diff --git a/patch.c b/patch.c
index d369417..e33fbf8 100644
--- a/patch.c
+++ b/patch.c
@@ -1,16 +1,16 @@
 #include "io_funcs.h"
 #include "patch.h"
 
-lp_UMDiffCommand cmd_buffer[CMD_BUFFER_SIZE];
+umdiff_Command cmd_buffer[CMD_BUFFER_SIZE];
 
-lp_UMDiffFile
+umdiff_File
 lp_PatchSet_open(const char *path)
 {
 
 }
 
 int
-lp_PatchSet_covered(lp_UMDiffCommand *ps, u32 offset)
+lp_PatchSet_covered(umdiff_Command *ps, u32 offset)
 {
 
 }
diff --git a/umdiff/main.c b/umdiff/main.c
index 6842362..132475f 100644
--- a/umdiff/main.c
+++ b/umdiff/main.c
@@ -11,6 +11,24 @@
 
 #include "usage.rl.h"
 
+int
+umdiff_delta(char *source, char *target, char *output)
+{
+    return 1;
+}
+
+int
+umdiff_patch(char *source, char *umdiff, char *output)
+{
+    return 1;
+}
+
+int
+umdiff_fromRdiff(char *rdiff, char *output)
+{
+    return 1;
+}
+
 int main(int argc, char *argv[])
 {
     int res;
@@ -25,6 +43,13 @@ int main(int argc, char *argv[])
         return 0;
     }
 
+    if (opts.delta)
+        return umdiff_delta(opts.source_file, opts.target_file, opts.output_file);
+    else if (opts.patch)
+        return umdiff_patch(opts.source_file, opts.umdiff_file, opts.output_file);
+    else if (opts.fromrdiff)
+        return umdiff_fromRdiff(opts.rdiff_file, opts.output_file);
+
     return 1;
 }
 
diff --git a/umdiff/rdiff.c b/umdiff/rdiff.c
index 256f0d6..dbd99ef 100644
--- a/umdiff/rdiff.c
+++ b/umdiff/rdiff.c
@@ -8,7 +8,67 @@
  * and convert it in-memory into the UMDiff format.
  */
 
+#include "umdiff.h"
+
 #include <librsync.h>
 
+#define ISO_SECTOR_SIZE 2048
+
+typedef union {
+    int fd;
+    void *opaque;
+} _impl_umdiff_OpaqueFd;
+
+rs_signature_t *workSignatures;
+
+rs_result
+_impl_umdiff_sigJobSink(rs_job_t *job, rs_buffers_t *buf, void *dest)
+{
+
+}
+
+rs_result
+_impl_umdiff_sigJobSource(rs_job_t *job, rs_buffers_t *buf, void *fd_)
+{
+    _impl_umdiff_OpaqueFd fd = { .opaque = fd_ };
+}
+
+rs_result
+_impl_umdiff_deltaJobSink(rs_job_t *job, rs_buffers_t *buf, void *unk)
+{
+
+}
+
+rs_result
+_impl_umdiff_deltaJobSource(rs_job_t *job, rs_buffers_t *buf, void *fd_)
+{
+    _impl_umdiff_OpaqueFd fd = { .opaque = fd_ };
+}
+
+
+umdiff_File *
+umdiff_File_fromCompare(int source_fd, int target_fd)
+{
+    _impl_umdiff_OpaqueFd source_fd_ = { .fd = source_fd };
+    _impl_umdiff_OpaqueFd target_fd_ = { .fd = target_fd };
+    umdiff_File *resultFile;
+
+    rs_buffers_t buffers;
+    rs_job_t *sigJob, *deltaJob;
+
+    sigJob = rs_sig_begin(ISO_SECTOR_SIZE,
+                          RS_DEFAULT_MIN_STRONG_LEN,
+                          RS_RK_BLAKE2_SIG_MAGIC);
+    deltaJob = rs_delta_begin(workSignatures);
+
+    rs_job_drive(sigJob, &buffers,
+                _impl_umdiff_sigJobSource,  source_fd_.opaque,
+                _impl_umdiff_sigJobSink,    workSignatures);
+    rs_job_drive(deltaJob, &buffers,
+                _impl_umdiff_deltaJobSource, target_fd_.opaque,
+                _impl_umdiff_deltaJobSink,   resultFile);
+
+    return resultFile;
+}
 
 // vim: ft=c.doxygen
diff --git a/umdiff/umdiff.h b/umdiff/umdiff.h
index eee5ed6..fbd4191 100644
--- a/umdiff/umdiff.h
+++ b/umdiff/umdiff.h
@@ -25,16 +25,27 @@
  * Pointers spanning past the end of the disc are undefined and shall not be
  * used.
  */
-typedef long lp_UMDiffIndex[2048];
+typedef long umdiff_CmdIndex[1024];
 
+/**
+ * @brief      UMDiff file header structure.
+ *
+ * This is the format for a UMDiff file header. The commands index is included,
+ * as with the constrained memory of the PSP, reading the index in full is
+ * mandatory.
+ *
+ * With the tradeoff of an O(n) space and O(n) time conversion process on PC,
+ * we gain a worst-case patch application process in O(1) space and O(log(n))
+ * time on PSP.
+ */
 typedef struct 
 __attribute__((packed)) {
     char magic[7]; /* = 0x7f 'UMDiff' */
     char version;
     long cmd_len;
     long data_start;
-    lp_UMDiffIndex index;
-} lp_UMDiffHeader;
+    umdiff_CmdIndex index;
+} umdiff_Header;
 
 /**
  * @brief      Definition for a single patch command.
@@ -62,15 +73,15 @@ typedef struct {
     long patch_sector_count; /* if < sector_count, repeat */
 
     long data_source; /* 0 = patchfile, 1 = source */
-} lp_UMDiffCommand;
+} umdiff_Command;
 
 // Commands shall start immediately after the full header
 #define UMDIFF_COMMANDS_START (sizeof lp_UMDiffHeader)
 
 typedef struct {
-    lp_UMDiffHeader *hdr;
-    lp_UMDiffCommand *commands;
-} lp_UMDiffFile;
+    umdiff_Header *hdr;
+    umdiff_Command *commands;
+} umdiff_File;
 
 #endif //__UMDIFF_H