Added fallbacks strlen_P, strncmp_P, strcmp_P and memcpy_P (fixes #1073)

src/ArduinoJson/Deserialization/FlashStringReader.hpp

@@ -15,7 +15,7 @@ class UnsafeFlashStringReader {
       : _ptr(reinterpret_cast<const char*>(ptr)) {}
 
   int read() {
-    return pgm_read_byte_near(_ptr++);
+    return pgm_read_byte(_ptr++);
   }
 };
 
@@ -29,7 +29,7 @@ class SafeFlashStringReader {
 
   int read() {
     if (_ptr < _end)
-      return pgm_read_byte_near(_ptr++);
+      return pgm_read_byte(_ptr++);
     else
       return -1;
   }

src/ArduinoJson/Polyfills/pgmspace.hpp

@@ -0,0 +1,62 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2019
+// MIT License
+
+#pragma once
+
+namespace ARDUINOJSON_NAMESPACE {
+// Wraps a const char* so that the our functions are picked only if the
+// originals are missing
+struct pgm_p {
+  pgm_p(const char* p) : address(p) {}
+  const char* address;
+};
+}  // namespace ARDUINOJSON_NAMESPACE
+
+#ifndef strlen_P
+inline size_t strlen_P(ARDUINOJSON_NAMESPACE::pgm_p s) {
+  const char* p = s.address;
+  while (pgm_read_byte(p)) p++;
+  return size_t(p - s.address);
+}
+#endif
+
+#ifndef strncmp_P
+inline int strncmp_P(const char* a, ARDUINOJSON_NAMESPACE::pgm_p b, size_t n) {
+  const char* s1 = a;
+  const char* s2 = b.address;
+  while (n-- > 0) {
+    char c1 = *s1++;
+    char c2 = static_cast<char>(pgm_read_byte(s2++));
+    if (c1 < c2) return -1;
+    if (c1 > c2) return 1;
+    if (c1 == 0 /* and c2 as well */) return 0;
+  }
+  return 0;
+}
+#endif
+
+#ifndef strcmp_P
+inline int strcmp_P(const char* a, ARDUINOJSON_NAMESPACE::pgm_p b) {
+  const char* s1 = a;
+  const char* s2 = b.address;
+  for (;;) {
+    char c1 = *s1++;
+    char c2 = static_cast<char>(pgm_read_byte(s2++));
+    if (c1 < c2) return -1;
+    if (c1 > c2) return 1;
+    if (c1 == 0 /* and c2 as well */) return 0;
+  }
+}
+#endif
+
+#ifndef memcpy_P
+inline void* memcpy_P(void* dst, ARDUINOJSON_NAMESPACE::pgm_p src, size_t n) {
+  uint8_t* d = reinterpret_cast<uint8_t*>(dst);
+  const char* s = src.address;
+  while (n-- > 0) {
+    *d++ = pgm_read_byte(s++);
+  }
+  return dst;
+}
+#endif

src/ArduinoJson/Strings/FlashStringAdapter.hpp

@@ -4,6 +4,8 @@
 
 #pragma once
 
+#include "../Polyfills/pgmspace.hpp"
+
 namespace ARDUINOJSON_NAMESPACE {
 
 class FlashStringAdapter {