From 2d9bca9a1eb75771a308668e2b365e82e5039e5a Mon Sep 17 00:00:00 2001
From: Tom Smeding <tom.smeding@gmail.com>
Date: Fri, 17 Jan 2020 10:50:47 +0100
Subject: Partial support for ID3v2.4

---
 src/encoding.rs | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

(limited to 'src/encoding.rs')

diff --git a/src/encoding.rs b/src/encoding.rs
index 9bc7290..598f993 100644
--- a/src/encoding.rs
+++ b/src/encoding.rs
@@ -34,15 +34,51 @@ pub fn from_ucs_2_bom(bytes: &[u8]) -> Option<String> {
             256 * bytes[2*i+1] as u16 + bytes[2*i] as u16
         };
 
-        match char::try_from(val as u32) {
+        match char::try_from(u32::from(val)) {
             Ok(c) => res.push(c),
             Err(_) => return None,
-        };
+        }
     }
 
     Some(res)
 }
 
+pub fn from_utf16_genericbom(bytes: &[u8], bom: u16) -> Option<String> {
+    let len = bytes.len();
+    guard!(len % 2 == 0);
+
+    let mut nibbles = Vec::with_capacity(len/2);
+
+    match bom {
+        0xfeff => {
+            for i in 1..len/2 {
+                nibbles.push((u16::from(bytes[2*i]) << 8) | u16::from(bytes[2*i+1]));
+            }
+        }
+
+        0xfffe => {
+            for i in 1..len/2 {
+                nibbles.push((u16::from(bytes[2*i+1]) << 8) | u16::from(bytes[2*i]));
+            }
+        }
+
+        _ => {  // Invalid BOM
+            return None
+        }
+    }
+
+    String::from_utf16(&nibbles).ok()
+}
+
+pub fn from_utf16_bom(bytes: &[u8]) -> Option<String> {
+    guard!(bytes.len() >= 2);
+    from_utf16_genericbom(&bytes[2..], read_big_endian(&bytes[0..2], 8) as u16)
+}
+
+pub fn from_utf16_nobom(bytes: &[u8]) -> Option<String> {
+    from_utf16_genericbom(bytes, 0xfeff)
+}
+
 pub fn from_utf8_mistaken_as_latin1(latin1: &str) -> io::Result<String> {
     latin1
         .chars()
-- 
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