encoding.c: Implement support for the auto-detected character set (utf-8 + codepoint-encoding).

src/libespeak-ng/encoding.c

 	return c;
 }
 
+static uint32_t
+string_decoder_getc_auto(espeak_ng_TEXT_DECODER *decoder)
+{
+	const uint8_t *ptr = decoder->current;
+	uint32_t c = string_decoder_getc_utf_8(decoder);
+	if (c == 0xFFFD) {
+		decoder->get = string_decoder_getc_codepage;
+		decoder->current = ptr;
+		c = decoder->get(decoder);
+	}
+	return c;
+}
+
 typedef struct
 {
 	uint32_t (*get)(espeak_ng_TEXT_DECODER *decoder);
 	return ENS_OK;
 }
 
+espeak_ng_STATUS
+text_decoder_decode_string_auto(espeak_ng_TEXT_DECODER *decoder,
+                                const char *string,
+                                int length,
+                                espeak_ng_ENCODING encoding)
+{
+	if (encoding > ESPEAKNG_ENCODING_ISO_10646_UCS_2)
+		return ENS_UNKNOWN_TEXT_ENCODING;
+
+	const encoding_t *enc = string_decoders + encoding;
+	if (enc->get == NULL)
+		return ENS_UNKNOWN_TEXT_ENCODING;
+
+	decoder->get = string_decoder_getc_auto;
+	decoder->codepage = enc->codepage;
+	decoder->current = (const uint8_t *)string;
+	decoder->end = (const uint8_t *)(string + length);
+	return ENS_OK;
+}
+
 espeak_ng_STATUS
 text_decoder_decode_wstring(espeak_ng_TEXT_DECODER *decoder,
                             const wchar_t *string,

src/libespeak-ng/encoding.h

                            int length,
                            espeak_ng_ENCODING encoding);
 
+espeak_ng_STATUS
+text_decoder_decode_string_auto(espeak_ng_TEXT_DECODER *decoder,
+                                const char *string,
+                                int length,
+                                espeak_ng_ENCODING encoding);
+
 espeak_ng_STATUS
 text_decoder_decode_wstring(espeak_ng_TEXT_DECODER *decoder,
                             const wchar_t *string,

src/libespeak-ng/translate.c

 	return 0;
 }
 
-static espeak_ng_STATUS init_wstring_decoder(const wchar_t *text)
+static inline espeak_ng_STATUS init_wstring_decoder(const wchar_t *text)
 {
 	return text_decoder_decode_wstring(p_decoder, text, wcslen(text) + 1);
 }
 
-static espeak_ng_STATUS init_string_decoder(const char *text, espeak_ng_ENCODING encoding)
+static inline espeak_ng_STATUS init_string_decoder(const char *text, espeak_ng_ENCODING encoding)
 {
 	return text_decoder_decode_string(p_decoder, text, strlen(text) + 1, encoding);
 }
 
+static inline espeak_ng_STATUS init_string_decoder_auto(const char *text, espeak_ng_ENCODING encoding)
+{
+	return text_decoder_decode_string_auto(p_decoder, text, strlen(text) + 1, encoding);
+}
+
 const void *TranslateClause(Translator *tr, const void *vp_input, int *tone_out, char **voice_change)
 {
 	int ix;
 	case espeakCHARS_WCHAR:
 		init_wstring_decoder((const wchar_t *)vp_input);
 		break;
-	case espeakCHARS_AUTO: // TODO: Implement UTF-8 => 8BIT fallback on 0xFFFD UTF-8 characters.
+	case espeakCHARS_AUTO:
+		init_string_decoder_auto((const char *)vp_input, tr->encoding);
+		break;
 	case espeakCHARS_UTF8:
 		init_string_decoder((const char *)vp_input, ESPEAKNG_ENCODING_UTF_8);
 		break;

tests/encoding.c

 	destroy_text_decoder(decoder);
 }
 
+void
+test_auto_decoder()
+{
+	printf("testing auto decoder (UTF-8 + codepage-based fallback)\n");
+
+	espeak_ng_TEXT_DECODER *decoder = create_text_decoder();
+
+	// UTF-8
+	assert(text_decoder_decode_string_auto(decoder, "aG\xC2\xA0 ", 5, ESPEAKNG_ENCODING_ISO_8859_1) == ENS_OK);
+	assert(text_decoder_eof(decoder) == 0);
+	assert(text_decoder_getc(decoder) == 'a');
+	assert(text_decoder_eof(decoder) == 0);
+	assert(text_decoder_getc(decoder) == 'G');
+	assert(text_decoder_eof(decoder) == 0);
+	assert(text_decoder_getc(decoder) == 0xA0);
+	assert(text_decoder_eof(decoder) == 0);
+	assert(text_decoder_getc(decoder) == ' ');
+	assert(text_decoder_eof(decoder) == 1);
+
+	// ISO-8859-1
+	assert(text_decoder_decode_string_auto(decoder, "aG\240f", 4, ESPEAKNG_ENCODING_ISO_8859_1) == ENS_OK);
+	assert(text_decoder_eof(decoder) == 0);
+	assert(text_decoder_getc(decoder) == 'a');
+	assert(text_decoder_eof(decoder) == 0);
+	assert(text_decoder_getc(decoder) == 'G');
+	assert(text_decoder_eof(decoder) == 0);
+	assert(text_decoder_getc(decoder) == 0xA0);
+	assert(text_decoder_eof(decoder) == 0);
+	assert(text_decoder_getc(decoder) == 'f');
+	assert(text_decoder_eof(decoder) == 1);
+
+	destroy_text_decoder(decoder);
+}
+
 int
 main(int argc, char **argv)
 {
 	test_iso_10646_ucs_2_encoding();
 
 	test_wchar_decoder();
+	test_auto_decoder();
 
 	printf("done\n");