cregit-Linux how code gets into the kernel

Release 4.11 drivers/acpi/acpica/utmath.c

/*******************************************************************************
 *
 * Module Name: utmath - Integer math support routines
 *
 ******************************************************************************/

/*
 * Copyright (C) 2000 - 2017, 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); }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds11785.40%114.29%
Len Brown107.30%114.29%
Robert Moore75.11%342.86%
Andy Grover32.19%228.57%
Total137100.00%7100.00%

/******************************************************************************* * * 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); }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds50594.57%112.50%
Andy Grover173.18%337.50%
Robert Moore122.25%450.00%
Total534100.00%8100.00%

#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); }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds7285.71%116.67%
Robert Moore1113.10%466.67%
Andy Grover11.19%116.67%
Total84100.00%6100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds6987.34%120.00%
Robert Moore911.39%360.00%
Andy Grover11.27%120.00%
Total79100.00%5100.00%

#endif

Overall Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds77987.63%15.56%
Robert Moore738.21%1055.56%
Andy Grover242.70%422.22%
Len Brown121.35%211.11%
Patrick Mochel10.11%15.56%
Total889100.00%18100.00%
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