Added a profiler.

profiler.h

@@ -0,0 +1,128 @@
+#ifndef PROFILER_H
+#define PROFILER_H
+
+#ifndef PROFILER
+#define PROFILER 1
+#endif
+
+#if PROFILER
+
+#include <stdlib.h> /* malloc */
+#include <string.h> /* memset */
+#include <time.h> /* clock_gettime */
+#include <stdio.h>
+
+unsigned long long profiler_get_time()
+{
+    struct timespec ts;
+    
+    if(clock_gettime(CLOCK_MONOTONIC_RAW, &ts) == 0) {
+        return (unsigned long long)ts.tv_sec * 1000000000ULL +
+               (unsigned long long)ts.tv_nsec;
+    }
+
+    return 0ULL;
+}
+
+struct profiler_block {
+    const char *name;
+
+    unsigned long long start;
+    unsigned long long end;
+};
+
+struct profiler_tree_node {
+    struct profiler_block data;
+
+    struct profiler_tree_node *parent; /* null for root node */
+
+    struct profiler_tree_node *prev_sibling; /* doubly-linked list */
+    struct profiler_tree_node *next_sibling;
+
+    int children_count;
+    struct profiler_tree_node *first_child;
+    struct profiler_tree_node *last_child;
+};
+
+struct profiler_tree_node *profiler_root_node = 0;
+struct profiler_tree_node *profiler_last_node = 0;
+
+static struct profiler_tree_node *profiler_tree_node(const char *name)
+{
+    struct profiler_tree_node *node =
+        malloc(sizeof(struct profiler_tree_node));
+    memset(node, 0, sizeof(struct profiler_tree_node));
+    node->data.name = name;
+    return node;
+}
+
+void profiler_begin(const char *name)
+{
+    if(!profiler_root_node) { /* create root node */
+        profiler_root_node = profiler_tree_node("TOTAL");
+        profiler_last_node = profiler_root_node;
+    }
+
+    struct profiler_tree_node *node = profiler_tree_node(name);
+    node->data.start = profiler_get_time();
+    node->parent = profiler_last_node;
+
+    if(!profiler_last_node->last_child) {
+        profiler_last_node->first_child = node;
+        profiler_last_node->last_child = node;
+    } else {
+        profiler_last_node->last_child->next_sibling = node;
+        node->prev_sibling = profiler_last_node->last_child;
+        profiler_last_node->last_child = node;
+    }
+    profiler_last_node->children_count++;
+
+    profiler_last_node = node;
+}
+
+static void profiler_do_print(struct profiler_tree_node *node,
+                              int indent_level)
+{
+    if(node) {
+        unsigned long long difference;
+
+        int i;
+        for(i = 0; i < indent_level; i++)
+            fprintf(stderr, "    ");
+
+        difference = node->data.end - node->data.start;
+
+        fprintf(stderr, "[%s] %lld ns (%.6f ms)\n",
+                node->data.name,
+                difference,
+                (double)(difference) / 1000000.0);
+
+        if(node->first_child) {
+            profiler_do_print(node->first_child, indent_level+1);
+        }
+        if(node->next_sibling) {
+            profiler_do_print(node->next_sibling, indent_level);
+        }
+    }
+}
+
+void profiler_print()
+{
+    profiler_do_print(profiler_root_node->first_child, 0);
+}
+
+void profiler_end()
+{
+    profiler_last_node->data.end = profiler_get_time();
+    profiler_last_node = profiler_last_node->parent;
+}
+
+#else
+
+#define profiler_begin(...)
+#define profiler_end(...)
+#define profiler_print(...)
+
+#endif
+
+#endif /* profiler_h */