Reorganizing source code. Created util dir

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/util/page.cpp

@@ -0,0 +1,68 @@
+/*++
+Copyright (c) 2006 Microsoft Corporation
+
+Module Name:
+
+    page.cpp
+
+Abstract:
+
+    Goodies for manipulating pages of memory.
+
+Author:
+
+    Leonardo de Moura (leonardo) 2011-02-27.
+
+Revision History:
+
+--*/
+#include"page.h"
+#include"debug.h"
+
+inline void set_page_header(char * page, char * prev, bool default_page) {
+    size_t header = reinterpret_cast<size_t>(prev) | static_cast<size_t>(default_page); 
+    reinterpret_cast<size_t *>(page)[-1] = header;
+    SASSERT(is_default_page(page) == default_page);
+    SASSERT(prev_page(page) == prev);
+}
+
+inline char * alloc_page(size_t s) { char * r = alloc_svect(char, s+PAGE_HEADER_SZ); return r + PAGE_HEADER_SZ; }
+
+inline void del_page(char * page) { dealloc_svect(page - PAGE_HEADER_SZ); }
+
+void del_pages(char * page) {
+    while (page != 0) {
+        char * prev = prev_page(page);
+        del_page(page);
+        page = prev;
+    }
+}
+
+char * allocate_default_page(char * prev, char * & free_pages) {
+    char * r;
+    if (free_pages) {
+        r = free_pages;
+        free_pages = prev_page(free_pages);
+    }
+    else {
+        r = alloc_page(DEFAULT_PAGE_SIZE);
+    }
+    set_page_header(r, prev, true);
+    return r;
+}
+
+char * allocate_page(char * prev, size_t sz) {
+    char * r = alloc_page(sz);
+    set_page_header(r, prev, false);
+    return r;
+}
+
+void recycle_page(char * p, char * & free_pages) {
+    if (is_default_page(p)) {
+        set_page_header(p, free_pages, true);
+        free_pages = p;
+    }
+    else {
+        del_page(p);
+    }
+}