text: /*******************************************************************************
   *
   * Module Name: utmath - Integer math support routines
   *
   ******************************************************************************/
  
  /*
   * Copyright (C) 2000 - 2003, R. Byron Moore
   * 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>
  
  
  #define _COMPONENT          ACPI_UTILITIES
  	 ACPI_MODULE_NAME    ("utmath")
  
  /*
   * Support for double-precision integer divide.  This code is included here
   * in order to support kernel environments where the double-precision math
   * library is not available.
   */
  
  #ifndef ACPI_USE_NATIVE_DIVIDE
  /*******************************************************************************
   *
   * FUNCTION:    acpi_ut_short_divide
   *
   * PARAMETERS:  in_dividend         - Pointer to the 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 (
  	acpi_integer                    *in_dividend,
  	u32                             divisor,
  	acpi_integer                    *out_quotient,
  	u32                             *out_remainder)
  {
  	union uint64_overlay            dividend;
  	union uint64_overlay            quotient;
  	u32                             remainder32;
  
  
  	ACPI_FUNCTION_TRACE ("ut_short_divide");
  
  	dividend.full = *in_dividend;
  
  	/* Always check for a zero divisor */
  
  	if (divisor == 0) {
  		ACPI_REPORT_ERROR (("acpi_ut_short_divide: Divide by zero\n"));
  		return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO);
  	}
  
  	/*
  	 * 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,
  			  quotient.part.hi, remainder32);
  	ACPI_DIV_64_BY_32 (remainder32, dividend.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         - Pointer to the dividend
   *              in_divisor          - Pointer to the 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 (
  	acpi_integer                    *in_dividend,
  	acpi_integer                    *in_divisor,
  	acpi_integer                    *out_quotient,
  	acpi_integer                    *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_REPORT_ERROR (("acpi_ut_divide: Divide by zero\n"));
  		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 = (acpi_integer) quotient.part.lo * divisor.part.lo;
  		partial3.full = (acpi_integer) 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
   *
   * 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 (
  	acpi_integer                    *in_dividend,
  	u32                             divisor,
  	acpi_integer                    *out_quotient,
  	u32                             *out_remainder)
  {
  
  	ACPI_FUNCTION_TRACE ("ut_short_divide");
  
  
  	/* Always check for a zero divisor */
  
  	if (divisor == 0) {
  		ACPI_REPORT_ERROR (("acpi_ut_short_divide: Divide by zero\n"));
  		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 (
  	acpi_integer                    *in_dividend,
  	acpi_integer                    *in_divisor,
  	acpi_integer                    *out_quotient,
  	acpi_integer                    *out_remainder)
  {
  	ACPI_FUNCTION_TRACE ("ut_divide");
  
  
  	/* Always check for a zero divisor */
  
  	if (*in_divisor == 0) {
  		ACPI_REPORT_ERROR (("acpi_ut_divide: Divide by zero\n"));
  		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
  
  
  