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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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9585763888
Signed-off-by: Erik Schmauss <erik.schmauss@intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
494 lines
13 KiB
C
494 lines
13 KiB
C
// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
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/*******************************************************************************
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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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#include <acpi/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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/* Structures used only for 64-bit divide */
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typedef struct uint64_struct {
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u32 lo;
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u32 hi;
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} uint64_struct;
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typedef union uint64_overlay {
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u64 full;
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struct uint64_struct part;
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} uint64_overlay;
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/*
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* Optional support for 64-bit double-precision integer multiply and shift.
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* This code is configurable and is implemented in order to support 32-bit
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* kernel environments where a 64-bit double-precision math library is not
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* available.
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*/
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#ifndef ACPI_USE_NATIVE_MATH64
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/*******************************************************************************
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*
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* FUNCTION: acpi_ut_short_multiply
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*
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* PARAMETERS: multiplicand - 64-bit multiplicand
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* multiplier - 32-bit multiplier
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* out_product - Pointer to where the product is returned
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*
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* DESCRIPTION: Perform a short multiply.
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*
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******************************************************************************/
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acpi_status
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acpi_ut_short_multiply(u64 multiplicand, u32 multiplier, u64 *out_product)
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{
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union uint64_overlay multiplicand_ovl;
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union uint64_overlay product;
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u32 carry32;
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ACPI_FUNCTION_TRACE(ut_short_multiply);
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multiplicand_ovl.full = multiplicand;
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/*
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* The Product is 64 bits, the carry is always 32 bits,
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* and is generated by the second multiply.
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*/
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ACPI_MUL_64_BY_32(0, multiplicand_ovl.part.hi, multiplier,
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product.part.hi, carry32);
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ACPI_MUL_64_BY_32(0, multiplicand_ovl.part.lo, multiplier,
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product.part.lo, carry32);
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product.part.hi += carry32;
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/* Return only what was requested */
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if (out_product) {
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*out_product = product.full;
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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: acpi_ut_short_shift_left
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*
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* PARAMETERS: operand - 64-bit shift operand
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* count - 32-bit shift count
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* out_result - Pointer to where the result is returned
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*
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* DESCRIPTION: Perform a short left shift.
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*
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******************************************************************************/
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acpi_status acpi_ut_short_shift_left(u64 operand, u32 count, u64 *out_result)
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{
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union uint64_overlay operand_ovl;
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ACPI_FUNCTION_TRACE(ut_short_shift_left);
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operand_ovl.full = operand;
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if ((count & 63) >= 32) {
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operand_ovl.part.hi = operand_ovl.part.lo;
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operand_ovl.part.lo = 0;
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count = (count & 63) - 32;
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}
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ACPI_SHIFT_LEFT_64_BY_32(operand_ovl.part.hi,
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operand_ovl.part.lo, count);
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/* Return only what was requested */
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if (out_result) {
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*out_result = operand_ovl.full;
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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: acpi_ut_short_shift_right
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*
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* PARAMETERS: operand - 64-bit shift operand
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* count - 32-bit shift count
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* out_result - Pointer to where the result is returned
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*
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* DESCRIPTION: Perform a short right shift.
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*
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******************************************************************************/
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acpi_status acpi_ut_short_shift_right(u64 operand, u32 count, u64 *out_result)
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{
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union uint64_overlay operand_ovl;
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ACPI_FUNCTION_TRACE(ut_short_shift_right);
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operand_ovl.full = operand;
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if ((count & 63) >= 32) {
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operand_ovl.part.lo = operand_ovl.part.hi;
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operand_ovl.part.hi = 0;
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count = (count & 63) - 32;
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}
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ACPI_SHIFT_RIGHT_64_BY_32(operand_ovl.part.hi,
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operand_ovl.part.lo, count);
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/* Return only what was requested */
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if (out_result) {
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*out_result = operand_ovl.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: acpi_ut_short_multiply
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*
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* PARAMETERS: See function headers above
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*
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* DESCRIPTION: Native version of the ut_short_multiply function.
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*
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******************************************************************************/
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acpi_status
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acpi_ut_short_multiply(u64 multiplicand, u32 multiplier, u64 *out_product)
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{
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ACPI_FUNCTION_TRACE(ut_short_multiply);
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/* Return only what was requested */
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if (out_product) {
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*out_product = multiplicand * multiplier;
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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: acpi_ut_short_shift_left
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*
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* PARAMETERS: See function headers above
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*
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* DESCRIPTION: Native version of the ut_short_shift_left function.
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*
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******************************************************************************/
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acpi_status acpi_ut_short_shift_left(u64 operand, u32 count, u64 *out_result)
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{
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ACPI_FUNCTION_TRACE(ut_short_shift_left);
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/* Return only what was requested */
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if (out_result) {
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*out_result = operand << count;
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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: acpi_ut_short_shift_right
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*
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* PARAMETERS: See function headers above
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*
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* DESCRIPTION: Native version of the ut_short_shift_right function.
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*
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******************************************************************************/
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acpi_status acpi_ut_short_shift_right(u64 operand, u32 count, u64 *out_result)
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{
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ACPI_FUNCTION_TRACE(ut_short_shift_right);
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/* Return only what was requested */
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if (out_result) {
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*out_result = operand >> count;
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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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/*
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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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/*******************************************************************************
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*
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* FUNCTION: acpi_ut_short_divide
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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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* out_quotient - Pointer to where the quotient is returned
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* out_remainder - 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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acpi_ut_short_divide(u64 dividend,
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u32 divisor, u64 *out_quotient, u32 *out_remainder)
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{
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union uint64_overlay dividend_ovl;
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union uint64_overlay quotient;
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u32 remainder32;
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ACPI_FUNCTION_TRACE(ut_short_divide);
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/* Always check for a zero divisor */
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if (divisor == 0) {
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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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dividend_ovl.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, dividend_ovl.part.hi, divisor,
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quotient.part.hi, remainder32);
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ACPI_DIV_64_BY_32(remainder32, dividend_ovl.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 (out_quotient) {
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*out_quotient = quotient.full;
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}
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if (out_remainder) {
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*out_remainder = 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: acpi_ut_divide
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*
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* PARAMETERS: in_dividend - Dividend
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* in_divisor - Divisor
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* out_quotient - Pointer to where the quotient is returned
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* out_remainder - 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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acpi_ut_divide(u64 in_dividend,
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u64 in_divisor, u64 *out_quotient, u64 *out_remainder)
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{
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union uint64_overlay dividend;
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union uint64_overlay divisor;
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union uint64_overlay quotient;
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union uint64_overlay remainder;
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union uint64_overlay normalized_dividend;
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union uint64_overlay normalized_divisor;
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u32 partial1;
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union uint64_overlay partial2;
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union uint64_overlay partial3;
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ACPI_FUNCTION_TRACE(ut_divide);
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/* Always check for a zero divisor */
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if (in_divisor == 0) {
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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 = in_divisor;
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dividend.full = in_dividend;
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if (divisor.part.hi == 0) {
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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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* 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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normalized_dividend = dividend;
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normalized_divisor = divisor;
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/* Normalize the operands (shift until the divisor is < 32 bits) */
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do {
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ACPI_SHIFT_RIGHT_64(normalized_divisor.part.hi,
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normalized_divisor.part.lo);
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ACPI_SHIFT_RIGHT_64(normalized_dividend.part.hi,
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normalized_dividend.part.lo);
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} while (normalized_divisor.part.hi != 0);
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/* Partial divide */
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ACPI_DIV_64_BY_32(normalized_dividend.part.hi,
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normalized_dividend.part.lo,
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normalized_divisor.part.lo, quotient.part.lo,
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partial1);
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/*
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* The quotient is always 32 bits, and simply requires
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* adjustment. 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 = (u64) quotient.part.lo * divisor.part.lo;
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partial3.full = (u64) 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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if (partial3.part.lo >= dividend.part.hi) {
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if (partial3.part.lo == dividend.part.hi) {
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if (partial2.part.lo > dividend.part.lo) {
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quotient.part.lo--;
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remainder.full -= divisor.full;
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}
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} else {
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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 = (u32)-((s32)remainder.part.hi);
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remainder.part.lo = (u32)-((s32)remainder.part.lo);
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if (remainder.part.lo) {
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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 (out_quotient) {
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*out_quotient = quotient.full;
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}
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if (out_remainder) {
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*out_remainder = 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: acpi_ut_short_divide, acpi_ut_divide
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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 ut_divide 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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acpi_ut_short_divide(u64 in_dividend,
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u32 divisor, u64 *out_quotient, u32 *out_remainder)
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{
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ACPI_FUNCTION_TRACE(ut_short_divide);
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/* Always check for a zero divisor */
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if (divisor == 0) {
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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 (out_quotient) {
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*out_quotient = in_dividend / divisor;
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}
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if (out_remainder) {
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*out_remainder = (u32) (in_dividend % 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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acpi_ut_divide(u64 in_dividend,
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u64 in_divisor, u64 *out_quotient, u64 *out_remainder)
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{
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ACPI_FUNCTION_TRACE(ut_divide);
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/* Always check for a zero divisor */
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if (in_divisor == 0) {
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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 (out_quotient) {
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*out_quotient = in_dividend / in_divisor;
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}
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if (out_remainder) {
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*out_remainder = in_dividend % in_divisor;
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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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