exti_io from Peter Ledvina

src/main/common/utils.h

@@ -18,6 +18,7 @@
 #pragma once
 
 #include <stddef.h>
+#include <stdint.h>
 
 #define ARRAYLEN(x) (sizeof(x) / sizeof((x)[0]))
 
@@ -27,6 +28,14 @@
 #define STR_HELPER(x) #x
 #define STR(x) STR_HELPER(x)
 
+#define EXPAND_I(x) x
+#define EXPAND(x) EXPAND_I(x)
+
+#define UNUSED(x) (void)(x)
+#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
+
+#define BIT(x) (1 << (x))
+
 /*
 http://resnet.uoregon.edu/~gurney_j/jmpc/bitwise.html
 */
@@ -35,6 +44,19 @@ http://resnet.uoregon.edu/~gurney_j/jmpc/bitwise.html
 
 #define UNUSED(x) (void)(x)
 
+/*
+ * https://groups.google.com/forum/?hl=en#!msg/comp.lang.c/attFnqwhvGk/sGBKXvIkY3AJ
+ * Return (v ? floor(log2(v)) : 0) when 0 <= v < 1<<[8, 16, 32, 64].
+ * Inefficient algorithm, intended for compile-time constants.
+ */
+#define LOG2_8BIT(v)  (8 - 90/(((v)/4+14)|1) - 2/((v)/2+1))
+#define LOG2_16BIT(v) (8*((v)>255) + LOG2_8BIT((v) >>8*((v)>255)))
+#define LOG2_32BIT(v) (16*((v)>65535L) + LOG2_16BIT((v)*1L >>16*((v)>65535L)))
+#define LOG2_64BIT(v) \
+    (32*((v)/2L>>31 > 0) \
+     + LOG2_32BIT((v)*1L >>16*((v)/2L>>31 > 0) \
+                         >>16*((v)/2L>>31 > 0)))
+    
 #if 0
 // ISO C version, but no type checking
 #define container_of(ptr, type, member) \