Port usage()

Cargo.toml

@@ -10,3 +10,4 @@ crate-type = ["staticlib"]
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+libc = "0.2"

main.c

@@ -32,44 +32,17 @@
 #include "util.h"
 
 const char version[] = VERSION;
-const char *copyright;
 
 extern char *optarg;
 extern int optind;
 
 extern void print_message_from_rust();
+extern void print_usage(const char* version);
 
 int trace_flag = 0;
 
-void usage()
-{
-    fprintf(stderr, "DMR Config, Version %s, %s\n", version, copyright);
-    fprintf(stderr, "Usage:\n");
-    fprintf(stderr, "    dmrconfig -r [-t]\n");
-    fprintf(stderr, "                         Read codeplug from the radio to a file 'device.img'.\n");
-    fprintf(stderr, "                         Save configuration to a text file 'device.conf'.\n");
-    fprintf(stderr, "    dmrconfig -w [-t] file.img\n");
-    fprintf(stderr, "                         Write codeplug to the radio.\n");
-    fprintf(stderr, "    dmrconfig -v [-t] file.conf\n");
-    fprintf(stderr, "                         Verify configuration script for the radio.\n");
-    fprintf(stderr, "    dmrconfig -c [-t] file.conf\n");
-    fprintf(stderr, "                         Apply configuration script to the radio.\n");
-    fprintf(stderr, "    dmrconfig -c file.img file.conf\n");
-    fprintf(stderr, "                         Apply configuration script to the codeplug image.\n");
-    fprintf(stderr, "                         Store modified copy to a file 'device.img'.\n");
-    fprintf(stderr, "    dmrconfig file.img\n");
-    fprintf(stderr, "                         Display configuration from the codeplug image.\n");
-    fprintf(stderr, "    dmrconfig -u [-t] file.csv\n");
-    fprintf(stderr, "                         Update contacts database from CSV file.\n");
-    fprintf(stderr, "Options:\n");
-    fprintf(stderr, "    -r           Read codeplug from the radio.\n");
-    fprintf(stderr, "    -w           Write codeplug to the radio.\n");
-    fprintf(stderr, "    -c           Configure the radio from a text script.\n");
-    fprintf(stderr, "    -v           Verify config file.\n");
-    fprintf(stderr, "    -u           Update contacts database.\n");
-    fprintf(stderr, "    -l           List all supported radios.\n");
-    fprintf(stderr, "    -t           Trace USB protocol.\n");
-    exit(-1);
+void usage() {
+  print_usage((const char*)version);
 }
 
 int main(int argc, char **argv)
@@ -78,7 +51,6 @@ int main(int argc, char **argv)
     int read_flag = 0, write_flag = 0, config_flag = 0, csv_flag = 0;
     int list_flag = 0, verify_flag = 0;
 
-    copyright = "Copyright (C) 2018 Serge Vakulenko KK6ABQ";
     trace_flag = 0;
     for (;;) {
         switch (getopt(argc, argv, "tcwrulv")) {

src/lib.rs

@@ -1,8 +1,48 @@
+use std::ffi::CStr;
+use libc::c_char;
+
+const COPYRIGHT: &'static str = "Copyright (C) 2018 Serge Vakulenko KK6ABQ";
+
 #[no_mangle]
 pub extern "C" fn print_message_from_rust() {
   println!("Calling from Rust!");
 }
 
+#[no_mangle]
+pub extern "C" fn print_usage(version_ptr: *const c_char) {
+  let version: String = unsafe { CStr::from_ptr(version_ptr) }.to_string_lossy().to_string();
+
+  print!("DMR Config, Version {}, {}", version, COPYRIGHT);
+
+  let msg = r#"
+Usage:
+    dmrconfig -r [-t]\n
+                          Read codeplug from the radio to a file 'device.img'.
+                          Save configuration to a text file 'device.conf'.
+    dmrconfig -w [-t] file.img
+                          Write codeplug to the radio.
+    dmrconfig -v [-t] file.conf
+                          Verify configuration script for the radio.
+    dmrconfig -c [-t] file.conf
+                          Apply configuration script to the radio.
+    dmrconfig -c file.img file.conf
+                          Apply configuration script to the codeplug image.
+                          Store modified copy to a file 'device.img'.
+    dmrconfig file.img
+                          Display configuration from the codeplug image.
+    dmrconfig -u [-t] file.csv
+                          Update contacts database from CSV file.
+Options:
+    -r           Read codeplug from the radio.
+    -w           Write codeplug to the radio.
+    -c           Configure the radio from a text script.
+    -v           Verify config file.
+    -u           Update contacts database.
+    -l           List all supported radios.
+    -t           Trace USB protocol."#;
+  print!("{}", msg);
+  std::process::exit(-1);
+}
 
 #[cfg(test)]
 mod tests {