347 lines
8.6 KiB
C
347 lines
8.6 KiB
C
/*
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* Copyright © 2015 Samsung Electronics Co., Ltd
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#ifndef WESTON_HELPERS_H
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#define WESTON_HELPERS_H
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#include "config.h"
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#include <stdint.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @file
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* Simple misc helper macros.
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*/
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/**
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* Compile-time computation of number of items in a hardcoded array.
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*
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* @param a the array being measured.
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* @return the number of items hardcoded into the array.
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*/
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#ifndef ARRAY_LENGTH
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#define ARRAY_LENGTH(a) (sizeof (a) / sizeof (a)[0])
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#endif
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/**
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* Compile-time copy of hardcoded arrays.
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*
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* @param dst the array to copy to.
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* @param src the source array.
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*/
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#ifndef ARRAY_COPY
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#define ARRAY_COPY(dst, src) \
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do { \
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static_assert(ARRAY_LENGTH(src) == ARRAY_LENGTH(dst), \
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"src and dst sizes must match"); \
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static_assert(sizeof(src) == sizeof(dst), \
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"src and dst sizes must match"); \
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memcpy((dst), (src), sizeof(src)); \
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} while (0)
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#endif
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/**
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* Returns the smaller of two values.
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*
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* @param x the first item to compare.
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* @param y the second item to compare.
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* @return the value that evaluates to lesser than the other.
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*/
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#ifndef MIN
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#define MIN(x,y) (((x) < (y)) ? (x) : (y))
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#endif
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/**
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* Returns the bigger of two values.
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*
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* @param x the first item to compare.
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* @param y the second item to compare.
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* @return the value that evaluates to more than the other.
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*/
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#ifndef MAX
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#define MAX(x,y) (((x) > (y)) ? (x) : (y))
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#endif
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/**
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* Clips the value to the maximum to the first item provided.
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*
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* @param c the first item to compare.
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* @param x the second item to compare.
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* @param y the third item to compare.
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* @return the value that evaluates to lesser than the maximum of
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* the two other parameters.
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*/
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#ifndef CLIP
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#define CLIP(c, x, y) MIN(MAX(c, x), y)
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#endif
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/**
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* Divides two integers, rounding up.
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*
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* @param n the numerator to divide.
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* @param d the denominator to divide by.
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* @return the rounded up result of the division n / d.
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*/
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#define DIV_ROUND_UP(n, d) \
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({ typeof(d) tmp = (d); ((n) + tmp - 1) / tmp; })
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/**
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* Round up to the next multiple of a power of 2.
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*
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* @param a the value to round up.
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* @param n the power of 2.
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* @return the rounded up value.
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*/
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#ifndef ROUND_UP_N
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#define ROUND_UP_N(a, n) (((a) + (n) - 1) & ~((n) - 1))
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#endif
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/**
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* Returns a pointer to the containing struct of a given member item.
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*
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* To demonstrate, the following example retrieves a pointer to
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* `example_container` given only its `destroy_listener` member:
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*
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* @code
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* struct example_container {
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* struct wl_listener destroy_listener;
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* // other members...
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* };
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*
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* void example_container_destroy(struct wl_listener *listener, void *data)
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* {
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* struct example_container *ctr;
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*
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* ctr = wl_container_of(listener, ctr, destroy_listener);
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* // destroy ctr...
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* }
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* @endcode
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*
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* @param ptr A valid pointer to the contained item.
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*
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* @param type A pointer to the type of content that the list item
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* stores. Type does not need be a valid pointer; a null or
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* an uninitialised pointer will suffice.
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*
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* @param member The named location of ptr within the sample type.
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*
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* @return The container for the specified pointer.
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*/
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#ifndef container_of
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#define container_of(ptr, type, member) ({ \
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const __typeof__( ((type *)0)->member ) *__mptr = (ptr); \
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(type *)( (char *)__mptr - offsetof(type,member) );})
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#endif
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/**
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* Build-time static assertion support
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*
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* A build-time equivalent to assert(), will generate a compilation error
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* if the supplied condition does not evaluate true.
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*
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* The following example demonstrates use of static_assert to ensure that
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* arrays which are supposed to mirror each other have a consistent
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* size.
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*
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* This is only a fallback definition; support must be provided by the
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* compiler itself.
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*
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* @code
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* int small[4];
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* long expanded[4];
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*
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* static_assert(ARRAY_LENGTH(small) == ARRAY_LENGTH(expanded),
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* "size mismatch between small and expanded arrays");
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* for (i = 0; i < ARRAY_LENGTH(small); i++)
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* expanded[i] = small[4];
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* @endcode
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*
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* @param cond Expression to check for truth
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* @param msg Message to print on failure
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*/
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#if !(defined(__cplusplus) && __cplusplus >= 201103L)
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#ifndef static_assert
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# ifdef _Static_assert
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# define static_assert(cond, msg) _Static_assert(cond, msg)
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# else
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# define static_assert(cond, msg)
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# endif
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#endif
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#endif
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/** Ensure argument is of given type */
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#ifndef TYPEVERIFY
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#define TYPEVERIFY(type, arg) ({ \
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typeof(arg) tmp___ = (arg); \
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(void)((type)0 == tmp___); \
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tmp___; })
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#endif
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/** Private symbol export for tests
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*
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* Symbols tagged with this are private libweston functions that are exported
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* only for the test suite to allow unit testing. Nothing else internal or
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* external to libweston is allowed to use these exports.
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*
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* Therefore, the ABI exported with this tag is completely unversioned, and
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* is allowed to break at any time without any indication or version bump.
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* This may happen in all git branches, including stable release branches.
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*/
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#define WESTON_EXPORT_FOR_TESTS __attribute__ ((visibility("default")))
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static inline uint64_t
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u64_from_u32s(uint32_t hi, uint32_t lo)
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{
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return ((uint64_t)hi << 32) + lo;
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}
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#ifndef __has_builtin
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# define __has_builtin(x) 0
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#endif
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#if defined(HAVE_UNREACHABLE) || __has_builtin(__builtin_unreachable)
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#define unreachable(str) \
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do { \
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assert(!str); \
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__builtin_unreachable(); \
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} while (0)
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#elif defined (_MSC_VER)
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#define unreachable(str) \
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do { \
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assert(!str); \
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__assume(0); \
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} while (0)
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#else
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#define unreachable(str) assert(!str)
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#endif
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#if __has_attribute(fallthrough)
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/* Supported at least by gcc and clang. */
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#define FALLTHROUGH __attribute__((fallthrough))
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#else
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#define FALLTHROUGH do {} while(0)
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#endif
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/**
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* Returns number of bits set in 32-bit value x.
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*
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* @param x a 32-bit value.
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* @return the number of bits set.
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*/
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static inline int
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bitcount32(uint32_t x)
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{
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#if defined(HAVE_BUILTIN_POPCOUNT)
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return __builtin_popcount(x);
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#else
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int n;
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for (n = 0; x; n++)
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x &= x - 1;
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return n;
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#endif
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}
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/**
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* Returns 32-bit value x in reversed byte order.
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*
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* @param x a 32-bit value.
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* @return the reversed 32-bit value.
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*/
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static inline uint32_t
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bswap32(uint32_t x)
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{
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#if defined(HAVE_BUILTIN_BSWAP32)
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return __builtin_bswap32(x);
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#else
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return (x >> 24) |
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((x >> 8) & 0x0000ff00) |
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((x << 8) & 0x00ff0000) |
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(x << 24);
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#endif
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}
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/**
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* Returns the highest power of two lesser than or equal to 32-bit value x.
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* Saturated to 0 (which isn't a power of two) if x is lesser than 2^0.
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*
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* @param x a 32-bit value.
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* @return the rounded down 32-bit value.
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*/
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static inline uint32_t
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round_down_pow2_32(uint32_t x)
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{
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#if defined(HAVE_BUILTIN_CLZ)
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/* clz depends on the underlying architecture when x is 0. */
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return x ? (1u << ((32 - __builtin_clz(x)) - 1)) : 0;
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#else
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/* See Hacker's Delight 2nd Edition, Chapter 3-2. */
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x |= x >> 1;
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x |= x >> 2;
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x |= x >> 4;
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x |= x >> 8;
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x |= x >> 16;
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x -= x >> 1;
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return x;
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#endif
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}
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/**
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* Returns the smallest power of two greater than or equal to 32-bit value x.
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* Saturated to 2^32 - 1 (which isn't a power of two) if x is greater than 2^31.
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*
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* @param x a 32-bit value.
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* @return the rounded up 32-bit value.
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*/
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static inline uint32_t
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round_up_pow2_32(uint32_t x)
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{
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if (x > (1u << 31))
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return UINT32_MAX;
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#if defined(HAVE_BUILTIN_CLZ)
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return (x > 1) ? (1 << (32 - __builtin_clz(x - 1))) : 1;
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#else
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/* Slight change from the Hacker's Delight version (which subtracts 1
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* unconditionally) in order to return 1 if x is 0. */
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x -= x != 0;
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x |= x >> 1;
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x |= x >> 2;
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x |= x >> 4;
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x |= x >> 8;
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x |= x >> 16;
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return x + 1;
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#endif
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}
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#ifdef __cplusplus
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}
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#endif
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#endif /* WESTON_HELPERS_H */
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