adds RISCV-VP platform

env/riscv_vp/bsp_write.c

@@ -0,0 +1,21 @@
+/* See LICENSE of license details. */
+
+#include "platform.h"
+#include <errno.h>
+#include <stdint.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+ssize_t _bsp_write(int fd, const void *ptr, size_t len) {
+  const uint8_t *current = (const uint8_t *)ptr;
+  if (isatty(fd)) {
+    for (size_t jj = 0; jj < len; jj++) {
+      uart_write(uart, current[jj]);
+      if (current[jj] == '\n') {
+        uart_write(uart, '\r');
+      }
+    }
+    return len;
+  }
+  return 1;
+}