Created student weenix repository

1 files changed, 78 insertions, 0 deletions

diff --git a/kernel/drivers/cmos.c b/kernel/drivers/cmos.c
new file mode 100644
index 0000000..5f6ed34
--- /dev/null
+++ b/kernel/drivers/cmos.c
@@ -0,0 +1,78 @@
+#include "drivers/cmos.h"
+
+int cmos_update_flag_set()
+{
+    outb(CMOS_ADDR, CMOS_REG_STAT_A);
+    return (inb(CMOS_DATA) & 0x80);
+}
+
+unsigned char cmos_read_register(int reg)
+{
+    outb(CMOS_ADDR, reg);
+    return inb(CMOS_DATA);
+}
+
+int rtc_time_match(rtc_time_t a, rtc_time_t b)
+{
+    return (a.second == b.second) && (a.minute == b.minute) &&
+           (a.hour == b.hour) && (a.day == b.day) && (a.month == b.month) &&
+           (a.year == b.year) && (a.__century == b.__century);
+}
+
+rtc_time_t __get_rtc_time()
+{
+    rtc_time_t tm;
+
+    while (cmos_update_flag_set())
+        ;
+
+    tm.second = cmos_read_register(CMOS_REG_SECOND);
+    tm.minute = cmos_read_register(CMOS_REG_MINUTE);
+    tm.hour = cmos_read_register(CMOS_REG_HOUR);
+    tm.day = cmos_read_register(CMOS_REG_DAY);
+    tm.month = cmos_read_register(CMOS_REG_MONTH);
+    tm.year = cmos_read_register(CMOS_REG_YEAR);
+    tm.__century = cmos_read_register(CMOS_REG_CENTURY);
+
+    return tm;
+}
+
+/* Our ticks -> time calculation is so suspect, we just get the time from the
+ * CMOS RTC */
+rtc_time_t rtc_get_time()
+{
+    // Check the result of CMOS twice to ensure we didn't get a torn read.
+    rtc_time_t tm_a;
+    rtc_time_t tm_b;
+
+    do
+    {
+        tm_a = __get_rtc_time();
+        tm_b = __get_rtc_time();
+    } while (!rtc_time_match(tm_a, tm_b));
+
+    unsigned char cmos_settings = cmos_read_register(CMOS_REG_STAT_B);
+
+    // Convert from BCD
+    if (!(cmos_settings & 0x04))
+    {
+        tm_a.second = (tm_a.second & 0x0F) + ((tm_a.second / 16) * 10);
+        tm_a.minute = (tm_a.minute & 0x0F) + ((tm_a.minute / 16) * 10);
+        tm_a.hour = ((tm_a.hour & 0x0F) + (((tm_a.hour & 0x70) / 16) * 10)) |
+                    (tm_a.hour & 0x80);
+        tm_a.day = (tm_a.day & 0x0F) + ((tm_a.day / 16) * 10);
+        tm_a.month = (tm_a.month & 0x0F) + ((tm_a.month / 16) * 10);
+        tm_a.year = (tm_a.year & 0x0F) + ((tm_a.year / 16) * 10);
+        tm_a.__century = (tm_a.__century & 0x0F) + ((tm_a.__century / 16) * 10);
+    }
+
+    // Convert 12-hour clock to 24-hour clock:
+    if (!(cmos_settings & 0x02) && (tm_a.hour & 0x80))
+    {
+        tm_a.hour = ((tm_a.hour & 0x7F) + 12) % 24;
+    }
+
+    tm_a.year += (tm_a.__century * 100);
+
+    return tm_a;
+}
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