From b9b8ef7da5490bf02f8a07fd179457164c8d1488 Mon Sep 17 00:00:00 2001 From: adamdunkels Date: Thu, 5 Oct 2006 09:23:41 +0000 Subject: [PATCH] GCR encoding/decoding --- core/lib/gcr.c | 163 +++++++++++++++++++++++++++++++++++++++++++++++++ core/lib/gcr.h | 52 ++++++++++++++++ 2 files changed, 215 insertions(+) create mode 100644 core/lib/gcr.c create mode 100644 core/lib/gcr.h diff --git a/core/lib/gcr.c b/core/lib/gcr.c new file mode 100644 index 000000000..3d89d073c --- /dev/null +++ b/core/lib/gcr.c @@ -0,0 +1,163 @@ +/* + * Copyright (c) 2006, Swedish Institute of Computer Science + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. 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. + * 3. Neither the name of the Institute nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE 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 INSTITUTE 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. + * + * This file is part of the Contiki operating system. + * + * @(#)$Id: gcr.c,v 1.1 2006/10/05 09:23:41 adamdunkels Exp $ + */ + +/** + * \file + * Implementation of GCR coding/decoding + * \author + * Joakim Eriksson + * + */ + +/* GCR conversion table - used for converting ordinary byte to 10-bits */ +/* (or 4 bits to 5) */ +static const unsigned char GCR_encode[16] = { + 0x0a, 0x0b, 0x12, 0x13, + 0x0e, 0x0f, 0x16, 0x17, + 0x09, 0x19, 0x1a, 0x1b, + 0x0d, 0x1d, 0x1e, 0x15 +}; + +/* 5 bits > 4 bits (0xff => invalid) */ +static const unsigned char GCR_decode[32] = { + 0xff, 0xff, 0xff, 0xff, // 0 - 3invalid... + 0xff, 0xff, 0xff, 0xff, // 4 - 7 invalid... + 0xff, 0x08, 0x00, 0x01, // 8 invalid... 9 = 8, a = 0, b = 1 + 0xff, 0x0c, 0x04, 0x05, // c invalid... d = c, e = 4, f = 5 + + 0xff, 0xff, 0x02, 0x03, // 10-11 invalid... + 0xff, 0x0f, 0x06, 0x07, // 14 invalid... + 0xff, 0x09, 0x0a, 0x0b, // 18 invalid... + 0xff, 0x0d, 0x0e, 0xff, // 1c, 1f invalid... + }; + +static unsigned char gcr_bits = 0; +static unsigned short gcr_val = 0; + +/* Call before starting encoding or decoding */ +void gcr_init() { + gcr_val = 0; + gcr_bits = 0; +} + +/* Use this to check if encoding / decoding is complete for now */ +unsigned char gcr_finished() { + return gcr_bits == 0; +} + +/* Encode one character - and store in bits - get encoded with get_encoded */ +void gcr_encode(unsigned char raw_data) { + gcr_val |= + ((GCR_encode[raw_data >> 4u] << 5u ) | + GCR_encode[raw_data & 0xf]) << gcr_bits; + gcr_bits += 10; +} + +/* Gets the current char of the encoded stream */ +unsigned char gcr_get_encoded(unsigned char *raw_data) { + if (gcr_bits >= 8) { + *raw_data = (unsigned char) (gcr_val & 0xff); + gcr_val = gcr_val >> 8u; + gcr_bits = gcr_bits - 8; + return 1; + } + return 0; +} + +/* Decode one char - result can be get from get_decoded */ +void gcr_decode(unsigned char gcr_data) { + gcr_val |= gcr_data << gcr_bits; + gcr_bits += 8; +} + +/* check if the current decoded stream is correct */ +unsigned char gcr_valid() { + if (gcr_bits >= 10) { + unsigned short val = gcr_val & 0x3ff; + if ((GCR_decode[val >> 5u] << 4u) == 0xff || + (GCR_decode[val & 0x1f]) == 0xff) { + return 0; + } + } + return 1; +} + +/* gets the decoded stream - if any char is available */ +unsigned char gcr_get_decoded(unsigned char *raw_data) { + if (gcr_bits >= 10) { + unsigned short val = gcr_val & 0x3ff; + *raw_data = (unsigned char) ((GCR_decode[val >> 5] << 4) | + (GCR_decode[val & 0x1f])); + gcr_val = gcr_val >> 10; + gcr_bits = gcr_bits - 10; + return 1; + } + return 0; +} + +/* +static const char encoded[] = { + 0x4a, 0x25, 0xa5, 0xfc, 0x96, 0xff, 0xff, 0xb5, 0xd4, 0x5a, 0xea, 0xff, 0xff, 0xaa, 0xd3, 0xff +}; + +int main(int argc, char **argv) { + // unsigned char c[] = "testing gcr 1 2 3 4 5 6..."; + unsigned char c[] = { 0, 8, 0xe0, 0x2b, 0xac, 0x10, 0x01, 0x11, 0x50, 0xff, 0xf4, 0xa4, 0x00 }; + unsigned char c2[200]; + int pos = 0, pos2 = 0, i = 0; + + printf("Testing GCR on: %s \n", c); + + gcr_init(); + for (i = 0; i < sizeof(c); i++) { + gcr_encode(c[i]); + while(gcr_get_encoded(&c2[pos])) { + printf("%02x=>%02x ", c[i], c2[pos]); + pos++; + } + } + printf("\n"); + printf("Encoded result %d chars (from %d) \n", pos, i); + gcr_init(); + for (i = 0; i < pos; i++) { + gcr_decode(c2[i]); + if(!gcr_valid()) { + printf("GCR: not valid\n"); + } + while(gcr_get_decoded(&c[pos2])) { + pos2++; + } + } + printf("GCR: %s\n",c); +} +*/ diff --git a/core/lib/gcr.h b/core/lib/gcr.h new file mode 100644 index 000000000..c62ee0444 --- /dev/null +++ b/core/lib/gcr.h @@ -0,0 +1,52 @@ +/* + * Copyright (c) 2006, Swedish Institute of Computer Science. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. 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. + * 3. Neither the name of the Institute nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE 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 INSTITUTE 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. + * + * $Id: gcr.h,v 1.1 2006/10/05 09:23:41 adamdunkels Exp $ + * + * ----------------------------------------------------------------- + * + * Author : Adam Dunkels, Joakim Eriksson, Niclas Finne + * Created : 2006-10-02 + * Updated : $Date: 2006/10/05 09:23:41 $ + * $Revision: 1.1 $ + */ + +#ifndef __GCR_H__ +#define __GCR_H__ + +void gcr_init(); +unsigned char gcr_finished(); + +void gcr_encode(unsigned char raw_data); + +void gcr_decode(unsigned char gcr_data); +unsigned char gcr_get_encoded(unsigned char *raw_data); +unsigned char gcr_get_decoded(unsigned char *raw_data); +unsigned char gcr_valid(); + +#endif /* __GCR_H__ */