feat(esp8266): Add ets_printf in SDK side

components/esp8266/source/ets_printf.c

@@ -0,0 +1,49 @@
+// Copyright 2018-2019 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <stdint.h>
+#include <stdarg.h>
+
+#include "esp_attr.h"
+
+#include "esp8266/eagle_soc.h"
+#include "esp8266/uart_register.h"
+#include "esp8266/rom_functions.h"
+
+static void IRAM_ATTR uart_tx_one_char(char c)
+{
+    while (1) {
+        uint32_t fifo_cnt = READ_PERI_REG(UART_STATUS(0)) & (UART_TXFIFO_CNT << UART_TXFIFO_CNT_S);
+
+        if ((fifo_cnt >> UART_TXFIFO_CNT_S & UART_TXFIFO_CNT) < 126)
+            break;
+    }
+
+    WRITE_PERI_REG(UART_FIFO(0) , c);
+}
+
+/* Re-write ets_printf in SDK side, since ets_printf in ROM will use a global
+ * variable which address is in heap region of SDK side. If use ets_printf in ROM,
+ * this variable maybe re-write when heap alloc and modification.*/
+int IRAM_ATTR ets_printf(const char* fmt, ...)
+{
+    va_list ap;
+    int ret;
+
+    va_start(ap, fmt);
+    ret = ets_vprintf(uart_tx_one_char, fmt, ap);
+    va_end(ap);
+
+    return ret;
+}