> -----Original Message-----
> From: Joyce Kong [mailto:joyce.k...@arm.com]
> Sent: Wednesday, October 23, 2019 4:55 AM
>
> There are a lot functions of bit operations scattered and
> duplicated in PMDs, consolidating them into a common API
> family is necessary. Furthermore, the bit operation is
> mostly applied to the IO devices, so use __ATOMIC_ACQ_REL
> to ensure the ordering.
>
> Signed-off-by: Joyce Kong <joyce.k...@arm.com>
> Reviewed-by: Gavin Hu <gavin...@arm.com>
> ---
> lib/librte_eal/common/Makefile | 1 +
> lib/librte_eal/common/include/rte_io_bitops.h | 112
> ++++++++++++++++++++++++++
> lib/librte_eal/common/meson.build | 1 +
> 3 files changed, 114 insertions(+)
> create mode 100644 lib/librte_eal/common/include/rte_io_bitops.h
>
> diff --git a/lib/librte_eal/common/Makefile
> b/lib/librte_eal/common/Makefile
> index a00d4fc..3831313 100644
> --- a/lib/librte_eal/common/Makefile
> +++ b/lib/librte_eal/common/Makefile
> @@ -18,6 +18,7 @@ INC += rte_malloc.h rte_keepalive.h rte_time.h
> INC += rte_service.h rte_service_component.h
> INC += rte_bitmap.h rte_vfio.h rte_hypervisor.h rte_test.h
> INC += rte_reciprocal.h rte_fbarray.h rte_uuid.h
> +INC += rte_io_bitops.h
>
> GENERIC_INC := rte_atomic.h rte_byteorder.h rte_cycles.h
> rte_prefetch.h
> GENERIC_INC += rte_memcpy.h rte_cpuflags.h
> diff --git a/lib/librte_eal/common/include/rte_io_bitops.h
> b/lib/librte_eal/common/include/rte_io_bitops.h
> new file mode 100644
> index 0000000..5f778b8
> --- /dev/null
> +++ b/lib/librte_eal/common/include/rte_io_bitops.h
> @@ -0,0 +1,112 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2019 Arm Limited
> + */
> +
> +#ifndef _RTE_IO_BITOPS_H_
> +#define _RTE_IO_BITOPS_H_
> +
> +/**
> + * @file
> + * Bit Operations
> + *
> + * This file defines a generic API for bit operations.
> + */
-> This file defines a generic API for I/O device bit operations.
> +
> +#include <rte_lcore.h>
This library doesn't do any lcore operations. Please use the appropriate
headers.
> +
> +/**
> + * Get a bit.
> + *
> + * @param nr
> + * The bit to get.
> + * @param addr
> + * The address to count from.
The address to count from. -> The address holding the bit. (Applies to all
functions.)
> + * @return
> + * The value of the bit.
The description of the return value can be misinterpreted. The return value is
not the value of the bit, which is 0 or 1, but the value of the word holding
the bit, masked with the bit position. (Applies to all functions returning a
value.)
> + */
> +static inline int32_t
> +rte_io_get_bit(uint32_t nr, uint64_t *addr)
The return type should be an unsigned type. (Applies to all functions returning
a value.)
The addr type for 32 bit operations should not be uint64_t *, but uint32_t *.
The __atomic_xxx functions actually use this type for something, and I think it
would access the wrong 32 bits on a big endian CPU.
In some of the functions below, nr is signed (int32_t); it should be unsigned
(uint32_t).
And a suggestion: Consider changing the type of nr from uint32_t to unsigned
int.
> +{
> + return __atomic_load_n(addr, __ATOMIC_ACQUIRE) & (1UL << nr);
> +}
> +
> +/**
> + * Set a bit to 1.
> + *
> + * @param nr
> + * The bit to set.
> + * @param addr
> + * The address to count from.
> + */
> +static inline void
> +rte_io_set_bit(uint32_t nr, uint64_t *addr)
> +{
> + __atomic_fetch_or(addr, (1UL << nr), __ATOMIC_ACQ_REL);
> +}
> +
> +/**
> + * Set a bit to 0.
> + *
> + * @param nr
> + * The bit to set.
> + * @param addr
> + * The address to count from.
> + */
> +static inline void
> +rte_io_clear_bit(int32_t nr, uint64_t *addr)
> +{
> + __atomic_fetch_and(addr, ~(1UL << nr), __ATOMIC_ACQ_REL);
> +}
> +
> +/**
> + * Test if a bit is 1.
> + *
> + * @param nr
> + * The bit to test.
> + * @param addr
> + * The address to count from.
> + * @return
> + * 1 if the bit is 1; else 0.
> + */
> +static inline int32_t
> +rte_io_test_bit(int32_t nr, uint64_t *addr)
> +{
> + return (__atomic_load_n(addr, __ATOMIC_ACQUIRE) & (1UL << nr)) !=
> 0;
> +}
All the other functions in this library return a word with the bit masked. This
function returns 0 or 1. I think it should return a word value, similar to the
other functions.
> +
> +/**
> + * Set a bit to 1 and return its old value.
> + *
> + * @param nr
> + * The bit to set.
> + * @param addr
> + * The address to count from.
> + * @return
> + * The old value of the bit.
> + */
> +static inline int32_t
> +rte_io_test_and_set_bit(int32_t nr, uint64_t *addr)
> +{
> + unsigned long mask = (1UL << nr);
unsigned long mask -> uint32_t mask. (Also applies to other functions.)
> +
> + return __atomic_fetch_or(addr, mask, __ATOMIC_ACQ_REL) & mask;
> +}
> +
> +/**
> + * Set a bit to 0 and return its old value.
> + *
> + * @param nr
> + * The bit to set.
> + * @param addr
> + * The address to count from.
> + * @return
> + * The old value of the bit.
> + */
> +static inline int32_t
> +rte_io_test_and_clear_bit(int32_t nr, uint64_t *addr)
> +{
> + unsigned long mask = (1UL << nr);
> +
> + return __atomic_fetch_and(addr, ~mask, __ATOMIC_ACQ_REL) & mask;
> +}
> +#endif /* _RTE_IO_BITOPS_H_ */
> diff --git a/lib/librte_eal/common/meson.build
> b/lib/librte_eal/common/meson.build
> index 386577c..0a65d04 100644
> --- a/lib/librte_eal/common/meson.build
> +++ b/lib/librte_eal/common/meson.build
> @@ -52,6 +52,7 @@ common_headers = files(
> 'include/rte_alarm.h',
> 'include/rte_branch_prediction.h',
> 'include/rte_bus.h',
> + 'include/rte_io_bitops.h',
> 'include/rte_bitmap.h',
> 'include/rte_class.h',
> 'include/rte_common.h',
> --
> 2.7.4
>
