utmath.c revision 229989 
1/*******************************************************************************
2 *
3 * Module Name: utmath - Integer math support routines
4 *
5 ******************************************************************************/
6
7/*
8 * Copyright (C) 2000 - 2012, 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 <contrib/dev/acpica/include/acpi.h>
48#include <contrib/dev/acpica/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
66typedef struct uint64_struct
67{
68    UINT32                          Lo;
69    UINT32                          Hi;
70
71} UINT64_STRUCT;
72
73typedef 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
98ACPI_STATUS
99AcpiUtShortDivide (
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
162ACPI_STATUS
163AcpiUtDivide (
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
311ACPI_STATUS
312AcpiUtShortDivide (
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
344ACPI_STATUS
345AcpiUtDivide (
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
380