initial commit

oscar64/include/c64/iecbus.c

@@ -0,0 +1,353 @@
+#include "iecbus.h"
+#include <c64/cia.h>
+#include <c64/vic.h>
+
+IEC_STATUS 	iec_status;
+char		iec_queue;
+
+#define CIA2B_ATNOUT	0x08
+#define CIA2B_CLKOUT	0x10
+#define CIA2B_DATAOUT	0x20
+
+#define CIA2B_CLKIN		0x40
+#define CIA2B_DATAIN	0x80
+
+#pragma optimize(push)
+#pragma optimize(1)
+
+// multiples of 5us
+static void delay(char n)
+{
+	__asm {
+		ldx n
+	l1:
+		dex
+		bne	l1
+	}
+}
+
+static inline void data_true(void)
+{
+	cia2.pra &= ~CIA2B_DATAOUT;
+}
+
+static inline void data_false(void)
+{
+	cia2.pra |= CIA2B_DATAOUT;
+}
+
+static inline void clock_true(void)
+{
+	cia2.pra &= ~CIA2B_CLKOUT;
+}
+
+static inline void cdata_true(void)
+{
+	cia2.pra &= ~(CIA2B_CLKOUT | CIA2B_DATAOUT);
+}
+
+static inline void clock_false(void)
+{
+	cia2.pra |= CIA2B_CLKOUT;
+}
+
+static inline void atn_true(void)
+{
+	cia2.pra &= ~CIA2B_ATNOUT;
+}
+
+static inline void atn_false(void)
+{
+	cia2.pra |= CIA2B_ATNOUT;
+}
+
+static inline bool data_in(void)
+{
+	return (cia2.pra & CIA2B_DATAIN) != 0;
+}
+
+static inline bool clock_in(void)
+{
+	return (cia2.pra & CIA2B_CLKIN) != 0;
+}
+
+static bool data_check(void)
+{
+ 	char cnt = 200;
+	while (cnt > 0 && data_in())
+	{
+		delay(5);
+		cnt--;
+	}
+
+	if (cnt)
+		return true;
+	else
+	{
+		iec_status = IEC_DATA_CHECK;
+		return false;
+	}	
+}
+
+static bool iec_eoib(void)
+{
+	clock_true();
+
+	while (!data_in());
+
+	delay(40);
+
+	return data_check();
+}
+
+static void iec_writeb(char b)
+{
+	clock_true();
+
+	while (!data_in());
+
+	delay(5);
+	for(char i=0; i<8; i++)
+	{
+		clock_false();
+		delay(5);
+		if (b & 1)
+			data_true();
+		else
+			data_false();		
+		clock_true();
+		b >>= 1;
+		delay(5);
+	}
+	clock_false();
+	data_true();
+}
+
+bool iec_write(char b)
+{
+	if (iec_status == IEC_QUEUED)
+	{
+		__asm
+		{
+			php
+			sei
+		}
+
+		iec_status = IEC_OK;
+		iec_writeb(iec_queue);
+
+	 	__asm
+		{
+			plp
+		}
+
+		data_check();
+	}
+	if (iec_status < IEC_ERROR)
+	{
+		iec_queue = b;
+		iec_status = IEC_QUEUED;
+		return true;
+	}
+
+	return false;
+}
+
+char iec_read(void)
+{
+	while (!clock_in());
+
+	__asm
+	{
+		php
+		sei
+	}
+
+ 	data_true();
+
+ 	char cnt = 100;
+	while (cnt > 0 && clock_in())
+		cnt--;
+
+	if (cnt == 0)
+	{
+		iec_status = IEC_EOF;
+ 		data_false();
+		delay(10);
+		data_true();
+
+		cnt = 200;
+		while (cnt > 0 && clock_in())
+			cnt--;
+
+		if (cnt == 0)
+		{
+			iec_status = IEC_TIMEOUT;
+
+		 	__asm
+			{
+				plp
+			}
+			
+			return 0;
+		}
+ 	}
+
+ 	char b = 0;
+ 	for(char i=0; i<8; i++)
+ 	{
+		char c;
+		while (!((c = cia2.pra) & CIA2B_CLKIN))
+			;
+
+		b >>= 1;
+		b |= c & 0x80;
+
+		while (cia2.pra & CIA2B_CLKIN)
+			;
+ 	}
+
+ 	data_false();
+ 	
+ 	__asm
+	{
+		plp
+	}
+
+ 	return b;
+}
+
+void iec_atn(char dev, char sec)
+{	
+	clock_true();
+	data_true();
+	atn_false();
+	clock_false();
+
+ 	delay(200);
+
+ 	while (data_in());
+
+	iec_writeb(dev);
+	data_check();
+	if (sec != 0xff)
+	{
+		iec_writeb(sec);
+		data_check();
+	}
+
+	atn_true();	
+}
+
+
+void iec_talk(char dev, char sec)
+{
+	iec_status = IEC_OK;
+
+	iec_atn(dev | 0x40, sec | 0x60);
+	data_false();
+
+	__asm
+	{
+		php
+		sei
+	}
+
+	clock_true();
+	char cnt = 200;
+	while (cnt > 0 && clock_in())
+		cnt--;
+
+ 	__asm
+	{
+		plp
+	}
+
+	delay(10);	
+}
+
+void iec_untalk(void)
+{
+	iec_atn(0x5f, 0xff);
+}
+
+void iec_listen(char dev, char sec)
+{
+	iec_status = IEC_OK;
+
+	iec_atn(dev | 0x20, sec | 0x60);
+}
+
+void iec_unlisten(void)
+{
+	__asm
+	{
+		php
+		sei
+	}
+
+	if (iec_status == IEC_QUEUED)
+	{
+		iec_status = IEC_OK;
+		iec_eoib();
+		iec_writeb(iec_queue);
+		data_check();
+	}
+
+	iec_atn(0x3f, 0xff);
+	clock_true();
+
+ 	__asm
+	{
+		plp
+	}
+}
+
+void iec_open(char dev, char sec, const char * fname)
+{
+	iec_status = IEC_OK;
+
+	iec_atn(dev | 0x20, sec | 0xf0);
+
+	char i = 0;
+	while (fname[i])
+	{
+		iec_write(fname[i]);
+		i++;
+	}
+	iec_unlisten();
+}
+
+void iec_close(char dev, char sec)
+{
+	iec_atn(dev | 0x20, sec | 0xe0);
+	iec_unlisten();
+}
+
+int iec_write_bytes(const char * data, int num)
+{
+	for(int i=0; i<num; i++)
+	{
+		if (!iec_write(data[i]))
+			return i;
+	}
+	return num;
+}
+
+int iec_read_bytes(char * data, int num)
+{
+	int i = 0;
+	while (i < num)
+	{
+		char ch = iec_read();
+		if (iec_status < IEC_ERROR)
+			data[i++] = ch;
+		if (iec_status != IEC_OK)
+			return i;
+	}
+	return num;
+}
+
+
+#pragma optimize(pop)
+