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[/] [wbuart32/] [trunk/] [bench/] [cpp/] [uartsim.cpp] - Blame information for rev 18

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////////////////////////////////////////////////////////////////////////////////
//
// Filename:    uartsim.cpp
//
// Project:     wbuart32, a full featured UART with simulator
//
// Purpose:     To forward a Verilator simulated UART link over a TCP/IP pipe.
//
// Creator:     Dan Gisselquist, Ph.D.
//              Gisselquist Technology, LLC
//
////////////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2015-2017, Gisselquist Technology, LLC
//
// This program is free software (firmware): 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 3 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 MERCHANTIBILITY 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.  (It's in the $(ROOT)/doc directory.  Run make with no
// target there if the PDF file isn't present.)  If not, see
// <http://www.gnu.org/licenses/> for a copy.
//
// License:     GPL, v3, as defined and found on www.gnu.org,
//              http://www.gnu.org/licenses/gpl.html
//
//
////////////////////////////////////////////////////////////////////////////////
//
//
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <poll.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <signal.h>
#include <ctype.h>
 
#include "uartsim.h"
 
void    UARTSIM::setup_listener(const int port) {
        struct  sockaddr_in     my_addr;
 
        signal(SIGPIPE, SIG_IGN);
 
        printf("Listening on port %d\n", port);
 
        m_skt = socket(AF_INET, SOCK_STREAM, 0);
        if (m_skt < 0) {
                perror("ERR: Could not allocate socket: ");
                exit(EXIT_FAILURE);
        }
 
        // Set the reuse address option
        {
                int optv = 1, er;
                er = setsockopt(m_skt, SOL_SOCKET, SO_REUSEADDR, &optv, sizeof(optv));
                if (er != 0) {
                        perror("ERR: SockOpt Err:");
                        exit(EXIT_FAILURE);
                }
        }
 
        memset(&my_addr, 0, sizeof(struct sockaddr_in)); // clear structure
        my_addr.sin_family = AF_INET;
        // Use *all* internet ports to this computer, allowing connections from
        // any/every one of them.
        my_addr.sin_addr.s_addr = htonl(INADDR_ANY);
        my_addr.sin_port = htons(port);
 
        if (bind(m_skt, (struct sockaddr *)&my_addr, sizeof(my_addr))!=0) {
                perror("ERR: BIND FAILED:");
                exit(EXIT_FAILURE);
        }
 
        if (listen(m_skt, 1) != 0) {
                perror("ERR: Listen failed:");
                exit(EXIT_FAILURE);
        }
}
 
UARTSIM::UARTSIM(const int port) {
        m_conrd = m_conwr = m_skt = -1;
        if (port == 0) {
                m_conrd = STDIN_FILENO;
                m_conwr = STDOUT_FILENO;
        } else
                setup_listener(port);
        setup(25);      // Set us up for (default) 8N1 w/ a baud rate of CLK/25
        m_rx_baudcounter = 0;
        m_tx_baudcounter = 0;
        m_rx_state = RXIDLE;
        m_tx_state = TXIDLE;
}
 
void    UARTSIM::kill(void) {
        fflush(stdout);
 
        // Quickly double check that we aren't about to close stdin/stdout
        if (m_conrd == STDIN_FILENO)
                m_conwr = -1;
        if (m_conwr == STDOUT_FILENO)
                m_conwr = -1;
        // Close any active connection
        if (m_conrd >= 0)                                close(m_conrd);
        if ((m_conwr >= 0)&&(m_conwr != m_conrd))        close(m_conwr);
        if (m_skt >= 0) close(m_skt);
 
        m_conrd = m_conwr = m_skt = -1;
}
 
void    UARTSIM::setup(unsigned isetup) {
        if (isetup != m_setup) {
                m_setup = isetup;
                m_baud_counts = (isetup & 0x0ffffff);
                m_nbits   = 8-((isetup >> 28)&0x03);
                m_nstop   =((isetup >> 27)&1)+1;
                m_nparity = (isetup >> 26)&1;
                m_fixdp   = (isetup >> 25)&1;
                m_evenp   = (isetup >> 24)&1;
        }
}
 
void    UARTSIM::check_for_new_connections(void) {
        if ((m_conrd < 0)&&(m_conwr<0)&&(m_skt>=0)) {
                // Can we accept a connection?
                struct  pollfd  pb;
 
                pb.fd = m_skt;
                pb.events = POLLIN;
                poll(&pb, 1, 0);
 
                if (pb.revents & POLLIN) {
                        m_conrd = accept(m_skt, 0, 0);
                        m_conwr = m_conrd;
 
                        if (m_conrd < 0)
                                perror("Accept failed:");
                        // else printf("New connection accepted!\n");
                }
        }
 
}
 
int     UARTSIM::nettick(int i_tx) {
        int     o_rx = 1, nr = 0;
 
        check_for_new_connections();
 
        if ((!i_tx)&&(m_last_tx))
                m_rx_changectr = 0;
        else    m_rx_changectr++;
        m_last_tx = i_tx;
 
        if (m_rx_state == RXIDLE) {
                if (!i_tx) {
                        m_rx_state = RXDATA;
                        m_rx_baudcounter =m_baud_counts+m_baud_counts/2-1;
                        m_rx_baudcounter -= m_rx_changectr;
                        m_rx_busy    = 0;
                        m_rx_data    = 0;
                }
        } else if (m_rx_baudcounter <= 0) {
                if (m_rx_busy >= (1<<(m_nbits+m_nparity+m_nstop-1))) {
                        m_rx_state = RXIDLE;
                        if (m_conwr >= 0) {
                                char    buf[1];
                                buf[0] = (m_rx_data >> (32-m_nbits-m_nstop-m_nparity))&0x0ff;
                                if (1 != send(m_conwr, buf, 1, 0)) {
                                        close(m_conwr);
                                        m_conrd = m_conwr = -1;
                                        fprintf(stderr, "Failed write, connection closed\n");
                                }
                        }
                } else {
                        m_rx_busy = (m_rx_busy << 1)|1;
                        // Low order bit is transmitted first, in this
                        // order:
                        //      Start bit (1'b1)
                        //      bit 0
                        //      bit 1
                        //      bit 2
                        //      ...
                        //      bit N-1
                        //      (possible parity bit)
                        //      stop bit
                        //      (possible secondary stop bit)
                        m_rx_data = ((i_tx&1)<<31) | (m_rx_data>>1);
                } m_rx_baudcounter = m_baud_counts-1;
        } else
                m_rx_baudcounter--;
 
        if (m_tx_state == TXIDLE) {
                struct  pollfd  pb;
                pb.fd = m_conrd;
                pb.events = POLLIN;
                if (poll(&pb, 1, 0) < 0)
                        perror("Polling error:");
                if (pb.revents & POLLIN) {
                        char    buf[1];
                        if (1 == (nr = recv(m_conrd, buf, 1, MSG_DONTWAIT))) {
                                m_tx_data = (-1<<(m_nbits+m_nparity+1))
                                        // << nstart_bits
                                        |((buf[0]<<1)&0x01fe);
                                if (m_nparity) {
                                        int     p;
 
                                        // If m_nparity is set, we need to then
                                        // create the parity bit.
                                        if (m_fixdp)
                                                p = m_evenp;
                                        else {
                                                p = (m_tx_data >> 1)&0x0ff;
                                                p = p ^ (p>>4);
                                                p = p ^ (p>>2);
                                                p = p ^ (p>>1);
                                                p &= 1;
                                                p ^= m_evenp;
                                        }
                                        m_tx_data |= (p<<(m_nbits+m_nparity));
                                }
                                m_tx_busy = (1<<(m_nbits+m_nparity+m_nstop+1))-1;
                                m_tx_state = TXDATA;
                                o_rx = 0;
                                m_tx_baudcounter = m_baud_counts-1;
                        } else if (nr == 0) {
                                close(m_conrd);
                                m_conrd = m_conwr = -1;
                                // printf("Closing network connection\n");
                        } else if (nr < 0) {
                                perror("O/S Read err:");
                                close(m_conrd);
                                m_conrd = m_conwr = -1;
                        }
                }
        } else if (m_tx_baudcounter <= 0) {
                m_tx_data >>= 1;
                m_tx_busy >>= 1;
                if (!m_tx_busy)
                        m_tx_state = TXIDLE;
                else
                        m_tx_baudcounter = m_baud_counts-1;
                o_rx = m_tx_data&1;
        } else {
                m_tx_baudcounter--;
                o_rx = m_tx_data&1;
        }
 
        return o_rx;
}
 
int     UARTSIM::fdtick(int i_tx) {
        int     o_rx = 1;
 
        if ((!i_tx)&&(m_last_tx))
                m_rx_changectr = 0;
        else    m_rx_changectr++;
        m_last_tx = i_tx;
 
        if (m_rx_state == RXIDLE) {
                if (!i_tx) {
                        m_rx_state = RXDATA;
                        m_rx_baudcounter =m_baud_counts+m_baud_counts/2-1;
                        m_rx_baudcounter -= m_rx_changectr;
                        m_rx_busy    = 0;
                        m_rx_data    = 0;
                }
        } else if (m_rx_baudcounter <= 0) {
                if (m_rx_busy >= (1<<(m_nbits+m_nparity+m_nstop-1))) {
                        m_rx_state = RXIDLE;
                        if (m_conwr >= 0) {
                                char    buf[1];
                                buf[0] = (m_rx_data >> (32-m_nbits-m_nstop-m_nparity))&0x0ff;
                                if (1 != write(m_conwr, buf, 1)) {
                                        fprintf(stderr, "ERR while attempting to write out--closing output port\n");
                                        perror("UARTSIM::write() ");
                                        m_conrd = m_conwr = -1;
                                }
                        }
                } else {
                        m_rx_busy = (m_rx_busy << 1)|1;
                        // Low order bit is transmitted first, in this
                        // order:
                        //      Start bit (1'b1)
                        //      bit 0
                        //      bit 1
                        //      bit 2
                        //      ...
                        //      bit N-1
                        //      (possible parity bit)
                        //      stop bit
                        //      (possible secondary stop bit)
                        m_rx_data = ((i_tx&1)<<31) | (m_rx_data>>1);
                } m_rx_baudcounter = m_baud_counts-1;
        } else
                m_rx_baudcounter--;
 
        if ((m_tx_state == TXIDLE)&&(m_conrd >= 0)) {
                struct  pollfd  pb;
                pb.fd = m_conrd;
                pb.events = POLLIN;
                if (poll(&pb, 1, 0) < 0)
                        perror("Polling error:");
                if (pb.revents & POLLIN) {
                        char    buf[1];
                        int     nr;
                        if (1==(nr = read(m_conrd, buf, 1))) {
                                m_tx_data = (-1<<(m_nbits+m_nparity+1))
                                        // << nstart_bits
                                        |((buf[0]<<1)&0x01fe);
                                if (m_nparity) {
                                        int     p;
 
                                        // If m_nparity is set, we need to then
                                        // create the parity bit.
                                        if (m_fixdp)
                                                p = m_evenp;
                                        else {
                                                p = (m_tx_data >> 1)&0x0ff;
                                                p = p ^ (p>>4);
                                                p = p ^ (p>>2);
                                                p = p ^ (p>>1);
                                                p &= 1;
                                                p ^= m_evenp;
                                        }
                                        m_tx_data |= (p<<(m_nbits+m_nparity));
                                }
                                m_tx_busy = (1<<(m_nbits+m_nparity+m_nstop+1))-1;
                                m_tx_state = TXDATA;
                                o_rx = 0;
                                m_tx_baudcounter = m_baud_counts-1;
                        } else if (nr < 0) {
                                fprintf(stderr, "ERR while attempting to read in--closing input port\n");
                                perror("UARTSIM::read() ");
                                m_conrd = -1;
                        } // and we really don't care if nr == 0 except that
                        // the poll above is supposed to keep it from happening
                }
        } else if (m_tx_baudcounter == 0) {
                m_tx_data >>= 1;
                m_tx_busy >>= 1;
                if (!m_tx_busy)
                        m_tx_state = TXIDLE;
                else
                        m_tx_baudcounter = m_baud_counts-1;
                o_rx = m_tx_data&1;
        } else {
                m_tx_baudcounter--;
                o_rx = m_tx_data&1;
        }
 
        return o_rx;
}
 

Line No.	Rev	Author	Line
1	2	dgisselq	`////////////////////////////////////////////////////////////////////////////////`
2			`//`
3			`// Filename: uartsim.cpp`
4			`//`
5			`// Project: wbuart32, a full featured UART with simulator`
6			`//`
7			`// Purpose: To forward a Verilator simulated UART link over a TCP/IP pipe.`
8			`//`
9			`// Creator: Dan Gisselquist, Ph.D.`
10			`// Gisselquist Technology, LLC`
11			`//`
12			`////////////////////////////////////////////////////////////////////////////////`
13			`//`
14	11	dgisselq	`// Copyright (C) 2015-2017, Gisselquist Technology, LLC`
15	2	dgisselq	`//`
16			`// This program is free software (firmware): you can redistribute it and/or`
17			`// modify it under the terms of the GNU General Public License as published`
18			`// by the Free Software Foundation, either version 3 of the License, or (at`
19			`// your option) any later version.`
20			`//`
21			`// This program is distributed in the hope that it will be useful, but WITHOUT`
22			`// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or`
23			`// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License`
24			`// for more details.`
25			`//`
26			`// You should have received a copy of the GNU General Public License along`
27	11	dgisselq	`// with this program. (It's in the $(ROOT)/doc directory. Run make with no`
28	2	dgisselq	`// target there if the PDF file isn't present.) If not, see`
29			`// <http://www.gnu.org/licenses/> for a copy.`
30			`//`
31			`// License: GPL, v3, as defined and found on www.gnu.org,`
32			`// http://www.gnu.org/licenses/gpl.html`
33			`//`
34			`//`
35			`////////////////////////////////////////////////////////////////////////////////`
36			`//`
37			`//`
38			`#include <stdio.h>`
39			`#include <stdlib.h>`
40			`#include <string.h>`
41			`#include <sys/types.h>`
42			`#include <sys/socket.h>`
43			`#include <poll.h>`
44			`#include <unistd.h>`
45			`#include <arpa/inet.h>`
46			`#include <signal.h>`
47			`#include <ctype.h>`
48
49			`#include "uartsim.h"`
50
51			`void UARTSIM::setup_listener(const int port) {`
52			`struct sockaddr_in my_addr;`
53
54			`signal(SIGPIPE, SIG_IGN);`
55
56			`printf("Listening on port %d\n", port);`
57
58			`m_skt = socket(AF_INET, SOCK_STREAM, 0);`
59			`if (m_skt < 0) {`
60	18	dgisselq	`perror("ERR: Could not allocate socket: ");`
61			`exit(EXIT_FAILURE);`
62	2	dgisselq	`}`
63
64			`// Set the reuse address option`
65			`{`
66			`int optv = 1, er;`
67			`er = setsockopt(m_skt, SOL_SOCKET, SO_REUSEADDR, &optv, sizeof(optv));`
68			`if (er != 0) {`
69	18	dgisselq	`perror("ERR: SockOpt Err:");`
70			`exit(EXIT_FAILURE);`
71	2	dgisselq	`}`
72			`}`
73
74			`memset(&my_addr, 0, sizeof(struct sockaddr_in)); // clear structure`
75			`my_addr.sin_family = AF_INET;`
76			`// Use all internet ports to this computer, allowing connections from`
77			`// any/every one of them.`
78			`my_addr.sin_addr.s_addr = htonl(INADDR_ANY);`
79			`my_addr.sin_port = htons(port);`
80
81			`if (bind(m_skt, (struct sockaddr *)&my_addr, sizeof(my_addr))!=0) {`
82	18	dgisselq	`perror("ERR: BIND FAILED:");`
83			`exit(EXIT_FAILURE);`
84	2	dgisselq	`}`
85
86			`if (listen(m_skt, 1) != 0) {`
87	18	dgisselq	`perror("ERR: Listen failed:");`
88			`exit(EXIT_FAILURE);`
89	2	dgisselq	`}`
90			`}`
91
92			`UARTSIM::UARTSIM(const int port) {`
93			`m_conrd = m_conwr = m_skt = -1;`
94			`if (port == 0) {`
95			`m_conrd = STDIN_FILENO;`
96			`m_conwr = STDOUT_FILENO;`
97			`} else`
98			`setup_listener(port);`
99			`setup(25); // Set us up for (default) 8N1 w/ a baud rate of CLK/25`
100			`m_rx_baudcounter = 0;`
101			`m_tx_baudcounter = 0;`
102			`m_rx_state = RXIDLE;`
103			`m_tx_state = TXIDLE;`
104			`}`
105
106			`void UARTSIM::kill(void) {`
107	11	dgisselq	`fflush(stdout);`
108
109			`// Quickly double check that we aren't about to close stdin/stdout`
110			`if (m_conrd == STDIN_FILENO)`
111			`m_conwr = -1;`
112			`if (m_conwr == STDOUT_FILENO)`
113			`m_conwr = -1;`
114	2	dgisselq	`// Close any active connection`
115			`if (m_conrd >= 0) close(m_conrd);`
116			`if ((m_conwr >= 0)&&(m_conwr != m_conrd)) close(m_conwr);`
117			`if (m_skt >= 0) close(m_skt);`
118
119			`m_conrd = m_conwr = m_skt = -1;`
120			`}`
121
122			`void UARTSIM::setup(unsigned isetup) {`
123			`if (isetup != m_setup) {`
124			`m_setup = isetup;`
125			`m_baud_counts = (isetup & 0x0ffffff);`
126			`m_nbits = 8-((isetup >> 28)&0x03);`
127			`m_nstop =((isetup >> 27)&1)+1;`
128			`m_nparity = (isetup >> 26)&1;`
129			`m_fixdp = (isetup >> 25)&1;`
130			`m_evenp = (isetup >> 24)&1;`
131			`}`
132			`}`
133
134	18	dgisselq	`void UARTSIM::check_for_new_connections(void) {`
135	2	dgisselq	`if ((m_conrd < 0)&&(m_conwr<0)&&(m_skt>=0)) {`
136			`// Can we accept a connection?`
137			`struct pollfd pb;`
138
139			`pb.fd = m_skt;`
140			`pb.events = POLLIN;`
141			`poll(&pb, 1, 0);`
142
143			`if (pb.revents & POLLIN) {`
144			`m_conrd = accept(m_skt, 0, 0);`
145			`m_conwr = m_conrd;`
146
147			`if (m_conrd < 0)`
148			`perror("Accept failed:");`
149	18	dgisselq	`// else printf("New connection accepted!\n");`
150	2	dgisselq	`}`
151			`}`
152
153	18	dgisselq	`}`
154
155			`int UARTSIM::nettick(int i_tx) {`
156			`int o_rx = 1, nr = 0;`
157
158			`check_for_new_connections();`
159
160	2	dgisselq	`if ((!i_tx)&&(m_last_tx))`
161			`m_rx_changectr = 0;`
162			`else m_rx_changectr++;`
163			`m_last_tx = i_tx;`
164
165			`if (m_rx_state == RXIDLE) {`
166			`if (!i_tx) {`
167			`m_rx_state = RXDATA;`
168	3	dgisselq	`m_rx_baudcounter =m_baud_counts+m_baud_counts/2-1;`
169	2	dgisselq	`m_rx_baudcounter -= m_rx_changectr;`
170			`m_rx_busy = 0;`
171			`m_rx_data = 0;`
172			`}`
173			`} else if (m_rx_baudcounter <= 0) {`
174			`if (m_rx_busy >= (1<<(m_nbits+m_nparity+m_nstop-1))) {`
175			`m_rx_state = RXIDLE;`
176			`if (m_conwr >= 0) {`
177			`char buf[1];`
178			`buf[0] = (m_rx_data >> (32-m_nbits-m_nstop-m_nparity))&0x0ff;`
179			`if (1 != send(m_conwr, buf, 1, 0)) {`
180			`close(m_conwr);`
181			`m_conrd = m_conwr = -1;`
182	18	dgisselq	`fprintf(stderr, "Failed write, connection closed\n");`
183	2	dgisselq	`}`
184			`}`
185			`} else {`
186			`m_rx_busy = (m_rx_busy << 1)\|1;`
187			`// Low order bit is transmitted first, in this`
188			`// order:`
189			`// Start bit (1'b1)`
190			`// bit 0`
191			`// bit 1`
192			`// bit 2`
193			`// ...`
194			`// bit N-1`
195			`// (possible parity bit)`
196			`// stop bit`
197			`// (possible secondary stop bit)`
198			`m_rx_data = ((i_tx&1)<<31) \| (m_rx_data>>1);`
199	3	dgisselq	`} m_rx_baudcounter = m_baud_counts-1;`
200	2	dgisselq	`} else`
201			`m_rx_baudcounter--;`
202
203			`if (m_tx_state == TXIDLE) {`
204			`struct pollfd pb;`
205			`pb.fd = m_conrd;`
206			`pb.events = POLLIN;`
207			`if (poll(&pb, 1, 0) < 0)`
208			`perror("Polling error:");`
209			`if (pb.revents & POLLIN) {`
210			`char buf[1];`
211	18	dgisselq	`if (1 == (nr = recv(m_conrd, buf, 1, MSG_DONTWAIT))) {`
212	2	dgisselq	`m_tx_data = (-1<<(m_nbits+m_nparity+1))`
213			`// << nstart_bits`
214			`\|((buf[0]<<1)&0x01fe);`
215			`if (m_nparity) {`
216			`int p;`
217
218			`// If m_nparity is set, we need to then`
219			`// create the parity bit.`
220			`if (m_fixdp)`
221			`p = m_evenp;`
222			`else {`
223			`p = (m_tx_data >> 1)&0x0ff;`
224			`p = p ^ (p>>4);`
225			`p = p ^ (p>>2);`
226			`p = p ^ (p>>1);`
227			`p &= 1;`
228			`p ^= m_evenp;`
229			`}`
230			`m_tx_data \|= (p<<(m_nbits+m_nparity));`
231			`}`
232			`m_tx_busy = (1<<(m_nbits+m_nparity+m_nstop+1))-1;`
233			`m_tx_state = TXDATA;`
234			`o_rx = 0;`
235	3	dgisselq	`m_tx_baudcounter = m_baud_counts-1;`
236	18	dgisselq	`} else if (nr == 0) {`
237			`close(m_conrd);`
238			`m_conrd = m_conwr = -1;`
239			`// printf("Closing network connection\n");`
240			`} else if (nr < 0) {`
241			`perror("O/S Read err:");`
242			`close(m_conrd);`
243			`m_conrd = m_conwr = -1;`
244	2	dgisselq	`}`
245			`}`
246	3	dgisselq	`} else if (m_tx_baudcounter <= 0) {`
247	2	dgisselq	`m_tx_data >>= 1;`
248			`m_tx_busy >>= 1;`
249			`if (!m_tx_busy)`
250			`m_tx_state = TXIDLE;`
251			`else`
252	3	dgisselq	`m_tx_baudcounter = m_baud_counts-1;`
253	2	dgisselq	`o_rx = m_tx_data&1;`
254			`} else {`
255			`m_tx_baudcounter--;`
256			`o_rx = m_tx_data&1;`
257			`}`
258
259			`return o_rx;`
260			`}`
261
262			`int UARTSIM::fdtick(int i_tx) {`
263			`int o_rx = 1;`
264
265			`if ((!i_tx)&&(m_last_tx))`
266			`m_rx_changectr = 0;`
267			`else m_rx_changectr++;`
268			`m_last_tx = i_tx;`
269
270			`if (m_rx_state == RXIDLE) {`
271			`if (!i_tx) {`
272			`m_rx_state = RXDATA;`
273	3	dgisselq	`m_rx_baudcounter =m_baud_counts+m_baud_counts/2-1;`
274	2	dgisselq	`m_rx_baudcounter -= m_rx_changectr;`
275			`m_rx_busy = 0;`
276			`m_rx_data = 0;`
277			`}`
278			`} else if (m_rx_baudcounter <= 0) {`
279			`if (m_rx_busy >= (1<<(m_nbits+m_nparity+m_nstop-1))) {`
280			`m_rx_state = RXIDLE;`
281			`if (m_conwr >= 0) {`
282			`char buf[1];`
283			`buf[0] = (m_rx_data >> (32-m_nbits-m_nstop-m_nparity))&0x0ff;`
284			`if (1 != write(m_conwr, buf, 1)) {`
285			`fprintf(stderr, "ERR while attempting to write out--closing output port\n");`
286			`perror("UARTSIM::write() ");`
287			`m_conrd = m_conwr = -1;`
288			`}`
289			`}`
290			`} else {`
291			`m_rx_busy = (m_rx_busy << 1)\|1;`
292			`// Low order bit is transmitted first, in this`
293			`// order:`
294			`// Start bit (1'b1)`
295			`// bit 0`
296			`// bit 1`
297			`// bit 2`
298			`// ...`
299			`// bit N-1`
300			`// (possible parity bit)`
301			`// stop bit`
302			`// (possible secondary stop bit)`
303			`m_rx_data = ((i_tx&1)<<31) \| (m_rx_data>>1);`
304	3	dgisselq	`} m_rx_baudcounter = m_baud_counts-1;`
305	2	dgisselq	`} else`
306			`m_rx_baudcounter--;`
307
308			`if ((m_tx_state == TXIDLE)&&(m_conrd >= 0)) {`
309			`struct pollfd pb;`
310			`pb.fd = m_conrd;`
311			`pb.events = POLLIN;`
312			`if (poll(&pb, 1, 0) < 0)`
313			`perror("Polling error:");`
314			`if (pb.revents & POLLIN) {`
315			`char buf[1];`
316			`int nr;`
317			`if (1==(nr = read(m_conrd, buf, 1))) {`
318			`m_tx_data = (-1<<(m_nbits+m_nparity+1))`
319			`// << nstart_bits`
320			`\|((buf[0]<<1)&0x01fe);`
321			`if (m_nparity) {`
322			`int p;`
323
324			`// If m_nparity is set, we need to then`
325			`// create the parity bit.`
326			`if (m_fixdp)`
327			`p = m_evenp;`
328			`else {`
329			`p = (m_tx_data >> 1)&0x0ff;`
330			`p = p ^ (p>>4);`
331			`p = p ^ (p>>2);`
332			`p = p ^ (p>>1);`
333			`p &= 1;`
334			`p ^= m_evenp;`
335			`}`
336			`m_tx_data \|= (p<<(m_nbits+m_nparity));`
337			`}`
338			`m_tx_busy = (1<<(m_nbits+m_nparity+m_nstop+1))-1;`
339			`m_tx_state = TXDATA;`
340			`o_rx = 0;`
341	3	dgisselq	`m_tx_baudcounter = m_baud_counts-1;`
342	2	dgisselq	`} else if (nr < 0) {`
343			`fprintf(stderr, "ERR while attempting to read in--closing input port\n");`
344			`perror("UARTSIM::read() ");`
345			`m_conrd = -1;`
346			`} // and we really don't care if nr == 0 except that`
347			`// the poll above is supposed to keep it from happening`
348			`}`
349			`} else if (m_tx_baudcounter == 0) {`
350			`m_tx_data >>= 1;`
351			`m_tx_busy >>= 1;`
352			`if (!m_tx_busy)`
353			`m_tx_state = TXIDLE;`
354			`else`
355	3	dgisselq	`m_tx_baudcounter = m_baud_counts-1;`
356	2	dgisselq	`o_rx = m_tx_data&1;`
357			`} else {`
358			`m_tx_baudcounter--;`
359			`o_rx = m_tx_data&1;`
360			`}`
361
362			`return o_rx;`
363			`}`
364

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