godot/core/safe_refcount.h
Rémi Verschelde c7bc44d5ad Welcome in 2017, dear changelog reader!
That year should bring the long-awaited OpenGL ES 3.0 compatible renderer
with state-of-the-art rendering techniques tuned to work as low as middle
end handheld devices - without compromising with the possibilities given
for higher end desktop games of course. Great times ahead for the Godot
community and the gamers that will play our games!
2017-01-01 22:03:33 +01:00

380 lines
7.1 KiB
C++

/*************************************************************************/
/* safe_refcount.h */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* http://www.godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur. */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/*************************************************************************/
#ifndef SAFE_REFCOUNT_H
#define SAFE_REFCOUNT_H
#include "os/mutex.h"
/* x86/x86_64 GCC */
#include "platform_config.h"
#ifdef NO_THREADS
struct SafeRefCount {
int count;
public:
// destroy() is called when weak_count_ drops to zero.
bool ref() { //true on success
if (count==0)
return false;
count++;
return true;
}
int refval() { //true on success
if (count==0)
return 0;
count++;
return count;
}
bool unref() { // true if must be disposed of
if (count>0)
count--;
return count==0;
}
long get() const { // nothrow
return static_cast<int const volatile &>( count );
}
void init(int p_value=1) {
count=p_value;
};
};
#else
#if defined( PLATFORM_REFCOUNT )
#include "platform_refcount.h"
#elif defined( __GNUC__ ) && ( defined( __i386__ ) || defined( __x86_64__ ) )
#define REFCOUNT_T volatile int
#define REFCOUNT_GET_T int const volatile&
static inline int atomic_conditional_increment( volatile int * pw ) {
// int rv = *pw;
// if( rv != 0 ) ++*pw;
// return rv;
int rv, tmp;
__asm__
(
"movl %0, %%eax\n\t"
"0:\n\t"
"test %%eax, %%eax\n\t"
"je 1f\n\t"
"movl %%eax, %2\n\t"
"incl %2\n\t"
"lock\n\t"
"cmpxchgl %2, %0\n\t"
"jne 0b\n\t"
"1:":
"=m"( *pw ), "=&a"( rv ), "=&r"( tmp ): // outputs (%0, %1, %2)
"m"( *pw ): // input (%3)
"cc" // clobbers
);
return rv;
}
static inline int atomic_decrement( volatile int *pw) {
// return --(*pw);
unsigned char rv;
__asm__
(
"lock\n\t"
"decl %0\n\t"
"setne %1":
"=m" (*pw), "=qm" (rv):
"m" (*pw):
"memory"
);
return static_cast<int>(rv);
}
/* PowerPC32/64 GCC */
#elif ( defined( __GNUC__ ) ) && ( defined( __powerpc__ ) || defined( __ppc__ ) )
#define REFCOUNT_T int
#define REFCOUNT_GET_T int const volatile&
inline int atomic_conditional_increment( int * pw )
{
// if( *pw != 0 ) ++*pw;
// return *pw;
int rv;
__asm__
(
"0:\n\t"
"lwarx %1, 0, %2\n\t"
"cmpwi %1, 0\n\t"
"beq 1f\n\t"
"addi %1, %1, 1\n\t"
"1:\n\t"
"stwcx. %1, 0, %2\n\t"
"bne- 0b":
"=m"( *pw ), "=&b"( rv ):
"r"( pw ), "m"( *pw ):
"cc"
);
return rv;
}
inline int atomic_decrement( int * pw )
{
// return --*pw;
int rv;
__asm__ __volatile__
(
"sync\n\t"
"0:\n\t"
"lwarx %1, 0, %2\n\t"
"addi %1, %1, -1\n\t"
"stwcx. %1, 0, %2\n\t"
"bne- 0b\n\t"
"isync":
"=m"( *pw ), "=&b"( rv ):
"r"( pw ), "m"( *pw ):
"memory", "cc"
);
return rv;
}
/* CW ARM */
#elif defined( __GNUC__ ) && ( defined( __arm__ ) )
#define REFCOUNT_T int
#define REFCOUNT_GET_T int const volatile&
inline int atomic_conditional_increment(volatile int* v)
{
int t;
int tmp;
__asm__ __volatile__(
"1: ldrex %0, [%2] \n"
" cmp %0, #0 \n"
" beq 2f \n"
" add %0, %0, #1 \n"
"2: \n"
" strex %1, %0, [%2] \n"
" cmp %1, #0 \n"
" bne 1b \n"
: "=&r" (t), "=&r" (tmp)
: "r" (v)
: "cc", "memory");
return t;
}
inline int atomic_decrement(volatile int* v)
{
int t;
int tmp;
__asm__ __volatile__(
"1: ldrex %0, [%2] \n"
" add %0, %0, #-1 \n"
" strex %1, %0, [%2] \n"
" cmp %1, #0 \n"
" bne 1b \n"
: "=&r" (t), "=&r" (tmp)
: "r" (v)
: "cc", "memory");
return t;
}
/* CW PPC */
#elif ( defined( __MWERKS__ ) ) && defined( __POWERPC__ )
inline long atomic_conditional_increment( register long * pw )
{
register int a;
asm
{
loop:
lwarx a, 0, pw
cmpwi a, 0
beq store
addi a, a, 1
store:
stwcx. a, 0, pw
bne- loop
}
return a;
}
inline long atomic_decrement( register long * pw )
{
register int a;
asm {
sync
loop:
lwarx a, 0, pw
addi a, a, -1
stwcx. a, 0, pw
bne- loop
isync
}
return a;
}
/* Any Windows (MSVC) */
#elif defined( _MSC_VER )
// made functions to not pollute namespace..
#define REFCOUNT_T long
#define REFCOUNT_GET_T long const volatile&
long atomic_conditional_increment( register long * pw );
long atomic_decrement( register long * pw );
#if 0
#elif defined( __GNUC__ ) && defined( ARMV6_ENABLED)
#endif
#else
#error This platform cannot use safe refcount, compile with NO_THREADS or implement it.
#endif
struct SafeRefCount {
REFCOUNT_T count;
public:
// destroy() is called when weak_count_ drops to zero.
bool ref() { //true on success
return atomic_conditional_increment( &count ) != 0;
}
int refval() { //true on success
return atomic_conditional_increment( &count );
}
bool unref() { // true if must be disposed of
if( atomic_decrement ( &count ) == 0 ) {
return true;
}
return false;
}
long get() const { // nothrow
return static_cast<REFCOUNT_GET_T>( count );
}
void init(int p_value=1) {
count=p_value;
};
};
#endif // no thread safe
#endif