44 files changed, 1005 insertions, 44 deletions
diff --git a/src/PL0/PL0_test.c b/src/arm/PL0/PL0_test.c
index 0bfebc7..0bfebc7 100644
--- a/src/PL0/PL0_test.c
+++ b/src/arm/PL0/PL0_test.c
diff --git a/src/PL0/PL0_test.ld b/src/arm/PL0/PL0_test.ld
index b1d06f4..b1d06f4 100644
--- a/src/PL0/PL0_test.ld
+++ b/src/arm/PL0/PL0_test.ld
diff --git a/src/PL0/PL0_utils.c b/src/arm/PL0/PL0_utils.c
index b9853fb..d83edb9 100644
--- a/src/PL0/PL0_utils.c
+++ b/src/arm/PL0/PL0_utils.c
@@ -1,7 +1,7 @@
 #include <stddef.h>
 #include <stdint.h>
 
-#include "../utils/svc_interface.h"
+#include "svc_interface.h"
 #include "PL0_utils.h"
 
 // most generic definition possible
diff --git a/src/PL0/PL0_utils.h b/src/arm/PL0/PL0_utils.h
index e87b1f0..c26a100 100644
--- a/src/PL0/PL0_utils.h
+++ b/src/arm/PL0/PL0_utils.h
@@ -1,6 +1,6 @@
 #ifndef PL0_UTILS_H
 #define PL0_UTILS_H
 
-#include "../utils/io.h"
+#include "io.h"
 
 #endif // PL0_UTILS_H
diff --git a/src/utils/svc.S b/src/arm/PL0/svc.S
index 65200d8..65200d8 100644
--- a/src/utils/svc.S
+++ b/src/arm/PL0/svc.S
diff --git a/src/global.h b/src/arm/PL1/PL1_common/global.h
index 4e17b44..4e17b44 100644
--- a/src/global.h
+++ b/src/arm/PL1/PL1_common/global.h
diff --git a/src/utils/uart.c b/src/arm/PL1/PL1_common/uart.c
index a389e41..4dd1c2b 100644
--- a/src/utils/uart.c
+++ b/src/arm/PL1/PL1_common/uart.c
@@ -1,7 +1,7 @@
 #include <stddef.h>
 #include <stdint.h>
 #include "uart.h"
-#include "../global.h"
+#include "global.h"
 
 // Loop <delay> times in a way that the compiler won't optimize away
 static inline void delay(int32_t count)
diff --git a/src/utils/uart.h b/src/arm/PL1/PL1_common/uart.h
index 2a8b7d4..96f3634 100644
--- a/src/utils/uart.h
+++ b/src/arm/PL1/PL1_common/uart.h
@@ -2,8 +2,8 @@
 #define UART_H
 
 #include <stdint.h>
-#include "../global.h"
-#include "../interrupts/interrupts.h"
+#include "global.h"
+#include "interrupts.h"
 
 // The offsets for reach register.
 
diff --git a/src/clock/armclock.h b/src/arm/PL1/kernel/armclock.h
index 0d83fc2..0792ad3 100644
--- a/src/clock/armclock.h
+++ b/src/arm/PL1/kernel/armclock.h
@@ -3,8 +3,8 @@
 
 #include <stdint.h>
 
-#include "../global.h"
-#include "../interrupts/interrupts.h"
+#include "global.h"
+#include "interrupts.h"
 #define ARMCLK_LOAD                 (ARM_BASE + 0x400)
 #define ARMCLK_VALUE                (ARM_BASE + 0x404)
 #define ARMCLK_CONTROL              (ARM_BASE + 0x408)
diff --git a/src/atags/atags.c b/src/arm/PL1/kernel/atags.c
index 54740d8..e2e6a24 100644
--- a/src/atags/atags.c
+++ b/src/arm/PL1/kernel/atags.c
@@ -1,5 +1,5 @@
 #include "atags.h"
-#include "../utils/io.h"
+#include "io.h"
 
 static inline struct atag_header *next_tag(struct atag_header *tag)
 {
diff --git a/src/atags/atags.h b/src/arm/PL1/kernel/atags.h
index 4b6879f..4b6879f 100644
--- a/src/atags/atags.h
+++ b/src/arm/PL1/kernel/atags.h
diff --git a/src/clock/bcmclock.h b/src/arm/PL1/kernel/bcmclock.h
index d08912b..462346d 100644
--- a/src/clock/bcmclock.h
+++ b/src/arm/PL1/kernel/bcmclock.h
@@ -2,8 +2,8 @@
 #define BCMCLOCK_H
 
 #include <stdint.h>
-#include "../interrupts/interrupts.h"
-#include "../global.h"
+#include "interrupts.h"
+#include "global.h"
 
 #define ST_BASE (PERIF_BASE + 0x3000) // System Timer
 
diff --git a/src/memory/cp_regs.h b/src/arm/PL1/kernel/cp_regs.h
index e5e7063..e5e7063 100644
--- a/src/memory/cp_regs.h
+++ b/src/arm/PL1/kernel/cp_regs.h
diff --git a/src/demo/demo_functionality.c b/src/arm/PL1/kernel/demo_functionality.c
index d9c0888..217a858 100644
--- a/src/demo/demo_functionality.c
+++ b/src/arm/PL1/kernel/demo_functionality.c
@@ -1,12 +1,12 @@
-#include "../utils/io.h"
-#include "../boot/psr.h"
-#include "../memory/memory.h"
-#include "../memory/translation_table_descriptors.h"
-#include "../memory/ramfs.h"
-#include "../utils/strings.h"
-#include "../memory/paging.h"
-#include "../clock/armclock.h"
-#include "../scheduler.h"
+#include "io.h"
+#include "psr.h"
+#include "memory.h"
+#include "translation_table_descriptors.h"
+#include "ramfs.h"
+#include "strings.h"
+#include "paging.h"
+#include "armclock.h"
+#include "scheduler.h"
 
 void demo_paging_support(void)
 {
diff --git a/src/demo/demo_functionality.h b/src/arm/PL1/kernel/demo_functionality.h
index a338c71..a338c71 100644
--- a/src/demo/demo_functionality.h
+++ b/src/arm/PL1/kernel/demo_functionality.h
diff --git a/src/interrupts/interrupt_vector.S b/src/arm/PL1/kernel/interrupt_vector.S
index 1ec80f7..1ec80f7 100644
--- a/src/interrupts/interrupt_vector.S
+++ b/src/arm/PL1/kernel/interrupt_vector.S
diff --git a/src/interrupts/interrupts.c b/src/arm/PL1/kernel/interrupts.c
index 5c30375..121d79c 100644
--- a/src/interrupts/interrupts.c
+++ b/src/arm/PL1/kernel/interrupts.c
@@ -1,8 +1,8 @@
-#include "../utils/io.h"
-#include "../utils/uart.h"
-#include "../utils/svc_interface.h"
-#include "../clock/armclock.h"
-#include "../scheduler.h"
+#include "io.h"
+#include "uart.h"
+#include "svc_interface.h"
+#include "armclock.h"
+#include "scheduler.h"
 /**
     @brief The undefined instruction interrupt handler
 **/
diff --git a/src/interrupts/interrupts.h b/src/arm/PL1/kernel/interrupts.h
index c2818ee..c2818ee 100644
--- a/src/interrupts/interrupts.h
+++ b/src/arm/PL1/kernel/interrupts.h
diff --git a/src/boot/kernel_stage1.S b/src/arm/PL1/kernel/kernel_stage1.S
index e770513..e770513 100644
--- a/src/boot/kernel_stage1.S
+++ b/src/arm/PL1/kernel/kernel_stage1.S
diff --git a/src/boot/kernel_stage1.ld b/src/arm/PL1/kernel/kernel_stage1.ld
index 3130634..3130634 100644
--- a/src/boot/kernel_stage1.ld
+++ b/src/arm/PL1/kernel/kernel_stage1.ld
diff --git a/src/boot/kernel_stage2.ld b/src/arm/PL1/kernel/kernel_stage2.ld
index 9411ca2..9411ca2 100644
--- a/src/boot/kernel_stage2.ld
+++ b/src/arm/PL1/kernel/kernel_stage2.ld
diff --git a/src/memory/memory.h b/src/arm/PL1/kernel/memory.h
index bdeba52..bdeba52 100644
--- a/src/memory/memory.h
+++ b/src/arm/PL1/kernel/memory.h
diff --git a/src/memory/paging.c b/src/arm/PL1/kernel/paging.c
index aa18087..771c681 100644
--- a/src/memory/paging.c
+++ b/src/arm/PL1/kernel/paging.c
@@ -1,8 +1,8 @@
 #include "cp_regs.h"
-#include "../utils/strings.h"
+#include "strings.h"
 #include "memory.h"
 #include "translation_table_descriptors.h"
-#include "../utils/io.h"
+#include "io.h"
 
 #include "paging.h"
 
diff --git a/src/memory/paging.h b/src/arm/PL1/kernel/paging.h
index 4ac8efa..4ac8efa 100644
--- a/src/memory/paging.h
+++ b/src/arm/PL1/kernel/paging.h
diff --git a/src/boot/psr.h b/src/arm/PL1/kernel/psr.h
index f300a7a..f300a7a 100644
--- a/src/boot/psr.h
+++ b/src/arm/PL1/kernel/psr.h
diff --git a/src/memory/ramfs.c b/src/arm/PL1/kernel/ramfs.c
index cc66b4c..cc66b4c 100644
--- a/src/memory/ramfs.c
+++ b/src/arm/PL1/kernel/ramfs.c
diff --git a/src/memory/ramfs.h b/src/arm/PL1/kernel/ramfs.h
index cf45736..cf45736 100644
--- a/src/memory/ramfs.h
+++ b/src/arm/PL1/kernel/ramfs.h
diff --git a/src/scheduler.c b/src/arm/PL1/kernel/scheduler.c
index 146eb29..141ba1d 100644
--- a/src/scheduler.c
+++ b/src/arm/PL1/kernel/scheduler.c
@@ -1,9 +1,9 @@
 #include "scheduler.h"
-#include "utils/uart.h"
-#include "utils/strings.h"
-#include "clock/armclock.h"
-#include "memory/memory.h"
-#include "utils/io.h"
+#include "uart.h"
+#include "strings.h"
+#include "armclock.h"
+#include "memory.h"
+#include "io.h"
 
 // for now we only have 1 process in "queue"
 // later there is going to be an actual queue
diff --git a/src/scheduler.h b/src/arm/PL1/kernel/scheduler.h
index 58f659c..8c0f569 100644
--- a/src/scheduler.h
+++ b/src/arm/PL1/kernel/scheduler.h
@@ -3,7 +3,7 @@
 
 #include <stdint.h>
 
-#include "boot/psr.h"
+#include "psr.h"
 
 extern PSR_t PL1_PSR;
 
diff --git a/src/boot/setup.c b/src/arm/PL1/kernel/setup.c
index 2f74e64..bf7c9a1 100644
--- a/src/boot/setup.c
+++ b/src/arm/PL1/kernel/setup.c
@@ -1,12 +1,12 @@
-#include "../utils/uart.h"
-#include "../utils/io.h"
-#include "../demo/demo_functionality.h"
-#include "../memory/paging.h"
-#include "../atags/atags.h"
+#include "uart.h"
+#include "io.h"
+#include "demo_functionality.h"
+#include "paging.h"
+#include "atags.h"
 // for POWER_OF_2() macro... perhaps the macro should be moved
-#include "../memory/memory.h"
-#include "../clock/armclock.h"
-#include "../scheduler.h"
+#include "memory.h"
+#include "armclock.h"
+#include "scheduler.h"
 
 void setup(uint32_t r0, uint32_t machine_type,
 	   struct atag_header *atags)
diff --git a/src/memory/translation_table_descriptors.h b/src/arm/PL1/kernel/translation_table_descriptors.h
index 981c3c7..981c3c7 100644
--- a/src/memory/translation_table_descriptors.h
+++ b/src/arm/PL1/kernel/translation_table_descriptors.h
diff --git a/src/boot/loader_stage1.S b/src/arm/PL1/loader/loader_stage1.S
index 69d78c5..69d78c5 100644
--- a/src/boot/loader_stage1.S
+++ b/src/arm/PL1/loader/loader_stage1.S
diff --git a/src/boot/loader_stage1_linker.ld b/src/arm/PL1/loader/loader_stage1_linker.ld
index 711fcbf..711fcbf 100644
--- a/src/boot/loader_stage1_linker.ld
+++ b/src/arm/PL1/loader/loader_stage1_linker.ld
diff --git a/src/boot/loader_stage2.c b/src/arm/PL1/loader/loader_stage2.c
index e08756b..fc3ae1c 100644
--- a/src/boot/loader_stage2.c
+++ b/src/arm/PL1/loader/loader_stage2.c
@@ -1,8 +1,8 @@
 #include <stddef.h>
 #include <stdint.h>
-#include "../utils/uart.h"
-#include "../utils/io.h"
-#include "../global.h"
+#include "uart.h"
+#include "io.h"
+#include "global.h"
 
 void *const kernel_load_addr = ((void*) 0x8000);
 
diff --git a/src/boot/loader_stage2_linker.ld b/src/arm/PL1/loader/loader_stage2_linker.ld
index 33e79e9..33e79e9 100644
--- a/src/boot/loader_stage2_linker.ld
+++ b/src/arm/PL1/loader/loader_stage2_linker.ld
diff --git a/src/utils/io.c b/src/arm/common/io.c
index bf9e0e3..bf9e0e3 100644
--- a/src/utils/io.c
+++ b/src/arm/common/io.c
diff --git a/src/utils/io.h b/src/arm/common/io.h
index dcad76e..dcad76e 100644
--- a/src/utils/io.h
+++ b/src/arm/common/io.h
diff --git a/src/utils/strings.c b/src/arm/common/strings.c
index 368d7dc..368d7dc 100644
--- a/src/utils/strings.c
+++ b/src/arm/common/strings.c
diff --git a/src/utils/strings.h b/src/arm/common/strings.h
index aff0533..aff0533 100644
--- a/src/utils/strings.h
+++ b/src/arm/common/strings.h
diff --git a/src/utils/svc_interface.h b/src/arm/common/svc_interface.h
index aa478ce..aa478ce 100644
--- a/src/utils/svc_interface.h
+++ b/src/arm/common/svc_interface.h
diff --git a/src/memory/makefs.c b/src/host/makefs.c
index 379e8c5..379e8c5 100644
--- a/src/memory/makefs.c
+++ b/src/host/makefs.c
diff --git a/src/utils/pipe_image.c b/src/host/pipe_image.c
index b148ac4..105f9a1 100644
--- a/src/utils/pipe_image.c
+++ b/src/host/pipe_image.c
@@ -3,7 +3,7 @@
 #include <endian.h>
 #include <stdint.h>
 #include <sys/types.h>
-#include "../../lib/rs232/rs232.h"
+#include "rs232.h"
 
 #define ANSI_FG_RED "\033[0;31m"
 #define ANSI_FG_DEFAULT "\033[0;39m"
diff --git a/src/lib/rs232/rs232.c b/src/lib/rs232/rs232.c
new file mode 100644
index 0000000..0ae2a59
--- /dev/null
+++ b/src/lib/rs232/rs232.c
@@ -0,0 +1,873 @@
+/*
+***************************************************************************
+*
+* Author: Teunis van Beelen
+*
+* Copyright (C) 2005 - 2019 Teunis van Beelen
+*
+* Email: teuniz@protonmail.com
+*
+***************************************************************************
+*
+* This program is free software: you can redistribute it and/or modify
+* it under the terms of the GNU General Public License as published by
+* the Free Software Foundation, either version 3 of the License, or
+* (at your option) any later version.
+*
+* This program is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License
+* along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*
+***************************************************************************
+*/
+
+
+/* Last revision: May 31, 2019 */
+/* Added support for hardware flow control using RTS and CTS lines */
+/* For more info and how to use this library, visit: http://www.teuniz.net/RS-232/ */
+
+
+#include "rs232.h"
+
+
+#if defined(__linux__) || defined(__FreeBSD__)   /* Linux & FreeBSD */
+
+#define RS232_PORTNR  38
+
+
+int Cport[RS232_PORTNR],
+    error;
+
+struct termios new_port_settings,
+       old_port_settings[RS232_PORTNR];
+
+char *comports[RS232_PORTNR]={"/dev/ttyS0","/dev/ttyS1","/dev/ttyS2","/dev/ttyS3","/dev/ttyS4","/dev/ttyS5",
+                       "/dev/ttyS6","/dev/ttyS7","/dev/ttyS8","/dev/ttyS9","/dev/ttyS10","/dev/ttyS11",
+                       "/dev/ttyS12","/dev/ttyS13","/dev/ttyS14","/dev/ttyS15","/dev/ttyUSB0",
+                       "/dev/ttyUSB1","/dev/ttyUSB2","/dev/ttyUSB3","/dev/ttyUSB4","/dev/ttyUSB5",
+                       "/dev/ttyAMA0","/dev/ttyAMA1","/dev/ttyACM0","/dev/ttyACM1",
+                       "/dev/rfcomm0","/dev/rfcomm1","/dev/ircomm0","/dev/ircomm1",
+                       "/dev/cuau0","/dev/cuau1","/dev/cuau2","/dev/cuau3",
+                       "/dev/cuaU0","/dev/cuaU1","/dev/cuaU2","/dev/cuaU3"};
+
+int RS232_OpenComport(int comport_number, int baudrate, const char *mode, int flowctrl)
+{
+  int baudr,
+      status;
+
+  if((comport_number>=RS232_PORTNR)||(comport_number<0))
+  {
+    printf("illegal comport number\n");
+    return(1);
+  }
+
+  switch(baudrate)
+  {
+    case      50 : baudr = B50;
+                   break;
+    case      75 : baudr = B75;
+                   break;
+    case     110 : baudr = B110;
+                   break;
+    case     134 : baudr = B134;
+                   break;
+    case     150 : baudr = B150;
+                   break;
+    case     200 : baudr = B200;
+                   break;
+    case     300 : baudr = B300;
+                   break;
+    case     600 : baudr = B600;
+                   break;
+    case    1200 : baudr = B1200;
+                   break;
+    case    1800 : baudr = B1800;
+                   break;
+    case    2400 : baudr = B2400;
+                   break;
+    case    4800 : baudr = B4800;
+                   break;
+    case    9600 : baudr = B9600;
+                   break;
+    case   19200 : baudr = B19200;
+                   break;
+    case   38400 : baudr = B38400;
+                   break;
+    case   57600 : baudr = B57600;
+                   break;
+    case  115200 : baudr = B115200;
+                   break;
+    case  230400 : baudr = B230400;
+                   break;
+    case  460800 : baudr = B460800;
+                   break;
+    case  500000 : baudr = B500000;
+                   break;
+    case  576000 : baudr = B576000;
+                   break;
+    case  921600 : baudr = B921600;
+                   break;
+    case 1000000 : baudr = B1000000;
+                   break;
+    case 1152000 : baudr = B1152000;
+                   break;
+    case 1500000 : baudr = B1500000;
+                   break;
+    case 2000000 : baudr = B2000000;
+                   break;
+    case 2500000 : baudr = B2500000;
+                   break;
+    case 3000000 : baudr = B3000000;
+                   break;
+    case 3500000 : baudr = B3500000;
+                   break;
+    case 4000000 : baudr = B4000000;
+                   break;
+    default      : printf("invalid baudrate\n");
+                   return(1);
+                   break;
+  }
+
+  int cbits=CS8,
+      cpar=0,
+      ipar=IGNPAR,
+      bstop=0;
+
+  if(strlen(mode) != 3)
+  {
+    printf("invalid mode \"%s\"\n", mode);
+    return(1);
+  }
+
+  switch(mode[0])
+  {
+    case '8': cbits = CS8;
+              break;
+    case '7': cbits = CS7;
+              break;
+    case '6': cbits = CS6;
+              break;
+    case '5': cbits = CS5;
+              break;
+    default : printf("invalid number of data-bits '%c'\n", mode[0]);
+              return(1);
+              break;
+  }
+
+  switch(mode[1])
+  {
+    case 'N':
+    case 'n': cpar = 0;
+              ipar = IGNPAR;
+              break;
+    case 'E':
+    case 'e': cpar = PARENB;
+              ipar = INPCK;
+              break;
+    case 'O':
+    case 'o': cpar = (PARENB | PARODD);
+              ipar = INPCK;
+              break;
+    default : printf("invalid parity '%c'\n", mode[1]);
+              return(1);
+              break;
+  }
+
+  switch(mode[2])
+  {
+    case '1': bstop = 0;
+              break;
+    case '2': bstop = CSTOPB;
+              break;
+    default : printf("invalid number of stop bits '%c'\n", mode[2]);
+              return(1);
+              break;
+  }
+
+/*
+http://pubs.opengroup.org/onlinepubs/7908799/xsh/termios.h.html
+
+http://man7.org/linux/man-pages/man3/termios.3.html
+*/
+
+  Cport[comport_number] = open(comports[comport_number], O_RDWR | O_NOCTTY | O_NDELAY);
+  if(Cport[comport_number]==-1)
+  {
+    perror("unable to open comport ");
+    return(1);
+  }
+
+  /* lock access so that another process can't also use the port */
+  if(flock(Cport[comport_number], LOCK_EX | LOCK_NB) != 0)
+  {
+    close(Cport[comport_number]);
+    perror("Another process has locked the comport.");
+    return(1);
+  }
+
+  error = tcgetattr(Cport[comport_number], old_port_settings + comport_number);
+  if(error==-1)
+  {
+    close(Cport[comport_number]);
+    flock(Cport[comport_number], LOCK_UN);  /* free the port so that others can use it. */
+    perror("unable to read portsettings ");
+    return(1);
+  }
+  memset(&new_port_settings, 0, sizeof(new_port_settings));  /* clear the new struct */
+
+  new_port_settings.c_cflag = cbits | cpar | bstop | CLOCAL | CREAD;
+  if(flowctrl)
+  {
+    new_port_settings.c_cflag |= CRTSCTS;
+  }
+  new_port_settings.c_iflag = ipar;
+  new_port_settings.c_oflag = 0;
+  new_port_settings.c_lflag = 0;
+  new_port_settings.c_cc[VMIN] = 0;      /* block untill n bytes are received */
+  new_port_settings.c_cc[VTIME] = 0;     /* block untill a timer expires (n * 100 mSec.) */
+
+  cfsetispeed(&new_port_settings, baudr);
+  cfsetospeed(&new_port_settings, baudr);
+
+  error = tcsetattr(Cport[comport_number], TCSANOW, &new_port_settings);
+  if(error==-1)
+  {
+    tcsetattr(Cport[comport_number], TCSANOW, old_port_settings + comport_number);
+    close(Cport[comport_number]);
+    flock(Cport[comport_number], LOCK_UN);  /* free the port so that others can use it. */
+    perror("unable to adjust portsettings ");
+    return(1);
+  }
+
+/* http://man7.org/linux/man-pages/man4/tty_ioctl.4.html */
+
+  if(ioctl(Cport[comport_number], TIOCMGET, &status) == -1)
+  {
+    tcsetattr(Cport[comport_number], TCSANOW, old_port_settings + comport_number);
+    flock(Cport[comport_number], LOCK_UN);  /* free the port so that others can use it. */
+    perror("unable to get portstatus");
+    return(1);
+  }
+
+  status |= TIOCM_DTR;    /* turn on DTR */
+  status |= TIOCM_RTS;    /* turn on RTS */
+
+  if(ioctl(Cport[comport_number], TIOCMSET, &status) == -1)
+  {
+    tcsetattr(Cport[comport_number], TCSANOW, old_port_settings + comport_number);
+    flock(Cport[comport_number], LOCK_UN);  /* free the port so that others can use it. */
+    perror("unable to set portstatus");
+    return(1);
+  }
+
+  return(0);
+}
+
+
+int RS232_PollComport(int comport_number, unsigned char *buf, int size)
+{
+  int n;
+
+  n = read(Cport[comport_number], buf, size);
+
+  if(n < 0)
+  {
+    if(errno == EAGAIN)  return 0;
+  }
+
+  return(n);
+}
+
+
+int RS232_SendByte(int comport_number, unsigned char byte)
+{
+  int n = write(Cport[comport_number], &byte, 1);
+  if(n < 0)
+  {
+    if(errno == EAGAIN)
+    {
+      return 0;
+    }
+    else
+    {
+      return 1;
+    }
+  }
+
+  return(0);
+}
+
+
+int RS232_SendBuf(int comport_number, unsigned char *buf, int size)
+{
+  int n = write(Cport[comport_number], buf, size);
+  if(n < 0)
+  {
+    if(errno == EAGAIN)
+    {
+      return 0;
+    }
+    else
+    {
+      return -1;
+    }
+  }
+
+  return(n);
+}
+
+
+void RS232_CloseComport(int comport_number)
+{
+  int status;
+
+  if(ioctl(Cport[comport_number], TIOCMGET, &status) == -1)
+  {
+    perror("unable to get portstatus");
+  }
+
+  status &= ~TIOCM_DTR;    /* turn off DTR */
+  status &= ~TIOCM_RTS;    /* turn off RTS */
+
+  if(ioctl(Cport[comport_number], TIOCMSET, &status) == -1)
+  {
+    perror("unable to set portstatus");
+  }
+
+  tcsetattr(Cport[comport_number], TCSANOW, old_port_settings + comport_number);
+  close(Cport[comport_number]);
+
+  flock(Cport[comport_number], LOCK_UN);  /* free the port so that others can use it. */
+}
+
+/*
+Constant  Description
+TIOCM_LE        DSR (data set ready/line enable)
+TIOCM_DTR       DTR (data terminal ready)
+TIOCM_RTS       RTS (request to send)
+TIOCM_ST        Secondary TXD (transmit)
+TIOCM_SR        Secondary RXD (receive)
+TIOCM_CTS       CTS (clear to send)
+TIOCM_CAR       DCD (data carrier detect)
+TIOCM_CD        see TIOCM_CAR
+TIOCM_RNG       RNG (ring)
+TIOCM_RI        see TIOCM_RNG
+TIOCM_DSR       DSR (data set ready)
+
+http://man7.org/linux/man-pages/man4/tty_ioctl.4.html
+*/
+
+int RS232_IsDCDEnabled(int comport_number)
+{
+  int status;
+
+  ioctl(Cport[comport_number], TIOCMGET, &status);
+
+  if(status&TIOCM_CAR) return(1);
+  else return(0);
+}
+
+
+int RS232_IsRINGEnabled(int comport_number)
+{
+  int status;
+
+  ioctl(Cport[comport_number], TIOCMGET, &status);
+
+  if(status&TIOCM_RNG) return(1);
+  else return(0);
+}
+
+
+int RS232_IsCTSEnabled(int comport_number)
+{
+  int status;
+
+  ioctl(Cport[comport_number], TIOCMGET, &status);
+
+  if(status&TIOCM_CTS) return(1);
+  else return(0);
+}
+
+
+int RS232_IsDSREnabled(int comport_number)
+{
+  int status;
+
+  ioctl(Cport[comport_number], TIOCMGET, &status);
+
+  if(status&TIOCM_DSR) return(1);
+  else return(0);
+}
+
+
+void RS232_enableDTR(int comport_number)
+{
+  int status;
+
+  if(ioctl(Cport[comport_number], TIOCMGET, &status) == -1)
+  {
+    perror("unable to get portstatus");
+  }
+
+  status |= TIOCM_DTR;    /* turn on DTR */
+
+  if(ioctl(Cport[comport_number], TIOCMSET, &status) == -1)
+  {
+    perror("unable to set portstatus");
+  }
+}
+
+
+void RS232_disableDTR(int comport_number)
+{
+  int status;
+
+  if(ioctl(Cport[comport_number], TIOCMGET, &status) == -1)
+  {
+    perror("unable to get portstatus");
+  }
+
+  status &= ~TIOCM_DTR;    /* turn off DTR */
+
+  if(ioctl(Cport[comport_number], TIOCMSET, &status) == -1)
+  {
+    perror("unable to set portstatus");
+  }
+}
+
+
+void RS232_enableRTS(int comport_number)
+{
+  int status;
+
+  if(ioctl(Cport[comport_number], TIOCMGET, &status) == -1)
+  {
+    perror("unable to get portstatus");
+  }
+
+  status |= TIOCM_RTS;    /* turn on RTS */
+
+  if(ioctl(Cport[comport_number], TIOCMSET, &status) == -1)
+  {
+    perror("unable to set portstatus");
+  }
+}
+
+
+void RS232_disableRTS(int comport_number)
+{
+  int status;
+
+  if(ioctl(Cport[comport_number], TIOCMGET, &status) == -1)
+  {
+    perror("unable to get portstatus");
+  }
+
+  status &= ~TIOCM_RTS;    /* turn off RTS */
+
+  if(ioctl(Cport[comport_number], TIOCMSET, &status) == -1)
+  {
+    perror("unable to set portstatus");
+  }
+}
+
+
+void RS232_flushRX(int comport_number)
+{
+  tcflush(Cport[comport_number], TCIFLUSH);
+}
+
+
+void RS232_flushTX(int comport_number)
+{
+  tcflush(Cport[comport_number], TCOFLUSH);
+}
+
+
+void RS232_flushRXTX(int comport_number)
+{
+  tcflush(Cport[comport_number], TCIOFLUSH);
+}
+
+
+#else  /* windows */
+
+#define RS232_PORTNR  32
+
+HANDLE Cport[RS232_PORTNR];
+
+
+char *comports[RS232_PORTNR]={"\\\\.\\COM1",  "\\\\.\\COM2",  "\\\\.\\COM3",  "\\\\.\\COM4",
+                              "\\\\.\\COM5",  "\\\\.\\COM6",  "\\\\.\\COM7",  "\\\\.\\COM8",
+                              "\\\\.\\COM9",  "\\\\.\\COM10", "\\\\.\\COM11", "\\\\.\\COM12",
+                              "\\\\.\\COM13", "\\\\.\\COM14", "\\\\.\\COM15", "\\\\.\\COM16",
+                              "\\\\.\\COM17", "\\\\.\\COM18", "\\\\.\\COM19", "\\\\.\\COM20",
+                              "\\\\.\\COM21", "\\\\.\\COM22", "\\\\.\\COM23", "\\\\.\\COM24",
+                              "\\\\.\\COM25", "\\\\.\\COM26", "\\\\.\\COM27", "\\\\.\\COM28",
+                              "\\\\.\\COM29", "\\\\.\\COM30", "\\\\.\\COM31", "\\\\.\\COM32"};
+
+char mode_str[128];
+
+
+int RS232_OpenComport(int comport_number, int baudrate, const char *mode, int flowctrl)
+{
+  if((comport_number>=RS232_PORTNR)||(comport_number<0))
+  {
+    printf("illegal comport number\n");
+    return(1);
+  }
+
+  switch(baudrate)
+  {
+    case     110 : strcpy(mode_str, "baud=110");
+                   break;
+    case     300 : strcpy(mode_str, "baud=300");
+                   break;
+    case     600 : strcpy(mode_str, "baud=600");
+                   break;
+    case    1200 : strcpy(mode_str, "baud=1200");
+                   break;
+    case    2400 : strcpy(mode_str, "baud=2400");
+                   break;
+    case    4800 : strcpy(mode_str, "baud=4800");
+                   break;
+    case    9600 : strcpy(mode_str, "baud=9600");
+                   break;
+    case   19200 : strcpy(mode_str, "baud=19200");
+                   break;
+    case   38400 : strcpy(mode_str, "baud=38400");
+                   break;
+    case   57600 : strcpy(mode_str, "baud=57600");
+                   break;
+    case  115200 : strcpy(mode_str, "baud=115200");
+                   break;
+    case  128000 : strcpy(mode_str, "baud=128000");
+                   break;
+    case  256000 : strcpy(mode_str, "baud=256000");
+                   break;
+    case  500000 : strcpy(mode_str, "baud=500000");
+                   break;
+    case  921600 : strcpy(mode_str, "baud=921600");
+                   break;
+    case 1000000 : strcpy(mode_str, "baud=1000000");
+                   break;
+    case 1500000 : strcpy(mode_str, "baud=1500000");
+                   break;
+    case 2000000 : strcpy(mode_str, "baud=2000000");
+                   break;
+    case 3000000 : strcpy(mode_str, "baud=3000000");
+                   break;
+    default      : printf("invalid baudrate\n");
+                   return(1);
+                   break;
+  }
+
+  if(strlen(mode) != 3)
+  {
+    printf("invalid mode \"%s\"\n", mode);
+    return(1);
+  }
+
+  switch(mode[0])
+  {
+    case '8': strcat(mode_str, " data=8");
+              break;
+    case '7': strcat(mode_str, " data=7");
+              break;
+    case '6': strcat(mode_str, " data=6");
+              break;
+    case '5': strcat(mode_str, " data=5");
+              break;
+    default : printf("invalid number of data-bits '%c'\n", mode[0]);
+              return(1);
+              break;
+  }
+
+  switch(mode[1])
+  {
+    case 'N':
+    case 'n': strcat(mode_str, " parity=n");
+              break;
+    case 'E':
+    case 'e': strcat(mode_str, " parity=e");
+              break;
+    case 'O':
+    case 'o': strcat(mode_str, " parity=o");
+              break;
+    default : printf("invalid parity '%c'\n", mode[1]);
+              return(1);
+              break;
+  }
+
+  switch(mode[2])
+  {
+    case '1': strcat(mode_str, " stop=1");
+              break;
+    case '2': strcat(mode_str, " stop=2");
+              break;
+    default : printf("invalid number of stop bits '%c'\n", mode[2]);
+              return(1);
+              break;
+  }
+
+  if(flowctrl)
+  {
+    strcat(mode_str, " xon=off to=off odsr=off dtr=on rts=off");
+  }
+  else
+  {
+    strcat(mode_str, " xon=off to=off odsr=off dtr=on rts=on");
+  }
+
+/*
+http://msdn.microsoft.com/en-us/library/windows/desktop/aa363145%28v=vs.85%29.aspx
+
+http://technet.microsoft.com/en-us/library/cc732236.aspx
+
+https://docs.microsoft.com/en-us/windows/desktop/api/winbase/ns-winbase-_dcb
+*/
+
+  Cport[comport_number] = CreateFileA(comports[comport_number],
+                      GENERIC_READ|GENERIC_WRITE,
+                      0,                          /* no share  */
+                      NULL,                       /* no security */
+                      OPEN_EXISTING,
+                      0,                          /* no threads */
+                      NULL);                      /* no templates */
+
+  if(Cport[comport_number]==INVALID_HANDLE_VALUE)
+  {
+    printf("unable to open comport\n");
+    return(1);
+  }
+
+  DCB port_settings;
+  memset(&port_settings, 0, sizeof(port_settings));  /* clear the new struct  */
+  port_settings.DCBlength = sizeof(port_settings);
+
+  if(!BuildCommDCBA(mode_str, &port_settings))
+  {
+    printf("unable to set comport dcb settings\n");
+    CloseHandle(Cport[comport_number]);
+    return(1);
+  }
+
+  if(flowctrl)
+  {
+    port_settings.fOutxCtsFlow = TRUE;
+    port_settings.fRtsControl = RTS_CONTROL_HANDSHAKE;
+  }
+
+  if(!SetCommState(Cport[comport_number], &port_settings))
+  {
+    printf("unable to set comport cfg settings\n");
+    CloseHandle(Cport[comport_number]);
+    return(1);
+  }
+
+  COMMTIMEOUTS Cptimeouts;
+
+  Cptimeouts.ReadIntervalTimeout         = MAXDWORD;
+  Cptimeouts.ReadTotalTimeoutMultiplier  = 0;
+  Cptimeouts.ReadTotalTimeoutConstant    = 0;
+  Cptimeouts.WriteTotalTimeoutMultiplier = 0;
+  Cptimeouts.WriteTotalTimeoutConstant   = 0;
+
+  if(!SetCommTimeouts(Cport[comport_number], &Cptimeouts))
+  {
+    printf("unable to set comport time-out settings\n");
+    CloseHandle(Cport[comport_number]);
+    return(1);
+  }
+
+  return(0);
+}
+
+
+int RS232_PollComport(int comport_number, unsigned char *buf, int size)
+{
+  int n;
+
+/* added the void pointer cast, otherwise gcc will complain about */
+/* "warning: dereferencing type-punned pointer will break strict aliasing rules" */
+
+  ReadFile(Cport[comport_number], buf, size, (LPDWORD)((void *)&n), NULL);
+
+  return(n);
+}
+
+
+int RS232_SendByte(int comport_number, unsigned char byte)
+{
+  int n;
+
+  WriteFile(Cport[comport_number], &byte, 1, (LPDWORD)((void *)&n), NULL);
+
+  if(n<0)  return(1);
+
+  return(0);
+}
+
+
+int RS232_SendBuf(int comport_number, unsigned char *buf, int size)
+{
+  int n;
+
+  if(WriteFile(Cport[comport_number], buf, size, (LPDWORD)((void *)&n), NULL))
+  {
+    return(n);
+  }
+
+  return(-1);
+}
+
+
+void RS232_CloseComport(int comport_number)
+{
+  CloseHandle(Cport[comport_number]);
+}
+
+/*
+http://msdn.microsoft.com/en-us/library/windows/desktop/aa363258%28v=vs.85%29.aspx
+*/
+
+int RS232_IsDCDEnabled(int comport_number)
+{
+  int status;
+
+  GetCommModemStatus(Cport[comport_number], (LPDWORD)((void *)&status));
+
+  if(status&MS_RLSD_ON) return(1);
+  else return(0);
+}
+
+
+int RS232_IsRINGEnabled(int comport_number)
+{
+  int status;
+
+  GetCommModemStatus(Cport[comport_number], (LPDWORD)((void *)&status));
+
+  if(status&MS_RING_ON) return(1);
+  else return(0);
+}
+
+
+int RS232_IsCTSEnabled(int comport_number)
+{
+  int status;
+
+  GetCommModemStatus(Cport[comport_number], (LPDWORD)((void *)&status));
+
+  if(status&MS_CTS_ON) return(1);
+  else return(0);
+}
+
+
+int RS232_IsDSREnabled(int comport_number)
+{
+  int status;
+
+  GetCommModemStatus(Cport[comport_number], (LPDWORD)((void *)&status));
+
+  if(status&MS_DSR_ON) return(1);
+  else return(0);
+}
+
+
+void RS232_enableDTR(int comport_number)
+{
+  EscapeCommFunction(Cport[comport_number], SETDTR);
+}
+
+
+void RS232_disableDTR(int comport_number)
+{
+  EscapeCommFunction(Cport[comport_number], CLRDTR);
+}
+
+
+void RS232_enableRTS(int comport_number)
+{
+  EscapeCommFunction(Cport[comport_number], SETRTS);
+}
+
+
+void RS232_disableRTS(int comport_number)
+{
+  EscapeCommFunction(Cport[comport_number], CLRRTS);
+}
+
+/*
+https://msdn.microsoft.com/en-us/library/windows/desktop/aa363428%28v=vs.85%29.aspx
+*/
+
+void RS232_flushRX(int comport_number)
+{
+  PurgeComm(Cport[comport_number], PURGE_RXCLEAR | PURGE_RXABORT);
+}
+
+
+void RS232_flushTX(int comport_number)
+{
+  PurgeComm(Cport[comport_number], PURGE_TXCLEAR | PURGE_TXABORT);
+}
+
+
+void RS232_flushRXTX(int comport_number)
+{
+  PurgeComm(Cport[comport_number], PURGE_RXCLEAR | PURGE_RXABORT);
+  PurgeComm(Cport[comport_number], PURGE_TXCLEAR | PURGE_TXABORT);
+}
+
+
+#endif
+
+
+void RS232_cputs(int comport_number, const char *text)  /* sends a string to serial port */
+{
+  while(*text != 0)   RS232_SendByte(comport_number, *(text++));
+}
+
+
+/* return index in comports matching to device name or -1 if not found */
+int RS232_GetPortnr(const char *devname)
+{
+  int i;
+
+  char str[32];
+
+#if defined(__linux__) || defined(__FreeBSD__)   /* Linux & FreeBSD */
+  strcpy(str, "/dev/");
+#else  /* windows */
+  strcpy(str, "\\\\.\\");
+#endif
+  strncat(str, devname, 16);
+  str[31] = 0;
+
+  for(i=0; i<RS232_PORTNR; i++)
+  {
+    if(!strcmp(comports[i], str))
+    {
+      return i;
+    }
+  }
+
+  return -1;  /* device not found */
+}
+
+
+
+
+
+
+
+
+
+
+
diff --git a/src/lib/rs232/rs232.h b/src/lib/rs232/rs232.h
new file mode 100644
index 0000000..73a2040
--- /dev/null
+++ b/src/lib/rs232/rs232.h
@@ -0,0 +1,88 @@
+/*
+***************************************************************************
+*
+* Author: Teunis van Beelen
+*
+* Copyright (C) 2005 - 2019 Teunis van Beelen
+*
+* Email: teuniz@protonmail.com
+*
+***************************************************************************
+*
+* This program is free software: you can redistribute it and/or modify
+* it under the terms of the GNU General Public License as published by
+* the Free Software Foundation, either version 3 of the License, or
+* (at your option) any later version.
+*
+* This program is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License
+* along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*
+***************************************************************************
+*/
+
+/* Last revision: May 31, 2019 */
+
+/* For more info and how to use this library, visit: http://www.teuniz.net/RS-232/ */
+
+
+#ifndef rs232_INCLUDED
+#define rs232_INCLUDED
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdio.h>
+#include <string.h>
+
+
+
+#if defined(__linux__) || defined(__FreeBSD__)
+
+#include <termios.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <limits.h>
+#include <sys/file.h>
+#include <errno.h>
+
+#else
+
+#include <windows.h>
+
+#endif
+
+int RS232_OpenComport(int, int, const char *, int);
+int RS232_PollComport(int, unsigned char *, int);
+int RS232_SendByte(int, unsigned char);
+int RS232_SendBuf(int, unsigned char *, int);
+void RS232_CloseComport(int);
+void RS232_cputs(int, const char *);
+int RS232_IsDCDEnabled(int);
+int RS232_IsRINGEnabled(int);
+int RS232_IsCTSEnabled(int);
+int RS232_IsDSREnabled(int);
+void RS232_enableDTR(int);
+void RS232_disableDTR(int);
+void RS232_enableRTS(int);
+void RS232_disableRTS(int);
+void RS232_flushRX(int);
+void RS232_flushTX(int);
+void RS232_flushRXTX(int);
+int RS232_GetPortnr(const char *);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif
+
+