diff --git a/sfw/time.cpp b/sfw/time.cpp
new file mode 100644
index 0000000..eb621a9
--- /dev/null
+++ b/sfw/time.cpp
@@ -0,0 +1,170 @@
+// ----------------------------------------------------------------------------
+// time
+
+#if 0
+uint64_t time_gpu() {
+    GLint64 t = 123456789;
+    glGetInteger64v(GL_TIMESTAMP, &t);
+    return (uint64_t)t;
+}
+#endif
+uint64_t date() {
+    time_t epoch = time(0);
+    struct tm *ti = localtime(&epoch);
+    return atoi64(va("%04d%02d%02d%02d%02d%02d",ti->tm_year+1900,ti->tm_mon+1,ti->tm_mday,ti->tm_hour,ti->tm_min,ti->tm_sec));
+}
+char *date_string() {
+    time_t epoch = time(0);
+    struct tm *ti = localtime(&epoch);
+    return va("%04d-%02d-%02d %02d:%02d:%02d",ti->tm_year+1900,ti->tm_mon+1,ti->tm_mday,ti->tm_hour,ti->tm_min,ti->tm_sec);
+}
+uint64_t date_epoch() {
+    time_t epoch = time(0);
+    return epoch;
+}
+#if 0
+double time_ss() {
+    return glfwGetTime();
+}
+double time_ms() {
+    return glfwGetTime() * 1000.0;
+}
+uint64_t time_us() {
+    return (uint64_t)(glfwGetTime() * 1000000.0); // @fixme: use a high resolution timer instead, or time_gpu below
+}
+uint64_t sleep_us(uint64_t us) { // @fixme: use a high resolution sleeper instead
+    return sleep_ms( us / 1000.0 );
+}
+double sleep_ms(double ms) {
+    double now = time_ms();
+    if( ms <= 0 ) {
+#if is(win32)
+        Sleep(0); // yield
+#else
+        usleep(0);
+#endif
+    } else {
+#if is(win32)
+        Sleep(ms);
+#else
+        usleep(ms * 1000);
+#endif
+    }
+    return time_ms() - now;
+}
+double sleep_ss(double ss) {
+    return sleep_ms( ss * 1000 ) / 1000.0;
+}
+#endif
+
+// high-perf functions
+
+#define TIMER_E3 1000ULL
+#define TIMER_E6 1000000ULL
+#define TIMER_E9 1000000000ULL
+
+#ifdef CLOCK_MONOTONIC_RAW
+#define TIME_MONOTONIC CLOCK_MONOTONIC_RAW
+#elif defined CLOCK_MONOTONIC
+#define TIME_MONOTONIC CLOCK_MONOTONIC
+#else
+// #define TIME_MONOTONIC CLOCK_REALTIME // untested
+#endif
+
+static uint64_t nanotimer(uint64_t *out_freq) {
+    if( out_freq ) {
+#if is(win32)
+        LARGE_INTEGER li;
+        QueryPerformanceFrequency(&li);
+        *out_freq = li.QuadPart;
+//#elif is(ANDROID)
+//      *out_freq = CLOCKS_PER_SEC;
+#elif defined TIME_MONOTONIC
+        *out_freq = TIMER_E9;
+#else
+        *out_freq = TIMER_E6;
+#endif
+    }
+#if is(win32)
+    LARGE_INTEGER li;
+    QueryPerformanceCounter(&li);
+    return (uint64_t)li.QuadPart;
+//#elif is(ANDROID)
+//    return (uint64_t)clock();
+#elif defined TIME_MONOTONIC
+    struct timespec ts;
+    clock_gettime(TIME_MONOTONIC, &ts);
+    return (TIMER_E9 * (uint64_t)ts.tv_sec) + ts.tv_nsec;
+#else
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    return (TIMER_E6 * (uint64_t)tv.tv_sec) + tv.tv_usec;
+#endif
+}
+
+uint64_t time_ns() {
+    static __thread uint64_t epoch = 0;
+    static __thread uint64_t freq = 0;
+    if( !freq ) {
+        epoch = nanotimer(&freq);
+    }
+
+    uint64_t a = nanotimer(NULL) - epoch;
+    uint64_t b = TIMER_E9;
+    uint64_t c = freq;
+
+    // Computes (a*b)/c without overflow, as long as both (a*b) and the overall result fit into 64-bits.
+    // [ref] https://github.com/rust-lang/rust/blob/3809bbf47c8557bd149b3e52ceb47434ca8378d5/src/libstd/sys_common/mod.rs#L124
+    uint64_t q = a / c;
+    uint64_t r = a % c;
+    return q * b + r * b / c;
+}
+uint64_t time_us() {
+    return time_ns() / TIMER_E3;
+}
+uint64_t time_ms() {
+    return time_ns() / TIMER_E6;
+}
+double time_ss() {
+    return time_ns() / 1e9; // TIMER_E9;
+}
+double time_mm() {
+    return time_ss() / 60;
+}
+double time_hh() {
+    return time_mm() / 60;
+}
+
+void sleep_ns( double ns ) {
+#if is(win32)
+    if( ns >= 100 ) {
+        LARGE_INTEGER li;      // Windows sleep in 100ns units
+        HANDLE timer = CreateWaitableTimer(NULL, TRUE, NULL);
+        li.QuadPart = (LONGLONG)(__int64)(-ns/100); // Negative for relative time
+        SetWaitableTimer(timer, &li, 0, NULL, NULL, FALSE);
+        WaitForSingleObject(timer, INFINITE);
+        CloseHandle(timer);
+#else
+    if( ns > 0 ) {
+        struct timespec wait = {0};
+        wait.tv_sec = ns / 1e9;
+        wait.tv_nsec = ns - wait.tv_sec * 1e9;
+        nanosleep(&wait, NULL);
+#endif
+    } else {
+#if is(win32)
+        Sleep(0); // yield, Sleep(0), SwitchToThread
+#else
+        usleep(0);
+#endif
+    }
+}
+void sleep_us( double us ) {
+    sleep_ns(us * 1e3);
+}
+void sleep_ms( double ms ) {
+    sleep_ns(ms * 1e6);
+}
+void sleep_ss( double ss ) {
+    sleep_ns(ss * 1e9);
+}
diff --git a/sfw/time.h b/sfw/time.h
new file mode 100644
index 0000000..b341250
--- /dev/null
+++ b/sfw/time.h
@@ -0,0 +1,21 @@
+// -----------------------------------------------------------------------------
+// time framework utils
+// - rlyeh, public domain.
+
+API uint64_t    date();        // YYYYMMDDhhmmss
+API uint64_t    date_epoch();  // linux epoch
+API char*       date_string(); // "YYYY-MM-DD hh:mm:ss"
+API double      time_hh();
+API double      time_mm();
+API double      time_ss();
+API uint64_t    time_ms();
+API uint64_t    time_us();
+API uint64_t    time_ns();
+API void        sleep_ss(double ss);
+API void        sleep_ms(double ms);
+API void        sleep_us(double us);
+API void        sleep_ns(double us);
+
+API unsigned    timer(unsigned ms, unsigned (*callback)(unsigned ms, void *arg), void *arg);
+API void        timer_destroy(unsigned timer_handle);
+