[dpdk-dev] [PATCH 02/12] Add atomic operations for IBM Power architecture

[Chao Zhu <bjzhuc@cn.ibm.com>]

The atomic operations implemented with assembly code in DPDK only
support x86. This patch add architecture specific atomic operations for
IBM Power architecture.

Signed-off-by: Chao Zhu <bjzhuc@cn.ibm.com>
---
 .../common/include/powerpc/arch/rte_atomic.h       |  387 ++++++++++++++++++++
 .../common/include/powerpc/arch/rte_atomic_arch.h  |  318 ++++++++++++++++
 2 files changed, 705 insertions(+), 0 deletions(-)
 create mode 100644 lib/librte_eal/common/include/powerpc/arch/rte_atomic.h
 create mode 100644 lib/librte_eal/common/include/powerpc/arch/rte_atomic_arch.h

diff --git a/lib/librte_eal/common/include/powerpc/arch/rte_atomic.h b/lib/librte_eal/common/include/powerpc/arch/rte_atomic.h
new file mode 100644
index 0000000..7f5214e
--- /dev/null
+++ b/lib/librte_eal/common/include/powerpc/arch/rte_atomic.h
@@ -0,0 +1,387 @@
+/*
+ *   BSD LICENSE
+ *
+ *   Copyright (C) IBM Corporation 2014.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of IBM Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/*
+ * Inspired from FreeBSD src/sys/powerpc/include/atomic.h
+ * Copyright (c) 2008 Marcel Moolenaar
+ * Copyright (c) 2001 Benno Rice
+ * Copyright (c) 2001 David E. O'Brien
+ * Copyright (c) 1998 Doug Rabson
+ * All rights reserved.
+ */
+
+#ifndef _RTE_ATOMIC_H_
+#error "don't include this file directly, please include generic <rte_atomic.h>"
+#endif
+
+#ifndef _RTE_POWERPC_64_ATOMIC_H_
+#define _RTE_POWERPC_64_ATOMIC_H_
+
+/*------------------------- 64 bit atomic operations -------------------------*/
+
+/**
+ * An atomic compare and set function used by the mutex functions.
+ * (atomic) equivalent to:
+ *   if (*dst == exp)
+ *     *dst = src (all 64-bit words)
+ *
+ * @param dst
+ *   The destination into which the value will be written.
+ * @param exp
+ *   The expected value.
+ * @param src
+ *   The new value.
+ * @return
+ *   Non-zero on success; 0 on failure.
+ */
+static inline int
+rte_atomic64_cmpset(volatile uint64_t *dst, uint64_t exp, uint64_t src)
+{
+	unsigned int ret = 0;
+
+	asm volatile (
+			"\tlwsync\n"
+			"1: ldarx %[ret], 0, %[dst]\n"
+			"cmpld %[exp], %[ret]\n"
+			"bne 2f\n"
+			"stdcx. %[src], 0, %[dst]\n"
+			"bne- 1b\n"
+			"li %[ret], 1\n"
+			"b 3f\n"
+			"2:\n"
+			"stdcx. %[ret], 0, %[dst]\n"
+			"li %[ret], 0\n"
+			"3:\n"
+			"isync\n"
+			: [ret] "=&r" (ret), "=m" (*dst)
+			: [dst] "r" (dst), [exp] "r" (exp), [src] "r" (src), "m" (*dst)
+			: "cc", "memory");
+	return ret;
+}
+
+/**
+ * The atomic counter structure.
+ */
+typedef struct {
+	volatile int64_t cnt;  /**< Internal counter value. */
+} rte_atomic64_t;
+
+/**
+ * Static initializer for an atomic counter.
+ */
+#define RTE_ATOMIC64_INIT(val) { (val) }
+
+/**
+ * Initialize the atomic counter.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ */
+static inline void
+rte_atomic64_init(rte_atomic64_t *v)
+{
+	v->cnt = 0;
+}
+
+/**
+ * Atomically read a 64-bit counter.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ * @return
+ *   The value of the counter.
+ */
+static inline int64_t
+rte_atomic64_read(rte_atomic64_t *v)
+{
+	long ret;
+
+	asm volatile("ld%U1%X1 %[ret],%[cnt]" : [ret] "=r"(ret) : [cnt] "m"(v->cnt));
+
+	return ret;
+}
+
+/**
+ * Atomically set a 64-bit counter.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ * @param new_value
+ *   The new value of the counter.
+ */
+static inline void
+rte_atomic64_set(rte_atomic64_t *v, int64_t new_value)
+{
+	asm volatile("std%U0%X0 %[new_value],%[cnt]" : [cnt] "=m"(v->cnt) : [new_value] "r"(new_value));
+}
+
+/**
+ * Atomically add a 64-bit value to a counter.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ * @param inc
+ *   The value to be added to the counter.
+ */
+static inline void
+rte_atomic64_add(rte_atomic64_t *v, int64_t inc)
+{
+	long t;
+
+	asm volatile(
+			"1: ldarx %[t],0,%[cnt]\n"
+			"add %[t],%[inc],%[t]\n"
+			"stdcx. %[t],0,%[cnt]\n"
+			"bne- 1b\n"
+			: [t] "=&r" (t), "=m" (v->cnt)
+			: [cnt] "r" (&v->cnt), [inc] "r" (inc), "m" (v->cnt)
+			: "cc", "memory");
+}
+
+/**
+ * Atomically subtract a 64-bit value from a counter.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ * @param dec
+ *   The value to be subtracted from the counter.
+ */
+static inline void
+rte_atomic64_sub(rte_atomic64_t *v, int64_t dec)
+{
+	long t;
+
+	asm volatile(
+			"1: ldarx %[t],0,%[cnt]\n"
+			"subf %[t],%[dec],%[t]\n"
+			"stdcx. %[t],0,%[cnt]\n"
+			"bne- 1b\n"
+			: [t] "=&r" (t), "+m" (v->cnt)
+			: [cnt] "r" (&v->cnt), [dec] "r" (dec), "m" (v->cnt)
+			: "cc", "memory");
+}
+
+/**
+ * Atomically increment a 64-bit counter by one and test.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ */
+static inline void
+rte_atomic64_inc(rte_atomic64_t *v)
+{
+	long t;
+
+	asm volatile(
+			"1: ldarx %[t],0,%[cnt]\n"
+			"addic %[t],%[t],1\n"
+			"stdcx. %[t],0,%[cnt] \n"
+			"bne- 1b\n"
+			: [t] "=&r" (t), "+m" (v->cnt)
+			: [cnt] "r" (&v->cnt), "m" (v->cnt)
+			: "cc", "xer", "memory");
+}
+
+/**
+ * Atomically decrement a 64-bit counter by one and test.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ */
+static inline void
+rte_atomic64_dec(rte_atomic64_t *v)
+{
+	long t;
+
+	asm volatile(
+			"1: ldarx %[t],0,%[cnt]\n"
+			"addic %[t],%[t],-1\n"
+			"stdcx. %[t],0,%[cnt]\n"
+			"bne- 1b\n"
+			: [t] "=&r" (t), "+m" (v->cnt)
+			: [cnt] "r" (&v->cnt), "m" (v->cnt)
+			: "cc", "xer", "memory");
+}
+
+/**
+ * Add a 64-bit value to an atomic counter and return the result.
+ *
+ * Atomically adds the 64-bit value (inc) to the atomic counter (v) and
+ * returns the value of v after the addition.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ * @param inc
+ *   The value to be added to the counter.
+ * @return
+ *   The value of v after the addition.
+ */
+static inline int64_t
+rte_atomic64_add_return(rte_atomic64_t *v, int64_t inc)
+{
+	long ret;
+
+	asm volatile(
+			"\n\tlwsync\n"
+			"1: ldarx %[ret],0,%[cnt]\n"
+			"add %[ret],%[inc],%[ret]\n"
+			"stdcx. %[ret],0,%[cnt]\n"
+			"bne- 1b\n"
+			"isync\n"
+			: [ret] "=&r" (ret)
+			: [inc] "r" (inc), [cnt] "r" (&v->cnt)
+			: "cc", "memory");
+
+	return ret;
+}
+
+/**
+ * Subtract a 64-bit value from an atomic counter and return the result.
+ *
+ * Atomically subtracts the 64-bit value (dec) from the atomic counter (v)
+ * and returns the value of v after the subtraction.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ * @param dec
+ *   The value to be subtracted from the counter.
+ * @return
+ *   The value of v after the subtraction.
+ */
+static inline int64_t
+rte_atomic64_sub_return(rte_atomic64_t *v, int64_t dec)
+{
+	long ret;
+
+	asm volatile(
+			"\n\tlwsync\n"
+			"1: ldarx %[ret],0,%[cnt]\n"
+			"subf %[ret],%[dec],%[ret]\n"
+			"stdcx. %[ret],0,%[cnt] \n"
+			"bne- 1b\n"
+			"isync\n"
+			: [ret] "=&r" (ret)
+			: [dec] "r" (dec), [cnt] "r" (&v->cnt)
+			: "cc", "memory");
+
+	return ret;
+}
+
+static __inline__ long rte_atomic64_inc_return(rte_atomic64_t *v)
+{
+	long ret;
+
+	asm volatile(
+			"\n\tlwsync\n"
+			"1: ldarx %[ret],0,%[cnt]\n"
+			"addic %[ret],%[ret],1\n"
+			"stdcx. %[ret],0,%[cnt]\n"
+			"bne- 1b\n"
+			"isync\n"
+			: [ret] "=&r" (ret)
+			: [cnt] "r" (&v->cnt)
+			: "cc", "xer", "memory");
+
+	return ret;
+}
+/**
+ * Atomically increment a 64-bit counter by one and test.
+ *
+ * Atomically increments the atomic counter (v) by one and returns
+ * true if the result is 0, or false in all other cases.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ * @return
+ *   True if the result after the addition is 0; false otherwise.
+ */
+#define rte_atomic64_inc_and_test(v) (rte_atomic64_inc_return(v) == 0)
+
+static __inline__ long rte_atomic64_dec_return(rte_atomic64_t *v)
+{
+	long ret;
+
+	asm volatile(
+			"\n\tlwsync\n"
+			"1: ldarx %[ret],0,%[cnt]\n"
+			"addic %[ret],%[ret],-1\n"
+			"stdcx. %[ret],0,%[cnt]\n"
+			"bne- 1b\n"
+			"isync\n"
+			: [ret] "=&r" (ret)
+			: [cnt] "r" (&v->cnt)
+			: "cc", "xer", "memory");
+
+	return ret;
+}
+/**
+ * Atomically decrement a 64-bit counter by one and test.
+ *
+ * Atomically decrements the atomic counter (v) by one and returns true if
+ * the result is 0, or false in all other cases.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ * @return
+ *   True if the result after subtraction is 0; false otherwise.
+ */
+#define rte_atomic64_dec_and_test(v)    (rte_atomic64_dec_return((v)) == 0)
+
+/**
+ * Atomically test and set a 64-bit atomic counter.
+ *
+ * If the counter value is already set, return 0 (failed). Otherwise, set
+ * the counter value to 1 and return 1 (success).
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ * @return
+ *   0 if failed; else 1, success.
+ */
+static inline int rte_atomic64_test_and_set(rte_atomic64_t *v)
+{
+	return rte_atomic64_cmpset((volatile uint64_t *)&v->cnt, 0, 1);
+}
+
+/**
+ * Atomically set a 64-bit counter to 0.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ */
+static inline void rte_atomic64_clear(rte_atomic64_t *v)
+{
+	v->cnt = 0;
+}
+
+#endif /* _RTE_POWERPC_64_ATOMIC_H_ */
+
diff --git a/lib/librte_eal/common/include/powerpc/arch/rte_atomic_arch.h b/lib/librte_eal/common/include/powerpc/arch/rte_atomic_arch.h
new file mode 100644
index 0000000..fe5666e
--- /dev/null
+++ b/lib/librte_eal/common/include/powerpc/arch/rte_atomic_arch.h
@@ -0,0 +1,318 @@
+/*
+ *   BSD LICENSE
+ *
+ *   Copyright (C) IBM Corporation 2014.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of IBM Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/*
+ * Inspired from FreeBSD src/sys/powerpc/include/atomic.h
+ * Copyright (c) 2008 Marcel Moolenaar
+ * Copyright (c) 2001 Benno Rice
+ * Copyright (c) 2001 David E. O'Brien
+ * Copyright (c) 1998 Doug Rabson
+ * All rights reserved.
+ */
+
+#ifndef _RTE_ATOMIC_H_
+#error "don't include this file directly, please include generic <rte_atomic.h>"
+#endif
+
+#ifndef _RTE_ATOMIC_ARCH_H_
+#define _RTE_ATOMIC_ARCH_H_
+
+#include <stdint.h>
+
+/**
+ * General memory barrier.
+ *
+ * Guarantees that the LOAD and STORE operations generated before the
+ * barrier occur before the LOAD and STORE operations generated after.
+ */
+#define	rte_arch_mb()  asm volatile("sync" : : : "memory")
+
+/**
+ * Write memory barrier.
+ *
+ * Guarantees that the STORE operations generated before the barrier
+ * occur before the STORE operations generated after.
+ */
+#define	rte_arch_wmb() asm volatile("sync" : : : "memory")
+
+/**
+ * Read memory barrier.
+ *
+ * Guarantees that the LOAD operations generated before the barrier
+ * occur before the LOAD operations generated after.
+ */
+#define	rte_arch_rmb() asm volatile("sync" : : : "memory")
+
+#define	rte_arch_compiler_barrier() do {		\
+	asm volatile ("" : : : "memory");	\
+} while(0)
+
+/*------------------------- 16 bit atomic operations -------------------------*/
+
+/**
+ * The atomic counter structure.
+ */
+typedef struct {
+	volatile int16_t cnt; /**< An internal counter value. */
+} rte_atomic16_t;
+
+/**
+ * Atomic compare and set.
+ *
+ * (atomic) equivalent to:
+ *   if (*dst == exp)
+ *     *dst = src (all 16-bit words)
+ *
+ * @param dst
+ *   The destination location into which the value will be written.
+ * @param exp
+ *   The expected value.
+ * @param src
+ *   The new value.
+ * @return
+ *   Non-zero on success; 0 on failure.
+ */
+static inline int
+rte_arch_atomic16_cmpset(volatile uint16_t *dst, uint16_t exp, uint16_t src)
+{
+	return __atomic_compare_exchange(dst, &exp, &src, 0, __ATOMIC_ACQUIRE, __ATOMIC_ACQUIRE) ? 1 : 0;
+}
+
+/**
+ * Atomically increment a counter by one.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ */
+static inline void
+rte_arch_atomic16_inc(rte_atomic16_t *v)
+{
+	__atomic_add_fetch(&v->cnt, 1, __ATOMIC_ACQUIRE);
+}
+
+/**
+ * Atomically decrement a counter by one.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ */
+static inline void
+rte_arch_atomic16_dec(rte_atomic16_t *v)
+{
+	__atomic_sub_fetch(&v->cnt, 1, __ATOMIC_ACQUIRE);
+}
+
+/**
+ * Atomically increment a 16-bit counter by one and test.
+ *
+ * Atomically increments the atomic counter (v) by one and returns true if
+ * the result is 0, or false in all other cases.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ * @return
+ *   True if the result after the increment operation is 0; false otherwise.
+ */
+static inline int rte_arch_atomic16_inc_and_test(rte_atomic16_t *v)
+{
+	return (__atomic_add_fetch(&v->cnt, 1, __ATOMIC_ACQUIRE) == 0);
+}
+
+/**
+ * Atomically decrement a 16-bit counter by one and test.
+ *
+ * Atomically decrements the atomic counter (v) by one and returns true if
+ * the result is 0, or false in all other cases.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ * @return
+ *   True if the result after the decrement operation is 0; false otherwise.
+ */
+static inline int rte_arch_atomic16_dec_and_test(rte_atomic16_t *v)
+{
+	return (__atomic_sub_fetch(&v->cnt, 1, __ATOMIC_ACQUIRE) == 0);
+}
+
+/*------------------------- 32 bit atomic operations -------------------------*/
+
+/**
+ * The atomic counter structure.
+ */
+typedef struct {
+	volatile int32_t cnt; /**< An internal counter value. */
+} rte_atomic32_t;
+
+/**
+ * Atomic compare and set.
+ *
+ * (atomic) equivalent to:
+ *   if (*dst == exp)
+ *     *dst = src (all 32-bit words)
+ *
+ * @param dst
+ *   The destination location into which the value will be written.
+ * @param exp
+ *   The expected value.
+ * @param src
+ *   The new value.
+ * @return
+ *   Non-zero on success; 0 on failure.
+ */
+static inline int
+rte_arch_atomic32_cmpset(volatile uint32_t *dst, uint32_t exp, uint32_t src)
+{
+	unsigned int ret = 0;
+
+	asm volatile(
+			"\tlwsync\n"
+			"1:\tlwarx %[ret], 0, %[dst]\n"
+			"cmplw %[exp], %[ret]\n"
+			"bne 2f\n"
+			"stwcx. %[src], 0, %[dst]\n"
+			"bne- 1b\n"
+			"li %[ret], 1\n"
+			"b 3f\n"
+			"2:\n"
+			"stwcx. %[ret], 0, %[dst]\n"   
+			"li %[ret], 0\n"
+			"3:\n"
+			"isync\n"
+			: [ret] "=&r" (ret), "=m" (*dst)
+			: [dst] "r" (dst), [exp] "r" (exp), [src] "r" (src), "m" (*dst)
+			: "cc", "memory");
+
+	return ret;
+}
+
+/**
+ * Atomically increment a counter by one.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ */
+static inline void
+rte_arch_atomic32_inc(rte_atomic32_t *v)
+{
+	int t;
+
+	asm volatile(
+			"1: lwarx %[t],0,%[cnt]\n"
+			"addic %[t],%[t],1\n"
+			"stwcx. %[t],0,%[cnt]\n"
+			"bne- 1b\n"
+			: [t] "=&r" (t), "=m" (v->cnt)
+			: [cnt] "r" (&v->cnt), "m" (v->cnt)
+			: "cc", "xer", "memory");
+}
+
+/**
+ * Atomically decrement a counter by one.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ */
+static inline void
+rte_arch_atomic32_dec(rte_atomic32_t *v)
+{
+	int t;
+
+	asm volatile(
+			"1: lwarx %[t],0,%[cnt]\n"
+			"addic %[t],%[t],-1\n"
+			"stwcx. %[t],0,%[cnt]\n"
+			"bne- 1b\n"
+			: [t] "=&r" (t), "=m" (v->cnt)
+			: [cnt] "r" (&v->cnt), "m" (v->cnt)
+			: "cc", "xer", "memory");
+}
+
+/**
+ * Atomically increment a 32-bit counter by one and test.
+ *
+ * Atomically increments the atomic counter (v) by one and returns true if
+ * the result is 0, or false in all other cases.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ * @return
+ *   True if the result after the increment operation is 0; false otherwise.
+ */
+static inline int rte_arch_atomic32_inc_and_test(rte_atomic32_t *v)
+{
+	int ret;
+
+	asm volatile(
+			"\n\tlwsync\n"
+			"1: lwarx %[ret],0,%[cnt]\n"
+			"addic	%[ret],%[ret],1\n"
+			"stwcx. %[ret],0,%[cnt]\n"
+			"bne- 1b\n"
+			"isync\n"
+			: [ret] "=&r" (ret)
+			: [cnt] "r" (&v->cnt)
+			: "cc", "xer", "memory");
+
+	return (ret == 0);
+}
+
+/**
+ * Atomically decrement a 32-bit counter by one and test.
+ *
+ * Atomically decrements the atomic counter (v) by one and returns true if
+ * the result is 0, or false in all other cases.
+ *
+ * @param v
+ *   A pointer to the atomic counter.
+ * @return
+ *   True if the result after the decrement operation is 0; false otherwise.
+ */
+static inline int rte_arch_atomic32_dec_and_test(rte_atomic32_t *v)
+{
+	int ret;
+
+	asm volatile(
+			"\n\tlwsync\n"
+			"1: lwarx %[ret],0,%[cnt]\n"
+			"addic %[ret],%[ret],-1\n"
+			"stwcx. %[ret],0,%[cnt]\n"
+			"bne- 1b\n"
+			"isync\n"
+			: [ret] "=&r" (ret)
+			: [cnt] "r" (&v->cnt)
+			: "cc", "xer", "memory");
+
+	return (ret == 0);
+}
+
+#endif /* _RTE_ATOMIC_ARCH_H_ */
+
-- 
1.7.1