add serial device struct

other changes:
  - change from main() to kmain() in crt0.s and kernel.c
  - new file devices.h to define all address locations for devices
  - new data type
      - register_t as volatile uint8_t for registers in devices
      - size_t from libc

3 files changed, 100 insertions, 0 deletions

diff --git a/sw/z80/kernel/include/devices.h b/sw/z80/kernel/include/devices.h
new file mode 100644
index 0000000..ea29065
--- /dev/null
+++ b/sw/z80/kernel/include/devices.h
@@ -0,0 +1,13 @@
+#ifndef __DEVICES_H__
+#define __DEVICES_H__
+
+#define ADDR_DEV_ROM_L      0x0000
+#define ADDR_DEV_ROM_H      0x2000
+
+#define ADDR_DEV_USART   0x4000
+#define ADDR_DEV_CTC     
+#define ADDR_DEV_PIO
+
+#define ADDR_DEV_RAM        0x8000
+
+#endif
diff --git a/sw/z80/kernel/include/serial.h b/sw/z80/kernel/include/serial.h
new file mode 100644
index 0000000..03e2448
--- /dev/null
+++ b/sw/z80/kernel/include/serial.h
@@ -0,0 +1,85 @@
+#ifndef __SERIAL_H__
+#define __SERIAL_H__
+
+#include "types.h"
+#include "devices.h"
+
+/* this structure is only for internal usage */
+struct _usart_device
+{
+    register_t buffer;  // also used as LSB for divisor latch
+
+    struct IER 
+    {
+        volatile int received_data_interrupt :1;
+        volatile int transmitter_empty_interrupt :1;
+        volatile int receiver_line_status_interrupt :1;
+        volatile int modem_status_interrupt :1;
+            volatile int reserved :4;
+    } IER;
+
+    struct IIR
+    {
+        volatile int interrupt_pending :1;
+        volatile int interrupt_id :3;
+        volatile int reserved :2;
+        volatile int fifos :2;
+    } IIR;
+
+    struct FCR
+    {
+        volatile int fifo_enable :1;
+        volatile int receiver_fifo_rst :1;
+    }
+
+    struct LCR
+    {
+        volatile int word_length :2;
+        volatile int stop_bits :1;
+        volatile int parity :1;
+        volatile int even_parity :1;
+        volatile int stick_parity :1;
+        volatile int break_control :1;
+        volatile int divisor_latch_access :1;
+    } LCR;
+
+    struct MCR
+    {
+        volatile int data_terminal_ready :1;
+        volatile int request_to_send :1;
+        volatile int out1;
+        volatile int out2;
+        volatile int loop;
+        volatile int autoflow :1;
+        volatile int reserved :2;
+    } MCR;
+
+    struct LSR 
+    {
+        volatile int data_ready :1;
+        volatile int overrun_error :1;
+        volatile int parity_error :1;
+        volatile int framing_error :1;
+        volatile int break_interrupt :1;
+        volatile int transmitter_register :1;
+        volatile int transmitter_emtpy :1;
+        volatile int fifo_recv_error :1;
+    } LSR;
+
+    struct MSR
+    {
+        volatile int delta_cts :1;
+        volatile int delta_data_set_ready :1;
+        volatile int trailing_edge_ring_indicator :1;
+        volatile int delta_data_carrier_detect :1;
+        volatile int clear_to_send :1;
+        volatile int data_set_ready :1;
+        volatile int ring_indicator :1;
+        volatile int data_carrier_detect :1;
+    } MSR;
+
+    register_t scratch;
+} *_usart = (_usart_device *) ADDR_DEV_USART;
+
+
+#endif // __SERIAL__H__
diff --git a/sw/z80/kernel/include/types.h b/sw/z80/kernel/include/types.h
index c24b311..552b7e9 100644
--- a/sw/z80/kernel/include/types.h
+++ b/sw/z80/kernel/include/types.h
@@ -1,6 +1,8 @@
 #ifndef __TYPES_H__
 #define __TYPES_H__
 
+#define register_t  volatile unsigned char
+
 #define int8_t      char
 #define uint8_t     unsigned char
 #define int16_t     int