README.md

 This is a variant of the Pintos Operating System for use as part of Operating Systems module at the University of the West of England (UWE).
+start the project

src/LICENSE

 Pintos, including its documentation, is subject to the following
 license:
 
+
     Copyright (C) 2004, 2005, 2006 Board of Trustees, Leland Stanford
     Jr. University.  All rights reserved.
 

src/Make.config

@@ -40,7 +40,7 @@ endif
 # Compiler and assembler invocation.
 DEFINES =
 WARNINGS = -Wall -W -Wstrict-prototypes -Wmissing-prototypes -Wsystem-headers
-CFLAGS = -g -msoft-float -O -DBEN_MODS -std=gnu99
+CFLAGS = -g -msoft-float -O
 CPPFLAGS = -nostdinc -I$(SRCDIR) -I$(SRCDIR)/lib
 ASFLAGS = -Wa,--gstabs
 LDFLAGS = 

src/devices/intq.h

@@ -40,4 +40,5 @@ bool intq_full (const struct intq *);
 uint8_t intq_getc (struct intq *);
 void intq_putc (struct intq *, uint8_t);
 
+
 #endif /* devices/intq.h */

src/devices/timer.c

@@ -7,7 +7,7 @@
 #include "threads/interrupt.h"
 #include "threads/synch.h"
 #include "threads/thread.h"
-  
+
 /* See [8254] for hardware details of the 8254 timer chip. */
 
 #if TIMER_FREQ < 19
@@ -33,7 +33,7 @@ static void real_time_delay (int64_t num, int32_t denom);
 /* Sets up the timer to interrupt TIMER_FREQ times per second,
    and registers the corresponding interrupt. */
 void
-timer_init (void) 
+timer_init (void)
 {
   pit_configure_channel (0, 2, TIMER_FREQ);
   intr_register_ext (0x20, timer_interrupt, "8254 Timer");
@@ -41,7 +41,7 @@ timer_init (void)
 
 /* Calibrates loops_per_tick, used to implement brief delays. */
 void
-timer_calibrate (void) 
+timer_calibrate (void)
 {
   unsigned high_bit, test_bit;
 
@@ -51,7 +51,7 @@ timer_calibrate (void)
   /* Approximate loops_per_tick as the largest power-of-two
      still less than one timer tick. */
   loops_per_tick = 1u << 10;
-  while (!too_many_loops (loops_per_tick << 1)) 
+  while (!too_many_loops (loops_per_tick << 1))
     {
       loops_per_tick <<= 1;
       ASSERT (loops_per_tick != 0);
@@ -68,7 +68,7 @@ timer_calibrate (void)
 
 /* Returns the number of timer ticks since the OS booted. */
 int64_t
-timer_ticks (void) 
+timer_ticks (void)
 {
   enum intr_level old_level = intr_disable ();
   int64_t t = ticks;
@@ -79,7 +79,7 @@ timer_ticks (void)
 /* Returns the number of timer ticks elapsed since THEN, which
    should be a value once returned by timer_ticks(). */
 int64_t
-timer_elapsed (int64_t then) 
+timer_elapsed (int64_t then)
 {
   return timer_ticks () - then;
 }
@@ -87,19 +87,24 @@ timer_elapsed (int64_t then)
 /* Sleeps for approximately TICKS timer ticks.  Interrupts must
    be turned on. */
 void
-timer_sleep (int64_t ticks) 
+timer_sleep (int64_t ticks)
 {
   int64_t start = timer_ticks ();
 
   ASSERT (intr_get_level () == INTR_ON);
-  while (timer_elapsed (start) < ticks) 
-    thread_yield ();
+  enum intr_level old_level = intr_disable ();
+
+  // sleep the thread for `ticks` seconds,
+  // until the tick becomes [start + ticks]
+  thread_sleep_until (start + ticks);
+
+  intr_set_level (old_level);
 }
 
 /* Sleeps for approximately MS milliseconds.  Interrupts must be
    turned on. */
 void
-timer_msleep (int64_t ms) 
+timer_msleep (int64_t ms)
 {
   real_time_sleep (ms, 1000);
 }
@@ -107,7 +112,7 @@ timer_msleep (int64_t ms)
 /* Sleeps for approximately US microseconds.  Interrupts must be
    turned on. */
 void
-timer_usleep (int64_t us) 
+timer_usleep (int64_t us)
 {
   real_time_sleep (us, 1000 * 1000);
 }
@@ -115,7 +120,7 @@ timer_usleep (int64_t us)
 /* Sleeps for approximately NS nanoseconds.  Interrupts must be
    turned on. */
 void
-timer_nsleep (int64_t ns) 
+timer_nsleep (int64_t ns)
 {
   real_time_sleep (ns, 1000 * 1000 * 1000);
 }
@@ -128,7 +133,7 @@ timer_nsleep (int64_t ns)
    will cause timer ticks to be lost.  Thus, use timer_msleep()
    instead if interrupts are enabled. */
 void
-timer_mdelay (int64_t ms) 
+timer_mdelay (int64_t ms)
 {
   real_time_delay (ms, 1000);
 }
@@ -141,7 +146,7 @@ timer_mdelay (int64_t ms)
    will cause timer ticks to be lost.  Thus, use timer_usleep()
    instead if interrupts are enabled. */
 void
-timer_udelay (int64_t us) 
+timer_udelay (int64_t us)
 {
   real_time_delay (us, 1000 * 1000);
 }
@@ -154,30 +159,30 @@ timer_udelay (int64_t us)
    will cause timer ticks to be lost.  Thus, use timer_nsleep()
    instead if interrupts are enabled.*/
 void
-timer_ndelay (int64_t ns) 
+timer_ndelay (int64_t ns)
 {
   real_time_delay (ns, 1000 * 1000 * 1000);
 }
 
 /* Prints timer statistics. */
 void
-timer_print_stats (void) 
+timer_print_stats (void)
 {
   printf ("Timer: %"PRId64" ticks\n", timer_ticks ());
 }
-
+
 /* Timer interrupt handler. */
 static void
 timer_interrupt (struct intr_frame *args UNUSED)
 {
   ticks++;
-  thread_tick ();
+  thread_tick ( timer_ticks() );
 }
 
 /* Returns true if LOOPS iterations waits for more than one timer
    tick, otherwise false. */
 static bool
-too_many_loops (unsigned loops) 
+too_many_loops (unsigned loops)
 {
   /* Wait for a timer tick. */
   int64_t start = ticks;
@@ -201,7 +206,7 @@ too_many_loops (unsigned loops)
    differently in different places the results would be difficult
    to predict. */
 static void NO_INLINE
-busy_wait (int64_t loops) 
+busy_wait (int64_t loops)
 {
   while (loops-- > 0)
     barrier ();
@@ -209,12 +214,12 @@ busy_wait (int64_t loops)
 
 /* Sleep for approximately NUM/DENOM seconds. */
 static void
-real_time_sleep (int64_t num, int32_t denom) 
+real_time_sleep (int64_t num, int32_t denom)
 {
   /* Convert NUM/DENOM seconds into timer ticks, rounding down.
-          
-        (NUM / DENOM) s          
-     ---------------------- = NUM * TIMER_FREQ / DENOM ticks. 
+
+        (NUM / DENOM) s
+     ---------------------- = NUM * TIMER_FREQ / DENOM ticks.
      1 s / TIMER_FREQ ticks
   */
   int64_t ticks = num * TIMER_FREQ / denom;
@@ -224,14 +229,14 @@ real_time_sleep (int64_t num, int32_t denom)
     {
       /* We're waiting for at least one full timer tick.  Use
          timer_sleep() because it will yield the CPU to other
-         processes. */                
-      timer_sleep (ticks); 
+         processes. */
+      timer_sleep (ticks);
     }
-  else 
+  else
     {
       /* Otherwise, use a busy-wait loop for more accurate
          sub-tick timing. */
-      real_time_delay (num, denom); 
+      real_time_delay (num, denom);
     }
 }
 
@@ -242,5 +247,5 @@ real_time_delay (int64_t num, int32_t denom)
   /* Scale the numerator and denominator down by 1000 to avoid
      the possibility of overflow. */
   ASSERT (denom % 1000 == 0);
-  busy_wait (loops_per_tick * num / 1000 * TIMER_FREQ / (denom / 1000)); 
+  busy_wait (loops_per_tick * num / 1000 * TIMER_FREQ / (denom / 1000));
 }

src/devices/vga.c

@@ -8,6 +8,7 @@
 #include "threads/interrupt.h"
 #include "threads/vaddr.h"
 
+
 /* VGA text screen support.  See [FREEVGA] for more information. */
 
 /* Number of columns and rows on the text display. */

src/examples/.gitignore

-cat
-cmp
-cp
-echo
-halt
-hex-dump
-ls
-mcat
-mcp
-mkdir
-pwd
-rm
-shell
-bubsort
-insult
-lineup
-matmult
-recursor
-*.d

src/examples/Makefile

 SRCDIR = ..
 
-# Test programs to compile, and a list of sources for each.
-# To add a new test, put its name on the PROGS list
-# and then add a name_SRC line that lists its source files.
 PROGS = cat cmp cp echo halt hex-dump ls mcat mcp mkdir pwd rm shell \
-	bubsort insult lineup matmult recursor my
+	bubsort insult lineup matmult recursor
 
-# Should work from project 2 onward.
 cat_SRC = cat.c
 cmp_SRC = cmp.c
 cp_SRC = cp.c
@@ -18,15 +14,10 @@ lineup_SRC = lineup.c
 ls_SRC = ls.c
 recursor_SRC = recursor.c
 rm_SRC = rm.c
-my_SRC = my.c
-
-# Should work in project 3; also in project 4 if VM is included.
 bubsort_SRC = bubsort.c
 matmult_SRC = matmult.c
 mcat_SRC = mcat.c
 mcp_SRC = mcp.c
-
-# Should work in project 4.
 mkdir_SRC = mkdir.c
 pwd_SRC = pwd.c
 shell_SRC = shell.c

src/examples/bubsort.c

-/* sort.c 
+/* sort.c
 
    Test program to sort a large number of integers.
- 
+
    Intention is to stress virtual memory system.
- 
+
    Ideally, we could read the unsorted array off of the file
    system, and store the result back to the file system! */
 #include <stdio.h>

src/examples/cat.c

@@ -6,21 +6,21 @@
 #include <syscall.h>
 
 int
-main (int argc, char *argv[]) 
+main (int argc, char *argv[])
 {
   bool success = true;
   int i;
-  
-  for (i = 1; i < argc; i++) 
+
+  for (i = 1; i < argc; i++)
     {
       int fd = open (argv[i]);
-      if (fd < 0) 
+      if (fd < 0)
         {
           printf ("%s: open failed\n", argv[i]);
           success = false;
           continue;
         }
-      for (;;) 
+      for (;;)
         {
           char buffer[1024];
           int bytes_read = read (fd, buffer, sizeof buffer);

src/examples/cmp.c

@@ -6,11 +6,11 @@
 #include <syscall.h>
 
 int
-main (int argc, char *argv[]) 
+main (int argc, char *argv[])
 {
   int fd[2];
 
-  if (argc != 3) 
+  if (argc != 3)
     {
       printf ("usage: cmp A B\n");
       return EXIT_FAILURE;
@@ -18,20 +18,20 @@ main (int argc, char *argv[])
 
   /* Open files. */
   fd[0] = open (argv[1]);
-  if (fd[0] < 0) 
+  if (fd[0] < 0)
     {
       printf ("%s: open failed\n", argv[1]);
       return EXIT_FAILURE;
     }
   fd[1] = open (argv[2]);
-  if (fd[1] < 0) 
+  if (fd[1] < 0)
     {
       printf ("%s: open failed\n", argv[1]);
       return EXIT_FAILURE;
     }
 
   /* Compare data. */
-  for (;;) 
+  for (;;)
     {
       int pos;
       char buffer[2][1024];
@@ -47,7 +47,7 @@ main (int argc, char *argv[])
         break;
 
       for (i = 0; i < min_read; i++)
-        if (buffer[0][i] != buffer[1][i]) 
+        if (buffer[0][i] != buffer[1][i])
           {
             printf ("Byte %d is %02hhx ('%c') in %s but %02hhx ('%c') in %s\n",
                     pos + i,

src/examples/cp.c

@@ -6,11 +6,11 @@ Copies one file to another. */
 #include <syscall.h>
 
 int
-main (int argc, char *argv[]) 
+main (int argc, char *argv[])
 {
   int in_fd, out_fd;
 
-  if (argc != 3) 
+  if (argc != 3)
     {
       printf ("usage: cp OLD NEW\n");
       return EXIT_FAILURE;
@@ -18,33 +18,33 @@ main (int argc, char *argv[])
 
   /* Open input file. */
   in_fd = open (argv[1]);
-  if (in_fd < 0) 
+  if (in_fd < 0)
     {
       printf ("%s: open failed\n", argv[1]);
       return EXIT_FAILURE;
     }
 
   /* Create and open output file. */
-  if (!create (argv[2], filesize (in_fd))) 
+  if (!create (argv[2], filesize (in_fd)))
     {
       printf ("%s: create failed\n", argv[2]);
       return EXIT_FAILURE;
     }
   out_fd = open (argv[2]);
-  if (out_fd < 0) 
+  if (out_fd < 0)
     {
       printf ("%s: open failed\n", argv[2]);
       return EXIT_FAILURE;
     }
 
   /* Copy data. */
-  for (;;) 
+  for (;;)
     {
       char buffer[1024];
       int bytes_read = read (in_fd, buffer, sizeof buffer);
       if (bytes_read == 0)
         break;
-      if (write (out_fd, buffer, bytes_read) != bytes_read) 
+      if (write (out_fd, buffer, bytes_read) != bytes_read)
         {
           printf ("%s: write failed\n", argv[2]);
           return EXIT_FAILURE;

src/examples/echo.c

@@ -4,7 +4,7 @@
 int
 main (int argc, char **argv)
 {
-    int i,j;
+  int i;
 
   for (i = 0; i < argc; i++)
     printf ("%s ", argv[i]);

src/examples/filetest.c

+#include <syscall.h>
+#include <stdio.h>
+
+int main(void) {
+  int fd = 0;  // Assume file descriptor 0 represents stdin
+  unsigned position = tell(fd);
+
+  printf("Current position of file pointer for fd %d: %u\n", fd, position);
+
+  return 0;
+}

src/examples/halt.c

 /* halt.c
 
    Simple program to test whether running a user program works.
- 	
+
    Just invokes a system call that shuts down the OS. */
 
 #include <syscall.h>

src/examples/hex-dump.c

@@ -6,21 +6,21 @@
 #include <syscall.h>
 
 int
-main (int argc, char *argv[]) 
+main (int argc, char *argv[])
 {
   bool success = true;
   int i;
-  
-  for (i = 1; i < argc; i++) 
+
+  for (i = 1; i < argc; i++)
     {
       int fd = open (argv[i]);
-      if (fd < 0) 
+      if (fd < 0)
         {
           printf ("%s: open failed\n", argv[i]);
           success = false;
           continue;
         }
-      for (;;) 
+      for (;;)
         {
           char buffer[1024];
           int pos = tell (fd);

src/examples/insult.c

-/* Insult.c
 
-   This is a version of the famous CS 107 random sentence
-   generator.  I wrote a program that reads a grammar definition
-   file and writes a C file containing that grammar as hard code
-   static C strings.  Thus the majority of the code below in
-   machine generated and totally unreadable.  The arrays created
-   are specially designed to make generating the sentences as
-   easy as possible.
-
-   Originally by Greg Hutchins, March 1998.
-   Modified by Ben Pfaff for Pintos, Sept 2004. */
 char *start[] =
   { "You", "1", "5", ".", "May", "13", ".", "With", "the", "19", "of", "18",
 ",", "may", "13", "."
@@ -250,13 +239,13 @@ usage (int ret_code, const char *message, ...)
 {
   va_list args;
 
-  if (message != NULL) 
+  if (message != NULL)
     {
       va_start (args, message);
       vprintf (message, args);
       va_end (args);
     }
-  
+
   printf ("\n"
           "Usage: insult [OPTION]...\n"
           "Prints random insults to screen.\n\n"
@@ -273,7 +262,7 @@ main (int argc, char *argv[])
 {
   int sentence_cnt, new_seed, i, file_flag, sent_flag, seed_flag;
   int handle;
-  
+
   new_seed = 4951;
   sentence_cnt = 4;
   file_flag = 0;
@@ -310,10 +299,6 @@ main (int argc, char *argv[])
 	  if (++i >= argc)
 	    usage (-1, "Missing value for -f");
 
-          /* Because files have fixed length in the basic Pintos
-             file system, the 0 argument means that this option
-             will not be useful until project 4 is
-             implemented. */
 	  create (argv[i], 0);
 	  handle = open (argv[i]);
           if (handle < 0)
@@ -337,7 +322,7 @@ main (int argc, char *argv[])
       expand (0, daGrammar, daGLoc, handle);
       hprintf (handle, "\n\n");
     }
-  
+
   if (file_flag)
     close (handle);