refactor: isolate OS functions in a dedicated file

src/Makefile

@@ -309,7 +309,7 @@ LIBCARTESI_OBJS:= \
 	clint.o \
 	clint-factory.o \
 	dtb.o \
-	tty.o \
+	os.o \
 	htif.o \
 	htif-factory.o \
 	shadow-state.o \

src/htif.cpp

@@ -17,9 +17,9 @@
 #include "htif.h"
 #include "i-device-state-access.h"
 #include "machine-runtime-config.h"
+#include "os.h"
 #include "pma-constants.h"
 #include "strict-aliasing.h"
-#include "tty.h"
 
 namespace cartesi {
 
@@ -101,15 +101,15 @@ static execute_status htif_console(htif_runtime_config *runtime_config, i_device
             // In microarchitecture runtime_config will always be nullptr,
             // therefore the HTIF runtime config is actually ignored.
             if (!runtime_config || !runtime_config->no_console_putchar) {
-                tty_putchar(ch);
+                os_putchar(ch);
             }
             a->write_htif_fromhost(HTIF_BUILD(HTIF_DEVICE_CONSOLE, cmd, 0));
         } else if (cmd == HTIF_CONSOLE_GETCHAR) {
             // In blockchain, this command will never be enabled as there is no way to input the same character
             // to every participant in a dispute: where would c come from? So if the code reached here in the
             // blockchain, there must be some serious bug
             // In interactive mode, we just get the next character from the console and send it back in the ack
-            const int c = tty_getchar();
+            const int c = os_getchar();
             a->write_htif_fromhost(HTIF_BUILD(HTIF_DEVICE_CONSOLE, cmd, c));
         }
     }

src/machine.cpp

@@ -45,13 +45,6 @@
 #include "uarch-step.h"
 #include "unique-c-ptr.h"
 
-#ifdef _WIN32
-#include <direct.h> // mkdir
-#define mkdir(a, b) _mkdir(a)
-#else
-#include <sys/stat.h> // mkdir
-#endif
-
 /// \file
 /// \brief Cartesi machine implementation
 
@@ -480,7 +473,7 @@ machine::machine(const machine_config &c, const machine_runtime_config &r) :
 
     // Initialize TTY if console input is enabled
     if (m_c.htif.console_getchar) {
-        tty_initialize();
+        os_open_tty();
     }
 
     // Initialize memory range descriptions returned by get_memory_ranges method
@@ -708,7 +701,7 @@ static void store_hash(const machine::hash_type &h, const std::string &dir) {
 }
 
 void machine::store(const std::string &dir) const {
-    if (mkdir(dir.c_str(), 0700)) {
+    if (os_mkdir(dir.c_str(), 0700)) {
         throw std::runtime_error{"error creating directory '" + dir + "'"};
     }
     if (!update_merkle_tree()) {
@@ -726,7 +719,7 @@ void machine::store(const std::string &dir) const {
 machine::~machine() {
     // Cleanup TTY if console input was enabled
     if (m_c.htif.console_getchar) {
-        tty_finalize();
+        os_close_tty();
     }
 #ifdef DUMP_HIST
     (void) fprintf(stderr, "\nInstruction Histogram:\n");