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/******************************************************************************* |
* |
* Module Name: utmath - Integer math support routines |
* |
******************************************************************************/ |
|
/* |
* Copyright (C) 2000 - 2015, Intel Corp. |
* All rights reserved. |
* |
* Redistribution and use in source and binary forms, with or without |
* modification, are permitted provided that the following conditions |
* are met: |
* 1. Redistributions of source code must retain the above copyright |
* notice, this list of conditions, and the following disclaimer, |
* without modification. |
* 2. Redistributions in binary form must reproduce at minimum a disclaimer |
* substantially similar to the "NO WARRANTY" disclaimer below |
* ("Disclaimer") and any redistribution must be conditioned upon |
* including a substantially similar Disclaimer requirement for further |
* binary redistribution. |
* 3. Neither the names of the above-listed copyright holders nor the names |
* of any contributors may be used to endorse or promote products derived |
* from this software without specific prior written permission. |
* |
* Alternatively, this software may be distributed under the terms of the |
* GNU General Public License ("GPL") version 2 as published by the Free |
* Software Foundation. |
* |
* NO WARRANTY |
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR |
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
* HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING |
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
* POSSIBILITY OF SUCH DAMAGES. |
*/ |
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#include <acpi/acpi.h> |
#include "accommon.h" |
|
#define _COMPONENT ACPI_UTILITIES |
ACPI_MODULE_NAME("utmath") |
|
/* |
* Optional support for 64-bit double-precision integer divide. This code |
* is configurable and is implemented in order to support 32-bit kernel |
* environments where a 64-bit double-precision math library is not available. |
* |
* Support for a more normal 64-bit divide/modulo (with check for a divide- |
* by-zero) appears after this optional section of code. |
*/ |
#ifndef ACPI_USE_NATIVE_DIVIDE |
/* Structures used only for 64-bit divide */ |
typedef struct uint64_struct { |
u32 lo; |
u32 hi; |
|
} uint64_struct; |
|
typedef union uint64_overlay { |
u64 full; |
struct uint64_struct part; |
|
} uint64_overlay; |
|
/******************************************************************************* |
* |
* FUNCTION: acpi_ut_short_divide |
* |
* PARAMETERS: dividend - 64-bit dividend |
* divisor - 32-bit divisor |
* out_quotient - Pointer to where the quotient is returned |
* out_remainder - Pointer to where the remainder is returned |
* |
* RETURN: Status (Checks for divide-by-zero) |
* |
* DESCRIPTION: Perform a short (maximum 64 bits divided by 32 bits) |
* divide and modulo. The result is a 64-bit quotient and a |
* 32-bit remainder. |
* |
******************************************************************************/ |
|
acpi_status |
acpi_ut_short_divide(u64 dividend, |
u32 divisor, u64 *out_quotient, u32 *out_remainder) |
{ |
union uint64_overlay dividend_ovl; |
union uint64_overlay quotient; |
u32 remainder32; |
|
ACPI_FUNCTION_TRACE(ut_short_divide); |
|
/* Always check for a zero divisor */ |
|
if (divisor == 0) { |
ACPI_ERROR((AE_INFO, "Divide by zero")); |
return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
} |
|
dividend_ovl.full = dividend; |
|
/* |
* The quotient is 64 bits, the remainder is always 32 bits, |
* and is generated by the second divide. |
*/ |
ACPI_DIV_64_BY_32(0, dividend_ovl.part.hi, divisor, |
quotient.part.hi, remainder32); |
ACPI_DIV_64_BY_32(remainder32, dividend_ovl.part.lo, divisor, |
quotient.part.lo, remainder32); |
|
/* Return only what was requested */ |
|
if (out_quotient) { |
*out_quotient = quotient.full; |
} |
if (out_remainder) { |
*out_remainder = remainder32; |
} |
|
return_ACPI_STATUS(AE_OK); |
} |
|
/******************************************************************************* |
* |
* FUNCTION: acpi_ut_divide |
* |
* PARAMETERS: in_dividend - Dividend |
* in_divisor - Divisor |
* out_quotient - Pointer to where the quotient is returned |
* out_remainder - Pointer to where the remainder is returned |
* |
* RETURN: Status (Checks for divide-by-zero) |
* |
* DESCRIPTION: Perform a divide and modulo. |
* |
******************************************************************************/ |
|
acpi_status |
acpi_ut_divide(u64 in_dividend, |
u64 in_divisor, u64 *out_quotient, u64 *out_remainder) |
{ |
union uint64_overlay dividend; |
union uint64_overlay divisor; |
union uint64_overlay quotient; |
union uint64_overlay remainder; |
union uint64_overlay normalized_dividend; |
union uint64_overlay normalized_divisor; |
u32 partial1; |
union uint64_overlay partial2; |
union uint64_overlay partial3; |
|
ACPI_FUNCTION_TRACE(ut_divide); |
|
/* Always check for a zero divisor */ |
|
if (in_divisor == 0) { |
ACPI_ERROR((AE_INFO, "Divide by zero")); |
return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
} |
|
divisor.full = in_divisor; |
dividend.full = in_dividend; |
if (divisor.part.hi == 0) { |
/* |
* 1) Simplest case is where the divisor is 32 bits, we can |
* just do two divides |
*/ |
remainder.part.hi = 0; |
|
/* |
* The quotient is 64 bits, the remainder is always 32 bits, |
* and is generated by the second divide. |
*/ |
ACPI_DIV_64_BY_32(0, dividend.part.hi, divisor.part.lo, |
quotient.part.hi, partial1); |
ACPI_DIV_64_BY_32(partial1, dividend.part.lo, divisor.part.lo, |
quotient.part.lo, remainder.part.lo); |
} |
|
else { |
/* |
* 2) The general case where the divisor is a full 64 bits |
* is more difficult |
*/ |
quotient.part.hi = 0; |
normalized_dividend = dividend; |
normalized_divisor = divisor; |
|
/* Normalize the operands (shift until the divisor is < 32 bits) */ |
|
do { |
ACPI_SHIFT_RIGHT_64(normalized_divisor.part.hi, |
normalized_divisor.part.lo); |
ACPI_SHIFT_RIGHT_64(normalized_dividend.part.hi, |
normalized_dividend.part.lo); |
|
} while (normalized_divisor.part.hi != 0); |
|
/* Partial divide */ |
|
ACPI_DIV_64_BY_32(normalized_dividend.part.hi, |
normalized_dividend.part.lo, |
normalized_divisor.part.lo, |
quotient.part.lo, partial1); |
|
/* |
* The quotient is always 32 bits, and simply requires adjustment. |
* The 64-bit remainder must be generated. |
*/ |
partial1 = quotient.part.lo * divisor.part.hi; |
partial2.full = (u64) quotient.part.lo * divisor.part.lo; |
partial3.full = (u64) partial2.part.hi + partial1; |
|
remainder.part.hi = partial3.part.lo; |
remainder.part.lo = partial2.part.lo; |
|
if (partial3.part.hi == 0) { |
if (partial3.part.lo >= dividend.part.hi) { |
if (partial3.part.lo == dividend.part.hi) { |
if (partial2.part.lo > dividend.part.lo) { |
quotient.part.lo--; |
remainder.full -= divisor.full; |
} |
} else { |
quotient.part.lo--; |
remainder.full -= divisor.full; |
} |
} |
|
remainder.full = remainder.full - dividend.full; |
remainder.part.hi = (u32) - ((s32) remainder.part.hi); |
remainder.part.lo = (u32) - ((s32) remainder.part.lo); |
|
if (remainder.part.lo) { |
remainder.part.hi--; |
} |
} |
} |
|
/* Return only what was requested */ |
|
if (out_quotient) { |
*out_quotient = quotient.full; |
} |
if (out_remainder) { |
*out_remainder = remainder.full; |
} |
|
return_ACPI_STATUS(AE_OK); |
} |
|
#else |
/******************************************************************************* |
* |
* FUNCTION: acpi_ut_short_divide, acpi_ut_divide |
* |
* PARAMETERS: See function headers above |
* |
* DESCRIPTION: Native versions of the ut_divide functions. Use these if either |
* 1) The target is a 64-bit platform and therefore 64-bit |
* integer math is supported directly by the machine. |
* 2) The target is a 32-bit or 16-bit platform, and the |
* double-precision integer math library is available to |
* perform the divide. |
* |
******************************************************************************/ |
acpi_status |
acpi_ut_short_divide(u64 in_dividend, |
u32 divisor, u64 *out_quotient, u32 *out_remainder) |
{ |
|
ACPI_FUNCTION_TRACE(ut_short_divide); |
|
/* Always check for a zero divisor */ |
|
if (divisor == 0) { |
ACPI_ERROR((AE_INFO, "Divide by zero")); |
return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
} |
|
/* Return only what was requested */ |
|
if (out_quotient) { |
*out_quotient = in_dividend / divisor; |
} |
if (out_remainder) { |
*out_remainder = (u32) (in_dividend % divisor); |
} |
|
return_ACPI_STATUS(AE_OK); |
} |
|
acpi_status |
acpi_ut_divide(u64 in_dividend, |
u64 in_divisor, u64 *out_quotient, u64 *out_remainder) |
{ |
ACPI_FUNCTION_TRACE(ut_divide); |
|
/* Always check for a zero divisor */ |
|
if (in_divisor == 0) { |
ACPI_ERROR((AE_INFO, "Divide by zero")); |
return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO); |
} |
|
/* Return only what was requested */ |
|
if (out_quotient) { |
*out_quotient = in_dividend / in_divisor; |
} |
if (out_remainder) { |
*out_remainder = in_dividend % in_divisor; |
} |
|
return_ACPI_STATUS(AE_OK); |
} |
|
#endif |