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 <contrib/dev/acpica/include/acpi.h>
45#include <contrib/dev/acpica/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
63typedef struct uint64_struct
64{
65    UINT32                          Lo;
66    UINT32                          Hi;
67
68} UINT64_STRUCT;
69
70typedef 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
95ACPI_STATUS
96AcpiUtShortDivide (
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
160ACPI_STATUS
161AcpiUtDivide (
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
309ACPI_STATUS
310AcpiUtShortDivide (
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
342ACPI_STATUS
343AcpiUtDivide (
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