Add utils for working with endianness, more documentation, refactor CMake

Decided to update the docs, as well as adding few new features and small
refactoring.

doc/Examples/CMakeLists.txt

@@ -0,0 +1,3 @@
+# PakReader
+add_executable(PakReader PakReader.c)
+target_link_libraries(PakReader BHLib)

doc/Examples/PakReader.c

@@ -0,0 +1,223 @@
+#include <BH/Args.h>
+#include <BH/IO.h>
+#include <BH/Util.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+
+/* PAK header and entry structures and some constants */
+#define HEADER_SIZE  12
+#define ENTRY_SIZE   64
+
+typedef struct PakHeader
+{
+    char id[4];
+    uint32_t offset;
+    uint32_t size;
+} PakHeader;
+
+
+typedef struct PakEntry
+{
+    char name[56];
+    uint32_t offset;
+    uint32_t size;
+} PakEntry;
+
+
+static int ParseHeader(BH_IO *io,
+                       PakHeader *header)
+{
+    char buffer[HEADER_SIZE];
+    size_t actual;
+
+    if (BH_IORead(io, buffer, HEADER_SIZE, &actual) || actual != HEADER_SIZE)
+        return BH_ERROR;
+
+    if (memcmp(buffer, "PACK", 4))
+        return BH_ERROR;
+
+    memcpy(header->id, buffer, 4);
+    header->offset = BH_Read32LEu(buffer + 4);
+    header->size = BH_Read32LEu(buffer + 8);
+
+    return BH_OK;
+}
+
+
+static int ParseEntry(BH_IO *io,
+                      PakEntry *entry)
+{
+    char buffer[ENTRY_SIZE];
+    size_t actual;
+
+    if (BH_IORead(io, buffer, ENTRY_SIZE, &actual) || actual != ENTRY_SIZE)
+        return BH_ERROR;
+
+    memcpy(entry->name, buffer, 56);
+    entry->offset = BH_Read32LEu(buffer + 56);
+    entry->size = BH_Read32LEu(buffer + 60);
+    entry->name[55] = 0;
+
+    return BH_OK;
+}
+
+
+/* Configuration and options  */
+typedef struct Config
+{
+    char *file;
+    char *input;
+    char *output;
+    int list;
+} Config;
+
+
+static BH_ArgsOption options[] = {
+    {'h', "help", 0, "Display this help"},
+    {'l', "list", 0, "List files in the archive instead of reading"},
+    {'i', "input", BH_ARGS_VALUE, "Input file in archive"},
+    {'o', "output", BH_ARGS_VALUE, "Output file"},
+    {0, NULL, 0, NULL}
+};
+
+
+static void PrintHelp(void)
+{
+    printf("Usage: PakReader [options...] <file>\n");
+    BH_ArgsHelp(options, 0);
+}
+
+
+static int OptionsCallback(int key,
+                           char *arg,
+                           void *data)
+{
+    Config *config = (Config *)data;
+
+    switch (key)
+    {
+    case BH_ARGS_UNKNOWN: break;
+    case BH_ARGS_ARGUMENT: if (!config->file) config->file = arg; break;
+    case 'h': PrintHelp(); exit(0);
+    case 'l': config->list = 1; break;
+    case 'i': config->input = arg; break;
+    case 'o': config->output = arg; break;
+    }
+
+    return BH_OK;
+}
+
+
+/* Copy data between two IO */
+static int CopyData(BH_IO *from,
+                    BH_IO *to,
+                    size_t size)
+{
+    size_t i, length, actual;
+    char tmp[512];
+
+    for (i = 0; i < size; i += sizeof(tmp))
+    {
+        length = size - i;
+        if (length > 512)
+            length = 512;
+
+        if (BH_IORead(from, tmp, length, &actual) || length != actual)
+            return BH_ERROR;
+
+        if (BH_IOWrite(to, tmp, length, &actual) || length != actual)
+            return BH_ERROR;
+    }
+
+    return BH_OK;
+}
+
+
+/* Process pack (list files or extract file) */
+static int ProcessPack(Config *config,
+                       BH_IO *io)
+{
+    PakHeader header;
+    PakEntry entry;
+    BH_IO *output;
+    size_t i;
+
+    /* Read header and seek to begging of the file table */
+    if (ParseHeader(io, &header))
+        return BH_ERROR;
+
+    if (BH_IOSeek(io, header.offset, BH_IO_SEEK_SET))
+        return BH_ERROR;
+
+    /* Parse and output entries */
+    for (i = header.size / 64; i; i--)
+    {
+        if (ParseEntry(io, &entry))
+            return BH_ERROR;
+
+        if (config->list)
+            printf("%s %d\n", entry.name, entry.size);
+        else
+        {
+            if (strcmp(entry.name, config->input))
+                continue;
+
+            output = BH_FileNew(config->output);
+            if (BH_IOOpen(output, BH_IO_WRITE) ||
+                BH_IOSeek(io, entry.offset, BH_IO_SEEK_SET) ||
+                CopyData(io, output, entry.size))
+            {
+                BH_IOFree(output);
+                return BH_ERROR;
+            }
+
+            BH_IOFree(output);
+            return BH_OK;
+        }
+    }
+
+    if (config->list)
+        return BH_OK;
+    return BH_ERROR;
+}
+
+
+/* Main entry */
+int main(int argc, char **argv)
+{
+    Config config;
+    BH_IO *io;
+    int result;
+
+    /* Parse arguments */
+    memset(&config, 0, sizeof(config));
+    if (BH_ArgsParse(argc, argv, options, OptionsCallback, &config) || !config.file)
+    {
+        PrintHelp();
+        return -1;
+    }
+
+    /* Check required arguments */
+    if (!config.list && (!config.input || !config.output))
+    {
+        printf("Specify input and output files\n");
+        PrintHelp();
+        return -1;
+    }
+
+    /* Read and write */
+    io = BH_FileNew(config.file);
+    if (BH_IOOpen(io, BH_IO_READ | BH_IO_EXIST))
+    {
+        printf("Can't open file %s\n", config.file);
+        BH_IOFree(io);
+        return -1;
+    }
+
+    result = ProcessPack(&config, io);
+    BH_IOFree(io);
+
+    return result;
+}