From 7c85dacd763da1ac8e082832c5dba110c107cfdc Mon Sep 17 00:00:00 2001
From: "Guillaume W. Bres" <guillaume.bressaix@gmail.com>
Date: Sun, 27 Mar 2022 21:15:12 +0200
Subject: [PATCH] M to control maximal compression order

---
 README.md   | 41 +++++++++++++++++++++--------------------
 src/cli.yml |  4 ++++
 src/main.rs | 14 +++++++++++---
 3 files changed, 36 insertions(+), 23 deletions(-)

diff --git a/README.md b/README.md
index 90fff38..350215e 100644
--- a/README.md
+++ b/README.md
@@ -22,8 +22,8 @@ refer to the `hatanaka` section of the library
 
 ## Supported revisions
 
-* [ ] CRINEX1  
-* [ ] CRINEX3  
+* [ ] CRINEX1 
+* [x] CRINEX3  
 
 CRINEX2 does not technically exist
 
@@ -32,7 +32,7 @@ CRINEX2 does not technically exist
 Decompress a `CRINEX` file with `-d`
 
 ```bash
-cargo run -- --filepath /tmp/data.22d -d
+cargo run -- -d --filepath /tmp/data.22d
 ```
 
 This produces an "output.rnx" RINEX file.   
@@ -40,23 +40,15 @@ This produces an "output.rnx" RINEX file.
 Use `-o` to set the output file name:
 
 ```bash
-cargo run -- -fp /tmp/data.22d -o /tmp/data.22o -d
-cargo run -- -fp /tmp/data.22d --output /tmp/data.22o -d
+cargo run -- -d --filepath /tmp/data.22d -o /tmp/myfile
+cargo run -- -d --filepath /tmp/data.22d --output /tmp/custom
 ```
 
 ## Modern Observation Data and `--strict` flag 
 
 `CRX2RNX` violates RINEX standard 
 when decompressing V > 2 (modern) RINEX Observation data,   
-because decompressed epochs are not wrapped and are larger than 80 characters.    
-
-This tool behaves like `CRX2RNX` by default,  
-but you can change that behavior
-to follow `RINEX` definitnios strictly, by passing the `--strict` flag:
-
-```bash
-cargo run -- -fp data.22d -d -s
-```
+because decompressed epochs are not contrainted to 80 characters.    
 
 ## Epoch events 
 
@@ -65,10 +57,19 @@ Just like `CRX2RNX`, epochs with weird events are left untouched.
 Therefore, explanations on these epochs events, 
 usually described in the form of `COMMENTS` are preserved. 
 
-## Compression algorithm 
+## Compression behavior & limitations 
+
+This tool uses an M=8 maximal compression order,   
+which should be fine for all CRINEX ever produced,   
+considering they were probably produced with `CRX2RNX`   
+which hardcodes an M=5 limitation.   
+
+Unlike `CRX2RNX`, this tool is not limited to M,   
+you can increase the default value if you think "higher"
+compression will be encountered in a given file: 
+```bash
+cargo run -- -d -m 8 --filepath /tmp/data.22d
+```
 
-Unlike `CRX2RNX`, this tool is not limited to 
-an M=5 compression / decompression order
-in the core algorithm.   
-It actually dynamically adapts and will never fail, as long
-as the input content is a valid CRINEX.
+Best compression performances seem to be obtained for m=4  
+which is handled by default.
diff --git a/src/cli.yml b/src/cli.yml
index 291c701..2ebab97 100644
--- a/src/cli.yml
+++ b/src/cli.yml
@@ -22,3 +22,7 @@ args:
         long: output
         takes_value: true
         help: Set output file name
+    - max-compression-order:
+        short: M
+        takes_value: true
+        help: control maximal compression order (default is M=8) 
diff --git a/src/main.rs b/src/main.rs
index 7e0b48c..742067e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -34,6 +34,8 @@ fn main() -> Result<(), Error> {
     
     let crx2rnx = matches.is_present("crx2rnx");
     let rnx2crx = matches.is_present("rnx2crx");
+    let m = u16::from_str_radix(matches.value_of("m")
+        .unwrap_or("8"),10).unwrap();
     let strict_flag = matches.is_present("strict");
 
     let outpath : String = match crx2rnx {
@@ -55,19 +57,25 @@ fn main() -> Result<(), Error> {
  
     let mut output = std::fs::File::create(outpath)?;
     if crx2rnx {
-        decompress(filepath, output)
+        decompress(filepath, m, output)?;
+        println!("RINEX file extracted");
+        Ok(())
     } else {
         Ok(())
     }
 }
 
-fn decompress (fp: &str, mut writer: std::fs::File) -> Result<(), Error> {
+/// Decompresses given file,   
+/// fp : filepath   
+/// m : maximal compression order for core algorithm    
+/// writer: stream
+fn decompress (fp: &str, m: u16, mut writer: std::fs::File) -> Result<(), Error> {
     let mut content = String::new();
     let mut hd_content = String::new();
     let input = std::fs::File::open(fp)?;
     let reader = BufReader::new(input);
     let mut header : header::Header = header::Header::default();
-    let mut decompressor = hatanaka::Decompressor::new(8); // TODO maximal order
+    let mut decompressor = hatanaka::Decompressor::new(m.into());
 
     let mut first_epoch = true;
     let mut epoch_len : usize = 0;