X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=z80comp2;a=blobdiff_plain;f=emu%2Fsrc%2Fduart.c;fp=emu%2Fsrc%2Fduart.c;h=35e23128e3c83442223c1261b8ab6c7d4ced43bf;hp=0000000000000000000000000000000000000000;hb=a0a85eb847ff3bb5da13e78618efdcd1b9f588cf;hpb=b55f31d1ac4a1991f2ad7b2d17be06969ea25e47

diff --git a/emu/src/duart.c b/emu/src/duart.c
new file mode 100644
index 0000000..35e2312
--- /dev/null
+++ b/emu/src/duart.c
@@ -0,0 +1,169 @@
+#include "duart.h"
+#include "emu.h"
+
+enum {
+	REG_MRA			= 0x0,
+	REG_SRA_CSRA	= 0x1,
+	REG_CRA			= 0x2,
+	REG_RBA_TBA		= 0x3,
+	REG_IPCR_ACR	= 0x4,
+	REG_ISR_IMR		= 0x5,
+	REG_CUR_CTUR	= 0x6,
+	REG_CLR_CTLR	= 0x7,
+	REG_MRB			= 0x8,
+	REG_SRB_CSRB	= 0x9,
+	REG_CRB			= 0xa,
+	REG_RBB_TBB		= 0xb,
+	REG_IVR			= 0xc,
+	REG_IP_OPCR		= 0xd,
+	REG_CSTART_OPSET= 0xe,
+	REG_CSTOP_OPCLR	= 0xf
+};
+
+enum {
+	CMD_RX_ONOFF	= 0x03,
+	CMD_TX_ONOFF	= 0x0c,
+	CMD_RST_MPTR	= 0x10,
+	CMD_RST_RX		= 0x20,
+	CMD_RST_TX		= 0x30,
+	CMD_RST_ERR		= 0x40,
+	CMD_RST_BRKINT	= 0x50,
+	CMD_START_BRK	= 0x60,
+	CMD_STOP_BRK	= 0x70
+};
+
+enum {
+	STAT_RXRDY		= 0x01,
+	STAT_FFULL		= 0x02,
+	STAT_TXRDY		= 0x04,
+	STAT_TXEMPTY	= 0x08,
+	STAT_ERR_OVR	= 0x10,
+	STAT_ERR_PAR	= 0x20,
+	STAT_ERR_FRM	= 0x40,
+	STAT_ERR_BRK	= 0x80
+};
+
+struct port {
+	uint8_t mode[2];
+	uint8_t clksel;
+	int modeptr;
+	int tx, rx;
+	uint8_t rxfifo[4];
+	int rxfifo_in, rxfifo_out;
+
+};
+
+static struct port port[2];
+static uint8_t reg_ipcr;
+static uint8_t reg_auxctl;
+static uint8_t reg_istat;
+static uint8_t reg_imask;
+static uint16_t reg_count;
+static uint8_t reg_ivec;
+static uint8_t reg_opcr;
+static uint8_t oport;
+
+void duart_reset(void)
+{
+	int i;
+
+	reg_imask = 0;
+	reg_istat = 0;
+	reg_opcr = 0;
+	reg_ivec = 0xf;
+	oport = 0;
+
+	for(i=0; i<2; i++) {
+		port[i].mode[0] = port[i].mode[1] = 0;
+		port[i].modeptr = 0;
+		port[i].tx = port[i].rx = 0;
+		port[i].rxfifo_in = port[i].rxfifo_out = 0;
+	}
+}
+
+void duart_serin(int port, int c)
+{
+}
+
+static int tx_ready(int pidx)
+{
+	return port[pidx].tx;
+}
+
+static int rx_ready(int pidx)
+{
+	return port[pidx].rxfifo_in != port[pidx].rxfifo_out;
+}
+
+static int rx_full(int pidx)
+{
+	return ((port[pidx].rxfifo_in + 1) & 3) == port[pidx].rxfifo_out;
+}
+
+static void command(int pidx, uint8_t data)
+{
+	if(data & CMD_RX_ONOFF) {
+		port[pidx].rx = (data & CMD_RX_ONOFF) == 1;
+	}
+	if(data & CMD_TX_ONOFF) {
+		port[pidx].tx = (data & CMD_TX_ONOFF) == 4;
+	}
+	switch(data & 0xf0) {
+	case CMD_RST_MPTR:
+		port[pidx].modeptr = 0;
+		break;
+
+	default:
+		break;
+	}
+}
+
+uint8_t duart_read(int rs)
+{
+	uint8_t res;
+	int pidx = (rs >> 3) & 1;
+
+	switch(rs) {
+	case REG_SRA_CSRA:
+	case REG_SRB_CSRB:
+		res = STAT_TXEMPTY | STAT_TXRDY;
+		if(rx_ready(pidx)) {
+			res |= STAT_RXRDY;
+		}
+		if(rx_full(pidx)) {
+			res |= STAT_FFULL;
+		}
+		return res;
+
+	default:
+		break;
+	}
+	return 0;
+}
+
+void duart_write(int rs, uint8_t data)
+{
+	int mptr;
+	int pidx = (rs >> 3) & 1;
+
+	switch(rs) {
+	case REG_CRA:
+	case REG_CRB:
+		command(pidx, data);
+		break;
+
+	case REG_MRA:
+	case REG_MRB:
+		mptr = port[pidx].modeptr;
+		port[pidx].mode[mptr] = data;
+		if(!mptr) port[pidx].modeptr = 1;
+		break;
+
+	case REG_RBA_TBA:
+	case REG_RBB_TBB:
+		if(tx_ready(pidx)) {
+			emu_serout(pidx, data);
+		}
+		break;
+	}
+}