From 26fcbbdd26a389b6979a966ae8dd49a40a6a1d05 Mon Sep 17 00:00:00 2001
From: pixel <pixel>
Date: Wed, 11 Jul 2007 14:23:29 +0000
Subject: Adding comments.

---
 mpq-file.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

(limited to 'mpq-file.c')

diff --git a/mpq-file.c b/mpq-file.c
index 7bafd2f..f6a26d8 100644
--- a/mpq-file.c
+++ b/mpq-file.c
@@ -33,7 +33,10 @@ struct mpq_file_t * mpqlib_open_file(struct mpq_archive_t * mpq_a, int entry) {
     
     __mpqlib_errno = MPQLIB_ERROR_NO_ERROR;
     
+    /* Basic checks of the entry. */
+    
     if (mpqlib_ioctl(mpq_a, MPQLIB_IOCTL_ENTRY_EXISTS, entry)) {
+        __mpqlib_errno = MPQLIB_ERROR_FILE_NOT_FOUND;
 	return NULL;
     }
     
@@ -49,6 +52,7 @@ struct mpq_file_t * mpqlib_open_file(struct mpq_archive_t * mpq_a, int entry) {
         return NULL;
     }
     
+    // We won't support anything else than compressed files yet.
     if (!(flags & MPQ_FLAGS_COMPRESSED)) {
         __mpqlib_errno = MPQLIB_ERROR_NOT_COMPRESSED;
         return NULL;
@@ -61,6 +65,7 @@ struct mpq_file_t * mpqlib_open_file(struct mpq_archive_t * mpq_a, int entry) {
     
     r->sector_size = mpqlib_ioctl(mpq_a, MPQLIB_IOCTL_GET_SECTOR_SIZE, 0);
     
+    /* Allocating and filling up the mpq_file_t structure. */
     if (!(r->buffer = malloc(r->sector_size))) {
 	free(r);
 	__mpqlib_errno = MPQLIB_ERROR_MEMORY;
@@ -95,6 +100,7 @@ struct mpq_file_t * mpqlib_open_file(struct mpq_archive_t * mpq_a, int entry) {
 	return NULL;
     }
     
+    /* Reading the offset table and building the size table */
     __mpqlib_seek(mpq_a, r->offset);
     for (i = 0; i <= r->number_of_sectors; i++) {
 	__mpqlib_read(mpq_a, &o, 4);
@@ -128,6 +134,7 @@ static int cache_sector(struct mpq_file_t * mpq_f, int sector) {
     static char in_buf[MPQ_BUFSIZ];
     int r = 1;
     
+    /* current_sector should be initialized to -1 */
     if (mpq_f->current_sector != sector) {
         int il, ol;
         __mpqlib_seek(mpq_f->mpq_a, mpq_f->offsets[sector]);
@@ -145,6 +152,10 @@ static int cache_sector(struct mpq_file_t * mpq_f, int sector) {
     return r;
 }
 
+/*
+ * The read function will call itself recursively, in order to split the calls across the sectors.
+ */
+
 uint32_t mpqlib_read(struct mpq_file_t * mpq_f, void * _buffer, uint32_t size) {
     char * buffer = (char *) _buffer;
     int sector_begin, sector_end;
@@ -155,6 +166,7 @@ uint32_t mpqlib_read(struct mpq_file_t * mpq_f, void * _buffer, uint32_t size) {
     
     uint32_t first_sector_begins, last_sector_ends;
     
+    /* Computing various cursors and stuff. */
     if ((size + mpq_f->cursor) >= mpq_f->file_size)
 	size = mpq_f->file_size - mpq_f->cursor;
 
@@ -171,17 +183,20 @@ uint32_t mpqlib_read(struct mpq_file_t * mpq_f, void * _buffer, uint32_t size) {
 	last_sector_ends = mpq_f->sector_size;
     }
     
+    /* Let's ask for the first sector */
     if (!cache_sector(mpq_f, sector_begin)) {
         __mpqlib_errno = MPQLIB_ERROR_COMPRESSION;
         return 0;
     }
     
+    /* If we've hit the end sector, let's just copy that over and exit. */
     if (sector_begin == sector_end) {
 	memcpy(buffer, mpq_f->buffer + first_sector_begins, size);
         mpq_f->cursor += size;
 	return size;
     }
     
+    /* Else, let's compute the cluster size, copy that chunk, and recurse. */
     cl_size = mpq_f->sector_size - first_sector_begins;
     memcpy(buffer, mpq_f->buffer + first_sector_begins, cl_size);
     mpq_f->cursor += cl_size;
-- 
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