readFile (and File.read) now uses Flat Strings to allow more memory efficient reads (fix #932)

ChangeLog

@@ -23,7 +23,8 @@
             nRF52: BLE HID support and switchable Nordic UART
             Fix STM32 regression where pinMode was set when it shouldn't have been
             Add Third option to pinMode to allow the pin mode to be set while keeping it 'unforced'
-            save and dump now keep track of whether pin mode had been forced or not
+            Save and dump now keep track of whether pin mode had been forced or not
+            readFile (and File.read) now uses Flat Strings to allow more memory efficient reads (fix #932)
 
      1v87 : Add support for compiling with float-abi=hard (even if it doesn't give us real-world benefits)
             Add shortcut for quick execution of common call types

libs/filesystem/jswrap_file.c

@@ -440,6 +440,7 @@ size_t jswrap_file_write(JsVar* parent, JsVar* buffer) {
 Read data in a file in byte size chunks
 */
 JsVar *jswrap_file_read(JsVar* parent, int length) {
+  if (length<0) length=0;
   JsVar *buffer = 0;
   JsvStringIterator it;
   FRESULT res = 0;
@@ -448,8 +449,19 @@ JsVar *jswrap_file_read(JsVar* parent, int length) {
     JsFile file;
     if (fileGetFromVar(&file, parent)) {
       if(file.data.mode == FM_READ || file.data.mode == FM_READ_WRITE) {
-        char buf[32];
         size_t actual = 0;
+#ifndef LINUX
+        // if we're able to load this into a flat string, do it!
+        size_t len = f_size(&file.data.handle)-f_tell(&file.data.handle);
+        if (len>(size_t)length) len=(size_t)length;
+        buffer = jsvNewFlatStringOfLength(len);
+        if (buffer) {
+          res = f_read(&file.data.handle, jsvGetFlatStringPointer(buffer), len, &actual);
+          if (res) jsfsReportError("Unable to read file", res);
+          return buffer;
+        }
+#endif
+        char buf[32];
 
         while (bytesRead < (size_t)length) {
           size_t requested = (size_t)length - bytesRead;

src/jswrap_pin.c

@@ -164,7 +164,7 @@ JsVar *jswrap_pin_getMode(JsVar *parent) {
 Set the mode of the given pin. See [`pinMode`](#l__global_pinMode) for more information on pin modes.
  */
 void jswrap_pin_mode(JsVar *parent, JsVar *mode) {
-  jswrap_io_pinMode(jshGetPinFromVar(parent), mode);  
+  jswrap_io_pinMode(jshGetPinFromVar(parent), mode, false);
 }
 
 /*JSON{