clean-up esp8266 PR to move symbols to flash

ChangeLog

@@ -1,5 +1,6 @@
      1v86 : Compile Telnet server into linux by default, Add '--telnet' command-line option to enable it
             Fix lock 'leak' in Telnet when Telnet is turned off
+            Add Telnet serial device to allow redirection
             Create errors for unterminated expressions (fix #814)
             Remove Espruino's built-in strcpy/etc
             Remove Espruino's built-in maths
@@ -14,6 +15,8 @@
             'Expecting a number or something iterable, got X' changed to exception rather than warning (gives stack trace)
             Drop '.init' and '.fini' symbols, allowing GCC 5.x compilation on STM32
             Ensure that pinMode/digitalWrite is re-constituted properly by dump() and save() (fix #833) 
+            ESP8266: add stack dump on fatal exception, ./targets/esp8266/printstack can extract a backtrace
+            ESP8266: move JswSymPtr and JswSymList to flash to free up gobs of RAM, bump jsvars to 1600
 
      1v85 : Ensure HttpServerResponse.writeHead actually sends the header right away
              - enables WebSocket Server support from JS

scripts/build_jswrapper.py

@@ -269,8 +269,9 @@ extern int os_printf_plus();
 
 JsVar *jswBinarySearch(const JswSymList *symbolsPtr, JsVar *parent, const char *name) {
   //os_printf_plus("bs%p %s\\n", symbolsPtr, name);
+  uint8_t symbolCount = READ_FLASH_UINT8(&symbolsPtr->symbolCount);
   int searchMin = 0;
-  int searchMax = symbolsPtr->symbolCount -1;
+  int searchMax = symbolCount - 1;
   while (searchMin <= searchMax) {
     int idx = (searchMin+searchMax) >> 1;
     const JswSymPtr *sym = &symbolsPtr->symbols[idx];

src/jswrap_object.c

@@ -222,13 +222,18 @@ void jswrap_object_keys_or_property_names_cb(
 
     while (symbols) {
       unsigned int i;
-      unsigned short symbolCount = READ_FLASH_UINT16(&symbols->symbolCount);
+      unsigned char symbolCount = READ_FLASH_UINT8(&symbols->symbolCount);
       unsigned short strOffset = READ_FLASH_UINT16(&symbols->symbols[i].strOffset);
       for (i=0;i<symbolCount;i++) {
-        char buf[256], *b, c;
+#ifndef ESP8266
+        JsVar *name = jsvNewFromString(&symbols->symbolChars[strOffset]);
+#else
+        // On the esp8266 the string is in flash, so we have to copy it to RAM first
+        char buf[64], *b, c;
         const char *s = &symbols->symbolChars[strOffset];
-        do { c = READ_FLASH_UINT8(s++); *b++ = c; } while(c);
+        do { c = READ_FLASH_UINT8(s++); *b++ = c; } while(c && b != buf+64);
         JsVar *name = jsvNewFromString(buf);
+#endif
         //os_printf_plus("OBJ cb %s\n", buf);
         callback(data, name);
         jsvUnLock(name);

src/jswrapper.h

@@ -58,19 +58,27 @@ typedef enum {
 // number of bits needed for each argument bit
 #define JSWAT_BITS GET_BIT_NUMBER(JSWAT_MASK+1)
 
+#ifndef ESP8266
+#define PACKED_JSW_SYM PACKED_FLAGS
+#else
+// On the esp8266 we put the JswSym* structures into flash and thus must make word-sized aligned
+// reads. Telling the compiler to pack the structs defeats that, so we have to take it out.
+#define PACKED_JSW_SYM
+#endif
+
 /// Structure for each symbol in the list of built-in symbols
 typedef struct {
   unsigned short strOffset;
   unsigned short functionSpec; // JsnArgumentType
   void (*functionPtr)(void);
-} JswSymPtr;//PACKED_FLAGS
+} PACKED_JSW_SYM JswSymPtr;
 
 /// Information for each list of built-in symbols
 typedef struct {
   const JswSymPtr *symbols;
   const char *symbolChars;
-  uint32_t symbolCount;
-} JswSymList;//PACKED_FLAGS
+  unsigned char symbolCount;
+} PACKED_JSW_SYM JswSymList;
 
 /// Do a binary search of the symbol table list
 JsVar *jswBinarySearch(const JswSymList *symbolsPtr, JsVar *parent, const char *name);