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

6 files changed, 104 insertions, 14 deletions

diff --git a/sw/z80/crt0.s b/sw/z80/crt0.s
index 7701ca6..00c7da1 100644
--- a/sw/z80/crt0.s
+++ b/sw/z80/crt0.s
@@ -27,7 +27,7 @@
 ;--------------------------------------------------------------------------
 
 	.module crt0
-	.globl	_main
+	.globl	_kmain
 
 	.area	_HEADER (ABS)
 	;; Reset vector
@@ -56,7 +56,7 @@ init:
 
 	;; Initialise global variables
 	call	gsinit
-	call	_main
+	call	_kmain
 	jp	    _exit
 
 	;; Ordering of segments for the linker.
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
diff --git a/sw/z80/kernel/kernel.c b/sw/z80/kernel/kernel.c
index fe87c3d..3db6579 100644
--- a/sw/z80/kernel/kernel.c
+++ b/sw/z80/kernel/kernel.c
@@ -1,10 +1,7 @@
 #include "types.h"
 
 
-void main(void)
+void kmain(void)
 {
-    int i, j = 20;
-    for (i = 0; i < 10; i++) {
-        j--;
-    }
+    
 }
diff --git a/sw/z80/libc/mem.c b/sw/z80/libc/mem.c
deleted file mode 100644
index 667a752..0000000
--- a/sw/z80/libc/mem.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include "types.h"
-#include "mem.h"
-
-void *malloc(size_t size)
-{
-    :
-}