AP_Common: add method to find the offset of a byte in a buffer

ArduPilot · Feb 26, 2024 · 9799832 · 9799832
1 parent f673617
commit 9799832
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diff --git a/libraries/AP_Common/AP_Common.cpp b/libraries/AP_Common/AP_Common.cpp
@@ -104,3 +104,13 @@ int16_t char_to_hex(char a)
     else
         return a - '0';
 }
+
+int16_t offset_of_byte_in_buffer(uint8_t byte, const uint8_t *buffer, uint16_t buffer_len)
+{
+    const uint8_t *p = (const uint8_t *)memchr(buffer, byte, buffer_len);
+    if (p == nullptr) {
+        // preamble not found
+        return -1;
+    }
+    return p - buffer;
+}
diff --git a/libraries/AP_Common/AP_Common.h b/libraries/AP_Common/AP_Common.h
@@ -170,6 +170,9 @@ size_t strncpy_noterm(char *dest, const char *src, size_t n);
 // return the numeric value of an ascii hex character
 int16_t char_to_hex(char a);
 
+// returns offset into buffer where byte is found, -1 if not found:
+int16_t offset_of_byte_in_buffer(uint8_t byte, const uint8_t *buffer, uint16_t buffer_len);
+
 /*
   Bit manipulation
  */