Add libqoi helper crate that wraps qoi.h

Cargo.toml

@@ -26,7 +26,7 @@ reference = []  # follows reference encoder implementation precisely, but may be
 bytemuck = "1.7"
 
 [workspace]
-members = ["bench"]
+members = ["libqoi", "bench"]
 
 [dev-dependencies]
 anyhow = "1.0"

libqoi/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "libqoi"
+version = "0.1.0"
+edition = "2018"
+license = "MIT/Apache-2.0"
+authors = ["Ivan Smirnov <rust@ivan.smirnov.ie>"]
+description = "Bindings to the original qoi.h (for test purposes only)"
+publish = false
+
+[dependencies]
+anyhow = "1.0"
+c_vec = "2.0"
+libc = "0.2"
+
+[build-dependencies]
+cc = "1.0"

libqoi/README.md

@@ -0,0 +1,2 @@
+This crate provides direct bindings around the original `qoi.h`,
+and is only used for testing and benchmarking purposes.

libqoi/build.rs

@@ -0,0 +1,18 @@
+use std::env;
+use std::fs;
+use std::path::PathBuf;
+
+fn main() {
+    let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
+    let out_src = out_dir.join("qoi.c");
+    fs::write(&out_src, "#include \"qoi.h\"\n").unwrap();
+
+    cc::Build::new()
+        .file(&out_src)
+        .include("../ext/qoi")
+        .define("QOI_NO_STDIO", None)
+        .define("QOI_IMPLEMENTATION", None)
+        .flag("-Wno-unsequenced")
+        .opt_level(3)
+        .compile("qoi");
+}

libqoi/src/lib.rs

@@ -0,0 +1,57 @@
+use anyhow::{ensure, Result};
+use c_vec::CVec;
+use libc::{c_int, c_void};
+
+mod ffi {
+    use libc::{c_int, c_uchar, c_uint, c_void};
+
+    #[derive(Debug, Copy, Clone, Default)]
+    #[repr(C)]
+    #[allow(non_camel_case_types)]
+    pub struct qoi_desc {
+        pub width: c_uint,
+        pub height: c_uint,
+        pub channels: c_uchar,
+        pub colorspace: c_uchar,
+    }
+
+    extern "C" {
+        pub fn qoi_encode(
+            data: *const c_void, desc: *const qoi_desc, out_len: *mut c_int,
+        ) -> *mut c_void;
+        pub fn qoi_decode(
+            data: *const c_void, size: c_int, desc: *mut qoi_desc, channels: c_int,
+        ) -> *mut c_void;
+    }
+}
+
+pub use ffi::qoi_desc;
+
+pub fn qoi_encode(data: &[u8], width: u32, height: u32, channels: u8) -> Result<CVec<u8>> {
+    let desc =
+        qoi_desc { width: width as _, height: height as _, channels: channels as _, colorspace: 0 };
+    let mut out_len: c_int = 0;
+    let out_ptr =
+        unsafe { ffi::qoi_encode(data.as_ptr().cast(), &desc as *const _, &mut out_len as *mut _) };
+    ensure!(!out_ptr.is_null(), "qoi.h: qoi_encode() returned null pointer");
+    ensure!(out_len > 0, "qoi.h: qoi_encode() returned non-positive out_len");
+    let vec = unsafe {
+        CVec::new_with_dtor(out_ptr.cast::<u8>(), out_len as _, |p| libc::free(p.cast::<c_void>()))
+    };
+    Ok(vec)
+}
+
+pub fn qoi_decode(data: &[u8], channels: u8) -> Result<(qoi_desc, CVec<u8>)> {
+    let mut desc = qoi_desc::default();
+    let out_ptr = unsafe {
+        ffi::qoi_decode(data.as_ptr() as _, data.len() as _, &mut desc as *mut _, channels as _)
+    };
+    ensure!(!out_ptr.is_null(), "qoi.h: qoi_decode() returned null pointer");
+    let out_len = (desc.width as usize)
+        .saturating_mul(desc.height as usize)
+        .saturating_mul(channels as usize);
+    let vec = unsafe {
+        CVec::new_with_dtor(out_ptr.cast::<u8>(), out_len, |p| libc::free(p.cast::<c_void>()))
+    };
+    Ok((desc, vec))
+}

libqoi/src/qoi.c

@@ -0,0 +1 @@
+#include "qoi.h"