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-rwxr-xr-xsrc/common/Makefile.am1
-rw-r--r--src/common/asm.c67
-rw-r--r--src/common/asm.h38
3 files changed, 106 insertions, 0 deletions
diff --git a/src/common/Makefile.am b/src/common/Makefile.am
index 198de32..7615f43 100755
--- a/src/common/Makefile.am
+++ b/src/common/Makefile.am
@@ -2,6 +2,7 @@
lib_LTLIBRARIES = libcommon.la
libcommon_la_SOURCES = \
+ asm.h asm.c \
bconst.h \
cpp.h \
dllist.h dllist.c \
diff --git a/src/common/asm.c b/src/common/asm.c
new file mode 100644
index 0000000..597013a
--- /dev/null
+++ b/src/common/asm.c
@@ -0,0 +1,67 @@
+
+/* Chrysalide - Outil d'analyse de fichiers binaires
+ * asm.c - implémentations génériques de fonctionnalités spécifiques
+ *
+ * Copyright (C) 2014 Cyrille Bagard
+ *
+ * This file is part of Chrysalide.
+ *
+ * OpenIDA 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.
+ *
+ * OpenIDA 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 Foobar. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+#include "asm.h"
+
+
+
+/******************************************************************************
+* *
+* Paramètres : v = valeur quelconque sur 32 bits. *
+* p = position du premier bit à 1 (poids fort). [OUT] *
+* *
+* Description : Détermine l'indice du premier bit à 1, côté gauche. *
+* *
+* Retour : true si le nombre est différent de zéro, false sinon. *
+* *
+* Remarques : - *
+* *
+******************************************************************************/
+
+bool msb_32(uint32_t v, unsigned int *p)
+{
+ static const unsigned int bval[] = { 0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4 };
+
+ /* S'il n'y a aucun bit à 1... */
+ if (v == 0) return false;
+
+ /**
+ * Il existe de nombreuses méthodes pour obtenir le résultat attendu
+ * sans recourir à des extensions GCC ou à des instructions d'assembleur :
+ *
+ * - http://stackoverflow.com/questions/2589096/find-most-significant-bit-left-most-that-is-set-in-a-bit-array
+ * - http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogObvious
+ *
+ */
+
+ *p = 0;
+
+ if (v & 0xffff0000) { *p += 16 / 1; v >>= 16 / 1; }
+ if (v & 0x0000ff00) { *p += 16 / 2; v >>= 16 / 2; }
+ if (v & 0x000000f0) { *p += 16 / 4; v >>= 16 / 4; }
+
+ *p += bval[v];
+
+ return true;
+
+}
diff --git a/src/common/asm.h b/src/common/asm.h
new file mode 100644
index 0000000..047d8db
--- /dev/null
+++ b/src/common/asm.h
@@ -0,0 +1,38 @@
+
+/* Chrysalide - Outil d'analyse de fichiers binaires
+ * asm.h - prototypes pour les implémentations génériques de fonctionnalités spécifiques
+ *
+ * Copyright (C) 2014 Cyrille Bagard
+ *
+ * This file is part of Chrysalide.
+ *
+ * OpenIDA 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.
+ *
+ * OpenIDA 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 Foobar. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+#ifndef _COMMON_ASM_H
+#define _COMMON_ASM_H
+
+
+#include <stdbool.h>
+#include <stdint.h>
+
+
+
+/* Détermine l'indice du premier bit à 1, côté gauche. */
+bool msb_32(uint32_t, unsigned int *);
+
+
+
+#endif /* _COMMON_ASM_H */