esp8266: Switch back to accumulating input data via ring buffer.

But now it's generic ring buffer implemented via ringbuf.h, and is intended
for any type of input, including dupterm's, not just UART. The general
process work like this: an interrupt-driven input source puts data into
input_buf, and then signals new data available via call to
mp_hal_signal_input().

esp8266/esp_mphal.c

@@ -39,6 +39,8 @@ extern void ets_wdt_disable(void);
 extern void wdt_feed(void);
 extern void ets_delay_us();
 
+STATIC byte input_buf_array[256];
+ringbuf_t input_buf = {input_buf_array, sizeof(input_buf_array)};
 void mp_hal_debug_tx_strn_cooked(void *env, const char *str, uint32_t len);
 const mp_print_t mp_debug_print = {NULL, mp_hal_debug_tx_strn_cooked};
 
@@ -151,3 +153,7 @@ void __assert_func(const char *file, int line, const char *func, const char *exp
     nlr_raise(mp_obj_new_exception_msg(&mp_type_AssertionError,
         "C-level assert"));
 }
+
+void mp_hal_signal_input(void) {
+    system_os_post(UART_TASK_ID, 0, 0);
+}

esp8266/esp_mphal.h

@@ -27,10 +27,16 @@
 #ifndef _INCLUDED_MPHAL_H_
 #define _INCLUDED_MPHAL_H_
 
+#include "py/ringbuf.h"
+
 struct _mp_print_t;
 // Structure for UART-only output via mp_printf()
 extern const struct _mp_print_t mp_debug_print;
 
+extern ringbuf_t input_buf;
+// Call this after putting data to input_buf
+void mp_hal_signal_input(void);
+
 void mp_hal_init(void);
 void mp_hal_rtc_init(void);
 void mp_hal_feed_watchdog(void);

esp8266/uart.c

@@ -159,7 +159,18 @@ static void uart0_rx_intr_handler(void *para) {
         read_chars:
 #if 1 //MICROPY_REPL_EVENT_DRIVEN is not available here
         ETS_UART_INTR_DISABLE();
-        system_os_post(UART_TASK_ID, 0, 0);
+
+        while (READ_PERI_REG(UART_STATUS(uart_no)) & (UART_RXFIFO_CNT << UART_RXFIFO_CNT_S)) {
+            uint8 RcvChar = READ_PERI_REG(UART_FIFO(uart_no)) & 0xff;
+            ringbuf_put(&input_buf, RcvChar);
+        }
+
+        mp_hal_signal_input();
+
+        // Clear pending FIFO interrupts
+        WRITE_PERI_REG(UART_INT_CLR(UART_REPL), UART_RXFIFO_TOUT_INT_CLR | UART_RXFIFO_FULL_INT_ST);
+        ETS_UART_INTR_ENABLE();
+
 #else
         while (READ_PERI_REG(UART_STATUS(uart_no)) & (UART_RXFIFO_CNT << UART_RXFIFO_CNT_S)) {
             uint8 RcvChar = READ_PERI_REG(UART_FIFO(uart_no)) & 0xff;
@@ -224,7 +235,7 @@ void mp_keyboard_interrupt(void);
 int interrupt_char;
 void uart_task_handler(os_event_t *evt) {
     int c, ret = 0;
-    while ((c = uart_rx_one_char(UART_REPL)) >= 0) {
+    while ((c = ringbuf_get(&input_buf)) >= 0) {
         if (c == interrupt_char) {
             mp_keyboard_interrupt();
         }
@@ -234,11 +245,6 @@ void uart_task_handler(os_event_t *evt) {
         }
     }
 
-    // Clear pending FIFO interrupts
-    WRITE_PERI_REG(UART_INT_CLR(UART_REPL), UART_RXFIFO_TOUT_INT_CLR | UART_RXFIFO_FULL_INT_ST);
-    // Enable UART interrupts, so our task will receive events again from IRQ handler
-    ETS_UART_INTR_ENABLE();
-
     if (ret & PYEXEC_FORCED_EXIT) {
         soft_reset();
     }