diff --git a/src/rvprof_output.c b/src/rvprof_output.c
index 56ed6f6..9c7a862 100644
--- a/src/rvprof_output.c
+++ b/src/rvprof_output.c
@@ -12,4 +12,50 @@ static int compare_functions(const void* fn_a, const void* fn_b){
     } else{
         return 0;
     }
-}
\ No newline at end of file
+}
+
+// actual report file generation
+rvprof_error_t rvprof_output_generate_report(void){
+    if(!g_rvprof.output_file || g_rvprof.functions.size == 0){
+        return RVPROF_ERROR_INVALID_STATE;
+    }
+
+    // safety measure: calculate total program time if not set or too small
+    uint64_t total_time_report = g_rvprof.total_program_time;
+    if (total_time_report == 0){
+        for(int i=0; i<g_rvprof.functions.size; i++){
+            function_stats_t* stats = &g_rvprof.functions.data[i];
+            // top-level (main)
+            if (strcmp(stats->caller, "---")==0){
+                if (stats->total_inclusive_time > total_time_report){
+                    total_time_report = stats->total_inclusive_time;
+                }
+            }
+        }
+    }
+
+    // if still zero, sum all exclusive times
+    if (total_time_report == 0){
+        for (int i=0; i<g_rvprof.functions.size; i++){
+            total_time_report += g_rvprof.functions.data[i].total_exclusive_time;
+
+        }
+    }
+
+    // calculate elapsed time fractions
+    for (int i=0; i<g_rvprof.functions.size; i++){
+        function_stats_t* stats = &g_rvprof.functions.data[i];
+        if(total_time_report > 0){
+            stats->exclusive_percent = (double)stats->total_exclusive_time * 100.0 / (double)total_time_report;
+            stats->inclusive_percent = (double)stats->total_inclusive_time * 100.0 / (double)total_time_report;           
+        } else{
+            stats->exclusive_percent = 0.0;
+            stats->inclusive_percent = 0.0;
+        }
+    }
+
+    // use stdlib's quicksort to sort functions by elapsed time
+    qsort(g_rvprof.functions.data, g_rvprof.functions.size, sizeof(function_stats_t), compare_functions);
+    
+    return RVPROF_SUCCESS;
+}