drivers/acpi/acpica/utmath.c - kernel/bruno - Git at Google

 /*******************************************************************************
  *
  * 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 <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
	/*******************************************************************************
	*
	* 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 <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