sr: Add sr_strerror() and sr_strerror_name().

Makefile.am

@@ -37,6 +37,7 @@ libsigrok_la_SOURCES = \
 	strutil.c \
 	log.c \
 	version.c
+	error.c
 
 libsigrok_la_LIBADD = \
 	$(LIBOBJS) \

error.c

@@ -0,0 +1,110 @@
+/*
+ * This file is part of the sigrok project.
+ *
+ * Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include "libsigrok.h"
+
+/**
+ * Return a human-readable error string for the given libsigrok error code.
+ *
+ * @param error_code A libsigrok error code number, such as SR_ERR_MALLOC.
+ * @return A const string containing a short, human-readable (English)
+ *         description of the error, such as "memory allocation error".
+ *         The string must NOT be free'd by the caller!
+ * @see sr_strerror_name
+ */
+SR_API const char *sr_strerror(int error_code)
+{
+	const char *str;
+
+	/*
+	 * Note: All defined SR_* error macros from libsigrok.h should have
+	 * an entry in this function, as well as in sr_strerror_name().
+	 */
+
+	switch (error_code) {
+	case SR_OK:
+		str = "no error";
+		break;
+	case SR_ERR:
+		str = "generic/unspecified error";
+		break;
+	case SR_ERR_MALLOC:
+		str = "memory allocation error";
+		break;
+	case SR_ERR_BUG:
+		str = "internal error";
+		break;
+	case SR_ERR_SAMPLERATE:
+		str = "invalid samplerate";
+		break;
+	default:
+		str = "unknown error";
+		break;
+	}
+
+	return str;
+}
+
+/**
+ * Return the "name" string of the given libsigrok error code.
+ *
+ * For example, the "name" of the SR_ERR_MALLOC error code is "SR_ERR_MALLOC",
+ * the name of the SR_OK code is "SR_OK", and so on.
+ *
+ * This function can be used for various purposes where the "name" string of
+ * a libsigrok error code is useful.
+ *
+ * @param error_code A libsigrok error code number, such as SR_ERR_MALLOC.
+ * @return A const string containing the "name" of the error code as string.
+ *         The string must NOT be free'd by the caller!
+ * @see sr_strerror
+ */
+SR_API const char *sr_strerror_name(int error_code)
+{
+	const char *str;
+
+	/*
+	 * Note: All defined SR_* error macros from libsigrok.h should have
+	 * an entry in this function, as well as in sr_strerror().
+	 */
+
+	switch (error_code) {
+	case SR_OK:
+		str = "SR_OK";
+		break;
+	case SR_ERR:
+		str = "SR_ERR";
+		break;
+	case SR_ERR_MALLOC:
+		str = "SR_ERR_MALLOC";
+		break;
+	case SR_ERR_BUG:
+		str = "SR_ERR_BUG";
+		break;
+	case SR_ERR_SAMPLERATE:
+		str = "SR_ERR_SAMPLERATE";
+		break;
+	default:
+		str = "unknown error code";
+		break;
+	}
+
+	return str;
+}

proto.h

@@ -141,4 +141,9 @@ SR_API int sr_lib_version_revision_get(void);
 SR_API int sr_lib_version_age_get(void);
 SR_API const char *sr_lib_version_string_get(void);
 
+/*--- error.c ---------------------------------------------------------------*/
+
+SR_API const char *sr_strerror(int error_code);
+SR_API const char *sr_strerror_name(int error_code);
+
 #endif