Create methods to deal with hex conversions.

3 files changed, 182 insertions, 0 deletions

diff --git a/src/common/Makefile.am b/src/common/Makefile.am
index 2162d8c..3379eed 100644
--- a/src/common/Makefile.am
+++ b/src/common/Makefile.am
@@ -13,6 +13,7 @@ libcommon_la_SOURCES =					\
 	endianness.h endianness.c			\
 	environment.h environment.c			\
 	extstr.h extstr.c					\
+	hex.h hex.c							\
 	ibuf.h ibuf.c						\
 	io.h io.c							\
 	fnv1a.h fnv1a.c						\
diff --git a/src/common/hex.c b/src/common/hex.c
new file mode 100644
index 0000000..afa23a8
--- /dev/null
+++ b/src/common/hex.c
@@ -0,0 +1,139 @@
+
+/* Chrysalide - Outil d'analyse de fichiers binaires
+ * hex.c - construction et interprétation de chaînes hexadécimales
+ *
+ * Copyright (C) 2021 Cyrille Bagard
+ *
+ *  This file is part of Chrysalide.
+ *
+ *  Chrysalide is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  Chrysalide 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 Chrysalide.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+#include "hex.h"
+
+
+#include <ctype.h>
+
+
+
+/******************************************************************************
+*                                                                             *
+*  Paramètres  : src   = source de données à considérer.                      *
+*                len   = quantité de ces données à traiter.                   *
+*                lower = spécifie un encodage à l'aide de minuscules.         *
+*                dst   = zone allouée pour les données résultantes. [OUT]     *
+*                                                                             *
+*  Description : Encode des données en chaîne hexadécimale.                   *
+*                                                                             *
+*  Retour      : -                                                            *
+*                                                                             *
+*  Remarques   : -                                                            *
+*                                                                             *
+******************************************************************************/
+
+void encode_hex(const char *src, size_t len, bool lower, char *dst)
+{
+    size_t i;                               /* Boucle de parcours #1       */
+    uint8_t index;                          /* Indice de recherche         */
+
+    /**
+     * base = "".join([ "%02X" % i for i in range(256) ])
+     * encoded = "\n".join([ base[i : i + 32] for i in range(0, 512, 32) ])
+     * print(encoded)
+     */
+    const char encoding_lookup[] = {
+        "000102030405060708090A0B0C0D0E0F"
+        "101112131415161718191A1B1C1D1E1F"
+        "202122232425262728292A2B2C2D2E2F"
+        "303132333435363738393A3B3C3D3E3F"
+        "404142434445464748494A4B4C4D4E4F"
+        "505152535455565758595A5B5C5D5E5F"
+        "606162636465666768696A6B6C6D6E6F"
+        "707172737475767778797A7B7C7D7E7F"
+        "808182838485868788898A8B8C8D8E8F"
+        "909192939495969798999A9B9C9D9E9F"
+        "A0A1A2A3A4A5A6A7A8A9AAABACADAEAF"
+        "B0B1B2B3B4B5B6B7B8B9BABBBCBDBEBF"
+        "C0C1C2C3C4C5C6C7C8C9CACBCCCDCECF"
+        "D0D1D2D3D4D5D6D7D8D9DADBDCDDDEDF"
+        "E0E1E2E3E4E5E6E7E8E9EAEBECEDEEEF"
+        "F0F1F2F3F4F5F6F7F8F9FAFBFCFDFEFF"
+    };
+
+    for (i = 0; i < len; i++)
+    {
+        index = src[i];
+
+        if (lower)
+        {
+            (*dst++) = tolower(encoding_lookup[index * 2]);
+            (*dst++) = tolower(encoding_lookup[index * 2 + 1]);
+        }
+        else
+        {
+            (*dst++) = encoding_lookup[index * 2];
+            (*dst++) = encoding_lookup[index * 2 + 1];
+        }
+
+    }
+
+    *dst = '\0';
+
+}
+
+
+/******************************************************************************
+*                                                                             *
+*  Paramètres  : digit = caractère hexadécimale à transcrire.                 *
+*                value = valeur récupérée. [OUT]                              *
+*                                                                             *
+*  Description : Décode un caractère hexadécimal.                             *
+*                                                                             *
+*  Retour      : Bilan de l'opération.                                        *
+*                                                                             *
+*  Remarques   : -                                                            *
+*                                                                             *
+******************************************************************************/
+
+bool decode_hex_digit(const char *digit, uint8_t *value)
+{
+    bool result;                            /* Validité à retourner        */
+
+    switch (*digit)
+    {
+        case '0' ... '9':
+            *value = (*digit) - '0';
+            result = true;
+            break;
+
+        case 'a' ... 'f':
+            *value = 0xa + (*digit) - 'a';
+            result = true;
+            break;
+
+        case 'A' ... 'F':
+            *value = 0xa + (*digit) - 'A';
+            result = true;
+            break;
+
+        default:
+            result = false;
+            break;
+
+    }
+
+    return result;
+
+}
diff --git a/src/common/hex.h b/src/common/hex.h
new file mode 100644
index 0000000..97cd0da
--- /dev/null
+++ b/src/common/hex.h
@@ -0,0 +1,42 @@
+
+/* Chrysalide - Outil d'analyse de fichiers binaires
+ * hex.h - prototypes pour la construction et l'interprétation de chaînes hexadécimales
+ *
+ * Copyright (C) 2021 Cyrille Bagard
+ *
+ *  This file is part of Chrysalide.
+ *
+ *  Chrysalide is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  Chrysalide 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 Chrysalide.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+#ifndef _COMMON_HEX_H
+#define _COMMON_HEX_H
+
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+
+
+/* Encode des données en chaîne hexadécimale. */
+void encode_hex(const char *, size_t, bool, char *);
+
+/* Décode un caractère hexadécimal. */
+bool decode_hex_digit(const char *, uint8_t *);
+
+
+
+#endif  /* _COMMON_HEX_H */