Use the ENOMEM errno code instead of ENE_OUT_OF_MEMORY.

src/include/espeak-ng/espeak_ng.h

 #endif
 
 typedef enum {
-	/* Success Codes (>= 0) */
-
 	ENS_OK = 0,
 
+	/* 0 to 255 : errno */
+
 	/* Error Codes (< 0) */
 
 	ENE_READ_ERROR = -1,
 	ENE_WRITE_ERROR = -2,
-	ENE_OUT_OF_MEMORY = -3,
 	ENE_COMPILE_ERRORS = -4,
 	ENE_VERSION_MISMATCH = -5,
 } espeak_ng_STATUS;

src/libespeak-ng/compiledata.c

 
 #include "config.h"
 
+#include <errno.h>
 #include <stdio.h>
 #include <string.h>
 #include <ctype.h>
 		fprintf(f_errors, "Failed to allocate data for tunes\n");
 		fclose(f_in);
 		fclose(f_errors);
-		return ENE_OUT_OF_MEMORY;
+		return ENOMEM;
 	}
 
 	sprintf(buf, "%s/intonations", path_home);

src/libespeak-ng/speak_lib.c

 
 #include "config.h"
 
+#include "errno.h"
 #include "stdio.h"
 #include "ctype.h"
 #include "string.h"
 	outbuf_size = (buffer_length * samplerate)/500;
 	outbuf = (unsigned char *)realloc(outbuf, outbuf_size);
 	if ((out_start = outbuf) == NULL)
-		return ENE_OUT_OF_MEMORY;
+		return ENOMEM;
 
 	// allocate space for event list.  Allow 200 events per second.
 	// Add a constant to allow for very small buf_length
 	n_event_list = (buffer_length*200)/1000 + 20;
 	if ((event_list = (espeak_EVENT *)realloc(event_list, sizeof(espeak_EVENT) * n_event_list)) == NULL)
-		return ENE_OUT_OF_MEMORY;
+		return ENOMEM;
 
 	return ENS_OK;
 }