[FEATURE] Port 708 decoder encoding module to RUST (#1607)

* feat: Add `decoder/encoding` new module

This `decoder/encoding.rs` file will contain the content of
`lib_ccx/ccx_708_decoder_encoding.c` file

* feat: Add encoding functions

* feat: Add conditional compilation to include Rust functions

* fix: conditional compilation logic

* refactor: Use of match statement instead of if-else

* fix: Calling C function for rust

* feat: Enable `derive_default` feature

src/lib_ccx/ccx_decoders_708_encoding.c

@@ -12,6 +12,8 @@ EIA-708, SO INTERNALLY WE USE THIS TABLE (FOR CONVENIENCE)
 A0-FF -> Group G1 as is - non-English characters and symbols
 */
 
+#if defined(DISABLE_RUST)
+
 unsigned char dtvcc_get_internal_from_G0(unsigned char g0_char)
 {
 	return g0_char;
@@ -43,3 +45,5 @@ unsigned char dtvcc_get_internal_from_G3(unsigned char g3_char)
 	// Rest unmapped, so we return a blank space
 	return 0x20;
 }
+
+#endif

src/lib_ccx/ccx_decoders_708_encoding.h

@@ -1,11 +1,18 @@
 #ifndef _CCX_DECODERS_708_ENCODING_H_
 #define _CCX_DECODERS_708_ENCODING_H_
 
-#define CCX_DTVCC_MUSICAL_NOTE_CHAR 9836	// Unicode Character 'BEAMED SIXTEENTH NOTES'
+#define CCX_DTVCC_MUSICAL_NOTE_CHAR 9836 // Unicode Character 'BEAMED SIXTEENTH NOTES'
 
+#ifndef DISABLE_RUST
+extern unsigned char dtvcc_get_internal_from_G0(unsigned char g0_char);
+extern unsigned char dtvcc_get_internal_from_G1(unsigned char g1_char);
+extern unsigned char dtvcc_get_internal_from_G2(unsigned char g2_char);
+extern unsigned char dtvcc_get_internal_from_G3(unsigned char g3_char);
+#else
 unsigned char dtvcc_get_internal_from_G0(unsigned char g0_char);
 unsigned char dtvcc_get_internal_from_G1(unsigned char g1_char);
 unsigned char dtvcc_get_internal_from_G2(unsigned char g2_char);
 unsigned char dtvcc_get_internal_from_G3(unsigned char g3_char);
+#endif
 
 #endif /*_CCX_DECODERS_708_ENCODING_H_*/

src/rust/build.rs

@@ -59,6 +59,8 @@ fn main() {
     }
 
     let bindings = builder
+        .derive_default(true)
+        .no_default("dtvcc_pen_attribs|dtvcc_pen_color|dtvcc_symbol")
         // Finish the builder and generate the bindings.
         .generate()
         // Unwrap the Result and panic on failure.

src/rust/src/decoder/encoding.rs

@@ -0,0 +1,45 @@
+/// 256 BYTES IS ENOUGH FOR ALL THE SUPPORTED CHARACTERS IN
+/// EIA-708, SO INTERNALLY WE USE THIS TABLE (FOR CONVENIENCE)
+///
+/// 00-1F -> Characters that are in the G2 group in 20-3F,
+///          except for 06, which is used for the closed captions
+///          sign "CC" which is defined in group G3 as 00. (this
+///          is by the article 33).
+/// 20-7F -> Group G0 as is - corresponds to the ASCII code
+/// 80-9F -> Characters that are in the G2 group in 60-7F
+///          (there are several blank characters here, that's OK)
+/// A0-FF -> Group G1 as is - non-English characters and symbols
+
+// NOTE: Same as `lib_ccx/ccx_decoder_708_encoding.c` file
+
+#[no_mangle]
+pub extern "C" fn dtvcc_get_internal_from_G0(g0_char: u8) -> u8 {
+    g0_char
+}
+
+#[no_mangle]
+pub extern "C" fn dtvcc_get_internal_from_G1(g1_char: u8) -> u8 {
+    g1_char
+}
+
+/// G2: Extended Control Code Set 1
+#[no_mangle]
+pub extern "C" fn dtvcc_get_internal_from_G2(g2_char: u8) -> u8 {
+    match g2_char {
+        0x20..=0x3F => g2_char - 0x20,
+        0x60..=0x7F => g2_char + 0x20,
+        _ => 0x20,
+    }
+}
+
+/// G3: Future Characters and Icon Expansion
+#[no_mangle]
+pub extern "C" fn dtvcc_get_internal_from_G3(g3_char: u8) -> u8 {
+    if g3_char == 0xa0 {
+        // The "CC" (closed captions) sign
+        0x06
+    } else {
+        // Rest unmapped, so we return a blank space
+        0x20
+    }
+}

src/rust/src/decoder/mod.rs

@@ -3,6 +3,7 @@
 //! Provides a CEA 708 decoder as defined by ANSI/CTA-708-E R-2018
 
 mod commands;
+mod encoding;
 mod output;
 mod service_decoder;
 mod timing;