Introduce CLAMP macro. Unify all MIN(MAX(a,b),c) uses.

With the CLAMP macro replacing the combination of MIN and MAX, we will
have at least two advantages:
1. It's more obvious semantically.
2. There are no more mixes of confusing uses like MIN(MAX(a,b),c) and
   MAX(MIN(a,b),c) and MIN(a,MAX(b,c)) appearing everywhere. We unify
   the 'clamping' with a single macro.
Note that the behavior of this CLAMP macro is different from
the combination `MAX(low,MIN(x,high))`.
* This CLAMP macro expands to two comparisons instead of three from
  MAX and MIN combination. In theory, this makes the code slightly
  smaller, in case that (low) or (high) or both are computed at
  runtime, so that compilers cannot optimize them. (The third
  comparison will matter if (low)>(high); see below.)
* CLAMP has a side effect, that if (low)>(high) it will produce weird
  results. Unlike MIN & MAX which will force either (low) or (high) to
  win. No assertion of ((low)<=(high)) is done in this macro, for now.

This CLAMP macro is implemented like described in glib
<http://developer.gnome.org/glib/stable/glib-Standard-Macros.html>
and does not handle weird uses like CLAMP(a++, low++, high--) .

2 files changed, 11 insertions, 1 deletions

diff --git a/freebsd/Platform.c b/freebsd/Platform.c
index a5e0e0b3..9e0c25b0 100644
--- a/freebsd/Platform.c
+++ b/freebsd/Platform.c
@@ -34,6 +34,10 @@ extern ProcessFieldData Process_fields[];
 
 }*/
 
+#ifndef CLAMP
+#define CLAMP(x,low,high) (((x)>(high))?(high):(((x)<(low))?(low):(x)))
+#endif
+
 ProcessField Platform_defaultFields[] = { PID, USER, PRIORITY, NICE, M_SIZE, M_RESIDENT, STATE, PERCENT_CPU, PERCENT_MEM, TIME, COMM, 0 };
 
 int Platform_numberOfFields = LAST_PROCESSFIELD;
@@ -171,7 +175,7 @@ double Platform_setCPUValues(Meter* this, int cpu) {
       percent = v[0]+v[1]+v[2];
    }
 
-   percent = MIN(100.0, MAX(0.0, percent));
+   percent = CLAMP(percent, 0.0, 100.0);
    if (isnan(percent)) percent = 0.0;
    return percent;
 }
diff --git a/freebsd/Platform.h b/freebsd/Platform.h
index ef46442a..ecc0dcd4 100644
--- a/freebsd/Platform.h
+++ b/freebsd/Platform.h
@@ -16,6 +16,10 @@ in the source distribution for its full text.
 extern ProcessFieldData Process_fields[];
 
 
+#ifndef CLAMP
+#define CLAMP(x,low,high) (((x)>(high))?(high):(((x)<(low))?(low):(x)))
+#endif
+
 extern ProcessField Platform_defaultFields[];
 
 extern int Platform_numberOfFields;
@@ -42,4 +46,6 @@ void Platform_setSwapValues(Meter* this);
 
 void Platform_setTasksValues(Meter* this);
 
+char* Platform_getProcessEnv(pid_t pid);
+
 #endif