Use ENS_ for eSpeak NG error codes, and standardize on a numbering scheme.

src/espeak-ng.c

 	espeak_ng_InitializePath(data_path);
 	espeak_ng_STATUS result = espeak_ng_Initialize();
 	if (result != ENS_OK) {
-		if (result == ENE_VERSION_MISMATCH)
+		if (result == ENS_VERSION_MISMATCH)
 			fprintf(stderr, "Wrong version of espeak-data\n");
 		else
 			fprintf(stderr, "Failed to load espeak-data\n");

src/include/espeak-ng/espeak_ng.h

 #endif
 
 typedef enum {
-	ENS_OK = 0,
+	ENS_GROUP_MASK               = 0x70000000,
+	ENS_GROUP_ERRNO              = 0x00000000, /* Values 0-255 map to errno error codes. */
+	ENS_GROUP_ESPEAK_NG          = 0x10000000, /* eSpeak NG error codes. */
 
-	/* 0 to 255 : errno */
-
-	/* Error Codes (< 0) */
-
-	ENE_COMPILE_ERRORS = -4,
-	ENE_VERSION_MISMATCH = -5,
+	ENS_OK                       = 0,
+	ENS_COMPILE_ERROR            = 0x100001FF,
+	ENS_VERSION_MISMATCH         = 0x100002FF,
 } espeak_ng_STATUS;
 
 typedef enum {

src/libespeak-ng/compiledata.c

 		fclose(f_errors);
 
 	ReadPhondataManifest();
-	return error_count > 0 ? ENE_COMPILE_ERRORS : ENS_OK;
+	return error_count > 0 ? ENS_COMPILE_ERROR : ENS_OK;
 }
 
 static const char *preset_tune_names[] = {
 
 	LoadPhData(NULL);
 
-	return error_count > 0 ? ENE_COMPILE_ERRORS : ENS_OK;
+	return error_count > 0 ? ENS_COMPILE_ERROR : ENS_OK;
 }
 
 espeak_ng_STATUS espeak_ng_CompilePhonemeData(long rate, FILE *log)

src/libespeak-ng/compiledict.c

 
 	LoadDictionary(translator, dict_name, 0);
 
-	return error_count > 0 ? ENE_COMPILE_ERRORS : ENS_OK;
+	return error_count > 0 ? ENS_COMPILE_ERROR : ENS_OK;
 }
 #pragma GCC visibility pop

src/libespeak-ng/speak_lib.c

 	espeak_ng_InitializePath(path);
 	espeak_ng_STATUS result = espeak_ng_Initialize();
 	if (result != ENS_OK) {
-		if (result == ENE_VERSION_MISMATCH)
+		if (result == ENS_VERSION_MISMATCH)
 			fprintf(stderr, "Wrong version of espeak-data (expected 0x%x) at %s\n", version_phdata, path_home);
 		else {
 			fprintf(stderr, "Failed to load espeak-data\n");

src/libespeak-ng/synthdata.c

 	}
 
 	if (version != version_phdata)
-		return ENE_VERSION_MISMATCH;
+		return ENS_VERSION_MISMATCH;
 
 	// set up phoneme tables
 	p = phoneme_tab_data;

src/speak-ng.c

 	espeak_ng_InitializePath(data_path);
 	espeak_ng_STATUS result = espeak_ng_Initialize();
 	if (result != ENS_OK) {
-		if (result == ENE_VERSION_MISMATCH)
+		if (result == ENS_VERSION_MISMATCH)
 			fprintf(stderr, "Wrong version of espeak-data (expected 0x%x) at %s\n", version_phdata, path_home);
 		else
 			fprintf(stderr, "Failed to load espeak-data\n");