generate std Error and display messages for errors

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "libfmod"
-version = "2.2.606"
+version = "2.2.607"
 edition = "2021"
 license = "MIT"
 description = "A library wrapper for integrating FMOD Engine in Rust applications."

README.md

@@ -12,7 +12,7 @@ For example for FMOD Engine 2.02.06 you should use:
 
 ```toml
 [dependencies]
-libfmod = "2.2.606"
+libfmod = "2.2.607"
 ```
 
 #### FMOD Development Libraries

src/lib.rs

@@ -1,6 +1,7 @@
 #![allow(unused_unsafe)]
 
 use std::ffi::{c_void, CStr, CString, IntoStringError, NulError};
+use std::fmt::{Display, Formatter};
 use std::mem::size_of;
 use std::os::raw::c_char;
 use std::ptr::{null, null_mut};
@@ -24,6 +25,41 @@ pub enum Error {
     NotDspFft,
 }
 
+impl Display for Error {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Error::Fmod {
+                function,
+                code,
+                message,
+            } => {
+                write!(f, "{}: {} ({})", function, message, code)
+            }
+            Error::EnumBindgen { enumeration, value } => {
+                write!(
+                    f,
+                    "FMOD returns unexpected value {} for {} enum",
+                    value, enumeration
+                )
+            }
+            Error::String(_) => {
+                write!(f, "invalid UTF-8 when converting C string")
+            }
+            Error::StringNul(_) => {
+                write!(
+                    f,
+                    "nul byte was found in the middle, C strings can't contain it"
+                )
+            }
+            Error::NotDspFft => {
+                write!(f, "trying get FFT from DSP which not FFT")
+            }
+        }
+    }
+}
+
+impl std::error::Error for Error {}
+
 impl From<NulError> for Error {
     fn from(error: NulError) -> Self {
         Error::StringNul(error)

tests/manual/dsp_usage.rs

@@ -39,6 +39,21 @@ fn test_fft_dsp() -> Result<(), Error> {
     system.release()
 }
 
+#[test]
+fn test_fft_from_type_mismatched_dsp() -> Result<(), Error> {
+    let system = System::create()?;
+    system.init(512, FMOD_INIT_NORMAL, None)?;
+
+    let sound = system.create_sound("./data/beep.wav", FMOD_DEFAULT, None)?;
+    let channel = system.play_sound(sound, None, false)?;
+    let echo_dsp = system.create_dsp_by_type(DspType::Echo)?;
+    channel.add_dsp(0, echo_dsp)?;
+    let fft = DspParameterFft::try_from(echo_dsp);
+    assert_eq!("trying get FFT from DSP which not FFT", format!("{}", fft.err().unwrap()));
+
+    system.release()
+}
+
 #[test]
 fn test_dps_description_name() -> Result<(), Error> {
     let system = System::create()?;