From 7cfd4eb53675a3a3be508d7658daf34be02bb1dd Mon Sep 17 00:00:00 2001
From: Alex <shadow8t4@tamu.edu>
Date: Mon, 19 Jun 2017 09:34:49 -0500
Subject: [PATCH] I lied, now the constructor is finished.

---
 MP2/MP2_Sources/cont_frame_pool.C | 92 ++++++++++++++++++++++---------
 1 file changed, 66 insertions(+), 26 deletions(-)

diff --git a/MP2/MP2_Sources/cont_frame_pool.C b/MP2/MP2_Sources/cont_frame_pool.C
index aeb5ec4..44ec1c0 100644
--- a/MP2/MP2_Sources/cont_frame_pool.C
+++ b/MP2/MP2_Sources/cont_frame_pool.C
@@ -137,7 +137,8 @@ ContFramePool::ContFramePool(unsigned long _base_frame_no,
     // since as stated in the instructions it is already big enough to
     // hold for 128MB of memory with one bit per frame, so should still
     // be enough for 64MB of memory with 2 bits per frame.
-    assert(_n_frames <= FRAME_SIZE * 8);
+    // Assertion changed to match max size of frames allowed.
+    assert(_n_frames <= FRAME_SIZE * 4);
     
     base_frame_no = _base_frame_no;
     nframes = _n_frames;
@@ -147,28 +148,14 @@ ContFramePool::ContFramePool(unsigned long _base_frame_no,
     
     // If _info_frame_no is zero then we keep management info in the first
     // frame(s), else we use the provided frame(s) to keep management info
-    // NOTE: need a second check for the number of info frames specified, if any.
+    // NOTE: bitmap needs to be allocated with n_info_frames if specified.
     if(info_frame_no == 0)
     {
-        if(n_info_frames == 0)
-        {
-          bitmap = (unsigned char *) (base_frame_no * FRAME_SIZE);
-        }
-        else
-        {
-          bitmap = (unsigned char *) (base_frame_no * FRAME_SIZE * n_info_frames);
-        }
+        bitmap = (unsigned char *) (base_frame_no * FRAME_SIZE);
     }
     else
     {
-        if(n_info_frames == 0)
-        {
-          bitmap = (unsigned char *) (info_frame_no * FRAME_SIZE);
-        }
-        else
-        {
-          bitmap = (unsigned char *) (info_frame_no * FRAME_SIZE * n_info_frames);
-        }
+        bitmap = (unsigned char *) (info_frame_no * FRAME_SIZE * n_info_frames);
     }
     
     // Number of frames must "fill" the bitmap!
@@ -176,19 +163,39 @@ ContFramePool::ContFramePool(unsigned long _base_frame_no,
     
     
     // Everything ok. Proceed to mark all bits in the bitmap
-    // NOTE: I don't think this needs to be changed...
-    for(int i=0; i*8 < _n_frames; i++)
+    // NOTE: changed to reflect that I need 2 bits per frame now
+    for(int i=0; i*4 < _n_frames; i++)
     {
         bitmap[i] = 0xFF;
     }
     
     // Mark the first frame as being used if it is being used
     // NOTE: need to mark multiple frames if needed.
-    unsigned long i = info_frame_no;
-    while(i < (info_frame_no + n_info_frames))
+    if(info_frame_no == 0)
     {
-        bitmap[i*8] = 0x7F;
-        nFreeFrames--;
+      bitmap[0] = 0x3F;
+      nFreeFrames--;
+    }
+    else
+    {
+      unsigned int i = info_frame_no / 4;
+      unsigned int r = info_frame_no % 4;
+      unsigned char mask = 0xC0;
+      mask = mask >> r*2;
+      
+      unsigned int c = 0;
+      while(c < n_info_frames)
+      {
+        bitmap[i] = bitmap[i] ^ mask;
+        if(mask == 0x00)
+        {
+          i++;
+          mask = 0xC0;
+        }
+        c++;
+      }
+
+      nFreeFrames--;
     }
     
     Console::puts("Frame Pool initialized\n");
@@ -196,8 +203,41 @@ ContFramePool::ContFramePool(unsigned long _base_frame_no,
 
 unsigned long ContFramePool::get_frames(unsigned int _n_frames)
 {
-    // TODO: IMPLEMENTATION NEEEDED!
-    assert(false);
+    // Are there enough frames left to allocate?
+    assert(nFreeFrames > _n_frames);
+    
+    // Find a frame that is not being used and return its frame index.
+    // Mark that frame as being used in the bitmap.
+    // NOTE: Must be updated to find a sequence of contiguous frames
+    // that are not being used and update the index of the head.
+    unsigned int frame_no = base_frame_no;
+    
+    unsigned int i = 0;
+    unsigned int c = 0;
+    while (true) {
+        if(bitmap[i] != 0x0)
+        {
+          while(c < _n_frames)
+          {
+
+          }
+        }
+        i++;
+    }
+    
+    frame_no += i * 8;
+    
+    unsigned char mask = 0x80;
+    while ((mask & bitmap[i]) == 0) {
+        mask = mask >> 1;
+        frame_no++;
+    }
+    nFreeFrames--;
+    
+    // Update bitmap
+    bitmap[i] = bitmap[i] ^ mask;
+    
+    return (frame_no);
 }
 
 void ContFramePool::mark_inaccessible(unsigned long _base_frame_no,