Remove dependency on libm

Introduce our own ceil implementation into the hash table functions,
so that we don't need to link against libm anymore.

3 files changed, 22 insertions, 5 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 708ac18..970d882 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -2,6 +2,6 @@ set(HASHTABLE_SRCS hashtable.c hashtable_itr.c)
 set(UNIONFS_SRCS unionfs.c stats.c opts.c debug.c findbranch.c readdir.c general.c unlink.c cow.c cow_utils.c string.c rmdir.c)
 
 add_executable(unionfs ${UNIONFS_SRCS} ${HASHTABLE_SRCS})
-target_link_libraries(unionfs fuse pthread m rt)
+target_link_libraries(unionfs fuse pthread rt)
 
 INSTALL(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/unionfs DESTINATION bin)
diff --git a/src/Makefile b/src/Makefile
index df98c94..2f51bf5 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -6,7 +6,6 @@ CPPFLAGS += -DFUSE_USE_VERSION=26
 LDFLAGS += 
 
 LIB = $(shell pkg-config --libs fuse)
-LIB += -lm  # For ceil(3)
 
 HASHTABLE_OBJ = hashtable.o hashtable_itr.o
 UNIONFS_OBJ = unionfs.o stats.o opts.o debug.o findbranch.o readdir.o general.o unlink.o rmdir.o cow.o cow_utils.o string.o
diff --git a/src/hashtable.c b/src/hashtable.c
index 763357e..ac29af3 100644
--- a/src/hashtable.c
+++ b/src/hashtable.c
@@ -5,7 +5,6 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
-#include <math.h>
 
 /*
 Credit for primes table: Aaron Krowne
@@ -24,6 +23,25 @@ static const unsigned int primes[] = {
 const unsigned int prime_table_length = sizeof(primes)/sizeof(primes[0]);
 const float max_load_factor = 0.65;
 
+#define TOL 1e-6 // float tolerance
+
+/**
+ * my_ceil - calculate ceil value
+ * Using C ceil() from math.h with -lm requires to link this library only for
+ * this simple function. As it is not performance relevent for the hash table 
+ * we use our own * implementation.
+ *
+ */
+static int my_ceil(float x)
+{
+        int y = (int) x;
+        if (y - x > TOL)
+                return y;
+        else
+                return y + 1;
+}
+
+
 /*****************************************************************************/
 struct hashtable *
 create_hashtable(unsigned int minsize,
@@ -48,7 +66,7 @@ create_hashtable(unsigned int minsize,
     h->entrycount   = 0;
     h->hashfn       = hashf;
     h->eqfn         = eqf;
-    h->loadlimit    = (unsigned int) ceil(size * max_load_factor);
+    h->loadlimit    = my_ceil(size * max_load_factor);
     return h;
 }
 
@@ -121,7 +139,7 @@ hashtable_expand(struct hashtable *h)
         }
     }
     h->tablelength = newsize;
-    h->loadlimit   = (unsigned int) ceil(newsize * max_load_factor);
+    h->loadlimit   = my_ceil(newsize * max_load_factor);
     return -1;
 }