From 297a9d5cb0afd63ca288725c106e11d32085ca0b Mon Sep 17 00:00:00 2001
From: Marcel Kummer <tanuva@posteo.de>
Date: Fri, 20 Oct 2023 15:26:33 +0200
Subject: [PATCH] Add ability to configure SML meter workarounds

Make use of libsml's workaround options to apply a workaround for DZG
meters. This builds upon the changes from [libsml PR #133](https://github.com/volkszaehler/libsml/pull/133).
---
 etc/vzlogger_generic.schema.json | 10 ++++++++++
 include/protocols/MeterSML.hpp   |  1 +
 src/protocols/MeterSML.cpp       | 12 ++++++++++--
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/etc/vzlogger_generic.schema.json b/etc/vzlogger_generic.schema.json
index e0bdbabf..86e1bd4a 100644
--- a/etc/vzlogger_generic.schema.json
+++ b/etc/vzlogger_generic.schema.json
@@ -517,6 +517,11 @@
                             "type": "boolean",
                             "default": false,
                             "description": "use the local time for reading timestamp?"
+                        },
+                        "dzg_fix_negative_values": {
+                            "type": "boolean",
+                            "default": false,
+                            "description": "work around wrongly encoded negative values on some DZG meters"
                         }
                     },
                 "required": ["protocol", "device", "baudrate", "parity"]
@@ -559,6 +564,11 @@
                             "type": "boolean",
                             "default": false,
                             "description": "use the local time for reading timestamp?"
+                        },
+                        "dzg_fix_negative_values": {
+                            "type": "boolean",
+                            "default": false,
+                            "description": "work around wrongly encoded negative values on some DZG meters"
                         }
                     },
                 "required": ["protocol", "host", "baudrate", "parity"]
diff --git a/include/protocols/MeterSML.hpp b/include/protocols/MeterSML.hpp
index fe305652..a5f61236 100644
--- a/include/protocols/MeterSML.hpp
+++ b/include/protocols/MeterSML.hpp
@@ -65,6 +65,7 @@ class MeterSML : public vz::protocol::Protocol {
 	parity_type_t _parity;
 	std::string _pull;
 	bool _use_local_time;
+	sml_workarounds _sml_workarounds;
 
 	int _fd;                 /* file descriptor of port */
 	struct termios _old_tio; /* required to reset port */
diff --git a/src/protocols/MeterSML.cpp b/src/protocols/MeterSML.cpp
index 5bdaf33e..42aa2bb7 100644
--- a/src/protocols/MeterSML.cpp
+++ b/src/protocols/MeterSML.cpp
@@ -57,7 +57,7 @@
 #define SML_BUFFER_LEN 8096
 
 MeterSML::MeterSML(std::list<Option> options)
-	: Protocol("sml"), _host(""), _device(""), BUFFER_LEN(SML_BUFFER_LEN) {
+	: Protocol("sml"), _host(""), _device(""), _sml_workarounds(0), BUFFER_LEN(SML_BUFFER_LEN) {
 	OptionList optlist;
 
 	/* connection */
@@ -194,6 +194,14 @@ MeterSML::MeterSML(std::list<Option> options)
 		print(log_alert, "Failed to parse the parity", name().c_str());
 		throw;
 	}
+
+	try {
+		if (optlist.lookup_bool(options, "dzg_fix_negative_values")) {
+			_sml_workarounds |= SML_WORKAROUND_DZG_NEGATIVE;
+		}
+	} catch (vz::OptionNotFoundException &e) {
+		// Leave disabled if the option wasn't provided.
+	}
 }
 
 MeterSML::MeterSML(const MeterSML &proto) : Protocol(proto), _fd(ERR), BUFFER_LEN(SML_BUFFER_LEN) {}
@@ -279,7 +287,7 @@ ssize_t MeterSML::read(std::vector<Reading> &rds, size_t n) {
 	}
 
 	/* parse SML file & stripping escape sequences */
-	file = sml_file_parse(buffer + 8, bytes - 16);
+	file = sml_file_parse(buffer + 8, bytes - 16, _sml_workarounds);
 
 	/* obtain SML messagebody of type getResponseList */
 	for (short i = 0; i < file->messages_len; i++) {