Subversion Repositories Kolibri OS

/*******************************************************************************

 *

 * 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.

 */

#include 

#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