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+/*
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * 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.
+ */
+/*
+ Copyright (c) 2012 Eliot Dresselhaus
+
+ 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 included_clib_smp_vec_h
+#define included_clib_smp_vec_h
+
+#include <vppinfra/smp.h>
+
+#define foreach_clib_smp_fifo_data_state \
+ _ (free) \
+ _ (write_alloc) \
+ _ (write_done) \
+ _ (read_fetch)
+
+typedef enum
+{
+#define _(f) CLIB_SMP_FIFO_DATA_STATE_##f,
+ foreach_clib_smp_fifo_data_state
+#undef _
+ CLIB_SMP_FIFO_N_DATA_STATE,
+} clib_smp_fifo_data_state_t;
+
+/* Footer at end of each data element. */
+typedef struct
+{
+ /* Magic number marking valid footer plus state encoded in low bits. */
+ u32 magic_state;
+} clib_smp_fifo_data_footer_t;
+
+#define CLIB_SMP_DATA_FOOTER_MAGIC 0xfafbfcf0
+
+always_inline clib_smp_fifo_data_state_t
+clib_smp_fifo_data_footer_get_state (clib_smp_fifo_data_footer_t * f)
+{
+ u32 s = f->magic_state - CLIB_SMP_DATA_FOOTER_MAGIC;
+
+ /* Check that magic number plus state is still valid. */
+ if (s >= CLIB_SMP_FIFO_N_DATA_STATE)
+ os_panic ();
+
+ return s;
+}
+
+always_inline void
+clib_smp_fifo_data_footer_set_state (clib_smp_fifo_data_footer_t * f,
+ clib_smp_fifo_data_state_t s)
+{
+ f->magic_state = CLIB_SMP_DATA_FOOTER_MAGIC + s;
+}
+
+typedef struct
+{
+ /* Read/write indices each on their own cache line.
+ Atomic incremented for each read/write. */
+ u32 read_index, write_index;
+
+ /* Power of 2 number of elements in fifo less one. */
+ u32 max_n_elts_less_one;
+
+ /* Log2 of above. */
+ u32 log2_max_n_elts;
+
+ /* Cache aligned data. */
+ void *data;
+} clib_smp_fifo_t;
+
+/* External functions. */
+clib_smp_fifo_t *clib_smp_fifo_init (uword max_n_elts, uword n_bytes_per_elt);
+
+/* Elements are always cache-line sized; this is to avoid smp cache thrashing. */
+always_inline uword
+clib_smp_fifo_round_elt_bytes (uword n_bytes_per_elt)
+{
+ return round_pow2 (n_bytes_per_elt, CLIB_CACHE_LINE_BYTES);
+}
+
+always_inline uword
+clib_smp_fifo_n_elts (clib_smp_fifo_t * f)
+{
+ uword n = f->write_index - f->read_index;
+ ASSERT (n <= f->max_n_elts_less_one + 1);
+ return n;
+}
+
+always_inline clib_smp_fifo_data_footer_t *
+clib_smp_fifo_get_data_footer (void *d, uword n_bytes_per_elt)
+{
+ clib_smp_fifo_data_footer_t *f;
+ f = d + clib_smp_fifo_round_elt_bytes (n_bytes_per_elt) - sizeof (f[0]);
+ return f;
+}
+
+always_inline void *
+clib_smp_fifo_elt_at_index (clib_smp_fifo_t * f, uword n_bytes_per_elt,
+ uword i)
+{
+ uword n_bytes_per_elt_cache_aligned;
+
+ ASSERT (i <= f->max_n_elts_less_one);
+
+ n_bytes_per_elt_cache_aligned =
+ clib_smp_fifo_round_elt_bytes (n_bytes_per_elt);
+
+ return f->data + i * n_bytes_per_elt_cache_aligned;
+}
+
+always_inline void *
+clib_smp_fifo_write_alloc (clib_smp_fifo_t * f, uword n_bytes_per_elt)
+{
+ void *d;
+ clib_smp_fifo_data_footer_t *t;
+ clib_smp_fifo_data_state_t s;
+ u32 wi0, wi1;
+
+ wi0 = f->write_index;
+
+ /* Fifo full? */
+ if (wi0 - f->read_index > f->max_n_elts_less_one)
+ return 0;
+
+ while (1)
+ {
+ wi1 = wi0 + 1;
+
+ d =
+ clib_smp_fifo_elt_at_index (f, n_bytes_per_elt,
+ wi0 & f->max_n_elts_less_one);
+ t = clib_smp_fifo_get_data_footer (d, n_bytes_per_elt);
+
+ s = clib_smp_fifo_data_footer_get_state (t);
+ if (s != CLIB_SMP_FIFO_DATA_STATE_free)
+ {
+ d = 0;
+ break;
+ }
+
+ wi1 = clib_smp_compare_and_swap (&f->write_index, wi1, wi0);
+
+ if (wi1 == wi0)
+ {
+ clib_smp_fifo_data_footer_set_state (t,
+ CLIB_SMP_FIFO_DATA_STATE_write_alloc);
+ break;
+ }
+
+ /* Other cpu wrote write index first: try again. */
+ wi0 = wi1;
+ }
+
+ return d;
+}
+
+always_inline void
+clib_smp_fifo_write_done (clib_smp_fifo_t * f, void *d, uword n_bytes_per_elt)
+{
+ clib_smp_fifo_data_footer_t *t;
+
+ /* Flush out pending writes before we change state to write_done.
+ This will hold off readers until data is flushed. */
+ CLIB_MEMORY_BARRIER ();
+
+ t = clib_smp_fifo_get_data_footer (d, n_bytes_per_elt);
+
+ ASSERT (clib_smp_fifo_data_footer_get_state (t) ==
+ CLIB_SMP_FIFO_DATA_STATE_write_alloc);
+ clib_smp_fifo_data_footer_set_state (t,
+ CLIB_SMP_FIFO_DATA_STATE_write_done);
+}
+
+always_inline void *
+clib_smp_fifo_read_fetch (clib_smp_fifo_t * f, uword n_bytes_per_elt)
+{
+ void *d;
+ clib_smp_fifo_data_footer_t *t;
+ clib_smp_fifo_data_state_t s;
+ u32 ri0, ri1;
+
+ ri0 = f->read_index;
+
+ /* Fifo empty? */
+ if (f->write_index - ri0 == 0)
+ return 0;
+
+ while (1)
+ {
+ ri1 = ri0 + 1;
+
+ d =
+ clib_smp_fifo_elt_at_index (f, n_bytes_per_elt,
+ ri0 & f->max_n_elts_less_one);
+ t = clib_smp_fifo_get_data_footer (d, n_bytes_per_elt);
+
+ s = clib_smp_fifo_data_footer_get_state (t);
+ if (s != CLIB_SMP_FIFO_DATA_STATE_write_done)
+ {
+ d = 0;
+ break;
+ }
+
+ ri1 = clib_smp_compare_and_swap (&f->read_index, ri1, ri0);
+ if (ri1 == ri0)
+ {
+ clib_smp_fifo_data_footer_set_state (t,
+ CLIB_SMP_FIFO_DATA_STATE_read_fetch);
+ break;
+ }
+
+ ri0 = ri1;
+ }
+
+ return d;
+}
+
+always_inline void
+clib_smp_fifo_read_done (clib_smp_fifo_t * f, void *d, uword n_bytes_per_elt)
+{
+ clib_smp_fifo_data_footer_t *t;
+
+ t = clib_smp_fifo_get_data_footer (d, n_bytes_per_elt);
+
+ ASSERT (clib_smp_fifo_data_footer_get_state (t) ==
+ CLIB_SMP_FIFO_DATA_STATE_read_fetch);
+ clib_smp_fifo_data_footer_set_state (t, CLIB_SMP_FIFO_DATA_STATE_free);
+}
+
+always_inline void
+clib_smp_fifo_memcpy (uword * dst, uword * src, uword n_bytes)
+{
+ word n_bytes_left = n_bytes;
+
+ while (n_bytes_left >= 4 * sizeof (uword))
+ {
+ dst[0] = src[0];
+ dst[1] = src[1];
+ dst[2] = src[2];
+ dst[3] = src[3];
+ dst += 4;
+ src += 4;
+ n_bytes_left -= 4 * sizeof (dst[0]);
+ }
+
+ while (n_bytes_left > 0)
+ {
+ dst[0] = src[0];
+ dst += 1;
+ src += 1;
+ n_bytes_left -= 1 * sizeof (dst[0]);
+ }
+}
+
+always_inline void
+clib_smp_fifo_write_inline (clib_smp_fifo_t * f, void *elt_to_write,
+ uword n_bytes_per_elt)
+{
+ uword *dst;
+ dst = clib_smp_fifo_write_alloc (f, n_bytes_per_elt);
+ clib_smp_fifo_memcpy (dst, elt_to_write, n_bytes_per_elt);
+ clib_smp_fifo_write_done (f, dst, n_bytes_per_elt);
+}
+
+always_inline void
+clib_smp_fifo_read_inline (clib_smp_fifo_t * f, void *elt_to_read,
+ uword n_bytes_per_elt)
+{
+ uword *src;
+ src = clib_smp_fifo_read_fetch (f, n_bytes_per_elt);
+ clib_smp_fifo_memcpy (elt_to_read, src, n_bytes_per_elt);
+ clib_smp_fifo_read_done (f, src, n_bytes_per_elt);
+}
+
+#endif /* included_clib_smp_vec_h */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */