document patch loader

io_funcs.h

@@ -2,7 +2,7 @@
 #define __IO_FUNCS_H
 
 /**
- * @file        io_funcs.c
+ * @file        io_funcs.h
  * @author      Karim Vergnes <me@thesola.io>
  * @copyright   GPLv2
  * @brief       Functions to interpose with UMD driver

patch.c

@@ -1,7 +1,7 @@
 #include "io_funcs.h"
 #include "patch.h"
 
-lp_UMDiffCommand cmd_buffer[1024];
+lp_UMDiffCommand cmd_buffer[CMD_BUFFER_SIZE];
 
 lp_UMDiffFile
 lp_PatchSet_open(const char *path)

patch.h

@@ -1,9 +1,43 @@
 #ifndef __PATCH_H
 #define __PATCH_H
 
+/**
+ * @file       patch.h
+ * @author     Karim Vergnes <me@thesola.io>
+ * @copyright  GPLv2
+ * @brief      UMDiff patch loader functions
+ *
+ * This module is responsible for interfacing with a UMDiff file, and carrying
+ * out the actual patching algorithm.
+ */
+
 #include "umdiff/umdiff.h"
 
+/**
+ * How many @ref lp_UMDiffCommand objects should be loaded in memory at once.
+ */
+#define CMD_BUFFER_SIZE 1024
+
+/**
+ * @brief      Load buffer with commands at index offset for sector
+ *
+ * This loader is designed with the worst-case scenario in mind -- one command
+ * per sector. Since the resulting commands table would weigh in at 1.6 million
+ * commands, each 20 bytes, we couldn't possibly hope to store all of it in the
+ * PSP's working memory. Instead, we load a buffer with @ref CMD_BUFFER_SIZE
+ * commands, and perform lookup within.
+ *
+ * This function is responsible for seeking to the index pointer containing the
+ * given sector, and filling the buffer with commands starting at that point.
+ *
+ * This function will not do anything if the buffer already contains commqnds
+ * from the requested index.
+ *
+ * @param sector       The sector offset the read request starts at.
+ */
 int
 lp_loadCmdsForIndex(long sector);
 
 #endif //__PATCH_H
+
+// vim: ft=c.doxygen