utmath.c revision 281075 
1/*******************************************************************************
2 *
3 * Module Name: utmath - Integer math support routines
4 *
5 ******************************************************************************/
6
7/*
8 * Copyright (C) 2000 - 2015, 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    ACPI_DIV_64_BY_32 (Remainder32, DividendOvl.Part.Lo, Divisor,
127                       Quotient.Part.Lo, Remainder32);
128
129    /* Return only what was requested */
130
131    if (OutQuotient)
132    {
133        *OutQuotient = Quotient.Full;
134    }
135    if (OutRemainder)
136    {
137        *OutRemainder = Remainder32;
138    }
139
140    return_ACPI_STATUS (AE_OK);
141}
142
143
144/*******************************************************************************
145 *
146 * FUNCTION:    AcpiUtDivide
147 *
148 * PARAMETERS:  InDividend          - Dividend
149 *              InDivisor           - Divisor
150 *              OutQuotient         - Pointer to where the quotient is returned
151 *              OutRemainder        - Pointer to where the remainder is returned
152 *
153 * RETURN:      Status (Checks for divide-by-zero)
154 *
155 * DESCRIPTION: Perform a divide and modulo.
156 *
157 ******************************************************************************/
158
159ACPI_STATUS
160AcpiUtDivide (
161    UINT64                  InDividend,
162    UINT64                  InDivisor,
163    UINT64                  *OutQuotient,
164    UINT64                  *OutRemainder)
165{
166    UINT64_OVERLAY          Dividend;
167    UINT64_OVERLAY          Divisor;
168    UINT64_OVERLAY          Quotient;
169    UINT64_OVERLAY          Remainder;
170    UINT64_OVERLAY          NormalizedDividend;
171    UINT64_OVERLAY          NormalizedDivisor;
172    UINT32                  Partial1;
173    UINT64_OVERLAY          Partial2;
174    UINT64_OVERLAY          Partial3;
175
176
177    ACPI_FUNCTION_TRACE (UtDivide);
178
179
180    /* Always check for a zero divisor */
181
182    if (InDivisor == 0)
183    {
184        ACPI_ERROR ((AE_INFO, "Divide by zero"));
185        return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
186    }
187
188    Divisor.Full  = InDivisor;
189    Dividend.Full = InDividend;
190    if (Divisor.Part.Hi == 0)
191    {
192        /*
193         * 1) Simplest case is where the divisor is 32 bits, we can
194         * just do two divides
195         */
196        Remainder.Part.Hi = 0;
197
198        /*
199         * The quotient is 64 bits, the remainder is always 32 bits,
200         * and is generated by the second divide.
201         */
202        ACPI_DIV_64_BY_32 (0, Dividend.Part.Hi, Divisor.Part.Lo,
203                           Quotient.Part.Hi, Partial1);
204        ACPI_DIV_64_BY_32 (Partial1, Dividend.Part.Lo, Divisor.Part.Lo,
205                           Quotient.Part.Lo, Remainder.Part.Lo);
206    }
207
208    else
209    {
210        /*
211         * 2) The general case where the divisor is a full 64 bits
212         * is more difficult
213         */
214        Quotient.Part.Hi   = 0;
215        NormalizedDividend = Dividend;
216        NormalizedDivisor  = Divisor;
217
218        /* Normalize the operands (shift until the divisor is < 32 bits) */
219
220        do
221        {
222            ACPI_SHIFT_RIGHT_64 (NormalizedDivisor.Part.Hi,
223                                 NormalizedDivisor.Part.Lo);
224            ACPI_SHIFT_RIGHT_64 (NormalizedDividend.Part.Hi,
225                                 NormalizedDividend.Part.Lo);
226
227        } while (NormalizedDivisor.Part.Hi != 0);
228
229        /* Partial divide */
230
231        ACPI_DIV_64_BY_32 (NormalizedDividend.Part.Hi,
232                           NormalizedDividend.Part.Lo,
233                           NormalizedDivisor.Part.Lo,
234                           Quotient.Part.Lo, Partial1);
235
236        /*
237         * The quotient is always 32 bits, and simply requires adjustment.
238         * The 64-bit remainder must be generated.
239         */
240        Partial1      = Quotient.Part.Lo * Divisor.Part.Hi;
241        Partial2.Full = (UINT64) Quotient.Part.Lo * Divisor.Part.Lo;
242        Partial3.Full = (UINT64) Partial2.Part.Hi + Partial1;
243
244        Remainder.Part.Hi = Partial3.Part.Lo;
245        Remainder.Part.Lo = Partial2.Part.Lo;
246
247        if (Partial3.Part.Hi == 0)
248        {
249            if (Partial3.Part.Lo >= Dividend.Part.Hi)
250            {
251                if (Partial3.Part.Lo == Dividend.Part.Hi)
252                {
253                    if (Partial2.Part.Lo > Dividend.Part.Lo)
254                    {
255                        Quotient.Part.Lo--;
256                        Remainder.Full -= Divisor.Full;
257                    }
258                }
259                else
260                {
261                    Quotient.Part.Lo--;
262                    Remainder.Full -= Divisor.Full;
263                }
264            }
265
266            Remainder.Full    = Remainder.Full - Dividend.Full;
267            Remainder.Part.Hi = (UINT32) -((INT32) Remainder.Part.Hi);
268            Remainder.Part.Lo = (UINT32) -((INT32) Remainder.Part.Lo);
269
270            if (Remainder.Part.Lo)
271            {
272                Remainder.Part.Hi--;
273            }
274        }
275    }
276
277    /* Return only what was requested */
278
279    if (OutQuotient)
280    {
281        *OutQuotient = Quotient.Full;
282    }
283    if (OutRemainder)
284    {
285        *OutRemainder = Remainder.Full;
286    }
287
288    return_ACPI_STATUS (AE_OK);
289}
290
291#else
292
293/*******************************************************************************
294 *
295 * FUNCTION:    AcpiUtShortDivide, AcpiUtDivide
296 *
297 * PARAMETERS:  See function headers above
298 *
299 * DESCRIPTION: Native versions of the UtDivide functions. Use these if either
300 *              1) The target is a 64-bit platform and therefore 64-bit
301 *                 integer math is supported directly by the machine.
302 *              2) The target is a 32-bit or 16-bit platform, and the
303 *                 double-precision integer math library is available to
304 *                 perform the divide.
305 *
306 ******************************************************************************/
307
308ACPI_STATUS
309AcpiUtShortDivide (
310    UINT64                  InDividend,
311    UINT32                  Divisor,
312    UINT64                  *OutQuotient,
313    UINT32                  *OutRemainder)
314{
315
316    ACPI_FUNCTION_TRACE (UtShortDivide);
317
318
319    /* Always check for a zero divisor */
320
321    if (Divisor == 0)
322    {
323        ACPI_ERROR ((AE_INFO, "Divide by zero"));
324        return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
325    }
326
327    /* Return only what was requested */
328
329    if (OutQuotient)
330    {
331        *OutQuotient = InDividend / Divisor;
332    }
333    if (OutRemainder)
334    {
335        *OutRemainder = (UINT32) (InDividend % Divisor);
336    }
337
338    return_ACPI_STATUS (AE_OK);
339}
340
341ACPI_STATUS
342AcpiUtDivide (
343    UINT64                  InDividend,
344    UINT64                  InDivisor,
345    UINT64                  *OutQuotient,
346    UINT64                  *OutRemainder)
347{
348    ACPI_FUNCTION_TRACE (UtDivide);
349
350
351    /* Always check for a zero divisor */
352
353    if (InDivisor == 0)
354    {
355        ACPI_ERROR ((AE_INFO, "Divide by zero"));
356        return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
357    }
358
359
360    /* Return only what was requested */
361
362    if (OutQuotient)
363    {
364        *OutQuotient = InDividend / InDivisor;
365    }
366    if (OutRemainder)
367    {
368        *OutRemainder = InDividend % InDivisor;
369    }
370
371    return_ACPI_STATUS (AE_OK);
372}
373
374#endif
375