Berry `int64.fromstring()` to convert a string to an int64 (#17953)

CHANGELOG.md

@@ -8,6 +8,7 @@ All notable changes to this project will be documented in this file.
 - ESP32 preliminary support for Matter protocol, milestone 1 (commissioning) by Stephan Hadinger
 - Basic support for Shelly Pro 4PM
 - Command ``DhtDelay<sensor> <high_delay>,<low_delay>`` to allow user control over high and low delay in microseconds (#17944)
+- Berry `int64.fromstring()` to convert a string to an int64
 
 ### Breaking Changed
 - TM1638 button and led support are handled as virtual switches and relays (#11031)

lib/libesp32/berry_int64/src/be_int64_class.c

@@ -53,6 +53,15 @@ char* int64_tostring(int64_t *i64) {
 }
 BE_FUNC_CTYPE_DECLARE(int64_tostring, "s", ".")
 
+int64_t* int64_fromstring(bvm *vm, const char* s) {
+  int64_t *i64 = (int64_t*)be_malloc(vm, sizeof(int64_t));
+  if (i64 == NULL) { be_raise(vm, "memory_error", "cannot allocate buffer"); }
+  if (s) { *i64 = atoll(s); }
+  else   { *i64 = 0; }
+  return i64;
+}
+BE_FUNC_CTYPE_DECLARE(int64_fromstring, "int64", "@s")
+
 int32_t int64_toint(int64_t *i64) {
   return (int32_t) *i64;
 }
@@ -190,6 +199,7 @@ class be_class_int64 (scope: global, name: int64) {
   set, ctype_func(int64_set)
 
   tostring, ctype_func(int64_tostring)
+  fromstring, static_ctype_func(int64_fromstring)
   toint, ctype_func(int64_toint)
 
   +, ctype_func(int64_add)