1 files changed, 63 insertions, 0 deletions
diff --git a/lib/verity/rs.h b/lib/verity/rs.h
new file mode 100644
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--- /dev/null
+++ b/lib/verity/rs.h
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+/*
+ * Reed-Solomon codecs, based on libfec
+ *
+ * Copyright (C) 2004 Phil Karn, KA9Q
+ * libcryptsetup modifications
+ *   Copyright (C) 2017-2021 Red Hat, Inc. All rights reserved.
+ *
+ * This file is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This file is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this file; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef _LIBFEC_RS_H
+#define _LIBFEC_RS_H
+
+/* Special reserved value encoding zero in index form. */
+#define A0 (rs->nn)
+
+#define RS_MIN(a, b) ((a) < (b) ? (a) : (b))
+
+typedef unsigned char data_t;
+
+/* Reed-Solomon codec control block */
+struct rs {
+	int mm;          /* Bits per symbol */
+	int nn;          /* Symbols per block (= (1<<mm)-1) */
+	data_t *alpha_to;/* log lookup table */
+	data_t *index_of;/* Antilog lookup table */
+	data_t *genpoly; /* Generator polynomial */
+	int nroots;      /* Number of generator roots = number of parity symbols */
+	int fcr;         /* First consecutive root, index form */
+	int prim;        /* Primitive element, index form */
+	int iprim;       /* prim-th root of 1, index form */
+	int pad;         /* Padding bytes in shortened block */
+};
+
+static inline int modnn(struct rs *rs, int x)
+{
+	while (x >= rs->nn) {
+		x -= rs->nn;
+		x = (x >> rs->mm) + (x & rs->nn);
+	}
+	return x;
+}
+
+struct rs *init_rs_char(int symsize, int gfpoly, int fcr, int prim, int nroots, int pad);
+void free_rs_char(struct rs *rs);
+
+/* General purpose RS codec, 8-bit symbols */
+void encode_rs_char(struct rs *rs, data_t *data, data_t *parity);
+int decode_rs_char(struct rs *rs, data_t *data);
+
+#endif