janwas
b4cf155040
fixes #159 fixes #160 lib: add moduleInit helpers (centralizes a bit of code and saves typing; sorry for the recompile) path_util: allow '\\' as separator (see rationale there) lockfree.cpp: use moduleInit, no longer rely on type/value of pthread_key_t (which was a hack) This was SVN commit r4635.
592 lines
17 KiB
C++
592 lines
17 KiB
C++
/**
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* =========================================================================
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* File : lib.h
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* Project : 0 A.D.
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* Description : various utility functions.
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*
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* @author Jan.Wassenberg@stud.uni-karlsruhe.de
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* =========================================================================
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*/
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/*
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* Copyright (c) 2003-2005 Jan Wassenberg
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*
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* Redistribution and/or modification are also permitted under the
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* terms of the GNU General Public License as published by the
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* Free Software Foundation (version 2 or later, at your option).
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*/
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/**
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low-level aka "lib"
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-------------------
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this codebase was grown from modules shared between several projects,
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i.e. my personal library; hence the name "lib". it has been expanded to
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fit the needs of 0ad - in particular, resource loading.
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owing to the dual-use situation, the 0ad coding conventions are not met;
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also, major changes are ill-advised because they may break other projects.
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design goals
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------------
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- fast and low-overhead, including startup time
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- portable: must run on Win32, Mac OS X and Linux
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- reusable across projects, i.e. no dependency on a
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central 'manager' that ties modules together.
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scope
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-----
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- POSIX definitions
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- resource management
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- debugging tools (including memory tracker)
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- low-level helper functions, e.g. ADTs, endian conversion and timing
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- platform-dependent system/feature detection
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**/
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#ifndef LIB_H__
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#define LIB_H__
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#include <stddef.h>
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#include <math.h> // fabsf
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#include "config.h"
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#include "lib/types.h"
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#if defined(__cplusplus)
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# define EXTERN_C extern "C"
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#else
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# define EXTERN_C extern
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#endif
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const size_t KiB = 1ul << 10;
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const size_t MiB = 1ul << 20;
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const size_t GiB = 1ul << 30;
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// generate a symbol containing the line number of the macro invocation.
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// used to give a unique name (per file) to types made by cassert.
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// we can't prepend __FILE__ to make it globally unique - the filename
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// may be enclosed in quotes. PASTE3_HIDDEN__ is needed to make sure
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// __LINE__ is expanded correctly.
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#define PASTE3_HIDDEN__(a, b, c) a ## b ## c
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#define PASTE3__(a, b, c) PASTE3_HIDDEN__(a, b, c)
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#define UID__ PASTE3__(LINE_, __LINE__, _)
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#define UID2__ PASTE3__(LINE_, __LINE__, _2)
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//-----------------------------------------------------------------------------
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// code-generating macros
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//-----------------------------------------------------------------------------
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/**
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* package code into a single statement.
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*
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* @param STMT_code__ code to be bundled. (must be interpretable as
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* a macro argument, i.e. sequence of tokens).
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* the argument name is chosen to avoid conflicts.
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*
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* notes:
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* - for(;;) { break; } and {} don't work because invocations of macros
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* implemented with STMT often end with ";", thus breaking if() expressions.
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* - we'd really like to eliminate "conditional expression is constant"
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* warnings. replacing 0 literals with extern volatile variables fools
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* VC7 but isn't guaranteed to be free of overhead. we will just
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* squelch the warning (unfortunately non-portable).
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**/
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#define STMT(STMT_code__) do { STMT_code__; } while(false)
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// must come after definition of STMT
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#include "lib/lib_errors.h"
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/**
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* execute the code passed as a parameter only the first time this is
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* reached.
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* may be called at any time (in particular before main), but is not
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* thread-safe. if that's important, use pthread_once() instead.
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**/
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#define ONCE(ONCE_code__)\
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STMT(\
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static bool ONCE_done__ = false;\
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if(!ONCE_done__)\
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{\
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ONCE_done__ = true;\
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ONCE_code__;\
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}\
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)
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/**
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* execute the code passed as a parameter except the first time this is
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* reached.
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* may be called at any time (in particular before main), but is not
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* thread-safe.
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**/
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#define ONCE_NOT(ONCE_code__)\
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STMT(\
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static bool ONCE_done__ = false;\
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if(!ONCE_done__)\
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ONCE_done__ = true;\
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else\
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ONCE_code__;\
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)
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/**
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* execute the code passed as a parameter before main is entered.
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*
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* WARNING: if the source file containing this is not directly referenced
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* from anywhere, linkers may discard that object file (unless linking
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* statically). see http://www.cbloom.com/3d/techdocs/more_coding.txt
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**/
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#define AT_STARTUP(code__)\
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namespace { struct UID__\
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{\
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UID__() { code__; }\
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} UID2__; }
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/**
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* C++ new wrapper: allocates an instance of the given type and stores a
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* pointer to it. sets pointer to 0 on allocation failure.
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*
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* this simplifies application code when on VC6, which may or
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* may not throw/return 0 on failure.
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**/
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#define SAFE_NEW(type, ptr)\
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type* ptr;\
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try\
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{\
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ptr = new type();\
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}\
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catch(std::bad_alloc)\
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{\
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ptr = 0;\
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}
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/**
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* delete memory ensuing from new and set the pointer to zero
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* (thus making double-frees safe / a no-op)
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**/
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#define SAFE_DELETE(p)\
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STMT(\
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delete (p); /* if p == 0, delete is a no-op */ \
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(p) = 0;\
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)
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/**
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* delete memory ensuing from new[] and set the pointer to zero
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* (thus making double-frees safe / a no-op)
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**/
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#define SAFE_ARRAY_DELETE(p)\
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STMT(\
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delete[] (p); /* if p == 0, delete is a no-op */ \
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(p) = 0;\
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)
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/**
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* free memory ensuing from malloc and set the pointer to zero
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* (thus making double-frees safe / a no-op)
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**/
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#define SAFE_FREE(p)\
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STMT(\
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free(p); /* if p == 0, free is a no-op */ \
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(p) = 0;\
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)
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//-----------------------------------------------------------------------------
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// source code annotation
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//-----------------------------------------------------------------------------
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/**
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* mark a function local variable or parameter as unused and avoid
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* the corresponding compiler warning.
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* use inside the function body, e.g. void f(int x) { UNUSED2(x); }
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**/
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#define UNUSED2(param) (void)param;
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/**
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* mark a function parameter as unused and avoid
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* the corresponding compiler warning.
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* wrap around the parameter name, e.g. void f(int UNUSED(x))
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**/
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#define UNUSED(param)
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/**
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* mark the copy constructor as inaccessible. this squelches
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* "cannot be generated" warnings for classes with const members.
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*
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* intended to be used at end of class definition.
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* must be followed by semicolon.
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**/
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#define NO_COPY_CTOR(class_name)\
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private:\
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class_name& operator=(const class_name&);\
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class_name(const class_name&)
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/**
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"unreachable code" helpers
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unreachable lines of code are often the source or symptom of subtle bugs.
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they are flagged by compiler warnings; however, the opposite problem -
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erroneously reaching certain spots (e.g. due to missing return statement)
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is worse and not detected automatically.
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to defend against this, the programmer can annotate their code to
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indicate to humans that a particular spot should never be reached.
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however, that isn't much help; better is a sentinel that raises an
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error if if it is actually reached. hence, the UNREACHABLE macro.
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ironically, if the code guarded by UNREACHABLE works as it should,
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compilers may flag the macro's code as unreachable. this would
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distract from genuine warnings, which is unacceptable.
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even worse, compilers differ in their code checking: GCC only complains if
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non-void functions end without returning a value (i.e. missing return
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statement), while VC checks if lines are unreachable (e.g. if they are
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preceded by a return on all paths).
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our implementation of UNREACHABLE solves this dilemna as follows:
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- on GCC: call abort(); since it has the noreturn attributes, the
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"non-void" warning disappears.
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- on VC: avoid generating any code. we allow the compiler to assume the
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spot is actually unreachable, which incidentally helps optimization.
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if reached after all, a crash usually results. in that case, compile with
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CONFIG_PARANOIA, which will cause an error message to be displayed.
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this approach still allows for the possiblity of automated
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checking, but does not cause any compiler warnings.
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**/
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#define UNREACHABLE // actually defined below.. this is for
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# undef UNREACHABLE // CppDoc's benefit only.
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// 1) final build: optimize assuming this location cannot be reached.
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// may crash if that turns out to be untrue, but removes checking overhead.
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#if CONFIG_FINAL
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# define UNREACHABLE SYS_UNREACHABLE
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// 2) normal build:
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#else
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// a) normal implementation: includes "abort", which is declared with
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// noreturn attribute and therefore avoids GCC's "execution reaches
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// end of non-void function" warning.
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# if !MSC_VERSION || CONFIG_PARANOIA
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# define UNREACHABLE\
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STMT(\
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debug_warn("hit supposedly unreachable code");\
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abort();\
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)
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// b) VC only: don't generate any code; squelch the warning and optimize.
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# else
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# define UNREACHABLE SYS_UNREACHABLE
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# endif
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#endif
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/**
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convenient specialization of UNREACHABLE for switch statements whose
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default can never be reached. example usage:
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int x;
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switch(x % 2)
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{
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case 0: break;
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case 1: break;
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NODEFAULT;
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}
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**/
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#define NODEFAULT default: UNREACHABLE
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//-----------------------------------------------------------------------------
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// cassert
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/**
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* compile-time debug_assert. causes a compile error if the expression
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* evaluates to zero/false.
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*
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* no runtime overhead; may be used anywhere, including file scope.
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* especially useful for testing sizeof types.
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*
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* this version has a more descriptive error message, but may cause a
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* struct redefinition warning if used from the same line in different files.
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*
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* note: alternative method in C++: specialize a struct only for true;
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* using it will raise 'incomplete type' errors if instantiated with false.
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*
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* @param expression that is expected to evaluate to non-zero at compile-time.
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**/
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#define cassert(expr) struct UID__ { int CASSERT_FAILURE: (expr); }
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/**
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* compile-time debug_assert. causes a compile error if the expression
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* evaluates to zero/false.
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*
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* no runtime overhead; may be used anywhere, including file scope.
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* especially useful for testing sizeof types.
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*
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* this version has a less helpful error message, but redefinition doesn't
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* trigger warnings.
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*
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* @param expression that is expected to evaluate to non-zero at compile-time.
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**/
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#define cassert2(expr) extern char CASSERT_FAILURE[1][(expr)]
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//-----------------------------------------------------------------------------
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// bit bashing
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//-----------------------------------------------------------------------------
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/**
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* value of bit number <n>.
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*
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* @param n bit index (0..CHAR_BIT*sizeof(int)-1)
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**/
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#define BIT(n) (1ul << (n))
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// these are declared in the header and inlined to aid compiler optimizations
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// (they can easily end up being time-critical).
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// note: GCC can't inline extern functions, while VC's "Whole Program
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// Optimization" can.
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/**
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* a mask that includes the lowest N bits
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*
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* @param num_bits number of bits in mask
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**/
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inline uint bit_mask(uint num_bits)
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{
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return (1u << num_bits)-1;
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}
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/**
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* extract the value of bits hi_idx:lo_idx within num
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*
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* example: bits(0x69, 2, 5) == 0x0A
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*
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* @param num number whose bits are to be extracted
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* @param lo_idx bit index of lowest bit to include
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* @param hi_idx bit index of highest bit to include
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* @return value of extracted bits.
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**/
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inline uint bits(uint num, uint lo_idx, uint hi_idx)
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{
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const uint count = (hi_idx - lo_idx)+1; // # bits to return
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uint result = num >> lo_idx;
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result &= bit_mask(count);
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return result;
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}
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/// is the given number a power of two?
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extern bool is_pow2(uint n);
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/**
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* base-2 logarithm; return -1 for non-integral powers of 2.
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**/
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extern int ilog2(uint n);
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/**
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* base-2 logarithm, rounded up.
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*
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* @param n input; MUST be > 0, else results are undefined.
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**/
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extern uint log2(uint x);
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/**
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* base-2 logarithm (uses the FPU normalization hardware).
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*
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* @param n input; MUST be > 0, else results are undefined.
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**/
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extern int ilog2(const float x);
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/**
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* round up to next larger power of two.
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**/
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extern uint round_up_to_pow2(uint x);
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//-----------------------------------------------------------------------------
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// misc arithmetic
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/// canonical minimum macro
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#ifndef MIN
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#define MIN(a, b) (((a) < (b))? (a) : (b))
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#endif
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/// canonical maximum macro
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#ifndef MAX
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#define MAX(a, b) (((a) > (b))? (a) : (b))
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#endif
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/// number of array elements
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#define ARRAY_SIZE(name) (sizeof(name) / sizeof(name[0]))
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/**
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* round number up/down to the next given multiple.
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*
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* @param multiple: must be a power of two.
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**/
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extern uintptr_t round_up (uintptr_t n, uintptr_t multiple);
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extern uintptr_t round_down(uintptr_t n, uintptr_t multiple);
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/// 16-bit saturating (does not overflow) addition.
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extern u16 addusw(u16 x, u16 y);
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/// 16-bit saturating (does not underflow) subtraction.
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extern u16 subusw(u16 x, u16 y);
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/**
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* are the given floats nearly "equal"?
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*
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* @return whether the numbers are within "epsilon" of each other.
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*
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* notes:
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* - the epsilon magic number varies with the magnitude of the inputs.
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* we use a sane default, but don't use this routine for very
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* large/small comparands.
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* - floating-point numbers don't magically lose precision. addition,
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* subtraction and multiplication results are precise up to the mantissa's
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* least-significant bit. only division, sqrt, sin/cos and other
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* trancendental operations introduce error.
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**/
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inline bool feq(float f1, float f2)
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{
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const float epsilon = 0.00001f;
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return fabsf(f1 - f2) < epsilon;
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}
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/**
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* return random integer in [min, max).
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* avoids several common pitfalls; see discussion at
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* http://www.azillionmonkeys.com/qed/random.html
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**/
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extern uint rand(uint min_inclusive, uint max_exclusive);
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//-----------------------------------------------------------------------------
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// type conversion
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// note: these avoid a common mistake in using >> (ANSI requires
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// shift count be less than the bit width of the type).
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extern u32 u64_hi(u64 x); /// return upper 32-bits
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extern u32 u64_lo(u64 x); /// return lower 32-bits
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extern u16 u32_hi(u32 x); /// return upper 16-bits
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extern u16 u32_lo(u32 x); /// return lower 16-bits
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extern u64 u64_from_u32(u32 hi, u32 lo); /// assemble u64 from u32
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extern u32 u32_from_u16(u16 hi, u16 lo); /// assemble u32 from u16
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/**
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* zero-extend <size> (truncated to 8) bytes of little-endian data to u64,
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* starting at address <p> (need not be aligned).
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**/
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extern u64 movzx_64le(const u8* p, size_t size);
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/**
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* sign-extend <size> (truncated to 8) bytes of little-endian data to i64,
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* starting at address <p> (need not be aligned).
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**/
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extern i64 movsx_64le(const u8* p, size_t size);
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/// convert double to u8; verifies number is in range.
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extern u8 fp_to_u8 (double in);
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/// convert double to u16; verifies number is in range.
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extern u16 fp_to_u16(double in);
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//-----------------------------------------------------------------------------
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// string processing
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/**
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* this is strcpy, but indicates that the programmer checked usage and
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* promises it is safe.
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**/
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#define SAFE_STRCPY strcpy
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/**
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* generate the base32 textual representation of a buffer.
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*
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* @param len size [bytes] of input
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* @param big-endian input data (assumed to be integral number of bytes)
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* @param output string; zero-terminated. must be big enough
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* (i.e. at least ceil(len*CHAR_BIT/5) + 1 chars)
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**/
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extern void base32(const size_t len, const u8* in, u8* out);
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/**
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* partial regex implementation: see if string matches pattern.
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*
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* @param s input string
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* @param w pseudo-regex to match against. case-insensitive;
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* may contain '?' and/or '*' wildcards. if NULL, matches everything.
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*
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* @return 1 if they match, otherwise 0.
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*
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* algorithmfrom http://www.codeproject.com/string/wildcmp.asp.
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**/
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extern int match_wildcard(const char* s, const char* w);
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/// unicode version of match_wildcard.
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extern int match_wildcardw(const wchar_t* s, const wchar_t* w);
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/**
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* calculate FNV1-A hash.
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*
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* @param buf input buffer.
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* @param len if 0 (default), treat buf as a C-string; otherwise,
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* indicates how many bytes of buffer to hash.
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* @return hash result. note: results are distinct for buffers containing
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* differing amounts of zero bytes because the hash value is seeded.
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*
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* rationale: this algorithm was chosen because it delivers 'good' results
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* for string data and is relatively simple. other good alternatives exist;
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* see Ozan Yigit's hash roundup.
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**/
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extern u32 fnv_hash(const void* buf, size_t len = 0);
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/// 64-bit version of fnv_hash.
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extern u64 fnv_hash64(const void* buf, size_t len = 0);
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/**
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* special version of fnv_hash for strings: first converts to lowercase
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* (useful for comparing mixed-case filenames)
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**/
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extern u32 fnv_lc_hash(const char* str, size_t len = 0);
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//-----------------------------------------------------------------------------
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// helpers for module init
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/**
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* initialization state of a module (class, source file, or whatever).
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*
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* can be declared as a static variable => no init needed, since 0 is
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* the correct initial value.
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**/
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enum ModuleInitState
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{
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MODULE_BEFORE_INIT = 0,
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MODULE_INITIALIZED,
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MODULE_SHUTDOWN,
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MODULE_ERROR
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};
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extern void moduleInit_assertCanInit(ModuleInitState init_state);
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extern void moduleInit_assertInitialized(ModuleInitState init_state);
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extern void moduleInit_assertCanShutdown(ModuleInitState init_state);
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extern void moduleInit_markInitialized(ModuleInitState* init_state);
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extern void moduleInit_markShutdown(ModuleInitState* init_state);
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#endif // #ifndef LIB_H__
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