1 /*******************************************************************************
2 *
3 * Module Name: utmath - Integer math support routines
4 *
5 ******************************************************************************/
6
7 /*
8 * Copyright (C) 2000 - 2016, Intel Corp.
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 #include "acpi.h"
45 #include "accommon.h"
46
47
48 #define _COMPONENT ACPI_UTILITIES
49 ACPI_MODULE_NAME ("utmath")
50
51 /*
52 * Optional support for 64-bit double-precision integer divide. This code
53 * is configurable and is implemented in order to support 32-bit kernel
54 * environments where a 64-bit double-precision math library is not available.
55 *
56 * Support for a more normal 64-bit divide/modulo (with check for a divide-
57 * by-zero) appears after this optional section of code.
58 */
59 #ifndef ACPI_USE_NATIVE_DIVIDE
60
61 /* Structures used only for 64-bit divide */
62
63 typedef struct uint64_struct
64 {
65 UINT32 Lo;
66 UINT32 Hi;
67
68 } UINT64_STRUCT;
69
70 typedef union uint64_overlay
71 {
72 UINT64 Full;
73 UINT64_STRUCT Part;
74
75 } UINT64_OVERLAY;
76
77
78 /*******************************************************************************
79 *
80 * FUNCTION: AcpiUtShortDivide
81 *
82 * PARAMETERS: Dividend - 64-bit dividend
83 * Divisor - 32-bit divisor
84 * OutQuotient - Pointer to where the quotient is returned
85 * OutRemainder - Pointer to where the remainder is returned
86 *
87 * RETURN: Status (Checks for divide-by-zero)
88 *
89 * DESCRIPTION: Perform a short (maximum 64 bits divided by 32 bits)
90 * divide and modulo. The result is a 64-bit quotient and a
91 * 32-bit remainder.
92 *
93 ******************************************************************************/
94
95 ACPI_STATUS
AcpiUtShortDivide(UINT64 Dividend,UINT32 Divisor,UINT64 * OutQuotient,UINT32 * OutRemainder)96 AcpiUtShortDivide (
97 UINT64 Dividend,
98 UINT32 Divisor,
99 UINT64 *OutQuotient,
100 UINT32 *OutRemainder)
101 {
102 UINT64_OVERLAY DividendOvl;
103 UINT64_OVERLAY Quotient;
104 UINT32 Remainder32;
105
106
107 ACPI_FUNCTION_TRACE (UtShortDivide);
108
109
110 /* Always check for a zero divisor */
111
112 if (Divisor == 0)
113 {
114 ACPI_ERROR ((AE_INFO, "Divide by zero"));
115 return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
116 }
117
118 DividendOvl.Full = Dividend;
119
120 /*
121 * The quotient is 64 bits, the remainder is always 32 bits,
122 * and is generated by the second divide.
123 */
124 ACPI_DIV_64_BY_32 (0, DividendOvl.Part.Hi, Divisor,
125 Quotient.Part.Hi, Remainder32);
126
127 ACPI_DIV_64_BY_32 (Remainder32, DividendOvl.Part.Lo, Divisor,
128 Quotient.Part.Lo, Remainder32);
129
130 /* Return only what was requested */
131
132 if (OutQuotient)
133 {
134 *OutQuotient = Quotient.Full;
135 }
136 if (OutRemainder)
137 {
138 *OutRemainder = Remainder32;
139 }
140
141 return_ACPI_STATUS (AE_OK);
142 }
143
144
145 /*******************************************************************************
146 *
147 * FUNCTION: AcpiUtDivide
148 *
149 * PARAMETERS: InDividend - Dividend
150 * InDivisor - Divisor
151 * OutQuotient - Pointer to where the quotient is returned
152 * OutRemainder - Pointer to where the remainder is returned
153 *
154 * RETURN: Status (Checks for divide-by-zero)
155 *
156 * DESCRIPTION: Perform a divide and modulo.
157 *
158 ******************************************************************************/
159
160 ACPI_STATUS
AcpiUtDivide(UINT64 InDividend,UINT64 InDivisor,UINT64 * OutQuotient,UINT64 * OutRemainder)161 AcpiUtDivide (
162 UINT64 InDividend,
163 UINT64 InDivisor,
164 UINT64 *OutQuotient,
165 UINT64 *OutRemainder)
166 {
167 UINT64_OVERLAY Dividend;
168 UINT64_OVERLAY Divisor;
169 UINT64_OVERLAY Quotient;
170 UINT64_OVERLAY Remainder;
171 UINT64_OVERLAY NormalizedDividend;
172 UINT64_OVERLAY NormalizedDivisor;
173 UINT32 Partial1;
174 UINT64_OVERLAY Partial2;
175 UINT64_OVERLAY Partial3;
176
177
178 ACPI_FUNCTION_TRACE (UtDivide);
179
180
181 /* Always check for a zero divisor */
182
183 if (InDivisor == 0)
184 {
185 ACPI_ERROR ((AE_INFO, "Divide by zero"));
186 return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
187 }
188
189 Divisor.Full = InDivisor;
190 Dividend.Full = InDividend;
191 if (Divisor.Part.Hi == 0)
192 {
193 /*
194 * 1) Simplest case is where the divisor is 32 bits, we can
195 * just do two divides
196 */
197 Remainder.Part.Hi = 0;
198
199 /*
200 * The quotient is 64 bits, the remainder is always 32 bits,
201 * and is generated by the second divide.
202 */
203 ACPI_DIV_64_BY_32 (0, Dividend.Part.Hi, Divisor.Part.Lo,
204 Quotient.Part.Hi, Partial1);
205
206 ACPI_DIV_64_BY_32 (Partial1, Dividend.Part.Lo, Divisor.Part.Lo,
207 Quotient.Part.Lo, Remainder.Part.Lo);
208 }
209
210 else
211 {
212 /*
213 * 2) The general case where the divisor is a full 64 bits
214 * is more difficult
215 */
216 Quotient.Part.Hi = 0;
217 NormalizedDividend = Dividend;
218 NormalizedDivisor = Divisor;
219
220 /* Normalize the operands (shift until the divisor is < 32 bits) */
221
222 do
223 {
224 ACPI_SHIFT_RIGHT_64 (
225 NormalizedDivisor.Part.Hi, NormalizedDivisor.Part.Lo);
226 ACPI_SHIFT_RIGHT_64 (
227 NormalizedDividend.Part.Hi, NormalizedDividend.Part.Lo);
228
229 } while (NormalizedDivisor.Part.Hi != 0);
230
231 /* Partial divide */
232
233 ACPI_DIV_64_BY_32 (
234 NormalizedDividend.Part.Hi, NormalizedDividend.Part.Lo,
235 NormalizedDivisor.Part.Lo, Quotient.Part.Lo, Partial1);
236
237 /*
238 * The quotient is always 32 bits, and simply requires
239 * adjustment. The 64-bit remainder must be generated.
240 */
241 Partial1 = Quotient.Part.Lo * Divisor.Part.Hi;
242 Partial2.Full = (UINT64) Quotient.Part.Lo * Divisor.Part.Lo;
243 Partial3.Full = (UINT64) Partial2.Part.Hi + Partial1;
244
245 Remainder.Part.Hi = Partial3.Part.Lo;
246 Remainder.Part.Lo = Partial2.Part.Lo;
247
248 if (Partial3.Part.Hi == 0)
249 {
250 if (Partial3.Part.Lo >= Dividend.Part.Hi)
251 {
252 if (Partial3.Part.Lo == Dividend.Part.Hi)
253 {
254 if (Partial2.Part.Lo > Dividend.Part.Lo)
255 {
256 Quotient.Part.Lo--;
257 Remainder.Full -= Divisor.Full;
258 }
259 }
260 else
261 {
262 Quotient.Part.Lo--;
263 Remainder.Full -= Divisor.Full;
264 }
265 }
266
267 Remainder.Full = Remainder.Full - Dividend.Full;
268 Remainder.Part.Hi = (UINT32) -((INT32) Remainder.Part.Hi);
269 Remainder.Part.Lo = (UINT32) -((INT32) Remainder.Part.Lo);
270
271 if (Remainder.Part.Lo)
272 {
273 Remainder.Part.Hi--;
274 }
275 }
276 }
277
278 /* Return only what was requested */
279
280 if (OutQuotient)
281 {
282 *OutQuotient = Quotient.Full;
283 }
284 if (OutRemainder)
285 {
286 *OutRemainder = Remainder.Full;
287 }
288
289 return_ACPI_STATUS (AE_OK);
290 }
291
292 #else
293
294 /*******************************************************************************
295 *
296 * FUNCTION: AcpiUtShortDivide, AcpiUtDivide
297 *
298 * PARAMETERS: See function headers above
299 *
300 * DESCRIPTION: Native versions of the UtDivide functions. Use these if either
301 * 1) The target is a 64-bit platform and therefore 64-bit
302 * integer math is supported directly by the machine.
303 * 2) The target is a 32-bit or 16-bit platform, and the
304 * double-precision integer math library is available to
305 * perform the divide.
306 *
307 ******************************************************************************/
308
309 ACPI_STATUS
310 AcpiUtShortDivide (
311 UINT64 InDividend,
312 UINT32 Divisor,
313 UINT64 *OutQuotient,
314 UINT32 *OutRemainder)
315 {
316
317 ACPI_FUNCTION_TRACE (UtShortDivide);
318
319
320 /* Always check for a zero divisor */
321
322 if (Divisor == 0)
323 {
324 ACPI_ERROR ((AE_INFO, "Divide by zero"));
325 return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
326 }
327
328 /* Return only what was requested */
329
330 if (OutQuotient)
331 {
332 *OutQuotient = InDividend / Divisor;
333 }
334 if (OutRemainder)
335 {
336 *OutRemainder = (UINT32) (InDividend % Divisor);
337 }
338
339 return_ACPI_STATUS (AE_OK);
340 }
341
342 ACPI_STATUS
343 AcpiUtDivide (
344 UINT64 InDividend,
345 UINT64 InDivisor,
346 UINT64 *OutQuotient,
347 UINT64 *OutRemainder)
348 {
349 ACPI_FUNCTION_TRACE (UtDivide);
350
351
352 /* Always check for a zero divisor */
353
354 if (InDivisor == 0)
355 {
356 ACPI_ERROR ((AE_INFO, "Divide by zero"));
357 return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
358 }
359
360
361 /* Return only what was requested */
362
363 if (OutQuotient)
364 {
365 *OutQuotient = InDividend / InDivisor;
366 }
367 if (OutRemainder)
368 {
369 *OutRemainder = InDividend % InDivisor;
370 }
371
372 return_ACPI_STATUS (AE_OK);
373 }
374
375 #endif
376