feat(esp8266): Add ets_printf in SDK side

components/esp8266/include/esp8266/rom_functions.h

@@ -2,13 +2,14 @@
 #define _ROM_FUNCTIONS_H
 
 #include <stdint.h>
+#include <stdarg.h>
 
 uint32_t Wait_SPI_Idle();
 
 void uart_div_modify(uint32_t uart_no, uint32_t baud_div);
 
 void ets_delay_us(uint32_t us);
-int ets_printf(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
+int ets_vprintf(void (*putc)(char), const char* fmt, va_list ap);
 
 void system_soft_wdt_feed();
 

components/esp8266/include/esp_libc.h

@@ -36,6 +36,18 @@ extern "C" {
 uint32_t os_random(void);
 int32_t os_get_random(unsigned char *buf, size_t len);
 
+/**
+  * @brief  Printf the strings to uart or other devices, similar with printf, simple than printf.
+  *         Can not print float point data format, or longlong data format.
+  *
+  * @param  const char *fmt : See printf.
+  *
+  * @param  ... : See printf.
+  *
+  * @return int : the length printed to the output device.
+  */
+int ets_printf(const char *fmt, ...);
+
 #ifndef os_printf
 #define os_printf   printf
 #endif

components/esp8266/ld/eagle.rom.addr.v6.ld

@@ -57,4 +57,4 @@ PROVIDE ( gpio_input_get = 0x40004cf0 );
 PROVIDE ( gpio_pin_wakeup_disable = 0x40004ed4 );
 PROVIDE ( gpio_pin_wakeup_enable = 0x40004e90 );
 
-PROVIDE ( ets_printf = 0x400024cc );
+PROVIDE ( ets_vprintf = 0x40001f00 );

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;
+}