Remove default routes

include/remove_default_routes.h

@@ -0,0 +1,79 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include "bitset.h"
+#include "routing_table.h"
+
+#ifndef __REMOVE_DEFAULT_ROUTES_H__
+
+static inline void remove_default_routes_minimise(table_t *table)
+{
+  // Mark the entries to be removed from the table
+  bitset_t remove;
+  bitset_init(&remove, table->size);
+
+  // Work up the table from the bottom, marking entries to remove
+  for (unsigned int i = table->size - 1; i < table->size; i--)
+  {
+    // Get the current entry
+    entry_t entry = table->entries[i];
+
+    // See if it can be removed
+    if (__builtin_popcount(entry.route) == 1 &&        // Only one output direction
+        (entry.route & 0x3f) &&                        // which is a link.
+        __builtin_popcount(entry.source) == 1 &&       // Only one input direction
+        (entry.source & 0x3f) &&                       // which is a link.
+        (entry.route >> 3) == (entry.source & 0x7) &&  // Source is opposite to sink
+        (entry.source >> 3) == (entry.route & 0x7))    // Source is opposite to sink
+    {
+      // The entry can be removed iff. it doesn't intersect with any entry
+      // further down the table.
+      bool remove_entry = true;
+      for (unsigned int j = i + 1; j < table->size; j++)
+      {
+        // If entry we're comparing with is already going to be removed, ignore
+        // it.
+        if (bitset_contains(&remove, j))
+        {
+          continue;
+        }
+
+        keymask_t a = entry.keymask;
+        keymask_t b = table->entries[j].keymask;
+
+        if (keymask_intersect(a, b))
+        {
+          remove_entry = false;
+          break;
+        }
+      }
+
+      if (remove_entry)
+      {
+        // Mark this entry as being removed
+        bitset_add(&remove, i);
+      }
+    }
+  }
+
+  // Remove the selected entries from the table
+  for (unsigned int insert = 0, read = 0; read < table->size; read++)
+  {
+    // Grab the current entry before we potentially overwrite it
+    entry_t current = table->entries[read];
+
+    // Insert the entry if it isn't being removed
+    if (!bitset_contains(&remove, read))
+    {
+      table->entries[insert++] = current;
+    }
+  }
+
+  // Update the table size
+  table->size -= remove.count;
+
+  // Clear up
+  bitset_delete(&remove);
+}
+
+#define __REMOVE_DEFAULT_ROUTES_H__
+#endif  // __REMOVE_DEFAULT_ROUTES_H__

tests/Makefile

@@ -1,10 +1,10 @@
-OBJECTS=tests.o test_bitset.o test_routing_table.o test_merge.o test_ordered_covering.o test_aliases.o test_mtrie.o
+OBJECTS=tests.o test_bitset.o test_routing_table.o test_merge.o test_ordered_covering.o test_aliases.o test_mtrie.o test_remove_default_routes.o
 INC_DIR=../include/
 CFLAGS+=-I ${INC_DIR} -fprofile-arcs -ftest-coverage -g --std=gnu99 -Wall -Werror
 LDFLAGS+=$(shell pkg-config --cflags --libs check)
 
 coverage : run_tests
-	gcov test_bitset test_routing_table test_merge test_aliases test_ordered_covering test_mtrie
+	gcov test_bitset test_routing_table test_merge test_aliases test_ordered_covering test_mtrie test_remove_default_routes
 
 run_tests : tests
 	valgrind --leak-check=full -q ./tests

tests/test_remove_default_routes.c

@@ -0,0 +1,117 @@
+#include "tests.h"
+#include "routing_table.h"
+#include "remove_default_routes.h"
+
+// Remove default routes from the table:
+//
+// S   -> 0000 -> N    # Remove
+// N   -> 0001 -> N    # Keep
+// ?   -> 0010 -> N    # Keep
+// N S -> 0011 -> N S  # Keep
+// 1   -> 0100 -> 1    # Keep
+entry_t orthogonal_entries[] = {
+  {{0x0, 0xf}, 0b000100, 0b100000},
+  {{0x1, 0xf}, 0b000100, 0b000100},
+  {{0x2, 0xf}, 0b000100, (1 << 24)},
+  {{0x3, 0xf}, 0b100100, 0b100100},
+  {{0x4, 0xf}, 0b1000000, 0b1000000},
+};
+entry_t orthogonal_entries_results[] = {
+  {{0x1, 0xf}, 0b000100, 0b000100},
+  {{0x2, 0xf}, 0b000100, (1 << 24)},
+  {{0x3, 0xf}, 0b100100, 0b100100},
+  {{0x4, 0xf}, 0b1000000, 0b1000000},
+};
+
+// Remove default routes from the table:
+//
+// S   -> 0000 -> N    # Remove
+// N   -> 0001 -> N    # Keep
+// ?   -> 0010 -> N    # Keep
+// N S -> 0011 -> N S  # Keep
+// W   -> 0100 -> E    # Remove
+entry_t orthogonal_entries2[] = {
+  {{0x0, 0xf}, 0b000100, 0b100000},
+  {{0x1, 0xf}, 0b000100, 0b000100},
+  {{0x2, 0xf}, 0b000100, (1 << 24)},
+  {{0x3, 0xf}, 0b100100, 0b100100},
+  {{0x4, 0xf}, 0b000001, 0b001000},
+};
+entry_t orthogonal_entries2_results[] = {
+  {{0x1, 0xf}, 0b000100, 0b000100},
+  {{0x2, 0xf}, 0b000100, (1 << 24)},
+  {{0x3, 0xf}, 0b100100, 0b100100},
+};
+
+// Remove default routes from the table:
+//
+// S -> 1000 -> N    # Remove
+// S -> 0000 -> N    # Keep
+// ? -> 0XXX -> N    # Keep
+entry_t nonorthogonal_entries[] = {
+  {{0x8, 0xf}, 0b000100, 0b100000},
+  {{0x0, 0xf}, 0b000100, 0b100000},
+  {{0x0, 0x8}, 0b000100, (1 << 24)},
+};
+entry_t nonorthogonal_entries_results[] = {
+  {{0x0, 0xf}, 0b000100, 0b100000},
+  {{0x0, 0x8}, 0b000100, (1 << 24)},
+};
+
+// Set up the fixtures
+table_t test_tables[] = {
+  {5, orthogonal_entries},
+  {5, orthogonal_entries2},
+  {3, nonorthogonal_entries},
+};
+
+table_t expected_tables[] = {
+  {4, orthogonal_entries_results},
+  {3, orthogonal_entries2_results},
+  {2, nonorthogonal_entries_results},
+};
+
+
+START_TEST(test_removal)
+{
+  // Grab the tables
+  table_t table = test_tables[_i];
+  table_t expected = expected_tables[_i];
+
+  // Minimise
+  remove_default_routes_minimise(&table);
+
+  // Check the result
+  ck_assert_int_eq(table.size, expected.size);
+
+  // Check the tables are equivalent
+  for (unsigned int i = 0; i < table.size; i++)
+  {
+    // Get the entries
+    entry_t e = table.entries[i];
+    entry_t f = expected.entries[i];
+
+    ck_assert_int_eq(e.keymask.key, f.keymask.key);
+    ck_assert_int_eq(e.keymask.mask, f.keymask.mask);
+    ck_assert_int_eq(e.route, f.route);
+    ck_assert_int_eq(e.source, f.source);
+  }
+}
+END_TEST
+
+
+Suite* remove_default_suite(void)
+{
+  Suite *s;
+  TCase *tests;
+
+  s = suite_create("Remove Default Routes");
+  tests = tcase_create("Core");
+  suite_add_tcase(s, tests);
+
+  // Add the tests
+  tcase_add_loop_test(tests, test_removal,
+                      0, sizeof(test_tables) / sizeof(table_t));
+
+  return s;
+}

tests/tests.c

@@ -23,6 +23,9 @@ int main(void)
   Suite *s_mtrie = mtrie_suite();
   srunner_add_suite(sr, s_mtrie);
 
+  Suite *s_rdr = remove_default_suite();
+  srunner_add_suite(sr, s_rdr);
+
   // Run the tests
   srunner_run_all(sr, CK_NORMAL);
 

tests/tests.h

@@ -9,6 +9,7 @@ Suite* merge_suite(void);
 Suite* ordered_covering_suite(void);
 Suite* aliases_suite(void);
 Suite* mtrie_suite(void);
+Suite* remove_default_suite(void);
 
 
 #define __TEST_H__