378 lines
11 KiB
C
378 lines
11 KiB
C
/*******************************************************************************
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*
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* Module Name: utmath - Integer math support routines
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*
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******************************************************************************/
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/*
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* Copyright (C) 2000 - 2014, Intel Corp.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions, and the following disclaimer,
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* without modification.
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* 2. Redistributions in binary form must reproduce at minimum a disclaimer
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* substantially similar to the "NO WARRANTY" disclaimer below
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* ("Disclaimer") and any redistribution must be conditioned upon
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* including a substantially similar Disclaimer requirement for further
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* binary redistribution.
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* 3. Neither the names of the above-listed copyright holders nor the names
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* of any contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL") version 2 as published by the Free
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* Software Foundation.
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*
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* NO WARRANTY
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGES.
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*/
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#define __UTMATH_C__
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#include "acpi.h"
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#include "accommon.h"
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#define _COMPONENT ACPI_UTILITIES
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ACPI_MODULE_NAME ("utmath")
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/*
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* Optional support for 64-bit double-precision integer divide. This code
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* is configurable and is implemented in order to support 32-bit kernel
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* environments where a 64-bit double-precision math library is not available.
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*
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* Support for a more normal 64-bit divide/modulo (with check for a divide-
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* by-zero) appears after this optional section of code.
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*/
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#ifndef ACPI_USE_NATIVE_DIVIDE
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/* Structures used only for 64-bit divide */
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typedef struct uint64_struct
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{
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UINT32 Lo;
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UINT32 Hi;
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} UINT64_STRUCT;
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typedef union uint64_overlay
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{
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UINT64 Full;
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UINT64_STRUCT Part;
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} UINT64_OVERLAY;
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/*******************************************************************************
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*
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* FUNCTION: AcpiUtShortDivide
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*
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* PARAMETERS: Dividend - 64-bit dividend
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* Divisor - 32-bit divisor
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* OutQuotient - Pointer to where the quotient is returned
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* OutRemainder - Pointer to where the remainder is returned
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*
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* RETURN: Status (Checks for divide-by-zero)
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*
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* DESCRIPTION: Perform a short (maximum 64 bits divided by 32 bits)
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* divide and modulo. The result is a 64-bit quotient and a
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* 32-bit remainder.
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*
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******************************************************************************/
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ACPI_STATUS
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AcpiUtShortDivide (
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UINT64 Dividend,
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UINT32 Divisor,
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UINT64 *OutQuotient,
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UINT32 *OutRemainder)
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{
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UINT64_OVERLAY DividendOvl;
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UINT64_OVERLAY Quotient;
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UINT32 Remainder32;
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ACPI_FUNCTION_TRACE (UtShortDivide);
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/* Always check for a zero divisor */
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if (Divisor == 0)
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{
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ACPI_ERROR ((AE_INFO, "Divide by zero"));
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return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
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}
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DividendOvl.Full = Dividend;
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/*
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* The quotient is 64 bits, the remainder is always 32 bits,
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* and is generated by the second divide.
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*/
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ACPI_DIV_64_BY_32 (0, DividendOvl.Part.Hi, Divisor,
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Quotient.Part.Hi, Remainder32);
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ACPI_DIV_64_BY_32 (Remainder32, DividendOvl.Part.Lo, Divisor,
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Quotient.Part.Lo, Remainder32);
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/* Return only what was requested */
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if (OutQuotient)
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{
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*OutQuotient = Quotient.Full;
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}
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if (OutRemainder)
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{
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*OutRemainder = Remainder32;
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}
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return_ACPI_STATUS (AE_OK);
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}
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/*******************************************************************************
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*
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* FUNCTION: AcpiUtDivide
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*
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* PARAMETERS: InDividend - Dividend
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* InDivisor - Divisor
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* OutQuotient - Pointer to where the quotient is returned
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* OutRemainder - Pointer to where the remainder is returned
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*
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* RETURN: Status (Checks for divide-by-zero)
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*
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* DESCRIPTION: Perform a divide and modulo.
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*
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******************************************************************************/
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ACPI_STATUS
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AcpiUtDivide (
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UINT64 InDividend,
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UINT64 InDivisor,
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UINT64 *OutQuotient,
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UINT64 *OutRemainder)
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{
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UINT64_OVERLAY Dividend;
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UINT64_OVERLAY Divisor;
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UINT64_OVERLAY Quotient;
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UINT64_OVERLAY Remainder;
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UINT64_OVERLAY NormalizedDividend;
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UINT64_OVERLAY NormalizedDivisor;
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UINT32 Partial1;
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UINT64_OVERLAY Partial2;
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UINT64_OVERLAY Partial3;
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ACPI_FUNCTION_TRACE (UtDivide);
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/* Always check for a zero divisor */
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if (InDivisor == 0)
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{
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ACPI_ERROR ((AE_INFO, "Divide by zero"));
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return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
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}
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Divisor.Full = InDivisor;
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Dividend.Full = InDividend;
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if (Divisor.Part.Hi == 0)
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{
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/*
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* 1) Simplest case is where the divisor is 32 bits, we can
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* just do two divides
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*/
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Remainder.Part.Hi = 0;
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/*
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* The quotient is 64 bits, the remainder is always 32 bits,
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* and is generated by the second divide.
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*/
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ACPI_DIV_64_BY_32 (0, Dividend.Part.Hi, Divisor.Part.Lo,
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Quotient.Part.Hi, Partial1);
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ACPI_DIV_64_BY_32 (Partial1, Dividend.Part.Lo, Divisor.Part.Lo,
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Quotient.Part.Lo, Remainder.Part.Lo);
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}
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else
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{
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/*
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* 2) The general case where the divisor is a full 64 bits
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* is more difficult
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*/
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Quotient.Part.Hi = 0;
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NormalizedDividend = Dividend;
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NormalizedDivisor = Divisor;
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/* Normalize the operands (shift until the divisor is < 32 bits) */
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do
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{
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ACPI_SHIFT_RIGHT_64 (NormalizedDivisor.Part.Hi,
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NormalizedDivisor.Part.Lo);
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ACPI_SHIFT_RIGHT_64 (NormalizedDividend.Part.Hi,
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NormalizedDividend.Part.Lo);
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} while (NormalizedDivisor.Part.Hi != 0);
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/* Partial divide */
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ACPI_DIV_64_BY_32 (NormalizedDividend.Part.Hi,
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NormalizedDividend.Part.Lo,
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NormalizedDivisor.Part.Lo,
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Quotient.Part.Lo, Partial1);
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/*
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* The quotient is always 32 bits, and simply requires adjustment.
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* The 64-bit remainder must be generated.
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*/
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Partial1 = Quotient.Part.Lo * Divisor.Part.Hi;
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Partial2.Full = (UINT64) Quotient.Part.Lo * Divisor.Part.Lo;
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Partial3.Full = (UINT64) Partial2.Part.Hi + Partial1;
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Remainder.Part.Hi = Partial3.Part.Lo;
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Remainder.Part.Lo = Partial2.Part.Lo;
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if (Partial3.Part.Hi == 0)
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{
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if (Partial3.Part.Lo >= Dividend.Part.Hi)
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{
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if (Partial3.Part.Lo == Dividend.Part.Hi)
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{
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if (Partial2.Part.Lo > Dividend.Part.Lo)
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{
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Quotient.Part.Lo--;
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Remainder.Full -= Divisor.Full;
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}
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}
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else
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{
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Quotient.Part.Lo--;
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Remainder.Full -= Divisor.Full;
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}
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}
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Remainder.Full = Remainder.Full - Dividend.Full;
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Remainder.Part.Hi = (UINT32) -((INT32) Remainder.Part.Hi);
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Remainder.Part.Lo = (UINT32) -((INT32) Remainder.Part.Lo);
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if (Remainder.Part.Lo)
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{
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Remainder.Part.Hi--;
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}
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}
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}
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/* Return only what was requested */
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if (OutQuotient)
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{
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*OutQuotient = Quotient.Full;
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}
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if (OutRemainder)
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{
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*OutRemainder = Remainder.Full;
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}
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return_ACPI_STATUS (AE_OK);
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}
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#else
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/*******************************************************************************
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*
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* FUNCTION: AcpiUtShortDivide, AcpiUtDivide
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*
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* PARAMETERS: See function headers above
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*
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* DESCRIPTION: Native versions of the UtDivide functions. Use these if either
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* 1) The target is a 64-bit platform and therefore 64-bit
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* integer math is supported directly by the machine.
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* 2) The target is a 32-bit or 16-bit platform, and the
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* double-precision integer math library is available to
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* perform the divide.
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*
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******************************************************************************/
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ACPI_STATUS
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AcpiUtShortDivide (
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UINT64 InDividend,
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UINT32 Divisor,
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UINT64 *OutQuotient,
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UINT32 *OutRemainder)
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{
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ACPI_FUNCTION_TRACE (UtShortDivide);
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/* Always check for a zero divisor */
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if (Divisor == 0)
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{
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ACPI_ERROR ((AE_INFO, "Divide by zero"));
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return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
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}
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/* Return only what was requested */
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if (OutQuotient)
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{
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*OutQuotient = InDividend / Divisor;
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}
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if (OutRemainder)
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{
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*OutRemainder = (UINT32) (InDividend % Divisor);
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}
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return_ACPI_STATUS (AE_OK);
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}
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ACPI_STATUS
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AcpiUtDivide (
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UINT64 InDividend,
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UINT64 InDivisor,
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UINT64 *OutQuotient,
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UINT64 *OutRemainder)
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{
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ACPI_FUNCTION_TRACE (UtDivide);
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/* Always check for a zero divisor */
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if (InDivisor == 0)
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{
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ACPI_ERROR ((AE_INFO, "Divide by zero"));
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return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
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}
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/* Return only what was requested */
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if (OutQuotient)
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{
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*OutQuotient = InDividend / InDivisor;
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}
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if (OutRemainder)
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{
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*OutRemainder = InDividend % InDivisor;
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}
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return_ACPI_STATUS (AE_OK);
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}
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#endif
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