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/*
GSport - an Apple //gs Emulator
Copyright (C) 2010 - 2014 by GSport contributors
Based on the KEGS emulator written by and Copyright (C) 2003 Kent Dickey
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 of the License, or (at your
option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "defc.h"
#include "scc_llap.h"
#ifdef UNDER_CE
#define vsnprintf _vsnprintf
#endif
extern int Verbose;
extern int g_code_yellow;
extern double g_cur_dcycs;
extern int g_serial_type[];
extern int g_serial_out_masking;
extern int g_irq_pending;
extern int g_c041_val;
extern int g_appletalk_bridging;
extern int g_appletalk_turbo;
/* my scc port 0 == channel A = slot 1 = c039/c03b */
/* port 1 == channel B = slot 2 = c038/c03a */
#include "scc.h"
#define SCC_R14_DPLL_SOURCE_BRG 0x100
#define SCC_R14_FM_MODE 0x200
#define SCC_DCYCS_PER_PCLK ((DCYCS_1_MHZ) / ((DCYCS_28_MHZ) /8))
#define SCC_DCYCS_PER_XTAL ((DCYCS_1_MHZ) / 3686400.0)
#define SCC_BR_EVENT 1
#define SCC_TX_EVENT 2
#define SCC_RX_EVENT 3
#define SCC_MAKE_EVENT(port, a) (((a) << 1) + (port))
Scc scc_stat[2];
int g_baud_table[] = {
110, 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400
};
static char* wr_names[] = {
"command", // 0
"interrupt and transfer mode", // 1
"interrupt vector", // 2
"receive params", // 3
"misc params", // 4
"trasmit params", // 5
"sync/addr field", // 6
"sync/flag", // 7
"transmit", // 8
"master interrupt", // 9
"trans/recv control", // 10
"clock mode", // 11
"baud rate (lower)", // 12
"baud rate (upper)", // 13
"misc control", // 14
"ext/status interrupt" // 15
};
static char* rr_names[] = {
"status",
"special condition",
"interrupt vector",
"pending",
"RR4",
"RR5",
"RR6",
"RR7",
"receive data",
"RR9",
"misc status",
"time constant (lower)",
"time constant (upper)",
"RR14",
"ext/status interrupt"
};
int g_scc_overflow = 0;
void
scc_init()
{
Scc *scc_ptr;
int i, j;
for(i = 0; i < 2; i++) {
scc_ptr = &(scc_stat[i]);
scc_ptr->accfd = -1;
scc_ptr->sockfd = -1;
scc_ptr->socket_state = -1;
scc_ptr->rdwrfd = -1;
scc_ptr->state = 0;
scc_ptr->host_handle = 0;
scc_ptr->host_handle2 = 0;
scc_ptr->br_event_pending = 0;
scc_ptr->rx_event_pending = 0;
scc_ptr->tx_event_pending = 0;
scc_ptr->char_size = 8;
scc_ptr->baud_rate = 115200;
scc_ptr->telnet_mode = 0;
scc_ptr->telnet_iac = 0;
scc_ptr->out_char_dcycs = 0.0;
scc_ptr->socket_num_rings = 0;
scc_ptr->socket_last_ring_dcycs = 0;
scc_ptr->modem_mode = 0;
scc_ptr->modem_dial_or_acc_mode = 0;
scc_ptr->modem_plus_mode = 0;
scc_ptr->modem_s0_val = 0;
scc_ptr->modem_cmd_len = 0;
scc_ptr->modem_cmd_str[0] = 0;
for(j = 0; j < 2; j++) {
scc_ptr->telnet_local_mode[j] = 0;
scc_ptr->telnet_remote_mode[j] = 0;
scc_ptr->telnet_reqwill_mode[j] = 0;
scc_ptr->telnet_reqdo_mode[j] = 0;
}
}
scc_reset();
}
void
scc_reset()
{
Scc *scc_ptr;
int i;
for(i = 0; i < 2; i++) {
scc_ptr = &(scc_stat[i]);
scc_ptr->port = i;
scc_ptr->mode = 0;
scc_ptr->reg_ptr = 0;
scc_ptr->in_rdptr = 0;
scc_ptr->in_wrptr = 0;
scc_ptr->lad = 0;
scc_ptr->out_rdptr = 0;
scc_ptr->out_wrptr = 0;
scc_ptr->dcd = 0;
scc_ptr->wantint_rx = 0;
scc_ptr->wantint_tx = 0;
scc_ptr->wantint_zerocnt = 0;
scc_ptr->did_int_rx_first = 0;
scc_ptr->irq_pending = 0;
scc_ptr->read_called_this_vbl = 0;
scc_ptr->write_called_this_vbl = 0;
scc_evaluate_ints(i);
scc_hard_reset_port(i);
}
}
void
scc_hard_reset_port(int port)
{
Scc *scc_ptr;
scc_reset_port(port);
scc_ptr = &(scc_stat[port]);
scc_ptr->reg[14] = 0; /* zero bottom two bits */
scc_ptr->reg[13] = 0;
scc_ptr->reg[12] = 0;
scc_ptr->reg[11] = 0x08;
scc_ptr->reg[10] = 0;
scc_ptr->reg[7] = 0;
scc_ptr->reg[6] = 0;
scc_ptr->reg[5] = 0;
scc_ptr->reg[4] = 0x04;
scc_ptr->reg[3] = 0;
scc_ptr->reg[2] = 0;
scc_ptr->reg[1] = 0;
/* HACK HACK: */
scc_stat[0].reg[9] = 0; /* Clear all interrupts */
scc_evaluate_ints(port);
scc_regen_clocks(port);
}
void
scc_reset_port(int port)
{
Scc *scc_ptr;
scc_ptr = &(scc_stat[port]);
scc_ptr->reg[15] = 0xf8;
scc_ptr->reg[14] &= 0x03; /* 0 most (including >= 0x100) bits */
scc_ptr->reg[10] = 0;
scc_ptr->reg[5] &= 0x65; /* leave tx bits and sdlc/crc bits */
scc_ptr->reg[4] |= 0x04; /* Set async mode */
scc_ptr->reg[3] &= 0xfe; /* clear receiver enable */
scc_ptr->reg[1] &= 0xfe; /* clear ext int enable */
scc_ptr->br_is_zero = 0;
scc_ptr->tx_buf_empty = 1;
scc_ptr->wantint_rx = 0;
scc_ptr->wantint_tx = 0;
scc_ptr->wantint_zerocnt = 0;
scc_ptr->rx_queue_depth = 0;
scc_ptr->sdlc_eof = 0;
scc_ptr->eom = 1;
scc_evaluate_ints(port);
scc_regen_clocks(port);
scc_clr_tx_int(port);
scc_clr_rx_int(port);
}
void
scc_regen_clocks(int port)
{
Scc *scc_ptr;
double br_dcycs, tx_dcycs, rx_dcycs;
double rx_char_size, tx_char_size;
double clock_mult;
word32 reg4;
word32 reg14;
word32 reg11;
word32 br_const;
word32 baud;
word32 max_diff;
word32 diff;
int sync_mode = 0;
int baud_entries;
int pos;
int i;
/* Always do baud rate generator */
scc_ptr = &(scc_stat[port]);
br_const = (scc_ptr->reg[13] << 8) + scc_ptr->reg[12];
br_const += 2; /* counts down past 0 */
reg4 = scc_ptr->reg[4];
clock_mult = 1.0;
switch((reg4 >> 6) & 3) {
case 0: /* x1 */
clock_mult = 1.0;
break;
case 1: /* x16 */
clock_mult = 16.0;
break;
case 2: /* x32 */
clock_mult = 32.0;
break;
case 3: /* x64 */
clock_mult = 64.0;
break;
}
br_dcycs = 0.01;
reg14 = scc_ptr->reg[14];
if(reg14 & 0x1) {
br_dcycs = SCC_DCYCS_PER_XTAL;
if(reg14 & 0x2) {
br_dcycs = SCC_DCYCS_PER_PCLK;
}
}
br_dcycs = br_dcycs * (double)br_const;
tx_dcycs = 1;
rx_dcycs = 1;
reg11 = scc_ptr->reg[11];
if(((reg11 >> 3) & 3) == 2) {
tx_dcycs = 2.0 * br_dcycs * clock_mult;
}
switch ((reg11 >> 5) & 3) {
case 0:
// Receive clock = RTxC pin (not emulated)
case 1:
// Receive clock = TRxC pin (not emulated)
// The real SCC has external pins that could provide the clock. But, this is not emulated.
break;
case 3:
// Receive clock = DPLL output
// Only LocalTalk uses the DPLL receive clock. We do not, however, emulate the DPLL.
// In this case, the receive clock should be about the same as the transmit clock.
rx_dcycs = tx_dcycs;
break;
case 2:
// Receive clock = BRG output
rx_dcycs = 2.0 * br_dcycs * clock_mult;
break;
}
tx_char_size = 8.0;
switch((scc_ptr->reg[5] >> 5) & 0x3) {
case 0: // 5 bits
tx_char_size = 5.0;
break;
case 1: // 7 bits
tx_char_size = 7.0;
break;
case 2: // 6 bits
tx_char_size = 6.0;
break;
}
scc_ptr->char_size = (int)tx_char_size;
switch((scc_ptr->reg[4] >> 2) & 0x3) {
case 0: // sync mode (no start or stop bits)
sync_mode = 1;
break;
case 1: // 1 stop bit
tx_char_size += 2.0; // 1 stop + 1 start bit
break;
case 2: // 1.5 stop bit
tx_char_size += 2.5; // 1.5 stop + 1 start bit
break;
case 3: // 2 stop bits
tx_char_size += 3.0; // 2.0 stop + 1 start bit
break;
}
if((scc_ptr->reg[4] & 1) && !sync_mode) {
// parity enabled
tx_char_size += 1.0;
}
if(scc_ptr->reg[14] & 0x10) {
/* loopback mode, make it go faster...*/
rx_char_size = 1.0;
tx_char_size = 1.0;
}
rx_char_size = tx_char_size; /* HACK */
baud = (int)(DCYCS_1_MHZ / tx_dcycs);
max_diff = 5000000;
pos = 0;
baud_entries = sizeof(g_baud_table)/sizeof(g_baud_table[0]);
for(i = 0; i < baud_entries; i++) {
diff = abs((int)(g_baud_table[i] - baud));
if(diff < max_diff) {
pos = i;
max_diff = diff;
}
}
scc_ptr->baud_rate = g_baud_table[pos];
scc_ptr->br_dcycs = br_dcycs;
scc_ptr->tx_dcycs = tx_dcycs * tx_char_size;
scc_ptr->rx_dcycs = rx_dcycs * rx_char_size;
switch (scc_ptr->state) {
case 1: /* socket */
scc_socket_change_params(port);
break;
case 2: /* real serial ports */
#ifdef MAC
scc_serial_mac_change_params(port);
#endif
#ifdef _WIN32
scc_serial_win_change_params(port);
#endif
break;
case 3: /* localtalk */
if (g_appletalk_turbo)
{
// If the user has selected AppleTalk "turbo" mode, increase the baud
// rate to be as fast as possible, limited primarily by the ability of
// the emulated GS to handle data.
scc_ptr->baud_rate = 0;
scc_ptr->br_dcycs = 1;
scc_ptr->tx_dcycs = 1;
scc_ptr->rx_dcycs = 1;
}
break;
case 4: /* Imagewriter */
scc_ptr->baud_rate = 0;
scc_ptr->tx_dcycs = tx_dcycs * 1.2; //Somehow this speeds up serial transfer without overrunning the buffer
scc_ptr->rx_dcycs = rx_dcycs * 1.2;
break;
}
}
void
scc_port_init(int port)
{
int state;
state = 0;
switch (g_serial_type[port]) {
case 0:
break;
case 1:
#ifdef MAC
state = scc_serial_mac_init(port);
#endif
#ifdef _WIN32
state = scc_serial_win_init(port);
#endif
break;
case 2:
state = scc_imagewriter_init(port);
break;
default:
break;
}
if(state <= 0) {
scc_socket_init(port);
}
}
void
scc_try_to_empty_writebuf(int port, double dcycs)
{
Scc *scc_ptr;
int state;
scc_ptr = &(scc_stat[port]);
state = scc_ptr->state;
if(scc_ptr->write_called_this_vbl) {
return;
}
scc_ptr->write_called_this_vbl = 1;
switch (state)
{
case 2:
#if defined(MAC)
scc_serial_mac_empty_writebuf(port);
#endif
#if defined(_WIN32)
scc_serial_win_empty_writebuf(port);
#endif
break;
case 1:
scc_socket_empty_writebuf(port, dcycs);
break;
case 3:
// When we're doing LocalTalk, the write buffer gets emptied at the end of the frame and does not use this function.
break;
case 4:
scc_imagewriter_empty_writebuf(port, dcycs);
break;
}
}
void
scc_try_fill_readbuf(int port, double dcycs)
{
Scc *scc_ptr;
int space_used_before_rx, space_left;
int space_used_after_rx;
int state;
scc_ptr = &(scc_stat[port]);
state = scc_ptr->state;
space_used_before_rx = scc_ptr->in_wrptr - scc_ptr->in_rdptr;
if(space_used_before_rx < 0) {
space_used_before_rx += SCC_INBUF_SIZE;
}
space_left = (7*SCC_INBUF_SIZE/8) - space_used_before_rx;
if(space_left < 1) {
/* Buffer is pretty full, don't try to get more */
return;
}
#if 0
if(scc_ptr->read_called_this_vbl) {
return;
}
#endif
scc_ptr->read_called_this_vbl = 1;
switch (state)
{
case 2:
#if defined(MAC)
scc_serial_mac_fill_readbuf(port, space_left, dcycs);
#endif
#if defined(_WIN32)
scc_serial_win_fill_readbuf(port, space_left, dcycs);
#endif
break;
case 1:
scc_socket_fill_readbuf(port, space_left, dcycs);
break;
case 3:
// LLAP deals with packets, and we only allow one packet in the read buffer at a time.
// If the buffer is empty, try to fill it with another packet.
if (g_appletalk_bridging && (space_used_before_rx == 0) && (scc_ptr->rx_queue_depth == 0) && !(scc_ptr->sdlc_eof))
{
scc_llap_fill_readbuf(port, space_left, dcycs);
//scc_maybe_rx_event(port, dcycs);
scc_ptr->sdlc_eof = 0;
break;
case 4:
scc_imagewriter_fill_readbuf(port, space_left, dcycs);
break;
}
break;
}
// Update the LAD (link activity detector), which LocalTalk uses in the CSMA/CA algorithm.
// The real LAD depends on the line coding and data, but the "get bigger when data on RX line"
// emulation is good enough since no software depends on the specific value of the LAD counter.
// Practically, the emulated LLAP interface never has collisions and the LAD, therefore, is not
// useful, but, for sake of correctness and more realisitic timing, emulate the LAD anyway.
space_used_after_rx = scc_ptr->in_wrptr - scc_ptr->in_rdptr;
if(space_used_after_rx < 0) {
space_used_after_rx += SCC_INBUF_SIZE;
}
scc_ptr->lad += space_used_after_rx - space_used_before_rx;
}
void
scc_update(double dcycs)
{
if (g_appletalk_bridging && (scc_stat[0].state == 3 || scc_stat[1].state == 3))
scc_llap_update();
/* called each VBL update */
scc_stat[0].write_called_this_vbl = 0;
scc_stat[1].write_called_this_vbl = 0;
scc_stat[0].read_called_this_vbl = 0;
scc_stat[1].read_called_this_vbl = 0;
scc_try_fill_readbuf(0, dcycs);
scc_try_fill_readbuf(1, dcycs);
scc_stat[0].read_called_this_vbl = 0;
scc_stat[1].read_called_this_vbl = 0;
/* LLAP mode only transfers complete packets. Retain the data in the
transmit and receive buffers until the buffers contain one complete packet */
if (scc_stat[0].state != 3)
{
scc_try_to_empty_writebuf(0, dcycs);
scc_stat[0].write_called_this_vbl = 0;
}
if (scc_stat[1].state != 3)
{
scc_try_to_empty_writebuf(1, dcycs);
scc_stat[1].write_called_this_vbl = 0;
}
}
void
do_scc_event(int type, double dcycs)
{
Scc *scc_ptr;
int port;
port = type & 1;
type = (type >> 1);
scc_ptr = &(scc_stat[port]);
if(type == SCC_BR_EVENT) {
/* baud rate generator counted down to 0 */
scc_ptr->br_event_pending = 0;
scc_set_zerocnt_int(port);
scc_maybe_br_event(port, dcycs);
} else if(type == SCC_TX_EVENT) {
scc_ptr->tx_event_pending = 0;
scc_ptr->tx_buf_empty = 1;
scc_handle_tx_event(port, dcycs);
} else if(type == SCC_RX_EVENT) {
scc_ptr->rx_event_pending = 0;
scc_maybe_rx_event(port, dcycs);
} else {
halt_printf("do_scc_event: %08x!\n", type);
}
return;
}
void
show_scc_state()
{
Scc *scc_ptr;
int i, j;
for(i = 0; i < 2; i++) {
scc_ptr = &(scc_stat[i]);
printf("SCC port: %d\n", i);
for(j = 0; j < 16; j += 4) {
printf("Reg %2d-%2d: %02x %02x %02x %02x\n", j, j+3,
scc_ptr->reg[j], scc_ptr->reg[j+1],
scc_ptr->reg[j+2], scc_ptr->reg[j+3]);
}
printf("state: %d, accfd: %d, rdwrfd: %d, host:%p, host2:%p\n",
scc_ptr->state, scc_ptr->accfd, scc_ptr->rdwrfd,
scc_ptr->host_handle, scc_ptr->host_handle2);
printf("in_rdptr: %04x, in_wr:%04x, out_rd:%04x, out_wr:%04x\n",
scc_ptr->in_rdptr, scc_ptr->in_wrptr,
scc_ptr->out_rdptr, scc_ptr->out_wrptr);
printf("rx_queue_depth: %d, queue: %02x, %02x, %02x, %02x\n",
scc_ptr->rx_queue_depth, scc_ptr->rx_queue[0],
scc_ptr->rx_queue[1], scc_ptr->rx_queue[2],
scc_ptr->rx_queue[3]);
printf("want_ints: rx:%d, tx:%d, zc:%d\n",
scc_ptr->wantint_rx, scc_ptr->wantint_tx,
scc_ptr->wantint_zerocnt);
printf("ev_pendings: rx:%d, tx:%d, br:%d\n",
scc_ptr->rx_event_pending,
scc_ptr->tx_event_pending,
scc_ptr->br_event_pending);
printf("br_dcycs: %f, tx_dcycs: %f, rx_dcycs: %f\n",
scc_ptr->br_dcycs, scc_ptr->tx_dcycs,
scc_ptr->rx_dcycs);
printf("char_size: %d, baud_rate: %d, mode: %d\n",
scc_ptr->char_size, scc_ptr->baud_rate,
scc_ptr->mode);
printf("modem_dial_mode:%d, telnet_mode:%d iac:%d, "
"modem_cmd_len:%d\n", scc_ptr->modem_dial_or_acc_mode,
scc_ptr->telnet_mode, scc_ptr->telnet_iac,
scc_ptr->modem_cmd_len);
printf("telnet_loc_modes:%08x %08x, telnet_rem_motes:"
"%08x %08x\n", scc_ptr->telnet_local_mode[0],
scc_ptr->telnet_local_mode[1],
scc_ptr->telnet_remote_mode[0],
scc_ptr->telnet_remote_mode[1]);
printf("modem_mode:%08x plus_mode: %d, out_char_dcycs: %f\n",
scc_ptr->modem_mode, scc_ptr->modem_plus_mode,
scc_ptr->out_char_dcycs);
}
}
#define LEN_SCC_LOG 5000
STRUCT(Scc_log) {
int regnum;
word32 val;
double dcycs;
};
Scc_log g_scc_log[LEN_SCC_LOG];
int g_scc_log_pos = 0;
#define SCC_REGNUM(wr,port,reg) ((wr << 8) + (port << 4) + reg)
void
scc_log(int regnum, word32 val, double dcycs)
{
int pos;
pos = g_scc_log_pos;
g_scc_log[pos].regnum = regnum;
g_scc_log[pos].val = val;
g_scc_log[pos].dcycs = dcycs;
pos++;
if(pos >= LEN_SCC_LOG) {
pos = 0;
}
g_scc_log_pos = pos;
}
void
show_scc_log(void)
{
double dcycs;
int regnum;
int pos;
int i;
char* name;
pos = g_scc_log_pos;
dcycs = g_cur_dcycs;
printf("SCC log pos: %d, cur dcycs:%f\n", pos, dcycs);
for(i = 0; i < LEN_SCC_LOG; i++) {
pos--;
if(pos < 0) {
pos = LEN_SCC_LOG - 1;
}
regnum = g_scc_log[pos].regnum;
if (regnum >> 8)
name = wr_names[regnum & 0xf];
else
name = rr_names[regnum & 0xf];
printf("%d:%d:\tport:%d wr:%d reg: %d (%s)\t\tval:%02x \tat t:%f\n",
i, pos, (regnum >> 4) & 0xf, (regnum >> 8),
(regnum & 0xf),
name,
g_scc_log[pos].val,
g_scc_log[pos].dcycs /*- dcycs*/);
}
}
word16 scc_read_lad(int port)
{
// The IIgs provides a "LocalTalk link activity detector (LAD)" through repurposing the
// MegaII mouse interface. Per the IIgs schematic, the MegaII mouse inputs connect via
// the MSEX and MSEY lines to the RX lines of the SCC between the SCC and the line drivers.
// So, if there's activity on the RX lines, the mouse counters increment. The firmware
// uses this for the "carrier sense" part of the CSMA/CA algorithm. Typical firmware usage
// is to (1) reset the mouse counter, (2) wait a bit, and (3) take action if some activity
// is present. The firmware does not appear to use the specific value of the LAD counter;
// rather, the firmware only considers "zero" and "not zero".
//
// Apple engineers invented the term LAD, and there are references to it in Gus.
if (port != 0 && port != 1)
{
halt_printf("Invalid SCC port.\n");
return 0;
}
Scc* scc_ptr = &(scc_stat[port]);
if (g_c041_val & C041_EN_MOUSE)
{
unsigned int temp = scc_ptr->lad;
scc_ptr->lad = 0;
return temp;
}
else
return 0;
}
word32
scc_read_reg(int port, double dcycs)
{
Scc *scc_ptr;
word32 ret;
int regnum;
scc_ptr = &(scc_stat[port]);
scc_ptr->mode = 0;
regnum = scc_ptr->reg_ptr;
/* port 0 is channel A, port 1 is channel B */
switch(regnum) {
case 0:
case 4:
ret = 0x20;
if (scc_ptr->eom)
ret |= 0x40;
if(scc_ptr->dcd) {
ret |= 0x08;
}
ret |= 0x8; /* HACK HACK */
if(scc_ptr->rx_queue_depth) {
ret |= 0x01;
}
if(scc_ptr->tx_buf_empty) {
ret |= 0x04;
}
if(scc_ptr->br_is_zero) {
ret |= 0x02;
}
//printf("Read scc[%d] stat: %f : %02x\n", port, dcycs, ret);
break;
case 1:
case 5:
/* HACK: residue codes not right */
ret = 0x07; /* all sent */
if (scc_ptr->state == 3 && scc_ptr->sdlc_eof)
ret |= 0x80;
break;
case 2:
case 6:
if(port == 0) {
ret = scc_ptr->reg[2];
} else {
halt_printf("Read of RR2B...stopping\n");
ret = 0;
#if 0
ret = scc_stat[0].reg[2];
wr9 = scc_stat[0].reg[9];
for(i = 0; i < 8; i++) {
if(ZZZ){};
}
if(wr9 & 0x10) {
/* wr9 status high */
}
#endif
}
break;
case 3:
case 7:
if(port == 0) {
// The interrupt pending register only exists in channel A.
ret = (scc_stat[0].irq_pending << 3) | scc_stat[1].irq_pending;
} else {
ret = 0;
}
break;
case 8:
ret = scc_read_data(port, dcycs);
break;
case 9:
case 13:
ret = scc_ptr->reg[13];
break;
case 10:
case 14:
ret = 0;
break;
case 11:
case 15:
ret = scc_ptr->reg[15];
break;
case 12:
ret = scc_ptr->reg[12];
break;
default:
halt_printf("Tried reading c03%x with regnum: %d!\n", 8+port,
regnum);
ret = 0;
}
scc_ptr->reg_ptr = 0;
scc_printf("Read c03%x, rr%d, ret: %02x\n", 8+port, regnum, ret);
//if(regnum != 0 && regnum != 3) {
scc_log(SCC_REGNUM(0,port,regnum), ret, dcycs);
//}
return ret;
}
void
scc_write_reg(int port, word32 val, double dcycs)
{
Scc *scc_ptr;
word32 old_val;
word32 changed_bits;
word32 irq_mask;
int regnum;
int mode;
int tmp1;
scc_ptr = &(scc_stat[port]);
regnum = scc_ptr->reg_ptr & 0xf;
mode = scc_ptr->mode;
// The SCC has more internal registers than memory locations mapped into the CPU's address space.
// To access alternate registers, the CPU writes a register selection code to WR0. The next write
// goes to the selected register. WR0 also contains several command and reset codes, and it is
// possible to write command, reset, and register selection in a single WR0 write.
if(mode == 0) {
// WR0 is selected, and this write goes to WR0.
// Extract the register selection code, which determines the next register access in conjunction with the "point high" command.
scc_ptr->reg_ptr = val & 0x07;
if (((val >> 3) & 0x07) == 0x01)
scc_ptr->reg_ptr |= 0x08;
// But, this write goes to WR0.
regnum = 0;
if (scc_ptr->reg_ptr)
scc_ptr->mode = 1;
} else {
// Some other register is selected, but the next access goes to register 0.
scc_ptr->reg_ptr = 0;
scc_ptr->mode = 0;
}
if ((regnum != 0) || // accesses to registers other than WR0
((regnum == 0) && (val & 0xf8)) || // accesses to WR0 only for selecting a register
((regnum == 0) && ((val & 0x38) == 0x80)) // access to WR0 with a point high register selection
)
// To keep the log shorter and easier to read, omit register selection code write to WR0. Log everything else.
scc_log(SCC_REGNUM(1,port,regnum), val, dcycs);
changed_bits = (scc_ptr->reg[regnum] ^ val) & 0xff;
/* Set reg reg */
switch(regnum) {
case 0: /* wr0 */
tmp1 = (val >> 3) & 0x7;
switch(tmp1) {
case 0x0: /* null code */
break;
case 0x1: /* point high */
break;
case 0x2: /* reset ext/status ints */
/* should clear other ext ints */
scc_clr_zerocnt_int(port);
break;
case 0x3: /* send abort (sdlc) */
halt_printf("Wr c03%x to wr0 of %02x, bad cmd cd:%x!\n",
8+port, val, tmp1);
scc_ptr->eom = 1;
break;
case 0x4: /* enable int on next rx char */
scc_ptr->did_int_rx_first = 0;
break;
case 0x5: /* reset tx int pending */
scc_clr_tx_int(port);
break;
case 0x6: /* reset rr1 bits */
// Per Section 5.2.1 of the SCC User's Manual, issuing an Error Reset when
// a special condition exists (e.g. EOF) while using "interrupt on first RX"
// mode causes loss of the the data with the special condition from the receive
// FIFO. In some cases, the GS relies on this behavior to clear the final CRC
// byte from the RX FIFO.
//
// Based on experimentation, checking for an active first RX interrupt is incorrect.
// System 5 fails to operate correctly with this check. Anyway, skipping this check
// seems to correct operation, but more investigation is necessary.
if ((scc_ptr->sdlc_eof == 1) /*&& (scc_ptr->did_int_rx_first == 1)*/)
{
// Remove and discard one byte (the one causing the current special condition) from the RX FIFO.
int depth = scc_ptr->rx_queue_depth;
if (depth != 0) {
for (int i = 1; i < depth; i++) {
scc_ptr->rx_queue[i - 1] = scc_ptr->rx_queue[i];
}
scc_ptr->rx_queue_depth = depth - 1;
scc_maybe_rx_event(port, dcycs);
scc_maybe_rx_int(port, dcycs);
}
}
// Reset emulated error bits. Note that we don't emulate all the bits.
scc_ptr->sdlc_eof = 0;
break;
case 0x7: /* reset highest pri int pending */
irq_mask = g_irq_pending;
if(port == 0) {
/* Move SCC0 ints into SCC1 positions */
irq_mask = irq_mask >> 3;
}
if(irq_mask & IRQ_PENDING_SCC1_RX) {
scc_clr_rx_int(port);
scc_ptr->irq_pending &= ~IRQ_PENDING_SCC1_RX;
} else if(irq_mask & IRQ_PENDING_SCC1_TX) {
scc_clr_tx_int(port);
scc_ptr->irq_pending &= ~IRQ_PENDING_SCC1_TX;
} else if(irq_mask & IRQ_PENDING_SCC1_ZEROCNT) {
scc_clr_zerocnt_int(port);
scc_ptr->irq_pending &= ~IRQ_PENDING_SCC1_ZEROCNT;
}
break;
default:
halt_printf("Wr c03%x to wr0 of %02x, bad cmd cd:%x!\n",
8+port, val, tmp1);
}
tmp1 = (val >> 6) & 0x3;
switch(tmp1) {
case 0x0: /* null code */
break;
case 0x1: /* reset rx crc */
// Do nothing. Emulated packets never have CRC errors.
break;
case 0x2: /* reset tx crc */
// Do nothing. Emulated packets never have CRC errors.
break;
case 0x3: /* reset tx underrun/eom latch */
/* if no extern status pending, or being reset now */
/* and tx disabled, ext int with tx underrun */
/* ah, just do nothing */
//if (!(scc_ptr->reg[5] & 0x08))
// First, this command has no effect unless the transmitter is disabled.
//scc_ptr->eom = 0;
break;
}
return;
case 1: /* wr1 */
/* proterm sets this == 0x10, which is int on all rx */
scc_ptr->reg[regnum] = val;
return;
case 2: /* wr2 */
/* All values do nothing, let 'em all through! */
scc_ptr->reg[regnum] = val;
return;
case 3: /* wr3 */
if((scc_ptr->state != 3) && ((val & 0x0e) != 0x0)) {
halt_printf("Wr c03%x to wr3 of %02x!\n", 8+port, val);
}
old_val = scc_ptr->reg[regnum];
scc_ptr->reg[regnum] = val;
if (!(old_val & 0x01) && (val & 0x01))
{
// If the receiver transitions from disabled to enabled, try to pull data into the FIFO.
scc_try_fill_readbuf(port, dcycs);
scc_maybe_rx_event(port, dcycs);
}
return;
case 4: /* wr4 */
if((val & 0x30) != 0x00 && (val & 0x30) != 0x20) {
halt_printf("Wr c03%x to wr4 of %02x!\n", 8+port, val);
}
if (((val >> 4) & 0x3) == 0x02 /* SDLC */ &&
((val >> 2) & 0x3) == 0x00 /* enable sync modes */)
{
if (g_appletalk_bridging)
{
// SDLC mode enabled. Redirect such data to the LocalTalk driver.
scc_ptr->state = 3;
scc_llap_init();
printf("Enabled LocalTalk on port %d.\n", port);
}
else
printf("Attempted to enable LocalTalk on port %d but bridging is disabled.\n", port);
}
scc_ptr->reg[regnum] = val;
if(changed_bits) {
scc_regen_clocks(port);
}
return;
case 5: /* wr5 */
if((val & 0x10) != 0x0) {
halt_printf("Wr c03%x to wr5 of %02x!\n", 8+port, val);
}
// Since we don't emulate the SDLC frame, ignore the CRC polynomial type (bit 2).
// Since the emulated link never has CRC errors, silently accept Tx CRC enable.
if (g_appletalk_bridging && scc_ptr->state == 3)
{
if ((scc_ptr->reg[regnum] & 0x08) && !(val & 0x08))
{
// When the TX enable changes from enabled to disabled, the GS is about to finish a frame.
// The GS will wait a bit longer for the hardware to finish sending the abort sequence, but
// this is of little concern since we don't have a "real line".
scc_llap_empty_writebuf(port, dcycs);
//scc_ptr->eom = 1;
}
}
scc_ptr->reg[regnum] = val;
if(changed_bits & 0x60) {
scc_regen_clocks(port);
}
return;
case 6: /* wr6 */
if (scc_ptr->state == 3) {
// In SDLC mode (state 3), WR6 contains the node ID for hardware address filtering.
printf("Trying LocalTalk node ID %d.\n", val);
scc_llap_set_node(val);
}
else if(val != 0) {
halt_printf("Wr c03%x to wr6 of %02x!\n", 8+port, val);
}
scc_ptr->reg[regnum] = val;
return;
case 7: /* wr7 */
if (((scc_ptr->state == 3) && (val != 0x7e)) || (scc_ptr->state != 3))
// SDLC requires a sync character of 0x7e, per the SDLC spec.
halt_printf("Wr c03%x to wr7 of %02x!\n", 8+port, val);
scc_ptr->reg[regnum] = val;
return;
case 8: /* wr8 */
scc_write_data(port, val, dcycs);
return;
case 9: /* wr9 */
if((val & 0xc0)) {
if(val & 0x80) {
scc_reset_port(0);
}
if(val & 0x40) {
scc_reset_port(1);
}
if((val & 0xc0) == 0xc0) {
scc_hard_reset_port(0);
scc_hard_reset_port(1);
}
}
if((val & 0x35) != 0x00) {
printf("Write c03%x to wr9 of %02x!\n", 8+port, val);
halt_printf("val & 0x35: %02x\n", (val & 0x35));
}
old_val = scc_stat[0].reg[9];
scc_stat[0].reg[regnum] = val;
scc_evaluate_ints(0);
scc_evaluate_ints(1);
return;
case 10: /* wr10 */
if(((val & 0xff) != 0x00) &&
((val & 0xe0) != 0xe0 && scc_ptr->state == 3) /* Allow FM0 */) {
printf("Wr c03%x to wr10 of %02x!\n", 8+port, val);
}
scc_ptr->reg[regnum] = val;
return;
case 11: /* wr11 */
scc_ptr->reg[regnum] = val;
if(changed_bits) {
scc_regen_clocks(port);
}
return;
case 12: /* wr12 */
scc_ptr->reg[regnum] = val;
if(changed_bits) {
scc_regen_clocks(port);
}
return;
case 13: /* wr13 */
scc_ptr->reg[regnum] = val;
if(changed_bits) {
scc_regen_clocks(port);
}
return;
case 14: /* wr14 */
old_val = scc_ptr->reg[regnum];
val = val + (old_val & (~0xff));
switch((val >> 5) & 0x7) {
case 0x0:
// Null command.
case 0x1:
// Enter search mode command.
case 0x2:
// Reset clock missing command
case 0x3:
// Disable PLL command.
break;
case 0x4: /* DPLL source is BR gen */
val |= SCC_R14_DPLL_SOURCE_BRG;
break;
case 0x6:
// Set FM mode.
//
// LocalTalk uses this mode.
// Ignore this command because we don't emulate line conding.
if (scc_ptr->state != 3)
halt_printf("Wr c03%x to wr14 of %02x, FM mode!\n",
8+port, val);
val |= SCC_R14_FM_MODE;
break;
case 0x5:
// Set source = /RTxC.
case 0x7:
// Set NRZI mode.
default:
halt_printf("Wr c03%x to wr14 of %02x, bad dpll cd!\n",
8+port, val);
}
if((val & 0x0c) != 0x0) {
halt_printf("Wr c03%x to wr14 of %02x!\n", 8+port, val);
}
scc_ptr->reg[regnum] = val;
if(changed_bits) {
scc_regen_clocks(port);
}
scc_maybe_br_event(port, dcycs);
return;
case 15: /* wr15 */
/* ignore all accesses since IIgs self test messes with it */
if((val & 0xff) != 0x0) {
scc_printf("Write c03%x to wr15 of %02x!\n", 8+port,
val);
}
if((scc_stat[0].reg[9] & 0x8) && (val != 0)) {
printf("Write wr15:%02x and master int en = 1!\n",val);
/* set_halt(1); */
}
scc_ptr->reg[regnum] = val;
scc_maybe_br_event(port, dcycs);
scc_evaluate_ints(port);
return;
default:
halt_printf("Wr c03%x to wr%d of %02x!\n", 8+port, regnum, val);
return;
}
}
void
scc_maybe_br_event(int port, double dcycs)
{
Scc *scc_ptr;
double br_dcycs;
scc_ptr = &(scc_stat[port]);
if(((scc_ptr->reg[14] & 0x01) == 0) || scc_ptr->br_event_pending) {
return;
}
/* also, if ext ints not enabled, don't do baud rate ints */
if((scc_ptr->reg[15] & 0x02) == 0) {
return;
}
br_dcycs = scc_ptr->br_dcycs;
if(br_dcycs < 1.0) {
halt_printf("br_dcycs: %f!\n", br_dcycs);
}
scc_ptr->br_event_pending = 1;
add_event_scc(dcycs + br_dcycs, SCC_MAKE_EVENT(port, SCC_BR_EVENT));
}
void
scc_evaluate_ints(int port)
{
Scc *scc_ptr;
word32 irq_add_mask, irq_remove_mask;
int mie;
scc_ptr = &(scc_stat[port]);
mie = scc_stat[0].reg[9] & 0x8; /* Master int en */
// The master interrupt enable (MIE) gates assertion of the interrupt line.
// Even if the MIE is disabled, the interrupt pending bits still reflect
// what interrupt would occur if MIE was enabled. Software could poll the
// pending bits, and AppleTalk does exactly this to detect the start of
// a packet. So, we must always calculate the pending interrupts.
irq_add_mask = 0;
irq_remove_mask = 0;
if(scc_ptr->wantint_rx) {
irq_add_mask |= IRQ_PENDING_SCC1_RX;
} else {
irq_remove_mask |= IRQ_PENDING_SCC1_RX;
}
if(scc_ptr->wantint_tx) {
irq_add_mask |= IRQ_PENDING_SCC1_TX;
} else {
irq_remove_mask |= IRQ_PENDING_SCC1_TX;
}
if(scc_ptr->wantint_zerocnt) {
irq_add_mask |= IRQ_PENDING_SCC1_ZEROCNT;
} else {
irq_remove_mask |= IRQ_PENDING_SCC1_ZEROCNT;
}
scc_stat[port].irq_pending &= ~irq_remove_mask;
scc_stat[port].irq_pending |= irq_add_mask;
if(!mie) {
/* There can be no interrupts if MIE=0 */
remove_irq(IRQ_PENDING_SCC1_RX | IRQ_PENDING_SCC1_TX |
IRQ_PENDING_SCC1_ZEROCNT |
IRQ_PENDING_SCC0_RX | IRQ_PENDING_SCC0_TX |
IRQ_PENDING_SCC0_ZEROCNT);
return;
}
if(port == 0) {
/* Port 1 is in bits 0-2 and port 0 is in bits 3-5 */
irq_add_mask = irq_add_mask << 3;
irq_remove_mask = irq_remove_mask << 3;
}
if(irq_add_mask) {
add_irq(irq_add_mask);
}
if(irq_remove_mask) {
remove_irq(irq_remove_mask);
}
}
void
scc_maybe_rx_event(int port, double dcycs)
{
Scc *scc_ptr;
double rx_dcycs;
int in_rdptr, in_wrptr;
int depth;
scc_ptr = &(scc_stat[port]);
if(scc_ptr->rx_event_pending) {
/* one pending already, wait for the event to arrive */
return;
}
if (!(scc_ptr->reg[3] & 0x01)) {
// If the receiver is disabled, don't transfer data into the RX FIFO.
return;
}
in_rdptr = scc_ptr->in_rdptr;
in_wrptr = scc_ptr->in_wrptr;
depth = scc_ptr->rx_queue_depth;
if((in_rdptr == in_wrptr) || (depth >= 3)) {
/* no more chars or no more space, just get out */
return;
}
if(depth < 0) {
depth = 0;
}
/* pull char from in_rdptr into queue */
scc_ptr->rx_queue[depth] = scc_ptr->in_buf[in_rdptr];
scc_ptr->in_rdptr = (in_rdptr + 1) & (SCC_INBUF_SIZE - 1);
scc_ptr->rx_queue_depth = depth + 1;
scc_maybe_rx_int(port, dcycs);
rx_dcycs = scc_ptr->rx_dcycs;
scc_ptr->rx_event_pending = 1;
add_event_scc(dcycs + rx_dcycs, SCC_MAKE_EVENT(port, SCC_RX_EVENT));
}
void
scc_maybe_rx_int(int port, double dcycs)
{
Scc *scc_ptr;
int depth;
int rx_int_mode;
scc_ptr = &(scc_stat[port]);
depth = scc_ptr->rx_queue_depth;
if(depth <= 0) {
/* no more chars, just get out */
scc_clr_rx_int(port);
return;
}
rx_int_mode = (scc_ptr->reg[1] >> 3) & 0x3;
switch (rx_int_mode)
{
case 0:
break;
case 1: /* Rx Int On First Characters or Special Condition */
// Based on experimentation, there's a delay in SDLC mode before the RX on first interrupt goes active.
// Most likely, this delay is due to the address matching requiring complete reception of the destination address field.
if (!scc_ptr->did_int_rx_first && ((scc_ptr->state != 3) || ((scc_ptr->state == 3) && (depth == 2))))
{
scc_ptr->did_int_rx_first = 1;
scc_ptr->wantint_rx = 1;
}
break;
case 2: /* Int On All Rx Characters or Special Condition */
scc_ptr->wantint_rx = 1;
break;
case 3:
halt_printf("Unsupported SCC RX interrupt mode 3 (Rx Int On Special Condition Only).");
break;
}
scc_evaluate_ints(port);
}
void
scc_clr_rx_int(int port)
{
scc_stat[port].wantint_rx = 0;
scc_evaluate_ints(port);
}
void
scc_handle_tx_event(int port, double dcycs)
{
Scc *scc_ptr;
int tx_int_mode;
scc_ptr = &(scc_stat[port]);
/* nothing pending, see if ints on */
tx_int_mode = (scc_ptr->reg[1] & 0x2);
if(tx_int_mode) {
scc_ptr->wantint_tx = 1;
}
scc_evaluate_ints(port);
}
void
scc_maybe_tx_event(int port, double dcycs)
{
Scc *scc_ptr;
double tx_dcycs;
scc_ptr = &(scc_stat[port]);
if(scc_ptr->tx_event_pending) {
/* one pending already, tx_buf is full */
scc_ptr->tx_buf_empty = 0;
} else {
/* nothing pending, see ints on */
scc_evaluate_ints(port);
tx_dcycs = scc_ptr->tx_dcycs;
scc_ptr->tx_event_pending = 1;
add_event_scc(dcycs + tx_dcycs,
SCC_MAKE_EVENT(port, SCC_TX_EVENT));
}
}
void
scc_clr_tx_int(int port)
{
scc_stat[port].wantint_tx = 0;
scc_evaluate_ints(port);
}
void
scc_set_zerocnt_int(int port)
{
Scc *scc_ptr;
scc_ptr = &(scc_stat[port]);
if(scc_ptr->reg[15] & 0x2) {
scc_ptr->wantint_zerocnt = 1;
}
scc_evaluate_ints(port);
}
void
scc_clr_zerocnt_int(int port)
{
scc_stat[port].wantint_zerocnt = 0;
scc_evaluate_ints(port);
}
void
scc_add_to_readbuf(int port, word32 val, double dcycs)
{
Scc *scc_ptr;
int in_wrptr;
int in_wrptr_next;
int in_rdptr;
scc_ptr = &(scc_stat[port]);
in_wrptr = scc_ptr->in_wrptr;
in_rdptr = scc_ptr->in_rdptr;
in_wrptr_next = (in_wrptr + 1) & (SCC_INBUF_SIZE - 1);
if(in_wrptr_next != in_rdptr) {
scc_ptr->in_buf[in_wrptr] = val;
scc_ptr->in_wrptr = in_wrptr_next;
scc_printf("scc in port[%d] add char 0x%02x, %d,%d != %d\n",
scc_ptr->port, val,
in_wrptr, in_wrptr_next, in_rdptr);
g_scc_overflow = 0;
} else {
if(g_scc_overflow == 0) {
g_code_yellow++;
printf("scc inbuf overflow port %d\n", port);
}
g_scc_overflow = 1;
}
scc_maybe_rx_event(port, dcycs);
}
void
scc_add_to_readbufv(int port, double dcycs, const char *fmt, ...)
{
va_list ap;
char *bufptr;
int len, c;
int i;
va_start(ap, fmt);
bufptr = (char*)malloc(4096); // OG cast added
bufptr[0] = 0;
vsnprintf(bufptr, 4090, fmt, ap);
len = strlen(bufptr);
for(i = 0; i < len; i++) {
c = bufptr[i];
if(c == 0x0a) {
scc_add_to_readbuf(port, 0x0d, dcycs);
}
scc_add_to_readbuf(port, c, dcycs);
}
va_end(ap);
}
void
scc_transmit(int port, word32 val, double dcycs)
{
Scc *scc_ptr;
int out_wrptr;
int out_rdptr;
scc_ptr = &(scc_stat[port]);
/* See if port initialized, if not, do so now */
if(scc_ptr->state == 0) {
scc_port_init(port);
}
if(scc_ptr->state < 0) {
/* No working serial port, just toss it and go */
return;
}
if(!scc_ptr->tx_buf_empty) {
/* toss character! */
printf("Tossing char\n");
return;
}
out_wrptr = scc_ptr->out_wrptr;
out_rdptr = scc_ptr->out_rdptr;
if(scc_ptr->tx_dcycs < 1.0) {
if(out_wrptr != out_rdptr) {
/* do just one char, then get out */
printf("tx_dcycs < 1\n");
return;
}
}
if(g_serial_out_masking &&
(scc_ptr->state != 3 /* never mask LLAP data */)) {
val = val & 0x7f;
}
scc_add_to_writebuf(port, val, dcycs);
}
void
scc_add_to_writebuf(int port, word32 val, double dcycs)
{
Scc *scc_ptr;
int out_wrptr;
int out_wrptr_next;
int out_rdptr;
scc_ptr = &(scc_stat[port]);
/* See if port initialized, if not, do so now */
if(scc_ptr->state == 0) {
scc_port_init(port);
}
if(scc_ptr->state < 0) {
/* No working serial port, just toss it and go */
return;
}
out_wrptr = scc_ptr->out_wrptr;
out_rdptr = scc_ptr->out_rdptr;
out_wrptr_next = (out_wrptr + 1) & (SCC_OUTBUF_SIZE - 1);
if(out_wrptr_next != out_rdptr) {
scc_ptr->out_buf[out_wrptr] = val;
scc_ptr->out_wrptr = out_wrptr_next;
scc_printf("scc wrbuf port %d had char 0x%02x added\n",
scc_ptr->port, val);
g_scc_overflow = 0;
} else {
if(g_scc_overflow == 0) {
g_code_yellow++;
printf("scc outbuf overflow port %d\n", port);
}
g_scc_overflow = 1;
}
}
word32
scc_read_data(int port, double dcycs)
{
Scc *scc_ptr;
word32 ret;
int depth;
int i;
scc_ptr = &(scc_stat[port]);
scc_try_fill_readbuf(port, dcycs);
depth = scc_ptr->rx_queue_depth;
ret = 0;
if(depth != 0) {
ret = scc_ptr->rx_queue[0];
for(i = 1; i < depth; i++) {
scc_ptr->rx_queue[i-1] = scc_ptr->rx_queue[i];
}
scc_ptr->rx_queue_depth = depth - 1;
scc_maybe_rx_event(port, dcycs);
scc_maybe_rx_int(port, dcycs);
int buffered_rx = scc_ptr->in_wrptr - scc_ptr->in_rdptr;
if(buffered_rx < 0) {
buffered_rx += SCC_INBUF_SIZE;
}
int bytes_left = buffered_rx + scc_ptr->rx_queue_depth;
if (scc_ptr->state == 3 /* SDLC mode */ && bytes_left == 1)
{
// Flag an end of frame.
scc_ptr->sdlc_eof = 1;
}
//printf("SCC read %04x: ret %02x, depth:%d, buffered: %d\n", 0xc03b - port, ret, scc_ptr->rx_queue_depth, buffered_rx);
}
scc_printf("SCC read %04x: ret %02x, depth:%d\n", 0xc03b-port, ret, depth);
scc_log(SCC_REGNUM(0,port,8), ret, dcycs);
return ret;
}
void
scc_write_data(int port, word32 val, double dcycs)
{
Scc *scc_ptr;
scc_printf("SCC write %04x: %02x\n", 0xc03b-port, val);
scc_log(SCC_REGNUM(1,port,8), val, dcycs);
scc_ptr = &(scc_stat[port]);
if(scc_ptr->reg[14] & 0x10) {
/* local loopback! */
scc_add_to_readbuf(port, val, dcycs);
} else {
scc_transmit(port, val, dcycs);
}
if (scc_ptr->state != 3) {
// If we're doing LLAP, empty the writebuf at the end of the packet.
// Otherwise, empty as soon as possible.
scc_try_to_empty_writebuf(port, dcycs);
}
scc_maybe_tx_event(port, dcycs);
}
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