T-Echo Card audio support initial stages - codec2 attempts

lib/codec2_nrf52/src/varicode.h

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+//==========================================================================
+// Name:            varicode.h
+// Purpose:         Varicode encoded and decode functions
+// Created:         Nov 24, 2012
+// Authors:         David Rowe
+//
+// License:
+//
+//  This program is free software; you can redistribute it and/or modify
+//  it under the terms of the GNU General Public License version 2.1,
+//  as published by the Free Software Foundation.  This program 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 General Public
+//  License for more details.
+//
+//  You should have received a copy of the GNU General Public License
+//  along with this program; if not, see <http://www.gnu.org/licenses/>.
+//
+//==========================================================================
+
+#ifndef __VARICODE__
+#define __VARICODE__
+
+#ifdef __cplusplus
+extern "C" {
+
+#endif
+
+#define VARICODE_MAX_BITS (10+2) /* max varicode bits for each ascii character */
+                                 /* 10 bits for code plus 2 0 bits for inter-character space */
+
+struct VARICODE_DEC {
+    int            state;
+    int            n_zeros;
+    int            v_len;
+    unsigned short packed;
+    int            code_num;
+    int            n_in;
+    int            in[2];
+};
+
+int varicode_encode(short varicode_out[], char ascii_in[], int max_out, int n_in, int code_num);
+void varicode_decode_init(struct VARICODE_DEC *dec_states, int code_num);
+int varicode_decode(struct VARICODE_DEC *dec_states, char ascii_out[], short varicode_in[], int max_out, int n_in);
+void varicode_set_code_num(struct VARICODE_DEC *dec_states, int code_num);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif