Added function draft.

info/archive_structure.md

@@ -13,10 +13,10 @@ Effective size : 32 bytes.
 ## File table
 ```markdown
 WRPG_PIAF_FILENAME         : char[8]      <=> 8 bytes (not \0 terminated)
-WRPG_PIAF_FILETYPE         : enumeration  <=> 4 bytes
+WRPG_PIAF_FILE_TYPE        : enumeration  <=> 4 bytes
 WRPG_PIAF_COMPRESSION_TYPE : enumeration  <=> 4 bytes
-WRPG_PIAF_FILESIZE         : unsigned int <=> 4 bytes
-WPRG_PIAF_DATA_OFFSET      : unsigned int <=> 4 bytes
+WRPG_PIAF_FILE_SIZE        : unsigned int <=> 4 bytes
+WPRG_PIAF_DATA_OFFSET      : unsigned int <=> 4 bytes // To being able to point directly to file data
 ```
 Effective size = 24 bytes per file.
 
@@ -35,3 +35,98 @@ Effective size = 24 bytes per file.
 1 = ZLIB
 2 = RLE (?)
 ```
+
+## Archive draft
+### class / structure
+```c++
+
+struct WRPG_PIAF_FILE_ENTRY {
+  char filename[8]; // or 9 if you want to put that \0.
+  enum WRPG_PIAF_FILE_TYPE file_type;
+  enum WRPG_PIAF_COMPRESSION_TYPE file_compresison;
+  unsigned int file_size;
+  unsigned int data_offset;
+}
+
+struct WRPG_PIAF_FILE {
+  char magic_header[8];
+  unsigned long long checksum;
+   // 0xAABBCCCC form
+   // AA = major version, BB = minor version, CC = hotfix
+  unsigned int version;
+  unsigned int nb_files;
+  unsigned int data_size;
+  unsigned int padidng;
+  WRPG_PIAF_FILE_ENTRY* entries;
+};
+
+```
+### Loading
+```c++
+// Does only load structure data. Gotta use loader functions to
+// load from this structure.
+struct WRPG_PIAF_FILE* load_structure_from_data(void* data, ssize_t size) {
+  if(data == nullptr)
+    return nullptr; // NPE
+
+  char* data_char = (char*) data;
+  if(strncmp(data_char, "WRPGPIAF", 8) != 0)
+    // BAD_COOKIE exception
+    return nullptr;
+
+  unsigned long long checksum;
+  memcpy(&checksum, &data_char[8], sizeof(unsigned long long));
+  bool check_ok = false;
+  // checksum routine goes here
+  if(!check_ok)
+    // BAD_CHECKSUM exception
+    return nullptr;
+
+  unsigned file_version;
+  memcpy(&file_version, &data_char[16], sizeof(unsigned));
+  if(file_version != CURRENT_PIAF_VERSION)
+    // BAD_VERSION exception
+    // Or manage older versions.
+    return nullptr;
+
+
+  unsigned nb_files;
+  memcpy(&nb_files, &data_char[20], sizeof(unsigned));
+
+  unsigned data_size;
+  memcpy(&data_size, &data_char[24], sizeof(unsigned));
+  if(data_size != size - 32 - 24*nb_files)
+    // BAD_SIZE exception
+    return nullptr;
+
+  struct WRPG_PIAF_FILE_ENTRY *file_table = malloc(nb_files * sizeof(struct WRPG_PIAF_FILE_ENTRY));
+  if(file_table == NULL)
+    // NO_MORE_MEMORY exception
+    return nullptr;
+  struct WRPG_PIAF_FILE *file = malloc(sizeof(struct WRPG_PIAF_FILE));
+  if(file == NULL) {
+    // NO_MORE_MEMORY exception
+    free(file_table);
+    return nullptr;
+  }
+
+  // I don't know if that works. It should because these structs are POD but well...
+  for (unsigned i = 0; i < nb_files; i++) {
+    memcpy(&file_table[i], &data_char[32+sizeof(WRPG_PIAF_FILE_ENTRY)*i]);
+  }
+  file_table[i].data = nullptr;
+
+  // Now the structure is parsed.
+
+  memcpy(file.magic_header, data_char, 8);
+  file.checksum = checksum;
+  file.version = file_version;
+  file.nb_files = nb_files;
+  file.data_size = data_size;
+  file.padding = 0XDEADBEEF;
+  file.entries = file_table;
+
+  return file;
+
+}
+```