When rx_avaiable is checked return rx_buffer plus rx_fifo. Then during rx_read and rx_peek functions copy over the data in the fifo as needed.

Author: mribble

cores/esp8266/uart.c

@@ -91,6 +91,33 @@ size_t uart_resize_rx_buffer(uart_t* uart, size_t new_size)
     return uart->rx_buffer->size;
 }
 
+inline size_t uart_rx_buffer_available(uart_t* uart) {
+    if(uart->rx_buffer->wpos < uart->rx_buffer->rpos) {
+      return (uart->rx_buffer->wpos + uart->rx_buffer->size) - uart->rx_buffer->rpos;
+    }
+    return uart->rx_buffer->wpos - uart->rx_buffer->rpos;
+}
+
+inline size_t uart_rx_fifo_available(uart_t* uart) {
+    return (USS(uart->uart_nr) >> USRXC) & 0x7F;
+}
+
+// Copy all the rx fifo bytes that fit into the rx buffer
+inline void uart_rx_copy_fifo_to_buffer(uart_t* uart) {
+    while(uart_rx_fifo_available(uart)){
+        size_t nextPos = (uart->rx_buffer->wpos + 1) % uart->rx_buffer->size;
+        if(nextPos != uart->rx_buffer->rpos) {
+            uint8_t data = USF(uart->uart_nr);
+            uart->rx_buffer->buffer[uart->rx_buffer->wpos] = data;
+            uart->rx_buffer->wpos = nextPos;
+        }
+        else {
+            // Stop copying if rx buffer is full
+            break;
+        }
+    }
+}
+
 int uart_peek_char(uart_t* uart)
 {
     if(uart == NULL || !uart->rx_enabled) {
@@ -99,6 +126,11 @@ int uart_peek_char(uart_t* uart)
     if (!uart_rx_available(uart)) {
         return -1;
     }
+    if (uart_rx_buffer_available(uart) == 0) {
+        ETS_UART_INTR_DISABLE();
+        uart_rx_copy_fifo_to_buffer(uart);
+        ETS_UART_INTR_ENABLE();
+    }
     return uart->rx_buffer->buffer[uart->rx_buffer->rpos];
 }
 
@@ -119,20 +151,7 @@ size_t uart_rx_available(uart_t* uart)
     if(uart == NULL || !uart->rx_enabled) {
         return 0;
     }
-    ETS_UART_INTR_DISABLE();
-    while((USS(uart->uart_nr) >> USRXC) & 0x7F){
-        uint8_t data = USF(uart->uart_nr);
-        size_t nextPos = (uart->rx_buffer->wpos + 1) % uart->rx_buffer->size;
-        if(nextPos != uart->rx_buffer->rpos) {
-            uart->rx_buffer->buffer[uart->rx_buffer->wpos] = data;
-            uart->rx_buffer->wpos = nextPos;
-        }
-    }
-    ETS_UART_INTR_ENABLE();
-    if(uart->rx_buffer->wpos < uart->rx_buffer->rpos) {
-      return (uart->rx_buffer->wpos + uart->rx_buffer->size) - uart->rx_buffer->rpos;
-    }
-    return uart->rx_buffer->wpos - uart->rx_buffer->rpos;
+    return uart_rx_buffer_available(uart) + uart_rx_fifo_available(uart);
 }
 
 
@@ -145,14 +164,7 @@ void ICACHE_RAM_ATTR uart_isr(void * arg)
         return;
     }
     if(USIS(uart->uart_nr) & ((1 << UIFF) | (1 << UITO))){
-        while((USS(uart->uart_nr) >> USRXC) & 0x7F){
-            uint8_t data = USF(uart->uart_nr);
-            size_t nextPos = (uart->rx_buffer->wpos + 1) % uart->rx_buffer->size;
-            if(nextPos != uart->rx_buffer->rpos) {
-                uart->rx_buffer->buffer[uart->rx_buffer->wpos] = data;
-                uart->rx_buffer->wpos = nextPos;
-            }
-        }
+        uart_rx_copy_fifo_to_buffer(uart);
     }
     USIC(uart->uart_nr) = USIS(uart->uart_nr);
 }