- reorganized project directory structure

[z80comp2] / emu / src / duart.c

diff --git a/emu/src/duart.c b/emu/src/duart.c
new file mode 100644 (file)
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;
+       }
+}