output binary for file output

README.md

@@ -1,6 +1,6 @@
 # RC2014 - Quazar OLED board
 
-This project provides MACRO-80 assembler code for `oled` program to drive OLED display for RC2014 by Quazar. It provides a Rust "script" to convert 128x32 black and white image to hex output suitable for the `oled` program.
+This project provides MACRO-80 assembler code for `oled` program for CP/M to drive OLED display for RC2014 by Quazar. It provides a Rust "script" to convert 128x32 black and white image to hex output suitable for the `oled` program.
 
 ## Compiling
 

oled-to-hex

@@ -8,6 +8,7 @@ edition = "2021"
 
 [dependencies]
 image = { version = "0.25.8", default-features = false, features = ["png"] }
+atty = { version = "0.2.14" }
 */
 
 use image::GenericImageView;
@@ -15,7 +16,7 @@ use image::ImageReader;
 use image::Pixel;
 use std::env;
 use std::error::Error;
-use std::io::{Error as IoError, ErrorKind};
+use std::io::{stdout, Error as IoError, ErrorKind, Write};
 
 /// Example script description
 fn main() -> Result<(), Box<dyn Error>> {
@@ -23,11 +24,11 @@ fn main() -> Result<(), Box<dyn Error>> {
         ErrorKind::NotFound,
         "expected PNG 128x32 file path",
     ))?;
-    println!("Loading {}", file);
+    eprintln!("Loading {}", file);
 
     let img = ImageReader::open(file)?.decode()?;
     let (w, h) = img.dimensions();
-    println!("Loaded file {}x{}", w, h);
+    eprintln!("Loaded file {}x{}", w, h);
     if w != 128 && h != 32 {
         return Err(Into::into(IoError::new(
             ErrorKind::InvalidData,
@@ -35,6 +36,8 @@ fn main() -> Result<(), Box<dyn Error>> {
         )));
     }
 
+    let out_hex = atty::is(atty::Stream::Stdout);
+
     for row in 0..4 {
         for column in 0..128 {
             let mut byte = 0u8;
@@ -48,7 +51,11 @@ fn main() -> Result<(), Box<dyn Error>> {
                     byte = byte | 128;
                 }
             }
+            if out_hex {
                 print!("{:02X}", byte);
+            } else {
+                stdout().write(&[byte]).unwrap();
+            }
         }
     }