1 /*******************************************************************************
2 *
3 * Module Name: utmath - Integer math support routines
4 *
5 ******************************************************************************/
6
7 /*
8 * Copyright (C) 2000 - 2011, 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
45 #define __UTMATH_C__
46
47 #include "acpi.h"
48 #include "accommon.h"
49
50
51 #define _COMPONENT ACPI_UTILITIES
52 ACPI_MODULE_NAME ("utmath")
53
54 /*
55 * Optional support for 64-bit double-precision integer divide. This code
56 * is configurable and is implemented in order to support 32-bit kernel
57 * environments where a 64-bit double-precision math library is not available.
58 *
59 * Support for a more normal 64-bit divide/modulo (with check for a divide-
60 * by-zero) appears after this optional section of code.
61 */
62 #ifndef ACPI_USE_NATIVE_DIVIDE
63
64 /* Structures used only for 64-bit divide */
65
66 typedef struct uint64_struct
67 {
68 UINT32 Lo;
69 UINT32 Hi;
70
71 } UINT64_STRUCT;
72
73 typedef union uint64_overlay
74 {
75 UINT64 Full;
76 UINT64_STRUCT Part;
77
78 } UINT64_OVERLAY;
79
80
81 /*******************************************************************************
82 *
83 * FUNCTION: AcpiUtShortDivide
84 *
85 * PARAMETERS: Dividend - 64-bit dividend
86 * Divisor - 32-bit divisor
87 * OutQuotient - Pointer to where the quotient is returned
88 * OutRemainder - Pointer to where the remainder is returned
89 *
90 * RETURN: Status (Checks for divide-by-zero)
91 *
92 * DESCRIPTION: Perform a short (maximum 64 bits divided by 32 bits)
93 * divide and modulo. The result is a 64-bit quotient and a
94 * 32-bit remainder.
95 *
96 ******************************************************************************/
97
98 ACPI_STATUS
99 AcpiUtShortDivide (
100 UINT64 Dividend,
101 UINT32 Divisor,
102 UINT64 *OutQuotient,
103 UINT32 *OutRemainder)
104 {
105 UINT64_OVERLAY DividendOvl;
106 UINT64_OVERLAY Quotient;
107 UINT32 Remainder32;
108
109
110 ACPI_FUNCTION_TRACE (UtShortDivide);
111
112
113 /* Always check for a zero divisor */
114
115 if (Divisor == 0)
116 {
117 ACPI_ERROR ((AE_INFO, "Divide by zero"));
118 return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
119 }
120
121 DividendOvl.Full = Dividend;
122
123 /*
124 * The quotient is 64 bits, the remainder is always 32 bits,
125 * and is generated by the second divide.
126 */
127 ACPI_DIV_64_BY_32 (0, DividendOvl.Part.Hi, Divisor,
128 Quotient.Part.Hi, Remainder32);
129 ACPI_DIV_64_BY_32 (Remainder32, DividendOvl.Part.Lo, Divisor,
130 Quotient.Part.Lo, Remainder32);
131
132 /* Return only what was requested */
133
134 if (OutQuotient)
135 {
136 *OutQuotient = Quotient.Full;
137 }
138 if (OutRemainder)
139 {
140 *OutRemainder = Remainder32;
141 }
142
143 return_ACPI_STATUS (AE_OK);
144 }
145
146
147 /*******************************************************************************
148 *
149 * FUNCTION: AcpiUtDivide
150 *
151 * PARAMETERS: InDividend - Dividend
152 * InDivisor - Divisor
153 * OutQuotient - Pointer to where the quotient is returned
154 * OutRemainder - Pointer to where the remainder is returned
155 *
156 * RETURN: Status (Checks for divide-by-zero)
157 *
158 * DESCRIPTION: Perform a divide and modulo.
159 *
160 ******************************************************************************/
161
162 ACPI_STATUS
163 AcpiUtDivide (
164 UINT64 InDividend,
165 UINT64 InDivisor,
166 UINT64 *OutQuotient,
167 UINT64 *OutRemainder)
168 {
169 UINT64_OVERLAY Dividend;
170 UINT64_OVERLAY Divisor;
171 UINT64_OVERLAY Quotient;
172 UINT64_OVERLAY Remainder;
173 UINT64_OVERLAY NormalizedDividend;
174 UINT64_OVERLAY NormalizedDivisor;
175 UINT32 Partial1;
176 UINT64_OVERLAY Partial2;
177 UINT64_OVERLAY Partial3;
178
179
180 ACPI_FUNCTION_TRACE (UtDivide);
181
182
183 /* Always check for a zero divisor */
184
185 if (InDivisor == 0)
186 {
187 ACPI_ERROR ((AE_INFO, "Divide by zero"));
188 return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
189 }
190
191 Divisor.Full = InDivisor;
192 Dividend.Full = InDividend;
193 if (Divisor.Part.Hi == 0)
194 {
195 /*
196 * 1) Simplest case is where the divisor is 32 bits, we can
197 * just do two divides
198 */
199 Remainder.Part.Hi = 0;
200
201 /*
202 * The quotient is 64 bits, the remainder is always 32 bits,
203 * and is generated by the second divide.
204 */
205 ACPI_DIV_64_BY_32 (0, Dividend.Part.Hi, Divisor.Part.Lo,
206 Quotient.Part.Hi, Partial1);
207 ACPI_DIV_64_BY_32 (Partial1, Dividend.Part.Lo, Divisor.Part.Lo,
208 Quotient.Part.Lo, Remainder.Part.Lo);
209 }
210
211 else
212 {
213 /*
214 * 2) The general case where the divisor is a full 64 bits
215 * is more difficult
216 */
217 Quotient.Part.Hi = 0;
218 NormalizedDividend = Dividend;
219 NormalizedDivisor = Divisor;
220
221 /* Normalize the operands (shift until the divisor is < 32 bits) */
222
223 do
224 {
225 ACPI_SHIFT_RIGHT_64 (NormalizedDivisor.Part.Hi,
226 NormalizedDivisor.Part.Lo);
227 ACPI_SHIFT_RIGHT_64 (NormalizedDividend.Part.Hi,
228 NormalizedDividend.Part.Lo);
229
230 } while (NormalizedDivisor.Part.Hi != 0);
231
232 /* Partial divide */
233
234 ACPI_DIV_64_BY_32 (NormalizedDividend.Part.Hi,
235 NormalizedDividend.Part.Lo,
236 NormalizedDivisor.Part.Lo,
237 Quotient.Part.Lo, Partial1);
238
239 /*
240 * The quotient is always 32 bits, and simply requires adjustment.
241 * The 64-bit remainder must be generated.
242 */
243 Partial1 = Quotient.Part.Lo * Divisor.Part.Hi;
244 Partial2.Full = (UINT64) Quotient.Part.Lo * Divisor.Part.Lo;
245 Partial3.Full = (UINT64) Partial2.Part.Hi + Partial1;
246
247 Remainder.Part.Hi = Partial3.Part.Lo;
248 Remainder.Part.Lo = Partial2.Part.Lo;
249
250 if (Partial3.Part.Hi == 0)
251 {
252 if (Partial3.Part.Lo >= Dividend.Part.Hi)
253 {
254 if (Partial3.Part.Lo == Dividend.Part.Hi)
255 {
256 if (Partial2.Part.Lo > Dividend.Part.Lo)
257 {
258 Quotient.Part.Lo--;
259 Remainder.Full -= Divisor.Full;
260 }
261 }
262 else
263 {
264 Quotient.Part.Lo--;
265 Remainder.Full -= Divisor.Full;
266 }
267 }
268
269 Remainder.Full = Remainder.Full - Dividend.Full;
270 Remainder.Part.Hi = (UINT32) -((INT32) Remainder.Part.Hi);
271 Remainder.Part.Lo = (UINT32) -((INT32) Remainder.Part.Lo);
272
273 if (Remainder.Part.Lo)
274 {
275 Remainder.Part.Hi--;
276 }
277 }
278 }
279
280 /* Return only what was requested */
281
282 if (OutQuotient)
283 {
284 *OutQuotient = Quotient.Full;
285 }
286 if (OutRemainder)
287 {
288 *OutRemainder = Remainder.Full;
289 }
290
291 return_ACPI_STATUS (AE_OK);
292 }
293
294 #else
295
296 /*******************************************************************************
297 *
298 * FUNCTION: AcpiUtShortDivide, AcpiUtDivide
299 *
300 * PARAMETERS: See function headers above
301 *
302 * DESCRIPTION: Native versions of the UtDivide functions. Use these if either
303 * 1) The target is a 64-bit platform and therefore 64-bit
304 * integer math is supported directly by the machine.
305 * 2) The target is a 32-bit or 16-bit platform, and the
306 * double-precision integer math library is available to
307 * perform the divide.
308 *
309 ******************************************************************************/
310
311 ACPI_STATUS
312 AcpiUtShortDivide (
313 UINT64 InDividend,
314 UINT32 Divisor,
315 UINT64 *OutQuotient,
316 UINT32 *OutRemainder)
317 {
318
319 ACPI_FUNCTION_TRACE (UtShortDivide);
320
321
322 /* Always check for a zero divisor */
323
324 if (Divisor == 0)
325 {
326 ACPI_ERROR ((AE_INFO, "Divide by zero"));
327 return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
328 }
329
330 /* Return only what was requested */
331
332 if (OutQuotient)
333 {
334 *OutQuotient = InDividend / Divisor;
335 }
336 if (OutRemainder)
337 {
338 *OutRemainder = (UINT32) (InDividend % Divisor);
339 }
340
341 return_ACPI_STATUS (AE_OK);
342 }
343
344 ACPI_STATUS
345 AcpiUtDivide (
346 UINT64 InDividend,
347 UINT64 InDivisor,
348 UINT64 *OutQuotient,
349 UINT64 *OutRemainder)
350 {
351 ACPI_FUNCTION_TRACE (UtDivide);
352
353
354 /* Always check for a zero divisor */
355
356 if (InDivisor == 0)
357 {
358 ACPI_ERROR ((AE_INFO, "Divide by zero"));
359 return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
360 }
361
362
363 /* Return only what was requested */
364
365 if (OutQuotient)
366 {
367 *OutQuotient = InDividend / InDivisor;
368 }
369 if (OutRemainder)
370 {
371 *OutRemainder = InDividend % InDivisor;
372 }
373
374 return_ACPI_STATUS (AE_OK);
375 }
376
377 #endif
378
379