real time clock

7 files changed, 393 insertions, 0 deletions

diff --git a/build.zig b/build.zig
index e673d1d..487681f 100644
--- a/build.zig
+++ b/build.zig
@@ -30,6 +30,7 @@ const kernel_src = &[_][]const u8{
     "kernel/cpu/idt.c",
     "kernel/cpu/idt.S",
     "kernel/cpu/pic.c",
+    "kernel/drivers/clock.c",
     "kernel/drivers/drivers.c",
     "kernel/drivers/pci.c",
     "kernel/drivers/tty.c",
@@ -71,6 +72,7 @@ const lib_src = &[_][]const u8{
     "lib/strncpy.c",
     "lib/strtoux.c",
     "lib/strtox.c",
+    "lib/timetostr.c",
     "lib/uxtoa.c",
     "lib/xtoa.c",
 };
diff --git a/include/time.h b/include/time.h
new file mode 100644
index 0000000..b3b0fc1
--- /dev/null
+++ b/include/time.h
@@ -0,0 +1,63 @@
+/**
+ * @file time.h
+ *
+ * @author Freya Murphy <freya@freyacat.org>
+ *
+ * System time structure
+ */
+
+#ifndef TIME_H_
+#define TIME_H_
+
+#include <stddef.h>
+
+typedef struct {
+    int sec;    /// Seconds [0,59]
+    int min;    /// Minutes [0,59]
+    int hour;   /// Hour [0,23]
+    int mday;   /// Day of month [1,31]
+    int mon;    /// Month of year [0,11]
+    int year;   /// Years since 1900
+    int wday;   /// Day of week [0,6] (Sunday = 0)
+    int yday;   /// Day of year [0,365]
+    int yn;     /// Year number [0,99]
+    int cen;    /// Century [19,20]
+    int leap;   /// If year is a leap year (True == 1)
+} time_t;
+
+typedef enum {
+    TZ_UTC = 0,
+    TZ_EST = -5,
+    TZ_EDT = -4,
+} timezone_t;
+
+/**
+ * Sets the current timezone
+ */
+extern void set_timezone(timezone_t tz);
+
+/**
+ * Returns current time in UTC
+ */
+extern time_t get_utctime(void);
+
+/**
+ * Returns current time from current Timezone
+ */
+extern time_t get_localtime(void);
+
+/**
+ * Return the time on the system clock
+ */
+extern size_t get_systemtime(void);
+
+/**
+ * Converts the time into a string format
+ *
+ * @param time - the current time
+ * @param format - see manpage for date
+ * @param buf - the buffer to store it in
+ */
+extern void timetostr(time_t *time, char *format, char *buf, size_t n);
+
+#endif /* time.h */
diff --git a/kernel/drivers/clock.c b/kernel/drivers/clock.c
new file mode 100644
index 0000000..80a44df
--- /dev/null
+++ b/kernel/drivers/clock.c
@@ -0,0 +1,159 @@
+#include <lib.h>
+#include <time.h>
+#include <comus/asm.h>
+#include <comus/drivers/clock.h>
+
+#define CMOS_WRITE_PORT 0x70
+#define CMOS_READ_PORT  0x71
+
+#define CMOS_REG_SEC    0x00
+#define CMOS_REG_MIN    0x02
+#define CMOS_REG_HOUR   0x04
+#define CMOS_REG_WDAY   0x06
+#define CMOS_REG_MDAY   0x07
+#define CMOS_REG_MON    0x08
+#define CMOS_REG_YEAR   0x09
+#define CMOS_REG_CEN    0x32
+
+// Live buffers to work on data
+static time_t time;
+static time_t localtime;
+
+// Front buffers so interupts dont request data that is half done
+static time_t curr_time;
+static time_t curr_localtime;
+
+// Current set time Zone
+static timezone_t curr_timezone = TZ_UTC;
+static timezone_t last_timezone = TZ_UTC;
+
+static uint8_t cmos_read(uint8_t reg) {
+    uint8_t hex, ret;
+
+    outb(CMOS_WRITE_PORT, reg);
+    hex = inb(CMOS_READ_PORT);
+
+    ret = hex & 0x0F;
+    ret += (hex & 0xF0) / 16 * 10;
+
+    return ret;
+}
+
+static int mday_offset[12] = {
+    0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
+};
+
+static int month_days[12] = {
+    31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
+};
+
+static void update_localtime(void) {
+
+    int change, max;
+
+    // set localtime
+    localtime = time;
+
+    // if tz is UTC, we dont need to do anythin
+    if (last_timezone == TZ_UTC) return;
+
+    localtime.hour += last_timezone;
+
+    // check if day rolled over
+    change = localtime.hour < 0 ? -1 : localtime.hour >= 24 ? 1 : 0;
+    if (!change) return;
+
+    // roll over day
+    localtime.hour = (localtime.hour + 24) % 24;
+    localtime.wday = (localtime.wday + change + 7) % 7;
+    localtime.mday += change;
+    localtime.yday += change;
+
+    // check if month rolled over
+    max = month_days[localtime.mon];
+    if (localtime.leap && localtime.mon == 1) max++;
+    change = localtime.mday < 0 ? -1 : localtime.mday >= max ? 1 : 0;
+    if (!change) return;
+
+    // roll over month
+    localtime.mon = (localtime.mon + change + 12) % 12;
+
+    // check if year rolled over
+    max = localtime.leap ? 366 : 365;
+    change = localtime.yday < 0 ? -1 : localtime.yday >= max ? 1 : 0;
+    if (!change) return;
+
+    // roll over year
+    localtime.yn += change;
+
+    // check if cen rolled over
+    change = localtime.yn < 0 ? -1 : localtime.yn >= 100 ? 1 : 0;
+    if (!change) goto year;
+
+    // roll over cen
+    localtime.cen += change;
+
+
+year:
+
+    localtime.year = localtime.yn + localtime.cen * 100;
+    localtime.leap = localtime.year % 4 == 0 && localtime.year % 100 != 0;
+
+    if (localtime.leap && localtime.yday == -1)
+        localtime.yday = 365;
+    else if (localtime.yday == -1)
+        localtime.yday = 364;
+    else
+        localtime.yday = 0;
+
+    localtime.year -= 1900;
+
+}
+
+void clock_update(void) {
+    time.sec = cmos_read(CMOS_REG_SEC);
+    time.min = cmos_read(CMOS_REG_MIN);
+    time.hour = cmos_read(CMOS_REG_HOUR);
+    time.wday = cmos_read(CMOS_REG_WDAY) - 1;
+    time.mday = cmos_read(CMOS_REG_MDAY);
+    time.mon = cmos_read(CMOS_REG_MON) - 1;
+    time.yn = cmos_read(CMOS_REG_YEAR);
+    time.cen = 20;
+
+    time.year = time.yn + time.cen * 100;
+
+    time.leap = time.year % 4 == 0 && time.year % 100 != 0;
+
+    time.yday = mday_offset[time.mon] + time.mday;
+
+    if (time.leap && time.mon > 2)
+        time.yday++;
+
+    time.year -= 1900;
+
+    update_localtime();
+
+    curr_time = time;
+    curr_localtime = localtime;
+}
+
+void set_timezone(timezone_t tz) {
+    curr_timezone = tz;
+}
+
+time_t get_utctime(void) {
+    return curr_time;
+}
+
+time_t get_localtime(void) {
+    if (curr_timezone != last_timezone) {
+        last_timezone = curr_timezone;
+        update_localtime();
+        curr_localtime = localtime;
+    }
+    return curr_localtime;
+}
+
+size_t get_systemtime(void) {
+    return 0;
+}
diff --git a/kernel/drivers/drivers.c b/kernel/drivers/drivers.c
index 4790c3a..b4c2c90 100644
--- a/kernel/drivers/drivers.c
+++ b/kernel/drivers/drivers.c
@@ -2,10 +2,12 @@
 #include <comus/drivers/uart.h>
 #include <comus/drivers/tty.h>
 #include <comus/drivers/pci.h>
+#include <comus/drivers/clock.h>
 
 void drivers_init(void)
 {
 	uart_init();
 	tty_init();
 	pci_init();
+	clock_update();
 }
diff --git a/kernel/include/comus/drivers/clock.h b/kernel/include/comus/drivers/clock.h
new file mode 100644
index 0000000..35f26c6
--- /dev/null
+++ b/kernel/include/comus/drivers/clock.h
@@ -0,0 +1,14 @@
+/**
+ * @file clock.h
+ *
+ * @author Freya Murphy <freya@freyacat.org>
+ *
+ * CMOS real time clock driver
+ */
+
+#ifndef CLOCK_H_
+#define CLOCK_H_
+
+extern void clock_update(void);
+
+#endif /* clock.h */
diff --git a/kernel/kernel.c b/kernel/kernel.c
index 4896b38..0b411be 100644
--- a/kernel/kernel.c
+++ b/kernel/kernel.c
@@ -3,6 +3,8 @@
 #include <comus/mboot.h>
 #include <comus/drivers.h>
 #include <lib.h>
+#include <stdio.h>
+#include <time.h>
 
 struct memory_map mmap;
 
@@ -23,6 +25,13 @@ void main(long magic, volatile void *mboot)
 	// initalize devices
 	drivers_init();
 
+	// print current time
+	char date[40];
+	set_timezone(TZ_EDT);
+	time_t time = get_localtime();
+	timetostr(&time, "%a %b %d %Y %H:%M:%S", date, 40);
+	printf("The date is: %s\n\n", date);
+
 	// halt
 	printf("halting...\n");
 }
diff --git a/lib/timetostr.c b/lib/timetostr.c
new file mode 100644
index 0000000..0d4e9a5
--- /dev/null
+++ b/lib/timetostr.c
@@ -0,0 +1,144 @@
+#include <lib.h>
+#include <time.h>
+
+static char* ABB_WEEKDAY[7] = {
+    "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
+};
+
+static char* FULL_WEEKDAY[7] = {
+    "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturady"
+};
+
+static char* ABB_MONTH[12] = {
+    "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+};
+
+static char* FULL_MONTH[12] = {
+    "January", "Feburary", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"
+};
+
+static char *write_num(unsigned int num, unsigned int pad, char *buf, size_t n) {
+    size_t digits = 1;
+    unsigned int x = num;
+
+    while (x /= 10, x > 0) digits++;
+    if (pad == 0) pad = digits;
+
+    for (size_t i = 0; i < pad; i++) {
+
+        size_t digit;
+        if (i >= digits) {
+            digit = 0;
+        } else {
+            digit = num % 10;
+            num /= 10;
+        }
+
+        if (pad - i - 1 >= n) continue;
+        buf[pad - i - 1] = '0' + digit;
+
+    }
+
+    if (pad > n) pad = n;
+
+    return buf + pad;
+}
+
+void timetostr(time_t *time, char *format, char *buf, size_t n) {
+    char *index = buf;
+    char c;
+    int space;
+
+    while (
+        c = *format++,
+        space = (buf + n) - index,
+        c != '\0' && space > 0
+    ) {
+        if (c != '%') {
+            *index++ = c;
+            continue;
+        } else {
+            c = *format++;
+        }
+
+        switch (c) {
+            case '%':
+                *index++ = '%';
+                break;
+            case 'a':
+                index = strncpy(index, ABB_WEEKDAY[time->wday], space);
+                break;
+            case 'A':
+                index = strncpy(index, FULL_WEEKDAY[time->wday], space);
+                break;
+            case 'b':
+            case 'h':
+                index = strncpy(index, ABB_MONTH[time->mon], space);
+                break;
+            case 'B':
+                index = strncpy(index, FULL_MONTH[time->mon], space);
+                break;
+            case 'C':
+                index = write_num(time->cen, 0, index, space);
+                break;
+            case 'd':
+                index = write_num(time->mday, 2, index, space);
+                break;
+            case 'H':
+                index = write_num(time->hour, 2, index, space);
+                break;
+            case 'I':
+                index = write_num((time->hour + 12) % 12 + 1, 2, index, space);
+                break;
+            case 'j':
+                index = write_num(time->yday, 3, index, space);
+                break;
+            case 'm':
+                index = write_num(time->mon + 1, 2, index, space);
+                break;
+            case 'M':
+                index = write_num(time->min, 2, index, space);
+                break;
+            case 'n':
+                *index++ = '\n';
+                break;
+            case 'p':
+                index = strncpy(index, time->hour > 11 ? "PM" : "AM", space);
+                break;
+            case 'P':
+                index = strncpy(index, time->hour > 11 ? "pm" : "am", space);
+                break;
+            case 'q':
+                index = write_num((time->mon + 3) / 3, 0, index, space);
+                break;
+            case 'S':
+                index = write_num(time->sec, 2, index, space);
+                break;
+            case 't':
+                *index++ = '\t';
+                break;
+            case 'u':
+                index = write_num(((time->wday + 1 )% 7) + 1, 0, index, space);
+                break;
+            case 'w':
+                index = write_num(time->wday, 0, index, space);
+                break;
+            case 'y':
+                index = write_num(time->yn, 2, index, space);
+                break;
+            case 'Y':
+                index = write_num(time->year + 1900, 0, index, space);
+                break;
+            default: {
+                char b[3] = {'%', c, '\0'};
+                index = strncpy(index, b, space);
+                break;
+            }
+        }
+    }
+
+    if (space < 1)
+        buf[n - 1] = '\0';
+    else
+        *index = '\0';
+}