dead simple rtc code for getting current datetime.

[lunaix-os.git] / lunaix-os / hal / rtc.c

diff --git a/lunaix-os/hal/rtc.c b/lunaix-os/hal/rtc.c
new file mode 100644 (file)
index 0000000..319ad65
--- /dev/null
+++ b/lunaix-os/hal/rtc.c
@@ -0,0 +1,47 @@
+#include <hal/rtc.h>
+
+uint8_t
+rtc_read_reg(uint8_t reg_selector)
+{
+    io_outb(RTC_INDEX_PORT, reg_selector);
+    return io_inb(RTC_TARGET_PORT);
+}
+
+uint8_t
+bcd2dec(uint8_t bcd)
+{
+    return (bcd >> 4) * 10 + (bcd & 0x0f);
+}
+
+void
+rtc_get_datetime(rtc_datetime* datetime)
+{
+    datetime->year = rtc_read_reg(RTC_REG_YRS);
+    datetime->month = rtc_read_reg(RTC_REG_MTH);
+    datetime->day = rtc_read_reg(RTC_REG_DAY);
+    datetime->weekday = rtc_read_reg(RTC_REG_WDY);
+    datetime->hour = rtc_read_reg(RTC_REG_HRS);
+    datetime->minute = rtc_read_reg(RTC_REG_MIN);
+    datetime->second = rtc_read_reg(RTC_REG_SEC);
+
+    uint8_t regbv = rtc_read_reg(RTC_REG_B);
+
+    // Convert from bcd to binary when needed
+    if (!RTC_BIN_ENCODED(regbv)) {
+        datetime->year = bcd2dec(datetime->year);
+        datetime->month = bcd2dec(datetime->month);
+        datetime->day = bcd2dec(datetime->day);
+        datetime->hour = bcd2dec(datetime->hour);
+        datetime->minute = bcd2dec(datetime->minute);
+        datetime->second = bcd2dec(datetime->second);
+    }
+
+
+    // To 24 hour format
+    if (!RTC_24HRS_ENCODED(regbv)) {
+        datetime->hour = (datetime->hour >> 7) ? (12 + datetime->hour & 0x80)
+                                               : (datetime->hour & 0x80);
+    }
+
+    datetime->year += RTC_CURRENT_CENTRY * 100;
+}
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