From ff8a73c2d140ee1847c308fc6d0bd4f3f3109a62 Mon Sep 17 00:00:00 2001
From: mulder-fbi <leonhard.stutz@googlemail.com>
Date: Wed, 16 Aug 2023 00:52:56 +0200
Subject: [PATCH] Fix 24 bit signed integer parsing in sml parser (#5250)

---
 esphome/components/sml/sml_parser.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/esphome/components/sml/sml_parser.cpp b/esphome/components/sml/sml_parser.cpp
index ff7da4cabd..91b320a30e 100644
--- a/esphome/components/sml/sml_parser.cpp
+++ b/esphome/components/sml/sml_parser.cpp
@@ -88,6 +88,11 @@ uint64_t bytes_to_uint(const bytes &buffer) {
   for (auto const value : buffer) {
     val = (val << 8) + value;
   }
+  // Some smart meters send 24 bit signed integers. Sign extend to 64 bit if the
+  // 24 bit value is negative.
+  if (buffer.size() == 3 && buffer[0] & 0x80) {
+    val |= 0xFFFFFFFFFF000000;
+  }
   return val;
 }