platform_bionic/libc/private/bionic_atomic_mips.h
Elliott Hughes 2b333b97a2 Clean up the pthread-only atomic stuff a little.
It looks like we can probably just use the generic GCC stuff instead;
the generated code looks pretty similar. We should come back to that.

These routines are only used by the pthread implementation, and
__bionic_atomic_inc isn't used, so we can remove it.

Change-Id: I8b5b8cb30a1b159f0e85c3675aee06ddef39b429
2013-12-16 10:18:11 -08:00

76 lines
3.1 KiB
C

/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef BIONIC_ATOMIC_MIPS_H
#define BIONIC_ATOMIC_MIPS_H
/* Define a full memory barrier, this is only needed if we build the
* platform for a multi-core device.
*/
__ATOMIC_INLINE__ void __bionic_memory_barrier() {
#if defined(ANDROID_SMP) && ANDROID_SMP == 1
__asm__ __volatile__ ( "sync" : : : "memory" );
#else
/* A simple compiler barrier. */
__asm__ __volatile__ ( "" : : : "memory" );
#endif
}
/* Compare-and-swap, without any explicit barriers. Note that this function
* returns 0 on success, and 1 on failure. The opposite convention is typically
* used on other platforms.
*/
__ATOMIC_INLINE__ int __bionic_cmpxchg(int32_t old_value, int32_t new_value, volatile int32_t* ptr) {
int32_t prev, status;
__asm__ __volatile__ ("1: move %[status], %[new_value] \n"
" ll %[prev], 0(%[ptr]) \n"
" bne %[old_value], %[prev], 2f \n"
" sc %[status], 0(%[ptr]) \n"
" beqz %[status], 1b \n"
"2: \n"
: [prev]"=&r"(prev), [status]"=&r"(status), "+m"(*ptr)
: [new_value]"r"(new_value), [old_value]"r"(old_value), [ptr]"r"(ptr)
: "memory");
return prev != old_value;
}
/* Swap, without any explicit barriers. */
__ATOMIC_INLINE__ int32_t __bionic_swap(int32_t new_value, volatile int32_t* ptr) {
int32_t prev, status;
__asm__ __volatile__ ("1: move %[status], %[new_value] \n"
" ll %[prev], 0(%[ptr]) \n"
" sc %[status], 0(%[ptr]) \n"
" beqz %[status], 1b \n"
: [prev]"=&r"(prev), [status]"=&r"(status), "+m"(*ptr)
: [ptr]"r"(ptr), [new_value]"r"(new_value)
: "memory");
return prev;
}
/* Atomic decrement, without explicit barriers. */
__ATOMIC_INLINE__ int32_t __bionic_atomic_dec(volatile int32_t* ptr) {
int32_t prev, status;
__asm__ __volatile__ ("1: ll %[prev], 0(%[ptr]) \n"
" addiu %[status], %[prev], -1 \n"
" sc %[status], 0(%[ptr]) \n"
" beqz %[status], 1b \n"
: [prev]"=&r" (prev), [status]"=&r"(status), "+m" (*ptr)
: [ptr]"r"(ptr)
: "memory");
return prev;
}
#endif /* BIONIC_ATOMIC_MIPS_H */