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1da177e4 LT |
1 | /******************************************************************************* |
2 | * | |
3 | * Module Name: utmath - Integer math support routines | |
4 | * | |
5 | ******************************************************************************/ | |
6 | ||
7 | /* | |
7735ca0e | 8 | * Copyright (C) 2000 - 2017, 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); |
1fad8738 | 114 | |
4be44fcd | 115 | ACPI_DIV_64_BY_32(remainder32, dividend_ovl.part.lo, divisor, |
1da177e4 LT |
116 | quotient.part.lo, remainder32); |
117 | ||
118 | /* Return only what was requested */ | |
119 | ||
120 | if (out_quotient) { | |
121 | *out_quotient = quotient.full; | |
122 | } | |
123 | if (out_remainder) { | |
124 | *out_remainder = remainder32; | |
125 | } | |
126 | ||
4be44fcd | 127 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
128 | } |
129 | ||
1da177e4 LT |
130 | /******************************************************************************* |
131 | * | |
132 | * FUNCTION: acpi_ut_divide | |
133 | * | |
134 | * PARAMETERS: in_dividend - Dividend | |
135 | * in_divisor - Divisor | |
136 | * out_quotient - Pointer to where the quotient is returned | |
137 | * out_remainder - Pointer to where the remainder is returned | |
138 | * | |
139 | * RETURN: Status (Checks for divide-by-zero) | |
140 | * | |
141 | * DESCRIPTION: Perform a divide and modulo. | |
142 | * | |
143 | ******************************************************************************/ | |
144 | ||
145 | acpi_status | |
5df7e6cb BM |
146 | acpi_ut_divide(u64 in_dividend, |
147 | u64 in_divisor, u64 *out_quotient, u64 *out_remainder) | |
1da177e4 | 148 | { |
4be44fcd LB |
149 | union uint64_overlay dividend; |
150 | union uint64_overlay divisor; | |
151 | union uint64_overlay quotient; | |
152 | union uint64_overlay remainder; | |
153 | union uint64_overlay normalized_dividend; | |
154 | union uint64_overlay normalized_divisor; | |
155 | u32 partial1; | |
156 | union uint64_overlay partial2; | |
157 | union uint64_overlay partial3; | |
158 | ||
b229cf92 | 159 | ACPI_FUNCTION_TRACE(ut_divide); |
1da177e4 LT |
160 | |
161 | /* Always check for a zero divisor */ | |
162 | ||
163 | if (in_divisor == 0) { | |
b8e4d893 | 164 | ACPI_ERROR((AE_INFO, "Divide by zero")); |
4be44fcd | 165 | return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
1da177e4 LT |
166 | } |
167 | ||
4be44fcd | 168 | divisor.full = in_divisor; |
1da177e4 LT |
169 | dividend.full = in_dividend; |
170 | if (divisor.part.hi == 0) { | |
171 | /* | |
172 | * 1) Simplest case is where the divisor is 32 bits, we can | |
173 | * just do two divides | |
174 | */ | |
175 | remainder.part.hi = 0; | |
176 | ||
177 | /* | |
178 | * The quotient is 64 bits, the remainder is always 32 bits, | |
179 | * and is generated by the second divide. | |
180 | */ | |
4be44fcd | 181 | ACPI_DIV_64_BY_32(0, dividend.part.hi, divisor.part.lo, |
1da177e4 | 182 | quotient.part.hi, partial1); |
1fad8738 | 183 | |
4be44fcd | 184 | ACPI_DIV_64_BY_32(partial1, dividend.part.lo, divisor.part.lo, |
1da177e4 LT |
185 | quotient.part.lo, remainder.part.lo); |
186 | } | |
187 | ||
188 | else { | |
189 | /* | |
190 | * 2) The general case where the divisor is a full 64 bits | |
191 | * is more difficult | |
192 | */ | |
4be44fcd | 193 | quotient.part.hi = 0; |
1da177e4 LT |
194 | normalized_dividend = dividend; |
195 | normalized_divisor = divisor; | |
196 | ||
197 | /* Normalize the operands (shift until the divisor is < 32 bits) */ | |
198 | ||
199 | do { | |
4be44fcd LB |
200 | ACPI_SHIFT_RIGHT_64(normalized_divisor.part.hi, |
201 | normalized_divisor.part.lo); | |
202 | ACPI_SHIFT_RIGHT_64(normalized_dividend.part.hi, | |
203 | normalized_dividend.part.lo); | |
1da177e4 LT |
204 | |
205 | } while (normalized_divisor.part.hi != 0); | |
206 | ||
207 | /* Partial divide */ | |
208 | ||
4be44fcd | 209 | ACPI_DIV_64_BY_32(normalized_dividend.part.hi, |
1da177e4 | 210 | normalized_dividend.part.lo, |
1fad8738 BM |
211 | normalized_divisor.part.lo, quotient.part.lo, |
212 | partial1); | |
1da177e4 LT |
213 | |
214 | /* | |
1fad8738 BM |
215 | * The quotient is always 32 bits, and simply requires |
216 | * adjustment. The 64-bit remainder must be generated. | |
1da177e4 | 217 | */ |
4be44fcd | 218 | partial1 = quotient.part.lo * divisor.part.hi; |
5df7e6cb BM |
219 | partial2.full = (u64) quotient.part.lo * divisor.part.lo; |
220 | partial3.full = (u64) partial2.part.hi + partial1; | |
1da177e4 LT |
221 | |
222 | remainder.part.hi = partial3.part.lo; | |
223 | remainder.part.lo = partial2.part.lo; | |
224 | ||
225 | if (partial3.part.hi == 0) { | |
226 | if (partial3.part.lo >= dividend.part.hi) { | |
227 | if (partial3.part.lo == dividend.part.hi) { | |
228 | if (partial2.part.lo > dividend.part.lo) { | |
229 | quotient.part.lo--; | |
230 | remainder.full -= divisor.full; | |
231 | } | |
4be44fcd | 232 | } else { |
1da177e4 LT |
233 | quotient.part.lo--; |
234 | remainder.full -= divisor.full; | |
235 | } | |
236 | } | |
237 | ||
4be44fcd | 238 | remainder.full = remainder.full - dividend.full; |
f5c1e1c5 LZ |
239 | remainder.part.hi = (u32)-((s32)remainder.part.hi); |
240 | remainder.part.lo = (u32)-((s32)remainder.part.lo); | |
1da177e4 LT |
241 | |
242 | if (remainder.part.lo) { | |
243 | remainder.part.hi--; | |
244 | } | |
245 | } | |
246 | } | |
247 | ||
248 | /* Return only what was requested */ | |
249 | ||
250 | if (out_quotient) { | |
251 | *out_quotient = quotient.full; | |
252 | } | |
253 | if (out_remainder) { | |
254 | *out_remainder = remainder.full; | |
255 | } | |
256 | ||
4be44fcd | 257 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
258 | } |
259 | ||
260 | #else | |
1da177e4 LT |
261 | /******************************************************************************* |
262 | * | |
263 | * FUNCTION: acpi_ut_short_divide, acpi_ut_divide | |
264 | * | |
44f6c012 RM |
265 | * PARAMETERS: See function headers above |
266 | * | |
1da177e4 LT |
267 | * DESCRIPTION: Native versions of the ut_divide functions. Use these if either |
268 | * 1) The target is a 64-bit platform and therefore 64-bit | |
269 | * integer math is supported directly by the machine. | |
270 | * 2) The target is a 32-bit or 16-bit platform, and the | |
271 | * double-precision integer math library is available to | |
272 | * perform the divide. | |
273 | * | |
274 | ******************************************************************************/ | |
1da177e4 | 275 | acpi_status |
5df7e6cb BM |
276 | acpi_ut_short_divide(u64 in_dividend, |
277 | u32 divisor, u64 *out_quotient, u32 *out_remainder) | |
1da177e4 LT |
278 | { |
279 | ||
b229cf92 | 280 | ACPI_FUNCTION_TRACE(ut_short_divide); |
1da177e4 LT |
281 | |
282 | /* Always check for a zero divisor */ | |
283 | ||
284 | if (divisor == 0) { | |
b8e4d893 | 285 | ACPI_ERROR((AE_INFO, "Divide by zero")); |
4be44fcd | 286 | return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
1da177e4 LT |
287 | } |
288 | ||
289 | /* Return only what was requested */ | |
290 | ||
291 | if (out_quotient) { | |
292 | *out_quotient = in_dividend / divisor; | |
293 | } | |
294 | if (out_remainder) { | |
1f549a24 | 295 | *out_remainder = (u32) (in_dividend % divisor); |
1da177e4 LT |
296 | } |
297 | ||
4be44fcd | 298 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
299 | } |
300 | ||
301 | acpi_status | |
5df7e6cb BM |
302 | acpi_ut_divide(u64 in_dividend, |
303 | u64 in_divisor, u64 *out_quotient, u64 *out_remainder) | |
1da177e4 | 304 | { |
b229cf92 | 305 | ACPI_FUNCTION_TRACE(ut_divide); |
1da177e4 LT |
306 | |
307 | /* Always check for a zero divisor */ | |
308 | ||
309 | if (in_divisor == 0) { | |
b8e4d893 | 310 | ACPI_ERROR((AE_INFO, "Divide by zero")); |
4be44fcd | 311 | return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
1da177e4 LT |
312 | } |
313 | ||
1da177e4 LT |
314 | /* Return only what was requested */ |
315 | ||
316 | if (out_quotient) { | |
317 | *out_quotient = in_dividend / in_divisor; | |
318 | } | |
319 | if (out_remainder) { | |
320 | *out_remainder = in_dividend % in_divisor; | |
321 | } | |
322 | ||
4be44fcd | 323 | return_ACPI_STATUS(AE_OK); |
1da177e4 LT |
324 | } |
325 | ||
326 | #endif |