Refactor libc stubs into libwrap

The --wrap feature of GNU ld supports a cleaner framework for linking in
alternative implementations of libc functions without cpp hacks.
Place wrappers in separate object files to reduce static code size.

1 files changed, 29 insertions, 0 deletions

diff --git a/bsp/libwrap/sys/write.c b/bsp/libwrap/sys/write.c
new file mode 100644
index 0000000..d00eb17
--- /dev/null
+++ b/bsp/libwrap/sys/write.c
@@ -0,0 +1,29 @@
+/* See LICENSE of license details. */
+
+#include <stdint.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#include "platform.h"
+#include "stub.h"
+
+ssize_t __wrap_write(int fd, const void* ptr, size_t len)
+{
+  const uint8_t * current = (const char *)ptr;
+
+  if (isatty(fd)) {
+    for (size_t jj = 0; jj < len; jj++) {
+      while (UART0_REG(UART_REG_TXFIFO) & 0x80000000) ;
+      UART0_REG(UART_REG_TXFIFO) = current[jj];
+
+      if (current[jj] == '\n') {
+        while (UART0_REG(UART_REG_TXFIFO) & 0x80000000) ;
+        UART0_REG(UART_REG_TXFIFO) = '\r';
+      }
+    }
+    return len;
+  }
+
+  return _stub(EBADF);
+}