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/*******************************************************************************
*
* Module Name: utmath - Integer math support routines
* $Revision: 7 $
*
******************************************************************************/
/*
* Copyright (C) 2000, 2001 R. Byron Moore
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "acpi.h"
#define _COMPONENT ACPI_UTILITIES
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)
{
uint64_overlay dividend;
uint64_overlay quotient;
u32 remainder32;
FUNCTION_TRACE ("Ut_short_divide");
dividend.full = *in_dividend;
/* Always check for a zero divisor */
if (divisor == 0) {
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)
{
uint64_overlay dividend;
uint64_overlay divisor;
uint64_overlay quotient;
uint64_overlay remainder;
uint64_overlay normalized_dividend;
uint64_overlay normalized_divisor;
u32 partial1;
uint64_overlay partial2;
uint64_overlay partial3;
FUNCTION_TRACE ("Ut_divide");
/* Always check for a zero divisor */
if (*in_divisor == 0) {
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 = 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 = -((s32) remainder.part.hi);
remainder.part.lo = -((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)
{
FUNCTION_TRACE ("Ut_short_divide");
/* Always check for a zero divisor */
if (divisor == 0) {
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)
{
FUNCTION_TRACE ("Ut_divide");
/* Always check for a zero divisor */
if (*in_divisor == 0) {
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
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