Add a bunch of helpful pakfs macros

include/joybus/common/n64_pak_fs.h

@@ -26,8 +26,26 @@
 /// The most banks whose system area fits in the first bank
 #define JOYBUS_N64_PAK_FS_MAX_BANKS 62
 
+/// Page of the first bank holding the four ID copies
+#define JOYBUS_N64_PAK_FS_ID_PAGE 0
+
+/// Page of the first bank holding a bank's inode table
+#define JOYBUS_N64_PAK_FS_INODE_PAGE(bank) (1 + (bank))
+
+/// Page of the first bank holding the mirror of a bank's inode table, for a given bank count
+#define JOYBUS_N64_PAK_FS_INODE_MIRROR_PAGE(banks, bank) (1 + (banks) + (bank))
+
+/// First page of the note table in the first bank, for a given bank count
+#define JOYBUS_N64_PAK_FS_NOTE_TABLE_PAGE(banks) (1 + 2 * (banks))
+
+/// Number of pages the note table takes
+#define JOYBUS_N64_PAK_FS_NOTE_TABLE_PAGES 2
+
 /// Number of system pages in the first bank for a given bank count
-#define JOYBUS_N64_PAK_FS_SYSTEM_PAGES(banks) (3 + 2 * (banks))
+#define JOYBUS_N64_PAK_FS_SYSTEM_PAGES(banks) (JOYBUS_N64_PAK_FS_NOTE_TABLE_PAGE(banks) + JOYBUS_N64_PAK_FS_NOTE_TABLE_PAGES)
+
+/// First page of a bank the filesystem allocates, for a given bank count. Page 0 of every later bank is reserved
+#define JOYBUS_N64_PAK_FS_FIRST_DATA_PAGE(banks, bank) ((bank) == 0 ? JOYBUS_N64_PAK_FS_SYSTEM_PAGES(banks) : 1)
 
 /**
  * Check whether a block address in the first bank holds a copy of the ID.

src/n64_pak_fs.c

@@ -84,7 +84,7 @@ static void build_id(uint8_t id[ID_SIZE], uint8_t banks, uint32_t random)
 static void inode_page(uint8_t *page, uint8_t bank, uint8_t banks)
 {
   // Bank 0's data starts after the system area, later banks' after a reserved first page
-  size_t first = bank == 0 ? JOYBUS_N64_PAK_FS_SYSTEM_PAGES(banks) : 1;
+  size_t first = JOYBUS_N64_PAK_FS_FIRST_DATA_PAGE(banks, bank);
 
   // Mark every data page free
   memset(page, 0, JOYBUS_N64_PAK_FS_PAGE_SIZE);
@@ -148,16 +148,22 @@ int joybus_n64_pak_fs_format_page(uint8_t page[JOYBUS_N64_PAK_FS_PAGE_SIZE], uin
   if (banks == 0 || banks > JOYBUS_N64_PAK_FS_MAX_BANKS || index >= JOYBUS_N64_PAK_FS_SYSTEM_PAGES(banks))
     return -JOYBUS_ERR_INVALID_ARG;
 
-  // One inode page per bank from page 1, then a mirror of each
-  if (index >= 1 && index <= 2 * banks) {
-    inode_page(page, (index - 1) % banks, banks);
+  // One inode page per bank, then a mirror of each
+  if (index >= JOYBUS_N64_PAK_FS_INODE_PAGE(0) && index < JOYBUS_N64_PAK_FS_INODE_PAGE(banks)) {
+    inode_page(page, index - JOYBUS_N64_PAK_FS_INODE_PAGE(0), banks);
     return 0;
   }
 
-  // Page 0 and the note table are empty, apart from the ID copies in page 0
+  if (index >= JOYBUS_N64_PAK_FS_INODE_MIRROR_PAGE(banks, 0) &&
+      index < JOYBUS_N64_PAK_FS_INODE_MIRROR_PAGE(banks, banks)) {
+    inode_page(page, index - JOYBUS_N64_PAK_FS_INODE_MIRROR_PAGE(banks, 0), banks);
+    return 0;
+  }
+
+  // The ID page and the note table are empty, apart from the ID copies
   memset(page, 0, JOYBUS_N64_PAK_FS_PAGE_SIZE);
 
-  if (index == 0) {
+  if (index == JOYBUS_N64_PAK_FS_ID_PAGE) {
     uint8_t id[ID_SIZE];
     build_id(id, banks, random);
 

test/test_n64_pak_fs.c

@@ -207,10 +207,38 @@ static void test_format_page_ids_valid_by_block()
   TEST_ASSERT_EQUAL(4, copies);
 }
 
+// Test that the layout macros name the pages the format writes, for sixteen banks and for one
+static void test_layout_pages()
+{
+  TEST_ASSERT_EQUAL(0, JOYBUS_N64_PAK_FS_ID_PAGE);
+  TEST_ASSERT_EQUAL(1, JOYBUS_N64_PAK_FS_INODE_PAGE(0));
+  TEST_ASSERT_EQUAL(16, JOYBUS_N64_PAK_FS_INODE_PAGE(15));
+  TEST_ASSERT_EQUAL(17, JOYBUS_N64_PAK_FS_INODE_MIRROR_PAGE(16, 0));
+  TEST_ASSERT_EQUAL(32, JOYBUS_N64_PAK_FS_INODE_MIRROR_PAGE(16, 15));
+  TEST_ASSERT_EQUAL(33, JOYBUS_N64_PAK_FS_NOTE_TABLE_PAGE(16));
+  TEST_ASSERT_EQUAL(35, JOYBUS_N64_PAK_FS_SYSTEM_PAGES(16));
+  TEST_ASSERT_EQUAL(35, JOYBUS_N64_PAK_FS_FIRST_DATA_PAGE(16, 0));
+  TEST_ASSERT_EQUAL(1, JOYBUS_N64_PAK_FS_FIRST_DATA_PAGE(16, 5));
+
+  TEST_ASSERT_EQUAL(2, JOYBUS_N64_PAK_FS_INODE_MIRROR_PAGE(1, 0));
+  TEST_ASSERT_EQUAL(3, JOYBUS_N64_PAK_FS_NOTE_TABLE_PAGE(1));
+  TEST_ASSERT_EQUAL(5, JOYBUS_N64_PAK_FS_SYSTEM_PAGES(1));
+  TEST_ASSERT_EQUAL(5, JOYBUS_N64_PAK_FS_FIRST_DATA_PAGE(1, 0));
+
+  // Every mirror page matches its inode page once formatted
+  joybus_n64_pak_fs_format(bank0, 16, 0);
+  for (int bank = 0; bank < 16; bank++) {
+    TEST_ASSERT_EQUAL_MEMORY(&bank0[JOYBUS_N64_PAK_FS_INODE_PAGE(bank) * 256],
+                             &bank0[JOYBUS_N64_PAK_FS_INODE_MIRROR_PAGE(16, bank) * 256], 256);
+  }
+}
+
 int main(int argc, char **argv)
 {
   UNITY_BEGIN();
 
+  RUN_TEST(test_layout_pages);
+
   RUN_TEST(test_id_valid);
   RUN_TEST(test_format_page_rejects_out_of_range);
   RUN_TEST(test_format_page_ids_valid_by_block);