ISA-L Cauchy support

This is for supporting ISA-L cauchy based matrix. The difference
from isa_l_rs_vand is only the matrix to use the encode/decode calculation.

As a known issue, isa_l_rs_vand backend has constraint for the
combinations of the available fragment to be able to decode/reconstuct.
(See related change in detail)

To avoid the constraint, this patch adds another isa-l backend to use
cauchy matrix and keep the backward compatibility, this is in
another isa_l_rs_cauchy namespace.

For implementation consieration, the code is almost same except the matrix
generation fucntion so that this patch makes isa_l_common.c file for
gathering common fucntions like init/encode/decode/reconstruct. And then the
common init funciton takes an extra args "gen_matrix_func_name" for entry
point to load the fucntion by dlsym from isa-l .so file.

Co-Authored-By: Clay Gerrard <clay.gerrard@gmail.com>

Related-Change: Icee788a0931fe692fe0de31fabc4ba450e338a87
Change-Id: I6eb150d9d0c3febf233570fa7729f9f72df2e9be

2 files changed, 71 insertions, 0 deletions

diff --git a/include/erasurecode/erasurecode.h b/include/erasurecode/erasurecode.h
index a17c45c..d1e8f4e 100644
--- a/include/erasurecode/erasurecode.h
+++ b/include/erasurecode/erasurecode.h
@@ -48,6 +48,7 @@ typedef enum {
     EC_BACKEND_ISA_L_RS_VAND          = 4,
     EC_BACKEND_SHSS                   = 5,
     EC_BACKEND_LIBERASURECODE_RS_VAND = 6,
+    EC_BACKEND_ISA_L_RS_CAUCHY        = 7,
     EC_BACKENDS_MAX,
 } ec_backend_id_t;
 
diff --git a/include/isa_l/isa_l_common.h b/include/isa_l/isa_l_common.h
new file mode 100644
index 0000000..caad19a
--- /dev/null
+++ b/include/isa_l/isa_l_common.h
@@ -0,0 +1,70 @@
+/*
+ * Copyright 2014 Kevin M Greenan
+ * Copyright 2014 Tushar Gohad
+ *
+ * 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.  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 HOLDER 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.
+ *
+ * isa_l_rs_vand backend implementation
+ *
+ * vi: set noai tw=79 ts=4 sw=4:
+ */
+
+#define ISA_L_W 8
+
+/* Forward declarations */
+typedef void (*ec_encode_data_func)(int, int, int, unsigned char*, unsigned char **, unsigned char **);
+typedef void (*ec_init_tables_func)(int, int, unsigned char*, unsigned char *);
+typedef void (*gf_gen_encoding_matrix_func)(unsigned char*, int, int);
+typedef int (*gf_invert_matrix_func)(unsigned char*, unsigned char*, const int);
+typedef unsigned char (*gf_mul_func)(unsigned char, unsigned char);
+
+typedef struct {
+    /* calls required for init */
+    ec_init_tables_func ec_init_tables;
+    gf_gen_encoding_matrix_func gf_gen_encoding_matrix;
+
+    /* calls required for encode */
+    ec_encode_data_func ec_encode_data;
+
+    /* calls required for decode and reconstruct */
+    gf_invert_matrix_func gf_invert_matrix;
+
+    /* multiplication function used by ISA-L */
+    gf_mul_func gf_mul;
+
+    /* fields needed to hold state */
+    unsigned char *matrix;
+    int k;
+    int m;
+    int w;
+} isa_l_descriptor;
+
+int isa_l_encode(void *desc, char **data, char **parity, int blocksize);
+int isa_l_decode(void *desc, char **data, char **parity, int *missing_idxs,
+        int blocksize);
+int isa_l_reconstruct(void *desc, char **data, char **parity,
+        int *missing_idxs, int destination_idx, int blocksize);
+int isa_l_min_fragments(void *desc, int *missing_idxs,
+        int *fragments_to_exclude, int *fragments_needed);
+int isa_l_element_size(void* desc);
+int isa_l_exit(void *desc);
+void * isa_l_common_init(struct ec_backend_args *args, void *backend_sohandle,
+        const char* gen_matrix_func_name);