Utility functions.

diff --git a/include/core/system.h b/include/core/system.h
index 9ebc2ee..a631b1f 100644 (file)
--- a/include/core/system.h
+++ b/include/core/system.h
@@ -33,6 +33,7 @@
 
 /* Error Values, from glibc errno.h and errno-base.h */
 #define EIO          5 /* Bad one: Input or Output error. */
+#define E2BIG        7 /* Argument list too long or Data size beyond buffer size */
 #define EAGAIN      11 /* Device already in use */
 #define EFAULT      14 /* Address error */
 #define EBUSY       16 /* Device or ressource Busy */

diff --git a/include/lib/stddef.h b/include/lib/stddef.h
new file mode 100644 (file)
index 0000000..b410eb6
--- /dev/null
+++ b/include/lib/stddef.h
@@ -0,0 +1,27 @@
+/****************************************************************************
+ *   lib/stddef.h
+ *
+ * Copyright 2014 Nathael Pajani <nathael.pajani@ed3l.fr>
+ *
+ r
+ * This program 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 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 LIB_STDDEF_H
+#define LIB_STDDEF_H
+
+#define offsetof(type, member)  __builtin_offsetof (type, member)
+
+#endif /* LIB_STDDEF_H */

diff --git a/include/lib/utils.h b/include/lib/utils.h
new file mode 100644 (file)
index 0000000..9a0a867
--- /dev/null
+++ b/include/lib/utils.h
@@ -0,0 +1,53 @@
+/****************************************************************************
+ *  lib/utils.c
+ *
+ * Copyright 2014 Nathael Pajani <nathael.pajani@ed3l.fr>
+ *
+ * This program 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 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 LIB_UTILS_H
+#define LIB_UTILS_H
+
+/***************************************************************************** */
+/* Library routines                                                            */
+/***************************************************************************** */
+
+#include <stddef.h>
+#include <stdint.h>
+
+
+/***************************************************************************** */
+/* Bit twidling hacks.
+ * http://graphics.stanford.edu/~seander/bithacks.html
+ */
+
+/* Counting consecutive trailing or leading zero bits (or finding bit indices)
+ * The ARM Cortex M0 core does not have the __builtin_clz() and __builtin_ctz()
+ * instructions.
+ */
+
+/* Count leading zeroes
+ * The following function is an effitient way to implement __builtin_clz().
+ */
+uint8_t clz(uint32_t x);
+
+/* Count traling zeroes
+ * The following function is an effitient way to implement __builtin_ctz().
+ */
+uint8_t ctz(uint32_t x);
+
+#endif /* LIB_UTILS_H */
+

diff --git a/lib/utils.c b/lib/utils.c
new file mode 100644 (file)
index 0000000..a207d08
--- /dev/null
+++ b/lib/utils.c
@@ -0,0 +1,68 @@
+/*
+ *  lib/utils.c
+ *
+ * Library routines..
+ *
+ */
+
+#include <stddef.h>
+#include <stdint.h>
+
+
+/***************************************************************************** */
+/* Bit twidling hacks.
+ * http://graphics.stanford.edu/~seander/bithacks.html
+ */
+
+/* Counting consecutive trailing or leading zero bits (or finding bit indices)
+ * The ARM Cortex M0 core does not have the __builtin_clz() and __builtin_ctz()
+ * instructions.
+ */
+
+/* Count leading zeroes
+ * The following function is an effitient way to implement __builtin_clz().
+ */
+uint8_t clz(uint32_t x)
+{
+       static const uint8_t bval[] = {0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4};
+       unsigned int r = 32;
+       if (x >= 0x10000) { /* Quicker than (x & 0xFFFF0000) on a 32bit arm arch */
+               r -= 16;
+               x >>= 16;
+       }
+       if (x & 0xFF00) {
+               r -= 8;
+               x >>= 8;
+       }
+       if (x & 0xF0) {
+               r -= 4;
+               x >>= 4;
+       }
+       return r - bval[x];
+}
+
+/* Count traling zeroes
+ * The following function is an effitient way to implement __builtin_ctz().
+ */
+uint8_t ctz(uint32_t x)
+{
+       static const uint8_t bval[] = {4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0};
+       unsigned int r = 0;
+       if (x & 0x1) {
+               /* special case for odd value (assumed to happen half of the time) */
+               return r;
+       }
+       if ((x & 0xFFFF) == 0) {
+               r += 16;
+               x >>= 16;
+       }
+       if ((x & 0xFF) == 0) {
+               r += 8;
+               x >>= 8;
+       }
+       if ((x & 0xF) == 0) {
+               r += 4;
+               x >>= 4;
+       }
+       return r + bval[(x & 0x0F)];
+}