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-rw-r--r--sw/z80/coding_rules.txt120
-rw-r--r--sw/z80/crt0.s4
-rw-r--r--sw/z80/kernel/include/devices.h13
-rw-r--r--sw/z80/kernel/include/pio.h35
-rw-r--r--sw/z80/kernel/include/types.h2
-rw-r--r--sw/z80/kernel/include/usart.h149
-rw-r--r--sw/z80/kernel/kernel.c9
-rw-r--r--sw/z80/kernel/pio.c18
-rw-r--r--sw/z80/kernel/usart.c91
-rw-r--r--sw/z80/libc/include/stdio.h11
-rw-r--r--sw/z80/libc/include/string.h8
-rw-r--r--sw/z80/libc/stdio.c12
-rw-r--r--sw/z80/libc/string.c13
13 files changed, 477 insertions, 8 deletions
diff --git a/sw/z80/coding_rules.txt b/sw/z80/coding_rules.txt
new file mode 100644
index 0000000..e5c11f0
--- /dev/null
+++ b/sw/z80/coding_rules.txt
@@ -0,0 +1,120 @@
+CODING STYLE FOR THIS PROJECT
+=============================
+
+In order to have a consistent codebase, there are the following rules on
+writing code in C (and assembly). For the most part they are similar to the
+Linux kernel coding rules by Torvalds.
+
+PROGRAM LOGIC
+-------------
+I expect a certain level of common sense from people so I won't mention the
+super-basic stuff. But I would like to point out a few thing I WON'T accept
+(unless there is a valid reason and an explanation of why). First, I believe
+that code has to be aesthetically pleasing to watch and with a clear logic
+flow so:
+
+ - Avoid deeply nested code and recursive black magic
+
+ - No special cases: generally the code of a function should behave the
+ same with any argument. Avoid horrible exceptions for magic values
+
+ - No extreme modularization: do not write code that is extremely
+ encapsulated with dozens of helper functions to control every signal
+ that runs through the damn motherboard
+
+EDITOR (SPACES > TABS)
+----------------------
+You can use your favourite editor but spaces are better than tabs, no
+discussion. For this project every source file must have an indent of 4
+spaces. Since 80 characters is the standard terminal width, the code has to be
+hard wrapped at 80, 78 or 72 characters. Also there shouldn't be any markup on
+the source code for your editor, not even in the comments; just the code.
+
+ - use spaces, 1 indent - 4 spaces
+ - hard wrap at 80 / 78 / 72 characters
+ - no markup for folds or any other editor specific feature
+
+
+C CODE INDENT AND BRACES
+------------------------
+I personally prefer the K&R coding style because it was used in 'The C
+Programming Language' book from Dennis Ritchie which is the 'standard' for
+learning C. But I also like Linus' kernel coding rules, so sometimes I might
+use some of his rules. Anyway, you can look them up if you want to or just
+look at the following example that sums most of the important stuff.
+
+ - K&R braces and function prototypes
+ - snake_case for variables and function names
+ - pointer asterisk in front of the variable ( ex: int *p; )
+
+Here's a short example that uses most of the stuff:
+
+ #include <stdio.h>
+ #include <stdlib.h>
+
+ #define MY_DEVICE_MEMORY_ADDR 0x5020
+
+ #define MY_DEVICE_FLAG_RDY 1
+ #define MY_DEVICE_FLAG_ERR 2
+
+ // same for unions
+ struct my_device
+ {
+ volatile uint8_t buffer;
+ volatile uint8_t flags;
+ } *_my_dev = (struct my_device *) MY_DEVICE_MEMORY_ADDR;
+
+
+ int my_device_write(uint8_t *data, size_t size);
+
+ /* This is the main function
+ * and this is a multiline comment to explain something if needed
+ */
+ int main(int argc, char *argv[])
+ {
+ int i;
+ int j = 0;
+ uint8_t data[2] = { 0xFF, 0xAB };
+ const char *string = "My magic string";
+
+ while (j < 100) {
+ j++;
+ }
+
+ printf("%s\n", string);
+
+ if (some_condition) {
+ // inline comment
+ } else {
+ my_device_write(data, 2);
+ }
+
+ switch (i) {
+ case 0:
+ some_function();
+ break;
+
+ case 1:
+ // ...
+ break;
+
+ default:
+ // ...
+ }
+ }
+
+ int my_device_write(uint8_t *data, size_t size)
+ {
+ int i;
+
+ for (i = 0; i < size; i++) {
+ _my_dev.buffer = data;
+ while (!(_my_dev.flags & (1<<MY_DEVICE_FLAG_RDY)));
+
+ if (_my_dev.flags & (1<<MY_DEVICE_FLAG_ERR)) {
+ return -1;
+ }
+ }
+
+ return i;
+ }
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..e8c183f
--- /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 0x4100
+#define ADDR_DEV_PIO 0x4200
+
+#define ADDR_DEV_RAM 0x8000
+
+#endif
diff --git a/sw/z80/kernel/include/pio.h b/sw/z80/kernel/include/pio.h
new file mode 100644
index 0000000..5d289ca
--- /dev/null
+++ b/sw/z80/kernel/include/pio.h
@@ -0,0 +1,35 @@
+#ifndef __PIO_H__
+#define __PIO_H__
+
+#include "devices.h"
+#include "types.h"
+
+#define PIO_A 0
+#define PIO_B 1
+
+#define PIO_MODE_0 0
+#define PIO_MODE_1 1
+#define PIO_MODE_2 2
+#define PIO_MODE_3 3
+
+#define PIO_INT_ACTIVE_HIGH (1<<5)
+#define PIO_INT_AND_MODE (1<<6)
+#define PIO_INT_ENABLE (1<<7)
+
+
+void _pio_data(int port, uint8_t data);
+void _pio_command(int port, uint8_t cmd);
+
+void pio_set_mode(int port, int mode);
+void pio_set_interrupts(int port, int control);
+void pio_set_interrupts_mask(int port, uint8_t mask);
+void pio_set_io(int port, uint8_t io);
+
+// uint8_t pio_read_data(int port);
+
+inline int pio_read_pin(int port, uint8_t pin);
+inline void pio_write_pin(int port, uint8_t pin);
+
+// TODO: implement mode (in/out/both) and interrupt vector
+
+#endif // __PIO_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/include/usart.h b/sw/z80/kernel/include/usart.h
new file mode 100644
index 0000000..3e5c070
--- /dev/null
+++ b/sw/z80/kernel/include/usart.h
@@ -0,0 +1,149 @@
+#ifndef __USART_H__
+#define __USART_H__
+
+#include "types.h"
+#include "devices.h"
+
+#include "string.h"
+
+// baudrate clock divisors
+// values from TL16C550C datasheet (table 9 for 1.8432 MHz crystal)
+#define USART_BAUDRATE_50 2304
+#define USART_BAUDRATE_75 1536
+#define USART_BAUDRATE_110 1047
+#define USART_BAUDRATE_134_5 857
+#define USART_BAUDRATE_150 768
+#define USART_BAUDRATE_300 384
+#define USART_BAUDRATE_600 192
+#define USART_BAUDRATE_1200 96
+#define USART_BAUDRATE_1800 64
+#define USART_BAUDRATE_2000 58
+#define USART_BAUDRATE_2400 48
+#define USART_BAUDRATE_3600 32
+#define USART_BAUDRATE_4800 24
+#define USART_BAUDRATE_7200 16
+#define USART_BAUDRATE_9600 12
+#define USART_BAUDRATE_19200 6
+#define USART_BAUDRATE_38400 3
+#define USART_BAUDRATE_56000 3
+
+// parity
+#define USART_PARITY_NONE 0
+#define USART_PARITY_EVEN 1
+#define USART_PARITY_ODD 2
+
+// stop bits
+#define USART_STOP_BITS_1 10
+#define USART_STOP_BITS_15 15
+#define USART_STOP_BITS_2 20
+
+// word lenght
+#define USART_WORD_LENGTH_5 0
+#define USART_WORD_LENGTH_6 1
+#define USART_WORD_LENGTH_7 2
+#define USART_WORD_LENGTH_8 3
+
+// autoflow
+#define USART_AUTOFLOW_ALL 3
+#define USART_AUTOFLOW_CTS 2
+#define USART_AUTOFLOW_OFF 0
+
+
+/* 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;
+ volatile int trasmitter_fifo_rst :1;
+ volatile int dma_mode_select :1;
+ volatile int reserved :1;
+ volatile int receiver_trigger :2;
+ } FCR;
+
+ 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_holder_empty :1;
+ volatile int transmitter_empty :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;
+};
+
+
+// setup functions (wrappers)
+void usart_set_baudrate(uint16_t baudrate);
+void usart_set_parity(int mode);
+void usart_set_stop_bits(int count);
+void usart_set_word_length(int length);
+void usart_set_autoflow(int mode);
+
+inline void usart_init(uint16_t baudrate, int parity, int stop_bits);
+
+void usart_transmit(uint8_t data);
+uint8_t usart_receive();
+
+int usart_write(uint8_t *data, size_t size);
+int usart_read(uint8_t *buffer, size_t count);
+
+#endif // __USART__H__
diff --git a/sw/z80/kernel/kernel.c b/sw/z80/kernel/kernel.c
index fe87c3d..3d5aeb6 100644
--- a/sw/z80/kernel/kernel.c
+++ b/sw/z80/kernel/kernel.c
@@ -1,10 +1,7 @@
#include "types.h"
+#include "usart.h"
-
-void main(void)
+void kmain(void)
{
- int i, j = 20;
- for (i = 0; i < 10; i++) {
- j--;
- }
+ usart_init(USART_BAUDRATE_9600, USART_PARITY_EVEN, USART_STOP_BITS_1);
}
diff --git a/sw/z80/kernel/pio.c b/sw/z80/kernel/pio.c
new file mode 100644
index 0000000..4b9caee
--- /dev/null
+++ b/sw/z80/kernel/pio.c
@@ -0,0 +1,18 @@
+#include "pio.h"
+
+static uint8_t *pio_port = (uint8_t *) ADDR_DEV_PIO;
+static uint8_t *pio_ctrl = (uint8_t *) (ADDR_DEV_PIO + 2);
+
+void _pio_data(int port, uint8_t data)
+{
+ *(pio_port + port) = data;
+}
+
+void _pio_command(int port, uint8_t cmd)
+{
+ *(pio_ctrl + port) = cmd;
+}
+
+void pio_set_mode(int port, int mode)
+{
+}
diff --git a/sw/z80/kernel/usart.c b/sw/z80/kernel/usart.c
new file mode 100644
index 0000000..9ec6dbd
--- /dev/null
+++ b/sw/z80/kernel/usart.c
@@ -0,0 +1,91 @@
+#include "usart.h"
+
+static struct _usart_device *_usart = (struct _usart_device *) ADDR_DEV_USART;
+
+void usart_set_baudrate(uint16_t baudrate)
+{
+ // enable latch access
+ _usart->LCR.divisor_latch_access = 1;
+ _usart->buffer = 0x00FF & baudrate; // LSBs
+ memcpy(&_usart->IER, &(baudrate >>8), 1);
+ // _usart->IER = 0x00FF & (baudrate >> 8); // MSBs
+ _usart->LCR.divisor_latch_access = 0;
+}
+
+void usart_set_parity(int mode)
+{
+ if (mode == USART_PARITY_EVEN) {
+ _usart->LCR.even_parity = 1;
+ }
+ else if (mode == USART_PARITY_ODD) {
+ _usart->LCR.even_parity = 0;
+ }
+
+ _usart->LCR.parity = (mode == USART_PARITY_NONE) ? 0 : 1;
+}
+
+void usart_set_stop_bits(int count)
+{
+ _usart->LCR.stop_bits = (count == USART_STOP_BITS_1) ? 0 : 1;
+}
+
+void usart_word_length(int length)
+{
+ _usart->LCR.word_length = length;
+}
+
+void usart_set_autoflow(int mode)
+{
+ _usart->MCR.autoflow = (mode == USART_AUTOFLOW_OFF) ? 0 : 1;
+ _usart->MCR.data_terminal_ready = (mode == USART_AUTOFLOW_ALL);
+}
+
+inline void usart_init(uint16_t baudrate, int parity, int stop_bits)
+{
+ usart_set_baudrate(baudrate);
+ usart_set_parity(parity);
+ usart_set_stop_bits(stop_bits);
+ usart_set_autoflow(USART_AUTOFLOW_OFF);
+}
+
+void usart_transmit(uint8_t data)
+{
+ _usart->buffer = data;
+ while (_usart->LSR.transmitter_holder_empty == 0); // wait
+}
+
+uint8_t usart_receive()
+{
+ return _usart->buffer;
+}
+
+int usart_write(uint8_t *data, size_t size)
+{
+ uint8_t *dp = data;
+
+ while (size--) {
+ _usart->buffer = *(dp++);
+ while (_usart->LSR.transmitter_empty);
+ }
+
+ // TODO: do something that actually counts for sent bytes
+ return size;
+}
+
+int usart_read(uint8_t *buffer, size_t count)
+{
+ uint8_t *bp = buffer;
+ size_t read_count = 0;
+
+ while (count--) {
+ *(bp++) = _usart->buffer;
+ // check for errors
+ if (_usart->LSR.framing_error || _usart->LSR.parity_error) {
+ bp--; // delete last byte (?)
+ } else {
+ read_count++;
+ }
+ }
+
+ return read_count;
+}
diff --git a/sw/z80/libc/include/stdio.h b/sw/z80/libc/include/stdio.h
new file mode 100644
index 0000000..b31cdfd
--- /dev/null
+++ b/sw/z80/libc/include/stdio.h
@@ -0,0 +1,11 @@
+#ifndef __STDIO_H__
+#define __STDIO_H__
+
+#include "types.h"
+
+extern uint8_t *stdout, stderr;
+
+void putc(char ch, uint8_t *buffer);
+int printf(const char *fmt, ...);
+
+#endif
diff --git a/sw/z80/libc/include/string.h b/sw/z80/libc/include/string.h
new file mode 100644
index 0000000..f224c87
--- /dev/null
+++ b/sw/z80/libc/include/string.h
@@ -0,0 +1,8 @@
+#ifndef __STRING_H__
+#define __STRING_H__
+
+#include "types.h"
+
+void *memcpy(void *dest, const void *src, size_t n);
+
+#endif
diff --git a/sw/z80/libc/stdio.c b/sw/z80/libc/stdio.c
new file mode 100644
index 0000000..c2548d6
--- /dev/null
+++ b/sw/z80/libc/stdio.c
@@ -0,0 +1,12 @@
+#include "stdio.h"
+
+void putc(char ch, uint8_t *buffer)
+{
+ *buffer = ch;
+ *(++buffer) = '\0';
+}
+
+
+int printf(const char *fmt, ...)
+{
+}
diff --git a/sw/z80/libc/string.c b/sw/z80/libc/string.c
new file mode 100644
index 0000000..fd6a7ff
--- /dev/null
+++ b/sw/z80/libc/string.c
@@ -0,0 +1,13 @@
+#include "string.h"
+
+void *memcpy(void *dest, void *src, size_t n)
+{
+ char *dp = dest;
+ char *sp = src;
+
+ while (n--) {
+ *dp++ = *sp++;
+ }
+
+ return dest;
+}
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