /******************************************************************************* |
2 | * | |
3 | * Module Name: utmath - Integer math support routines | |
4 | * | |
5 | ******************************************************************************/ | |
6 | ||
7 | /* | |
75a44ce0 | 8 | * Copyright (C) 2000 - 2008, Intel Corp. |
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 | 44 | #include <acpi/acpi.h> |
e2f7a777 | 45 | #include "accommon.h" |
1da177e4 | 46 | |
1da177e4 | 47 | #define _COMPONENT ACPI_UTILITIES |
4be44fcd | 48 | ACPI_MODULE_NAME("utmath") |
1da177e4 LT |
49 | |
50 | /* | |
51 | * Support for double-precision integer divide. This code is included here | |
52 | * in order to support kernel environments where the double-precision math | |
53 | * library is not available. | |
54 | */ | |
1da177e4 LT |
55 | #ifndef ACPI_USE_NATIVE_DIVIDE |
56 | /******************************************************************************* | |
57 | * | |
58 | * FUNCTION: acpi_ut_short_divide | |
59 | * | |
60 | * PARAMETERS: Dividend - 64-bit dividend | |
61 | * Divisor - 32-bit divisor | |
62 | * out_quotient - Pointer to where the quotient is returned | |
63 | * out_remainder - Pointer to where the remainder is returned | |
64 | * | |
65 | * RETURN: Status (Checks for divide-by-zero) | |
66 | * | |
67 | * DESCRIPTION: Perform a short (maximum 64 bits divided by 32 bits) | |
68 | * divide and modulo. The result is a 64-bit quotient and a | |
69 | * 32-bit remainder. | |
70 | * | |
71 | ******************************************************************************/ | |
1da177e4 | 72 | acpi_status |
4be44fcd LB |
73 | acpi_ut_short_divide(acpi_integer dividend, |
74 | u32 divisor, | |
75 | acpi_integer * out_quotient, u32 * out_remainder) | |
1da177e4 | 76 | { |
4be44fcd LB |
77 | union uint64_overlay dividend_ovl; |
78 | union uint64_overlay quotient; | |
79 | u32 remainder32; | |
1da177e4 | 80 | |
b229cf92 | 81 | ACPI_FUNCTION_TRACE(ut_short_divide); |
1da177e4 LT |
82 | |
83 | /* Always check for a zero divisor */ | |
84 | ||
85 | if (divisor == 0) { | |
b8e4d893 | 86 | ACPI_ERROR((AE_INFO, "Divide by zero")); |
4be44fcd | 87 | return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
1da177e4 LT |
88 | } |
89 | ||
90 | dividend_ovl.full = dividend; | |
91 | ||
92 | /* | |
93 | * The quotient is 64 bits, the remainder is always 32 bits, | |
94 | * and is generated by the second divide. | |
95 | */ | |
4be44fcd | 96 | ACPI_DIV_64_BY_32(0, dividend_ovl.part.hi, divisor, |
1da177e4 | 97 | quotient.part.hi, remainder32); |
4be44fcd | 98 | ACPI_DIV_64_BY_32(remainder32, dividend_ovl.part.lo, divisor, |
1da177e4 LT |
99 | quotient.part.lo, remainder32); |
100 | ||
101 | /* Return only what was requested */ | |
102 | ||
103 | if (out_quotient) { | |
104 | *out_quotient = quotient.full; | |
105 | } | |
106 | if (out_remainder) { | |
107 | *out_remainder = remainder32; | |
108 | } | |
109 | ||
4be44fcd | 110 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
111 | } |
112 | ||
1da177e4 LT |
113 | /******************************************************************************* |
114 | * | |
115 | * FUNCTION: acpi_ut_divide | |
116 | * | |
117 | * PARAMETERS: in_dividend - Dividend | |
118 | * in_divisor - Divisor | |
119 | * out_quotient - Pointer to where the quotient is returned | |
120 | * out_remainder - Pointer to where the remainder is returned | |
121 | * | |
122 | * RETURN: Status (Checks for divide-by-zero) | |
123 | * | |
124 | * DESCRIPTION: Perform a divide and modulo. | |
125 | * | |
126 | ******************************************************************************/ | |
127 | ||
128 | acpi_status | |
4be44fcd LB |
129 | acpi_ut_divide(acpi_integer in_dividend, |
130 | acpi_integer in_divisor, | |
131 | acpi_integer * out_quotient, acpi_integer * out_remainder) | |
1da177e4 | 132 | { |
4be44fcd LB |
133 | union uint64_overlay dividend; |
134 | union uint64_overlay divisor; | |
135 | union uint64_overlay quotient; | |
136 | union uint64_overlay remainder; | |
137 | union uint64_overlay normalized_dividend; | |
138 | union uint64_overlay normalized_divisor; | |
139 | u32 partial1; | |
140 | union uint64_overlay partial2; | |
141 | union uint64_overlay partial3; | |
142 | ||
b229cf92 | 143 | ACPI_FUNCTION_TRACE(ut_divide); |
1da177e4 LT |
144 | |
145 | /* Always check for a zero divisor */ | |
146 | ||
147 | if (in_divisor == 0) { | |
b8e4d893 | 148 | ACPI_ERROR((AE_INFO, "Divide by zero")); |
4be44fcd | 149 | return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
1da177e4 LT |
150 | } |
151 | ||
4be44fcd | 152 | divisor.full = in_divisor; |
1da177e4 LT |
153 | dividend.full = in_dividend; |
154 | if (divisor.part.hi == 0) { | |
155 | /* | |
156 | * 1) Simplest case is where the divisor is 32 bits, we can | |
157 | * just do two divides | |
158 | */ | |
159 | remainder.part.hi = 0; | |
160 | ||
161 | /* | |
162 | * The quotient is 64 bits, the remainder is always 32 bits, | |
163 | * and is generated by the second divide. | |
164 | */ | |
4be44fcd | 165 | ACPI_DIV_64_BY_32(0, dividend.part.hi, divisor.part.lo, |
1da177e4 | 166 | quotient.part.hi, partial1); |
4be44fcd | 167 | ACPI_DIV_64_BY_32(partial1, dividend.part.lo, divisor.part.lo, |
1da177e4 LT |
168 | quotient.part.lo, remainder.part.lo); |
169 | } | |
170 | ||
171 | else { | |
172 | /* | |
173 | * 2) The general case where the divisor is a full 64 bits | |
174 | * is more difficult | |
175 | */ | |
4be44fcd | 176 | quotient.part.hi = 0; |
1da177e4 LT |
177 | normalized_dividend = dividend; |
178 | normalized_divisor = divisor; | |
179 | ||
180 | /* Normalize the operands (shift until the divisor is < 32 bits) */ | |
181 | ||
182 | do { | |
4be44fcd LB |
183 | ACPI_SHIFT_RIGHT_64(normalized_divisor.part.hi, |
184 | normalized_divisor.part.lo); | |
185 | ACPI_SHIFT_RIGHT_64(normalized_dividend.part.hi, | |
186 | normalized_dividend.part.lo); | |
1da177e4 LT |
187 | |
188 | } while (normalized_divisor.part.hi != 0); | |
189 | ||
190 | /* Partial divide */ | |
191 | ||
4be44fcd | 192 | ACPI_DIV_64_BY_32(normalized_dividend.part.hi, |
1da177e4 LT |
193 | normalized_dividend.part.lo, |
194 | normalized_divisor.part.lo, | |
195 | quotient.part.lo, partial1); | |
196 | ||
197 | /* | |
198 | * The quotient is always 32 bits, and simply requires adjustment. | |
199 | * The 64-bit remainder must be generated. | |
200 | */ | |
4be44fcd LB |
201 | partial1 = quotient.part.lo * divisor.part.hi; |
202 | partial2.full = | |
203 | (acpi_integer) quotient.part.lo * divisor.part.lo; | |
1da177e4 LT |
204 | partial3.full = (acpi_integer) partial2.part.hi + partial1; |
205 | ||
206 | remainder.part.hi = partial3.part.lo; | |
207 | remainder.part.lo = partial2.part.lo; | |
208 | ||
209 | if (partial3.part.hi == 0) { | |
210 | if (partial3.part.lo >= dividend.part.hi) { | |
211 | if (partial3.part.lo == dividend.part.hi) { | |
212 | if (partial2.part.lo > dividend.part.lo) { | |
213 | quotient.part.lo--; | |
214 | remainder.full -= divisor.full; | |
215 | } | |
4be44fcd | 216 | } else { |
1da177e4 LT |
217 | quotient.part.lo--; |
218 | remainder.full -= divisor.full; | |
219 | } | |
220 | } | |
221 | ||
4be44fcd LB |
222 | remainder.full = remainder.full - dividend.full; |
223 | remainder.part.hi = (u32) - ((s32) remainder.part.hi); | |
224 | remainder.part.lo = (u32) - ((s32) remainder.part.lo); | |
1da177e4 LT |
225 | |
226 | if (remainder.part.lo) { | |
227 | remainder.part.hi--; | |
228 | } | |
229 | } | |
230 | } | |
231 | ||
232 | /* Return only what was requested */ | |
233 | ||
234 | if (out_quotient) { | |
235 | *out_quotient = quotient.full; | |
236 | } | |
237 | if (out_remainder) { | |
238 | *out_remainder = remainder.full; | |
239 | } | |
240 | ||
4be44fcd | 241 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
242 | } |
243 | ||
244 | #else | |
1da177e4 LT |
245 | /******************************************************************************* |
246 | * | |
247 | * FUNCTION: acpi_ut_short_divide, acpi_ut_divide | |
248 | * | |
44f6c012 RM |
249 | * PARAMETERS: See function headers above |
250 | * | |
1da177e4 LT |
251 | * DESCRIPTION: Native versions of the ut_divide functions. Use these if either |
252 | * 1) The target is a 64-bit platform and therefore 64-bit | |
253 | * integer math is supported directly by the machine. | |
254 | * 2) The target is a 32-bit or 16-bit platform, and the | |
255 | * double-precision integer math library is available to | |
256 | * perform the divide. | |
257 | * | |
258 | ******************************************************************************/ | |
1da177e4 | 259 | acpi_status |
4be44fcd LB |
260 | acpi_ut_short_divide(acpi_integer in_dividend, |
261 | u32 divisor, | |
262 | acpi_integer * out_quotient, u32 * out_remainder) | |
1da177e4 LT |
263 | { |
264 | ||
b229cf92 | 265 | ACPI_FUNCTION_TRACE(ut_short_divide); |
1da177e4 LT |
266 | |
267 | /* Always check for a zero divisor */ | |
268 | ||
269 | if (divisor == 0) { | |
b8e4d893 | 270 | ACPI_ERROR((AE_INFO, "Divide by zero")); |
4be44fcd | 271 | return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
1da177e4 LT |
272 | } |
273 | ||
274 | /* Return only what was requested */ | |
275 | ||
276 | if (out_quotient) { | |
277 | *out_quotient = in_dividend / divisor; | |
278 | } | |
279 | if (out_remainder) { | |
1f549a24 | 280 | *out_remainder = (u32) (in_dividend % divisor); |
1da177e4 LT |
281 | } |
282 | ||
4be44fcd | 283 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
284 | } |
285 | ||
286 | acpi_status | |
4be44fcd LB |
287 | acpi_ut_divide(acpi_integer in_dividend, |
288 | acpi_integer in_divisor, | |
289 | acpi_integer * out_quotient, acpi_integer * out_remainder) | |
1da177e4 | 290 | { |
b229cf92 | 291 | ACPI_FUNCTION_TRACE(ut_divide); |
1da177e4 LT |
292 | |
293 | /* Always check for a zero divisor */ | |
294 | ||
295 | if (in_divisor == 0) { | |
b8e4d893 | 296 | ACPI_ERROR((AE_INFO, "Divide by zero")); |
4be44fcd | 297 | return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
1da177e4 LT |
298 | } |
299 | ||
1da177e4 LT |
300 | /* Return only what was requested */ |
301 | ||
302 | if (out_quotient) { | |
303 | *out_quotient = in_dividend / in_divisor; | |
304 | } | |
305 | if (out_remainder) { | |
306 | *out_remainder = in_dividend % in_divisor; | |
307 | } | |
308 | ||
4be44fcd | 309 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
310 | } |
311 | ||
312 | #endif |