chelper: Add compiler.h header

Add the compiler.h header file to the chelper code - this adds a
number of useful gcc definitions.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/chelper/compiler.h

@@ -0,0 +1,46 @@
+#ifndef __COMPILER_H
+#define __COMPILER_H
+// Low level definitions for C languange and gcc compiler.
+
+#define barrier() __asm__ __volatile__("": : :"memory")
+
+#define likely(x)       __builtin_expect(!!(x), 1)
+#define unlikely(x)     __builtin_expect(!!(x), 0)
+
+#define noinline __attribute__((noinline))
+#ifndef __always_inline
+#define __always_inline inline __attribute__((always_inline))
+#endif
+#define __visible __attribute__((externally_visible))
+#define __noreturn __attribute__((noreturn))
+
+#define PACKED __attribute__((packed))
+#ifndef __aligned
+#define __aligned(x) __attribute__((aligned(x)))
+#endif
+#ifndef __section
+#define __section(S) __attribute__((section(S)))
+#endif
+
+#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
+#define ALIGN(x,a)              __ALIGN_MASK(x,(typeof(x))(a)-1)
+#define __ALIGN_MASK(x,mask)    (((x)+(mask))&~(mask))
+#define ALIGN_DOWN(x,a)         ((x) & ~((typeof(x))(a)-1))
+
+#define container_of(ptr, type, member) ({                      \
+        const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
+        (type *)( (char *)__mptr - offsetof(type,member) );})
+
+#define __stringify_1(x)        #x
+#define __stringify(x)          __stringify_1(x)
+
+#define ___PASTE(a,b) a##b
+#define __PASTE(a,b) ___PASTE(a,b)
+
+#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
+#define DIV_ROUND_CLOSEST(x, divisor)({                 \
+            typeof(divisor) __divisor = divisor;        \
+            (((x) + ((__divisor) / 2)) / (__divisor));  \
+        })
+
+#endif // compiler.h

klippy/chelper/pyhelper.h

@@ -1,9 +1,6 @@
 #ifndef PYHELPER_H
 #define PYHELPER_H
 
-#define likely(x)       __builtin_expect(!!(x), 1)
-#define unlikely(x)     __builtin_expect(!!(x), 0)
-
 double get_monotonic(void);
 struct timespec fill_time(double time);
 void set_python_logging_callback(void (*func)(const char *));

klippy/chelper/stepcompress.c

@@ -20,6 +20,7 @@
 #include <stdio.h> // fprintf
 #include <stdlib.h> // malloc
 #include <string.h> // memset
+#include "compiler.h" // DIV_ROUND_UP
 #include "pyhelper.h" // errorf
 #include "serialqueue.h" // struct queue_message
 
@@ -44,12 +45,10 @@ struct stepcompress {
  * Step compression
  ****************************************************************/
 
-#define DIV_UP(n,d) (((n) + (d) - 1) / (d))
-
 static inline int32_t
 idiv_up(int32_t n, int32_t d)
 {
-    return (n>=0) ? DIV_UP(n,d) : (n/d);
+    return (n>=0) ? DIV_ROUND_UP(n,d) : (n/d);
 }
 
 static inline int32_t
@@ -116,7 +115,7 @@ compress_bisect_add(struct stepcompress *sc)
             int32_t nextaddfactor = nextcount*(nextcount-1)/2;
             int32_t c = add*nextaddfactor;
             if (nextmininterval*nextcount < nextpoint.minp - c)
-                nextmininterval = DIV_UP(nextpoint.minp - c, nextcount);
+                nextmininterval = DIV_ROUND_UP(nextpoint.minp - c, nextcount);
             if (nextmaxinterval*nextcount > nextpoint.maxp - c)
                 nextmaxinterval = (nextpoint.maxp - c) / nextcount;
             if (nextmininterval > nextmaxinterval)