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1da177e4 LT |
1 | /******************************************************************************* |
2 | * | |
3 | * Module Name: utmath - Integer math support routines | |
4 | * | |
5 | ******************************************************************************/ | |
6 | ||
7 | /* | |
82a80941 | 8 | * Copyright (C) 2000 - 2015, 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 | /* | |
e786db75 BM |
51 | * Optional support for 64-bit double-precision integer divide. This code |
52 | * is configurable and is implemented in order to support 32-bit kernel | |
53 | * environments where a 64-bit double-precision math library is not available. | |
54 | * | |
55 | * Support for a more normal 64-bit divide/modulo (with check for a divide- | |
56 | * by-zero) appears after this optional section of code. | |
1da177e4 | 57 | */ |
1da177e4 | 58 | #ifndef ACPI_USE_NATIVE_DIVIDE |
e786db75 BM |
59 | /* Structures used only for 64-bit divide */ |
60 | typedef struct uint64_struct { | |
61 | u32 lo; | |
62 | u32 hi; | |
63 | ||
64 | } uint64_struct; | |
65 | ||
66 | typedef union uint64_overlay { | |
67 | u64 full; | |
68 | struct uint64_struct part; | |
69 | ||
70 | } uint64_overlay; | |
71 | ||
1da177e4 LT |
72 | /******************************************************************************* |
73 | * | |
74 | * FUNCTION: acpi_ut_short_divide | |
75 | * | |
ba494bee BM |
76 | * PARAMETERS: dividend - 64-bit dividend |
77 | * divisor - 32-bit divisor | |
1da177e4 LT |
78 | * out_quotient - Pointer to where the quotient is returned |
79 | * out_remainder - Pointer to where the remainder is returned | |
80 | * | |
81 | * RETURN: Status (Checks for divide-by-zero) | |
82 | * | |
83 | * DESCRIPTION: Perform a short (maximum 64 bits divided by 32 bits) | |
73a3090a | 84 | * divide and modulo. The result is a 64-bit quotient and a |
1da177e4 LT |
85 | * 32-bit remainder. |
86 | * | |
87 | ******************************************************************************/ | |
e786db75 | 88 | |
1da177e4 | 89 | acpi_status |
5df7e6cb BM |
90 | acpi_ut_short_divide(u64 dividend, |
91 | u32 divisor, u64 *out_quotient, u32 *out_remainder) | |
1da177e4 | 92 | { |
4be44fcd LB |
93 | union uint64_overlay dividend_ovl; |
94 | union uint64_overlay quotient; | |
95 | u32 remainder32; | |
1da177e4 | 96 | |
b229cf92 | 97 | ACPI_FUNCTION_TRACE(ut_short_divide); |
1da177e4 LT |
98 | |
99 | /* Always check for a zero divisor */ | |
100 | ||
101 | if (divisor == 0) { | |
b8e4d893 | 102 | ACPI_ERROR((AE_INFO, "Divide by zero")); |
4be44fcd | 103 | return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
1da177e4 LT |
104 | } |
105 | ||
106 | dividend_ovl.full = dividend; | |
107 | ||
108 | /* | |
109 | * The quotient is 64 bits, the remainder is always 32 bits, | |
110 | * and is generated by the second divide. | |
111 | */ | |
4be44fcd | 112 | ACPI_DIV_64_BY_32(0, dividend_ovl.part.hi, divisor, |
1da177e4 | 113 | quotient.part.hi, remainder32); |
4be44fcd | 114 | ACPI_DIV_64_BY_32(remainder32, dividend_ovl.part.lo, divisor, |
1da177e4 LT |
115 | quotient.part.lo, remainder32); |
116 | ||
117 | /* Return only what was requested */ | |
118 | ||
119 | if (out_quotient) { | |
120 | *out_quotient = quotient.full; | |
121 | } | |
122 | if (out_remainder) { | |
123 | *out_remainder = remainder32; | |
124 | } | |
125 | ||
4be44fcd | 126 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
127 | } |
128 | ||
1da177e4 LT |
129 | /******************************************************************************* |
130 | * | |
131 | * FUNCTION: acpi_ut_divide | |
132 | * | |
133 | * PARAMETERS: in_dividend - Dividend | |
134 | * in_divisor - Divisor | |
135 | * out_quotient - Pointer to where the quotient is returned | |
136 | * out_remainder - Pointer to where the remainder is returned | |
137 | * | |
138 | * RETURN: Status (Checks for divide-by-zero) | |
139 | * | |
140 | * DESCRIPTION: Perform a divide and modulo. | |
141 | * | |
142 | ******************************************************************************/ | |
143 | ||
144 | acpi_status | |
5df7e6cb BM |
145 | acpi_ut_divide(u64 in_dividend, |
146 | u64 in_divisor, u64 *out_quotient, u64 *out_remainder) | |
1da177e4 | 147 | { |
4be44fcd LB |
148 | union uint64_overlay dividend; |
149 | union uint64_overlay divisor; | |
150 | union uint64_overlay quotient; | |
151 | union uint64_overlay remainder; | |
152 | union uint64_overlay normalized_dividend; | |
153 | union uint64_overlay normalized_divisor; | |
154 | u32 partial1; | |
155 | union uint64_overlay partial2; | |
156 | union uint64_overlay partial3; | |
157 | ||
b229cf92 | 158 | ACPI_FUNCTION_TRACE(ut_divide); |
1da177e4 LT |
159 | |
160 | /* Always check for a zero divisor */ | |
161 | ||
162 | if (in_divisor == 0) { | |
b8e4d893 | 163 | ACPI_ERROR((AE_INFO, "Divide by zero")); |
4be44fcd | 164 | return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
1da177e4 LT |
165 | } |
166 | ||
4be44fcd | 167 | divisor.full = in_divisor; |
1da177e4 LT |
168 | dividend.full = in_dividend; |
169 | if (divisor.part.hi == 0) { | |
170 | /* | |
171 | * 1) Simplest case is where the divisor is 32 bits, we can | |
172 | * just do two divides | |
173 | */ | |
174 | remainder.part.hi = 0; | |
175 | ||
176 | /* | |
177 | * The quotient is 64 bits, the remainder is always 32 bits, | |
178 | * and is generated by the second divide. | |
179 | */ | |
4be44fcd | 180 | ACPI_DIV_64_BY_32(0, dividend.part.hi, divisor.part.lo, |
1da177e4 | 181 | quotient.part.hi, partial1); |
4be44fcd | 182 | ACPI_DIV_64_BY_32(partial1, dividend.part.lo, divisor.part.lo, |
1da177e4 LT |
183 | quotient.part.lo, remainder.part.lo); |
184 | } | |
185 | ||
186 | else { | |
187 | /* | |
188 | * 2) The general case where the divisor is a full 64 bits | |
189 | * is more difficult | |
190 | */ | |
4be44fcd | 191 | quotient.part.hi = 0; |
1da177e4 LT |
192 | normalized_dividend = dividend; |
193 | normalized_divisor = divisor; | |
194 | ||
195 | /* Normalize the operands (shift until the divisor is < 32 bits) */ | |
196 | ||
197 | do { | |
4be44fcd LB |
198 | ACPI_SHIFT_RIGHT_64(normalized_divisor.part.hi, |
199 | normalized_divisor.part.lo); | |
200 | ACPI_SHIFT_RIGHT_64(normalized_dividend.part.hi, | |
201 | normalized_dividend.part.lo); | |
1da177e4 LT |
202 | |
203 | } while (normalized_divisor.part.hi != 0); | |
204 | ||
205 | /* Partial divide */ | |
206 | ||
4be44fcd | 207 | ACPI_DIV_64_BY_32(normalized_dividend.part.hi, |
1da177e4 LT |
208 | normalized_dividend.part.lo, |
209 | normalized_divisor.part.lo, | |
210 | quotient.part.lo, partial1); | |
211 | ||
212 | /* | |
213 | * The quotient is always 32 bits, and simply requires adjustment. | |
214 | * The 64-bit remainder must be generated. | |
215 | */ | |
4be44fcd | 216 | partial1 = quotient.part.lo * divisor.part.hi; |
5df7e6cb BM |
217 | partial2.full = (u64) quotient.part.lo * divisor.part.lo; |
218 | partial3.full = (u64) partial2.part.hi + partial1; | |
1da177e4 LT |
219 | |
220 | remainder.part.hi = partial3.part.lo; | |
221 | remainder.part.lo = partial2.part.lo; | |
222 | ||
223 | if (partial3.part.hi == 0) { | |
224 | if (partial3.part.lo >= dividend.part.hi) { | |
225 | if (partial3.part.lo == dividend.part.hi) { | |
226 | if (partial2.part.lo > dividend.part.lo) { | |
227 | quotient.part.lo--; | |
228 | remainder.full -= divisor.full; | |
229 | } | |
4be44fcd | 230 | } else { |
1da177e4 LT |
231 | quotient.part.lo--; |
232 | remainder.full -= divisor.full; | |
233 | } | |
234 | } | |
235 | ||
4be44fcd LB |
236 | remainder.full = remainder.full - dividend.full; |
237 | remainder.part.hi = (u32) - ((s32) remainder.part.hi); | |
238 | remainder.part.lo = (u32) - ((s32) remainder.part.lo); | |
1da177e4 LT |
239 | |
240 | if (remainder.part.lo) { | |
241 | remainder.part.hi--; | |
242 | } | |
243 | } | |
244 | } | |
245 | ||
246 | /* Return only what was requested */ | |
247 | ||
248 | if (out_quotient) { | |
249 | *out_quotient = quotient.full; | |
250 | } | |
251 | if (out_remainder) { | |
252 | *out_remainder = remainder.full; | |
253 | } | |
254 | ||
4be44fcd | 255 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
256 | } |
257 | ||
258 | #else | |
1da177e4 LT |
259 | /******************************************************************************* |
260 | * | |
261 | * FUNCTION: acpi_ut_short_divide, acpi_ut_divide | |
262 | * | |
44f6c012 RM |
263 | * PARAMETERS: See function headers above |
264 | * | |
1da177e4 LT |
265 | * DESCRIPTION: Native versions of the ut_divide functions. Use these if either |
266 | * 1) The target is a 64-bit platform and therefore 64-bit | |
267 | * integer math is supported directly by the machine. | |
268 | * 2) The target is a 32-bit or 16-bit platform, and the | |
269 | * double-precision integer math library is available to | |
270 | * perform the divide. | |
271 | * | |
272 | ******************************************************************************/ | |
1da177e4 | 273 | acpi_status |
5df7e6cb BM |
274 | acpi_ut_short_divide(u64 in_dividend, |
275 | u32 divisor, u64 *out_quotient, u32 *out_remainder) | |
1da177e4 LT |
276 | { |
277 | ||
b229cf92 | 278 | ACPI_FUNCTION_TRACE(ut_short_divide); |
1da177e4 LT |
279 | |
280 | /* Always check for a zero divisor */ | |
281 | ||
282 | if (divisor == 0) { | |
b8e4d893 | 283 | ACPI_ERROR((AE_INFO, "Divide by zero")); |
4be44fcd | 284 | return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
1da177e4 LT |
285 | } |
286 | ||
287 | /* Return only what was requested */ | |
288 | ||
289 | if (out_quotient) { | |
290 | *out_quotient = in_dividend / divisor; | |
291 | } | |
292 | if (out_remainder) { | |
1f549a24 | 293 | *out_remainder = (u32) (in_dividend % divisor); |
1da177e4 LT |
294 | } |
295 | ||
4be44fcd | 296 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
297 | } |
298 | ||
299 | acpi_status | |
5df7e6cb BM |
300 | acpi_ut_divide(u64 in_dividend, |
301 | u64 in_divisor, u64 *out_quotient, u64 *out_remainder) | |
1da177e4 | 302 | { |
b229cf92 | 303 | ACPI_FUNCTION_TRACE(ut_divide); |
1da177e4 LT |
304 | |
305 | /* Always check for a zero divisor */ | |
306 | ||
307 | if (in_divisor == 0) { | |
b8e4d893 | 308 | ACPI_ERROR((AE_INFO, "Divide by zero")); |
4be44fcd | 309 | return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
1da177e4 LT |
310 | } |
311 | ||
1da177e4 LT |
312 | /* Return only what was requested */ |
313 | ||
314 | if (out_quotient) { | |
315 | *out_quotient = in_dividend / in_divisor; | |
316 | } | |
317 | if (out_remainder) { | |
318 | *out_remainder = in_dividend % in_divisor; | |
319 | } | |
320 | ||
4be44fcd | 321 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
322 | } |
323 | ||
324 | #endif |