/******************************************************************************* * * Module Name: utmath - Integer math support routines * ******************************************************************************/ /* * Copyright (C) 2000 - 2012, 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