2 files changed, 25 insertions, 2 deletions
diff --git a/qtmips_machine/serialport.cpp b/qtmips_machine/serialport.cpp
index 9e4177b..c636d38 100644
--- a/qtmips_machine/serialport.cpp
+++ b/qtmips_machine/serialport.cpp
@@ -51,6 +51,7 @@ using namespace machine;
 
 SerialPort::SerialPort() {
     rx_st_reg = 0;
+    rx_data_reg = 0;
     tx_st_reg = 0;
 }
 
@@ -58,6 +59,18 @@ SerialPort::~SerialPort() {
 
 }
 
+void SerialPort::pool_rx_byte() const {
+    unsigned int byte = 0;
+    bool available = false;
+    if (!(rx_st_reg & SERP_RX_ST_REG_READY_m)) {
+        emit rx_byte_pool(0, byte, available);
+        if (available) {
+            rx_data_reg = byte;
+            rx_st_reg |= SERP_RX_ST_REG_READY_m;
+        }
+    }
+}
+
 bool SerialPort::wword(std::uint32_t address, std::uint32_t value) {
 #if 0
     printf("SerialPort::wword address 0x%08lx data 0x%08lx\n",
@@ -90,10 +103,17 @@ std::uint32_t SerialPort::rword(std::uint32_t address, bool debug_access) const
 #endif
     switch (address) {
     case SERP_RX_ST_REG_o:
+        pool_rx_byte();
         value = rx_st_reg;
         break;
     case SERP_RX_DATA_REG_o:
-        value = 0;
+        pool_rx_byte();
+        if (rx_st_reg & SERP_RX_ST_REG_READY_m) {
+            value = rx_data_reg;
+            rx_st_reg &= ~SERP_RX_ST_REG_READY_m;
+        } else {
+            value = 0;
+        }
         break;
     case SERP_TX_ST_REG_o:
         value = tx_st_reg | SERP_TX_ST_REG_READY_m;
diff --git a/qtmips_machine/serialport.h b/qtmips_machine/serialport.h
index add1fe6..5262720 100644
--- a/qtmips_machine/serialport.h
+++ b/qtmips_machine/serialport.h
@@ -52,6 +52,7 @@ public:
 
 signals:
     void tx_byte(unsigned int data);
+    void rx_byte_pool(int fd, unsigned int &data, bool &available) const;
     void write_notification(std::uint32_t address, std::uint32_t value);
     void read_notification(std::uint32_t address, std::uint32_t *value) const;
 
@@ -59,7 +60,9 @@ public:
     bool wword(std::uint32_t address, std::uint32_t value);
     std::uint32_t rword(std::uint32_t address, bool debug_access = false) const;
 private:
-    std::uint32_t rx_st_reg;
+    void pool_rx_byte() const;
+    mutable std::uint32_t rx_st_reg;
+    mutable std::uint32_t rx_data_reg;
     std::uint32_t tx_st_reg;
 };