os: Implement new default stdout for x86-pc

Author: fwsGonzo

api/kernel/os.hpp

@@ -131,16 +131,18 @@ class OS {
   /**
    *  Write data to standard out callbacks
    */
-  static size_t print(const char* ptr, const size_t len);
+  static void print(const char* ptr, const size_t len);
 
   /**
    *  Add handler for standard output.
    */
   static void add_stdout(print_func func);
   /**
-   *  Add stdout handler that calls OS::default_stdout
+   *  Add stdout handler that simply calls OS::default_stdout
   **/
-  static void add_default_stdout();
+  static void add_default_stdout() {
+    add_stdout(OS::default_stdout);
+  }
 
   /**
    *  The default output method preferred by each platform

src/include/kprint

@@ -33,6 +33,7 @@ extern "C" {
 #endif
 
 extern void __serial_print1(const char* cstr);
+extern void __serial_print(const char* str, size_t len);
 
 /**
  * The earliest possible print function (requires no heap, global ctors etc.)

src/kernel/os.cpp

@@ -101,23 +101,15 @@ void OS::add_stdout(OS::print_func func)
 {
   os_print_handlers.add(func);
 }
-void OS::add_default_stdout()
-{
-  add_stdout(
-  [] (const char* str, const size_t len) {
-      OS::default_stdout(str, len);
-  });
-}
 __attribute__ ((weak))
 void default_stdout_handlers()
 {
   OS::add_default_stdout();
 }
-size_t OS::print(const char* str, const size_t len)
+void OS::print(const char* str, const size_t len)
 {
   for (auto& func : os_print_handlers)
       func(str, len);
-  return len;
 }
 
 void OS::legacy_boot() {

src/platform/x86_pc/os.cpp

@@ -20,7 +20,6 @@
 
 #include <cstdio>
 #include <boot/multiboot.h>
-#include <hw/cmos.hpp>
 #include <kernel/os.hpp>
 #include <kernel/irq_manager.hpp>
 #include <kernel/rtc.hpp>
@@ -96,6 +95,10 @@ void OS::halt() {
       *os_cycles_hlt += cycles_since_boot() - *os_cycles_total;
 }
 
+void OS::default_stdout(const char* str, const size_t len)
+{
+  __serial_print(str, len);
+}
 
 void OS::start(uint32_t boot_magic, uint32_t boot_addr)
 {

src/platform/x86_pc/serial1.cpp

@@ -22,3 +22,11 @@ void __serial_print1(const char* cstr)
     hw::outb(port, *cstr++);
   }
 }
+extern "C"
+void __serial_print(const char* str, size_t len)
+{
+  for (size_t i = 0; i < len; i++) {
+    while (not (hw::inb(port + 5) & 0x20));
+    hw::outb(port, str[i]);
+  }
+}

src/posix/unistd.cpp

@@ -93,7 +93,8 @@ int read(int fd, void* buf, size_t len)
 int write(int fd, const void* ptr, size_t len)
 {
   if (fd < 4) {
-    return OS::print((const char*) ptr, len);
+    OS::print((const char*) ptr, len);
+    return len;
   }
   else if (fd == rng_fd) {
     rng_absorb(ptr, len);