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Diffstat (limited to 'drivers/acpi/utilities/utmath.c')
| -rw-r--r-- | drivers/acpi/utilities/utmath.c | 311 |
1 files changed, 311 insertions, 0 deletions
diff --git a/drivers/acpi/utilities/utmath.c b/drivers/acpi/utilities/utmath.c new file mode 100644 index 0000000..c927324 --- /dev/null +++ b/drivers/acpi/utilities/utmath.c @@ -0,0 +1,311 @@ +/******************************************************************************* + * + * Module Name: utmath - Integer math support routines + * + ******************************************************************************/ + +/* + * Copyright (C) 2000 - 2008, 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> + +#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: 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(acpi_integer dividend, + u32 divisor, + acpi_integer * 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(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_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 = + (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 + * + * 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(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_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(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_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 |
