From 72c6e9763ca61bc9d7de5f7080ee1c8a1c7c1562 Mon Sep 17 00:00:00 2001
From: Miguel <m.i@gmx.at>
Date: Tue, 21 Aug 2018 19:42:33 +0200
Subject: cleaning up a bit

---
 driver/timer.c | 167 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 167 insertions(+)
 create mode 100644 driver/timer.c

(limited to 'driver/timer.c')

diff --git a/driver/timer.c b/driver/timer.c
new file mode 100644
index 0000000..2d4c7ff
--- /dev/null
+++ b/driver/timer.c
@@ -0,0 +1,167 @@
+#define FOOLOS_MODULE_NAME "timer"
+#include "timer.h"
+
+#include "asm/x86.h"
+
+static volatile uint64_t task_system_clock_start=0;
+
+// CMOS RTC
+ 
+// read real time clock register
+static unsigned char get_rtc_reg(int reg) {
+      x86_outb(0x70, reg);	//cmos at addr 0x70
+      return x86_inb(0x71);	//cmos data at addr 0x71
+}
+
+// check if cmos rtc update in progress
+static int get_rtc_update_flag() {
+      x86_outb(0x70, 0x0A);
+      return (x86_inb(0x71) & 0x80);
+}
+
+// get real time clock rom cmos (seconds since jan)
+static uint64_t get_rtc_time()
+{
+      int CURRENT_YEAR = 2018;        // Change this each year!
+ 
+      int century_register = 0x00;    // Set by ACPI table parsing code if possible
+    
+      unsigned char second;
+      unsigned char minute;
+      unsigned char hour;
+      unsigned char day;
+      unsigned char month;
+      unsigned int year;
+
+      unsigned char century;
+      unsigned char last_second;
+      unsigned char last_minute;
+      unsigned char last_hour;
+      unsigned char last_day;
+      unsigned char last_month;
+      unsigned char last_year;
+      unsigned char last_century;
+      unsigned char registerB;
+ 
+      // Note: This uses the "read registers until you get the same values twice in a row" technique
+      //       to avoid getting dodgy/inconsistent values due to RTC updates
+ 
+      while (get_rtc_update_flag());                // Make sure an update isn't in progress
+      second = get_rtc_reg(0x00);
+      minute = get_rtc_reg(0x02);
+      hour = get_rtc_reg(0x04);
+      day = get_rtc_reg(0x07);
+      month = get_rtc_reg(0x08);
+      year = get_rtc_reg(0x09);
+
+      if(century_register != 0) {
+            century = get_rtc_reg(century_register);
+      }
+ 
+      do {
+            last_second = second;
+            last_minute = minute;
+            last_hour = hour;
+            last_day = day;
+            last_month = month;
+            last_year = year;
+            last_century = century;
+ 
+            while (get_rtc_update_flag());           // Make sure an update isn't in progress
+            second = get_rtc_reg(0x00);
+            minute = get_rtc_reg(0x02);
+            hour = get_rtc_reg(0x04);
+            day = get_rtc_reg(0x07);
+            month = get_rtc_reg(0x08);
+            year = get_rtc_reg(0x09);
+            if(century_register != 0) {
+                  century = get_rtc_reg(century_register);
+            }
+      } while( (last_second != second) || (last_minute != minute) || (last_hour != hour) ||
+               (last_day != day) || (last_month != month) || (last_year != year) ||
+               (last_century != century) );
+ 
+      registerB = get_rtc_reg(0x0B);
+ 
+      // Convert BCD to binary values if necessary
+      if (!(registerB & 0x04)) {
+            second = (second & 0x0F) + ((second / 16) * 10);
+            minute = (minute & 0x0F) + ((minute / 16) * 10);
+            hour = ( (hour & 0x0F) + (((hour & 0x70) / 16) * 10) ) | (hour & 0x80);
+            day = (day & 0x0F) + ((day / 16) * 10);
+            month = (month & 0x0F) + ((month / 16) * 10);
+            year = (year & 0x0F) + ((year / 16) * 10);
+            if(century_register != 0) {
+                  century = (century & 0x0F) + ((century / 16) * 10);
+            }
+      }
+ 
+      // Convert 12 hour clock to 24 hour clock if necessary
+      if (!(registerB & 0x02) && (hour & 0x80)) {
+            hour = ((hour & 0x7F) + 12) % 24;
+      }
+ 
+      // Calculate the full (4-digit) year
+      if(century_register != 0) {
+            year += century * 100;
+      } else {
+            year += (CURRENT_YEAR / 100) * 100;
+            if(year < CURRENT_YEAR) year += 100;
+      }
+    
+     // thank you doug16k @ #osdev
+     // https://github.com/doug65536/dgos/blob/eab7080e69360493381669e7ce0ff27587d3127a/kernel/lib/time.cc
+          int days[] = {
+        31,
+        (year-1900) % 4 ? 28 :
+        (year-1900) % 100 ? 29 :
+        (year-1900) % 400 ? 28 :
+        29,
+        31,
+        30,
+        31,
+        30,
+        31,
+        31,
+        30,
+        31,
+        30,
+        31
+    };
+
+    int yday = 0;
+    for (int m = 1; m < month; ++m)
+        yday += days[m-1];
+    yday += day - 1;
+
+      uint64_t epoch_seconds= ((uint64_t)(second)) +
+            minute * 60 +
+            hour * 3600 +
+            (yday) * 86400 +
+            (year-1900 - 70) * 365 * 86400 +
+            ((year-1900 - 69) / 4) * 86400 -
+            ((year-1900 - 1) / 100) * 86400 +
+            ((year-1900 + 299) / 400) * 86400;
+
+      return epoch_seconds;
+}
+
+
+// PIT
+uint64_t timer_init()
+{
+    uint64_t epoch_time=get_rtc_time();
+    task_system_clock_start=epoch_time*25; // since pit ticks 25times a second
+    pit_init();
+    return epoch_time;
+}
+
+uint64_t timer_get_ms()
+{
+    return (pit_get_ticks()+task_system_clock_start)*40;
+}
+
+uint64_t timer_get_uptime_ms()
+{
+    return pit_get_ticks()*40;
+}
-- 
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