feat: usart retarget

Core/Src/retarget.c

@@ -0,0 +1,98 @@
+#include <_ansi.h>
+#include <_syslist.h>
+#include <errno.h>
+#include <sys/time.h>
+#include <sys/times.h>
+#include <retarget.h>
+#include <stdint.h>
+
+#if !defined(OS_USE_SEMIHOSTING)
+
+#define STDIN_FILENO  0
+#define STDOUT_FILENO 1
+#define STDERR_FILENO 2
+
+UART_HandleTypeDef *gHuart;
+
+void RetargetInit(UART_HandleTypeDef *huart)
+{
+    gHuart = huart;
+    
+        /* Disable I/O buffering for STDOUT stream, so that
+         * chars are sent out as soon as they are printed. */
+        setvbuf(stdout, NULL, _IONBF, 0);
+}
+
+int _isatty(int fd)
+{
+    if (fd >= STDIN_FILENO && fd <= STDERR_FILENO)
+        return 1;
+    
+        errno = EBADF;
+    return 0;
+}
+
+int _write(int fd, char *ptr, int len)
+{
+    HAL_StatusTypeDef hstatus;
+    
+        if (fd == STDOUT_FILENO || fd == STDERR_FILENO)
+        {
+            hstatus = HAL_UART_Transmit(gHuart, (uint8_t *) ptr, len, HAL_MAX_DELAY);
+            if (hstatus == HAL_OK)
+                return len;
+            else
+                return EIO;
+        }
+    errno = EBADF;
+    return -1;
+}
+
+int _close(int fd)
+{
+    if (fd >= STDIN_FILENO && fd <= STDERR_FILENO)
+        return 0;
+    
+        errno = EBADF;
+    return -1;
+}
+
+int _lseek(int fd, int ptr, int dir)
+{
+    (void) fd;
+    (void) ptr;
+    (void) dir;
+    
+        errno = EBADF;
+    return -1;
+}
+
+int _read(int fd, char *ptr, int len)
+{
+    HAL_StatusTypeDef hstatus;
+    
+        if (fd == STDIN_FILENO)
+        {
+            hstatus = HAL_UART_Receive(gHuart, (uint8_t *) ptr, 1, HAL_MAX_DELAY);
+            if (hstatus == HAL_OK)
+                return 1;
+            else
+                return EIO;
+        }
+    errno = EBADF;
+    return -1;
+}
+
+int _fstat(int fd, struct stat *st)
+{
+    if (fd >= STDIN_FILENO && fd <= STDERR_FILENO)
+    {
+        st->st_mode = S_IFCHR;
+        return 0;
+    }
+    
+        errno = EBADF;
+    return 0;
+}
+
+#endif //#if !defined(OS_USE_SEMIHOSTING)