1 files changed, 53 insertions, 0 deletions
diff --git a/src/timevalarith.c b/src/timevalarith.c
new file mode 100644
index 0000000..1091192
--- /dev/null
+++ b/src/timevalarith.c
@@ -0,0 +1,53 @@
+#include "timevalarith.h"
+
+struct timeval timeval_max(struct timeval a, struct timeval b) {
+
+    if (a.tv_sec > b.tv_sec)
+        return a;
+
+    if (a.tv_sec < b.tv_sec)
+        return b;
+
+    if (a.tv_usec > b.tv_usec)
+        return a;
+
+    return b;
+}
+
+struct timeval timeval_add(struct timeval a, uint32_t d) {
+    uint64_t sec, usec;
+    struct timeval r;
+
+    sec = (uint64_t) a.tv_sec + (d / 1000000L);
+    usec = (uint64_t) a.tv_usec + (d % 1000000L);
+
+    while (usec > 1000000L) {
+        usec -= 1000000L;
+        sec++;
+    }
+
+    r.tv_sec = (long) sec;
+    r.tv_usec = (long) usec;
+    return r;
+}
+
+struct timeval timeval_sub(struct timeval a, uint32_t d) {
+    uint64_t sec, usec;
+    struct timeval r;
+
+    sec = (uint64_t) a.tv_sec - (d / 1000000L);
+    usec = (uint64_t) a.tv_usec;
+
+    d = (d % 1000000L);
+    
+    if (usec > d)
+        usec -= d;
+    else {
+        sec--;
+        usec = 1000000L + usec - d;
+    }
+
+    r.tv_sec = (long) sec;
+    r.tv_usec = (long) usec;
+    return r;
+}