Use the half crate instead of requiring nightly feature f16

Cargo.toml

@@ -17,8 +17,9 @@ bytemuck = { version = "1.15", default-features = false, features = ["derive"] }
 memmap2 = { version = "0.9", optional = true }
 
 [dev-dependencies]
-tempfile = "3.8"
 criterion = { version = "0.5", features = ["html_reports"] }
+half = "2.6.0"
+tempfile = "3.8"
 
 [[example]]
 name = "test_real_mrc"

README.md

@@ -365,7 +365,7 @@ fn calculate_statistics(data: &[f32]) -> Statistics {
 | `std` | Standard library support | ✅ | File I/O, Error trait |
 | `mmap` | Memory-mapped I/O | ✅ | Large file processing |
 | `file` | File operations | ✅ | `MrcFile::open()` |
-| `f16` | Half-precision support | ❌ | Requires nightly Rust |
+| `f16` | Half-precision support | ❌ |  |
 
 ### no_std Usage
 
@@ -492,10 +492,6 @@ We welcome contributions! Here's how to get started:
 git clone https://github.com/your-org/mrc.git
 cd mrc
 
-# Install nightly Rust (required for f16)
-rustup install nightly
-rustup override set nightly
-
 # Install dependencies
 cargo build --all-features
 

examples/generate_mrc_files.rs

@@ -1,5 +1,4 @@
-#![feature(f16)]
-
+use half::f16;
 use mrc::Header;
 use mrc::Mode;
 use std::fs::File;
@@ -90,7 +89,7 @@ fn create_ball_data_2d(mode: Mode, width: usize, height: usize, diameter: f32) -
                     } else {
                         0.0f32
                     };
-                    let f16_value = value as f16;
+                    let f16_value = f16::from_f32(value);
                     data.extend_from_slice(&f16_value.to_le_bytes());
                 }
             }
@@ -165,7 +164,7 @@ fn create_ball_data_3d(
                         } else {
                             0.0f32
                         };
-                        let f16_value = value as f16;
+                        let f16_value = f16::from_f32(value);
                         data.extend_from_slice(&f16_value.to_le_bytes());
                     }
                 }
@@ -275,7 +274,7 @@ fn create_mrc_file(mode: i32, filename: &str) -> std::io::Result<()> {
         }
         Mode::Float16 => {
             for chunk in data.chunks_exact(2) {
-                let val = f16::from_le_bytes([chunk[0], chunk[1]]) as f32;
+                let val = f16::from_le_bytes([chunk[0], chunk[1]]).into();
                 min_val = min_val.min(val);
                 max_val = max_val.max(val);
                 sum += val as f64;

src/lib.rs

@@ -1,5 +1,5 @@
 #![no_std]
-#![cfg_attr(feature = "f16", feature(f16))]
+#[cfg(feature = "std")]
 extern crate alloc;
 
 mod header;

src/view.rs

@@ -244,6 +244,7 @@ impl<'a> MrcViewMut<'a> {
             }
             Some(Mode::Float16) => {
                 // 2-byte f16 types - use u16 for bytemuck compatibility
+                // TODO: this should return f16s when the f16 feature is enabled
                 let data = self.view_mut::<u16>()?;
                 for val in data.iter_mut() {
                     let bytes = bytemuck::bytes_of_mut(val);