3 files changed, 25 insertions, 16 deletions
diff --git a/Makefile b/Makefile
index ce35988..e12763a 100644
--- a/Makefile
+++ b/Makefile
@@ -3,13 +3,14 @@
 CONFIGFILE = config.mk
 include $(CONFIGFILE)
 
+
 all: median
 
-median: median.o
-	$(CC) -o $@ median.o $(LDFLAGS)
+.o:
+	$(CC) -o $@ $< $(LDFLAGS)
 
-median.o: median.c
-	$(CC) -c -o $@ median.c $(CFLAGS) $(CPPFLAGS)
+.c.o:
+	$(CC) -c -o $@ $< $(CFLAGS) $(CPPFLAGS)
 
 check: median
 	test "$$(printf '%s\n' 1 5 2 | ./median)" = 2
@@ -36,7 +37,7 @@ uninstall:
 	-rm -f -- "$(DESTDIR)$(MANPREFIX)/man1/median.1"
 
 clean:
-	-rm -f -- median *.o
+	-rm -f -- median *.o *.su
 
 .SUFFIXES:
 .SUFFIXES: .c .o
diff --git a/config.mk b/config.mk
index 2e90419..aa81003 100644
--- a/config.mk
+++ b/config.mk
@@ -1,6 +1,8 @@
 PREFIX    = /usr
 MANPREFIX = $(PREFIX)/share/man
 
-CPPFLAGS  = -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_XOPEN_SOURCE=700
-CFLAGS    = -std=c99 -Wall -O2
-LDFLAGS   = -s
+CC = cc
+
+CPPFLAGS = -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_XOPEN_SOURCE=700
+CFLAGS   = -std=c99 -Wall -O2
+LDFLAGS  = -s
diff --git a/median.c b/median.c
index d282426..693b8fd 100644
--- a/median.c
+++ b/median.c
@@ -6,6 +6,12 @@
 #include <stdlib.h>
 #include <string.h>
 
+#if defined(__GNUC__)
+# define PURE __attribute__((__pure__))
+#else
+# define PURE
+#endif
+
 
 struct group {
 	char *key;
@@ -24,7 +30,7 @@ static struct group groups_head;
 static struct group groups_tail;
 
 
-static int
+PURE static int
 isnumerical(const char *s)
 {
 	if (*s == '+' || *s == '-')
@@ -42,11 +48,11 @@ isnumerical(const char *s)
 }
 
 
-static int
+PURE static int
 cmp_num(const void *apv, const void *bpv)
 {
-	const char *a = *(const char **)apv;
-	const char *b = *(const char **)bpv;
+	const char *a = *(const char *const *)apv;
+	const char *b = *(const char *const *)bpv;
 	int mul = 1;
 	size_t an = 0, bn = 0, i;
 
@@ -100,8 +106,8 @@ cmp_num(const void *apv, const void *bpv)
 static int
 cmp_str(const void *apv, const void *bpv)
 {
-	const char *a = *(const char **)apv;
-	const char *b = *(const char **)bpv;
+	const char *a = *(const char *const *)apv;
+	const char *b = *(const char *const *)bpv;
 	return strcmp(a, b);
 }
 
@@ -114,7 +120,7 @@ avg(char *a, const char *b)
 	for (i = 0; a[i]; i++) {
 		val = (a[i] & 15) + (b[i] & 15);
 		carry = val & 1;
-		a[i] = (val >> 1) | '0';
+		a[i] = (char)((val >> 1) | '0');
 	}
 	return carry;
 }
@@ -128,7 +134,7 @@ subavg(char *a, const char *b)
 	for (i = 0; a[i]; i++) {
 		val = (a[i] & 15) - (b[i] & 15);
 		carry = val & 1;
-		a[i] = (val >> 1) | '0';
+		a[i] = (char)((val >> 1) | '0');
 	}
 	return carry;
 }