From f933da28cf3fc6156bba10269745f05c676b2166 Mon Sep 17 00:00:00 2001 From: Ahmad Fatoum Date: Tue, 29 Dec 2020 13:32:54 +0100 Subject: include: : sync with upstream The header implements definitions for the 64-bit division helpers on 64-bit builds only. For 32-bit builds, it can only provide prototypes and the actual implementation will need to come from elsewhere. We didn't have any out-of-line definitions in barebox with the result that functions like div_s64_rem() were so far only usable in 64-bit barebox builds. On 32-bit builds, they would result in a linker error. Import the Linux v5.11-rc1 generic out-of-line 64-bit math on 32-bit implementation to fix this. While at it, synchronize the header to reduce diff to upstream. Signed-off-by: Ahmad Fatoum Signed-off-by: Sascha Hauer --- lib/Makefile | 1 + lib/math/Makefile | 1 + lib/math/div64.c | 235 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 237 insertions(+) create mode 100644 lib/math/Makefile create mode 100644 lib/math/div64.c (limited to 'lib') diff --git a/lib/Makefile b/lib/Makefile index ba6af6f2ab..9c6f4133d7 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -25,6 +25,7 @@ obj-y += cmdlinepart.o obj-y += recursive_action.o obj-y += make_directory.o obj-y += math.o +obj-y += math/ obj-$(CONFIG_XXHASH) += xxhash.o obj-$(CONFIG_BZLIB) += decompress_bunzip2.o obj-$(CONFIG_ZLIB) += decompress_inflate.o zlib_inflate/ diff --git a/lib/math/Makefile b/lib/math/Makefile new file mode 100644 index 0000000000..3341a8e474 --- /dev/null +++ b/lib/math/Makefile @@ -0,0 +1 @@ +obj-y += div64.o diff --git a/lib/math/div64.c b/lib/math/div64.c new file mode 100644 index 0000000000..386497592b --- /dev/null +++ b/lib/math/div64.c @@ -0,0 +1,235 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2003 Bernardo Innocenti + * + * Based on former do_div() implementation from asm-parisc/div64.h: + * Copyright (C) 1999 Hewlett-Packard Co + * Copyright (C) 1999 David Mosberger-Tang + * + * + * Generic C version of 64bit/32bit division and modulo, with + * 64bit result and 32bit remainder. + * + * The fast case for (n>>32 == 0) is handled inline by do_div(). + * + * Code generated for this function might be very inefficient + * for some CPUs. __div64_32() can be overridden by linking arch-specific + * assembly versions such as arch/ppc/lib/div64.S and arch/sh/lib/div64.S + * or by defining a preprocessor macro in arch/include/asm/div64.h. + */ + +#include +#include +#include +#include +#include + +/* Not needed on 64bit architectures */ +#if BITS_PER_LONG == 32 + +#ifndef __div64_32 +uint32_t __attribute__((weak)) __div64_32(uint64_t *n, uint32_t base) +{ + uint64_t rem = *n; + uint64_t b = base; + uint64_t res, d = 1; + uint32_t high = rem >> 32; + + /* Reduce the thing a bit first */ + res = 0; + if (high >= base) { + high /= base; + res = (uint64_t) high << 32; + rem -= (uint64_t) (high*base) << 32; + } + + while ((int64_t)b > 0 && b < rem) { + b = b+b; + d = d+d; + } + + do { + if (rem >= b) { + rem -= b; + res += d; + } + b >>= 1; + d >>= 1; + } while (d); + + *n = res; + return rem; +} +EXPORT_SYMBOL(__div64_32); +#endif + +/** + * div_s64_rem - signed 64bit divide with 64bit divisor and remainder + * @dividend: 64bit dividend + * @divisor: 64bit divisor + * @remainder: 64bit remainder + */ +#ifndef div_s64_rem +s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder) +{ + u64 quotient; + + if (dividend < 0) { + quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder); + *remainder = -*remainder; + if (divisor > 0) + quotient = -quotient; + } else { + quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder); + if (divisor < 0) + quotient = -quotient; + } + return quotient; +} +EXPORT_SYMBOL(div_s64_rem); +#endif + +/** + * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder + * @dividend: 64bit dividend + * @divisor: 64bit divisor + * @remainder: 64bit remainder + * + * This implementation is a comparable to algorithm used by div64_u64. + * But this operation, which includes math for calculating the remainder, + * is kept distinct to avoid slowing down the div64_u64 operation on 32bit + * systems. + */ +#ifndef div64_u64_rem +u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder) +{ + u32 high = divisor >> 32; + u64 quot; + + if (high == 0) { + u32 rem32; + quot = div_u64_rem(dividend, divisor, &rem32); + *remainder = rem32; + } else { + int n = fls(high); + quot = div_u64(dividend >> n, divisor >> n); + + if (quot != 0) + quot--; + + *remainder = dividend - quot * divisor; + if (*remainder >= divisor) { + quot++; + *remainder -= divisor; + } + } + + return quot; +} +EXPORT_SYMBOL(div64_u64_rem); +#endif + +/** + * div64_u64 - unsigned 64bit divide with 64bit divisor + * @dividend: 64bit dividend + * @divisor: 64bit divisor + * + * This implementation is a modified version of the algorithm proposed + * by the book 'Hacker's Delight'. The original source and full proof + * can be found here and is available for use without restriction. + * + * 'http://www.hackersdelight.org/hdcodetxt/divDouble.c.txt' + */ +#ifndef div64_u64 +u64 div64_u64(u64 dividend, u64 divisor) +{ + u32 high = divisor >> 32; + u64 quot; + + if (high == 0) { + quot = div_u64(dividend, divisor); + } else { + int n = fls(high); + quot = div_u64(dividend >> n, divisor >> n); + + if (quot != 0) + quot--; + if ((dividend - quot * divisor) >= divisor) + quot++; + } + + return quot; +} +EXPORT_SYMBOL(div64_u64); +#endif + +/** + * div64_s64 - signed 64bit divide with 64bit divisor + * @dividend: 64bit dividend + * @divisor: 64bit divisor + */ +#ifndef div64_s64 +s64 div64_s64(s64 dividend, s64 divisor) +{ + s64 quot, t; + + quot = div64_u64(abs(dividend), abs(divisor)); + t = (dividend ^ divisor) >> 63; + + return (quot ^ t) - t; +} +EXPORT_SYMBOL(div64_s64); +#endif + +#endif /* BITS_PER_LONG == 32 */ + +/* + * Iterative div/mod for use when dividend is not expected to be much + * bigger than divisor. + */ +u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder) +{ + return __iter_div_u64_rem(dividend, divisor, remainder); +} +EXPORT_SYMBOL(iter_div_u64_rem); + +#ifndef mul_u64_u64_div_u64 +u64 mul_u64_u64_div_u64(u64 a, u64 b, u64 c) +{ + u64 res = 0, div, rem; + int shift; + + /* can a * b overflow ? */ + if (ilog2(a) + ilog2(b) > 62) { + /* + * (b * a) / c is equal to + * + * (b / c) * a + + * (b % c) * a / c + * + * if nothing overflows. Can the 1st multiplication + * overflow? Yes, but we do not care: this can only + * happen if the end result can't fit in u64 anyway. + * + * So the code below does + * + * res = (b / c) * a; + * b = b % c; + */ + div = div64_u64_rem(b, c, &rem); + res = div * a; + b = rem; + + shift = ilog2(a) + ilog2(b) - 62; + if (shift > 0) { + /* drop precision */ + b >>= shift; + c >>= shift; + if (!c) + return res; + } + } + + return res + div64_u64(a * b, c); +} +#endif -- cgit v1.2.3