Merge remote-tracking branch 'remotes/esp8266/esp8266' into esp8266

cores/esp8266/Arduino.h

@@ -39,6 +39,7 @@ extern "C" {
 #include "twi.h"
 
 void yield(void);
+void optimistic_yield(void);
 
 #define HIGH 0x1
 #define LOW  0x0

cores/esp8266/HardwareSerial.cpp

@@ -552,13 +552,17 @@ bool HardwareSerial::isRxEnabled(void) {
 }
 
 int HardwareSerial::available(void) {
-    if(_uart == 0)
-        return 0;
-    if(_uart->rxEnabled) {
-        return static_cast<int>(_rx_buffer->getSize());
-    } else {
-        return 0;
+    int result = 0;
+
+    if (_uart != NULL && _uart->rxEnabled) {
+        result = static_cast<int>(_rx_buffer->getSize());
     }
+
+    if (!result) {
+        optimistic_yield();
+    }
+
+    return result;
 }
 
 int HardwareSerial::peek(void) {

cores/esp8266/core_esp8266_main.cpp

@@ -34,6 +34,8 @@ extern "C" {
 #define LOOP_TASK_PRIORITY 0
 #define LOOP_QUEUE_SIZE    1
 
+#define OPTIMISTIC_YIELD_TIME_US 16000
+
 struct rst_info resetInfo;
 
 int atexit(void (*func)()) {
@@ -62,11 +64,8 @@ extern void (*__init_array_end)(void);
 cont_t g_cont __attribute__ ((aligned (16)));
 static os_event_t g_loop_queue[LOOP_QUEUE_SIZE];
 
-static uint32_t g_micros_at_task_start;
+static uint32_t g_micros_at_last_task_yield;
 
-extern "C" uint32_t esp_micros_at_task_start() {
-    return g_micros_at_task_start;
-}
 
 extern "C" void abort() {
     while(1) {
@@ -74,6 +73,7 @@ extern "C" void abort() {
 }
 
 extern "C" void esp_yield() {
+    g_micros_at_last_task_yield = system_get_time();
     cont_yield(&g_cont);
 }
 
@@ -87,6 +87,14 @@ extern "C" void __yield() {
 }
 extern "C" void yield(void) __attribute__ ((weak, alias("__yield")));
 
+extern "C" void optimistic_yield(void) {
+    if (!ETS_INTR_WITHINISR() && 
+        (system_get_time() - g_micros_at_last_task_yield) > OPTIMISTIC_YIELD_TIME_US)
+    {
+        __yield();
+    }
+}
+
 static void loop_wrapper() {
     static bool setup_done = false;
     if(!setup_done) {
@@ -99,7 +107,7 @@ static void loop_wrapper() {
 }
 
 static void loop_task(os_event_t *events) {
-    g_micros_at_task_start = system_get_time();
+    g_micros_at_last_task_yield = system_get_time();
     cont_run(&g_cont, &loop_wrapper);
     if(cont_check(&g_cont) != 0) {
         ets_printf("\r\nheap collided with sketch stack\r\n");

cores/esp8266/core_esp8266_si2c.c

@@ -1,9 +1,9 @@
-/* 
+/*
   si2c.c - Software I2C library for esp8266
 
   Copyright (c) 2015 Hristo Gochkov. All rights reserved.
   This file is part of the esp8266 core for Arduino environment.
- 
+
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
@@ -26,10 +26,10 @@ unsigned char twi_dcount = 18;
 static unsigned char twi_sda, twi_scl;
 
 #define SDA_LOW()   (GPES = (1 << twi_sda)) //Enable SDA (becomes output and since GPO is 0 for the pin, it will pull the line low)
-#define SDA_HIGH()  (GPEC = (1 << twi_sda)) //Disable SDA (becomes input and since it has pullup it will go high) 
+#define SDA_HIGH()  (GPEC = (1 << twi_sda)) //Disable SDA (becomes input and since it has pullup it will go high)
 #define SDA_READ()  ((GPI & (1 << twi_sda)) != 0)
-#define SCL_LOW()   (GPES = (1 << twi_scl)) 
-#define SCL_HIGH()  (GPEC = (1 << twi_scl)) 
+#define SCL_LOW()   (GPES = (1 << twi_scl))
+#define SCL_HIGH()  (GPEC = (1 << twi_scl))
 #define SCL_READ()  ((GPI & (1 << twi_scl)) != 0)
 
 #ifndef FCPU80
@@ -37,9 +37,9 @@ static unsigned char twi_sda, twi_scl;
 #endif
 
 #if F_CPU == FCPU80
-#define TWI_CLOCK_STRETCH 200
+#define TWI_CLOCK_STRETCH 800
 #else
-#define TWI_CLOCK_STRETCH 400
+#define TWI_CLOCK_STRETCH 1600
 #endif
 
 void twi_setClock(unsigned int freq){
@@ -99,7 +99,7 @@ static bool twi_write_stop(void){
   twi_delay(twi_dcount);
   SDA_HIGH();
   twi_delay(twi_dcount);
-  
+
   return true;
 }
 
@@ -166,7 +166,8 @@ unsigned char twi_readFrom(unsigned char address, unsigned char* buf, unsigned i
   unsigned int i;
   if(!twi_write_start()) return 4;//line busy
   if(!twi_write_byte(((address << 1) | 1) & 0xFF)) return 2;//received NACK on transmit of address
-  for(i=0; i<len; i++) buf[i] = twi_read_byte(false);
+  for(i=0; i<(len-1); i++) buf[i] = twi_read_byte(false);
+  buf[len-1] = twi_read_byte(true);
   if(sendStop) twi_write_stop();
   i = 0;
   while(SDA_READ() == 0 && (i++) < 10){