source: software/tty/readtty_power.c @ 5

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <termios.h>
#include <sys/ioctl.h>

struct scale {
        float read;
        float result;
};

const struct scale *current_scale = NULL;
const struct scale *voltage_scale = NULL;
float current_r = 0;

const struct scale current_scale_1 = {3851, 0.5367};
const float current_r_1 = 0.2;
const struct scale current_scale_2 = {3651, 0.9761};
const float current_r_2 = 0.1;
// const float current_r_3 = 0.05;
const struct scale voltage_scale_1 = {4041.5, 5.996};
const struct scale voltage_scale_2 = {4063.5, 13.547};
const struct scale voltage_scale_3 = {4038, 23.672};

volatile int quit;
const char *prog;

static void
set_quit(int s)
{
        quit = 1;
}

static void
usage()
{
        errx(1, "usage: %s -c [1|2] -v [1|2|3] <device>", prog);
}
int
main(int argc, char * const argv[])
{
        int d;
        int bytes;
        int nfds;
        char buf[256];
        int i;
        fd_set rfds;
        char gpio[2], current[4], tension[4];
        char *endp;
        int currenti, tensioni;
        float current_a, tension_v;
        int val;
        extern char *optarg;
        extern int optind;
        int ch;
        enum {
                INIT,
                GPIO,
                CURRENT,
                TENSION,
                MARK
        } state;

        struct termios t, ot;

        prog = argv[0];
        state = INIT;
        currenti = tensioni = 0;

        while ((ch = getopt(argc, argv, "c:v:")) != -1) {
                switch (ch) {
                case 'c':
                        val = atoi(optarg);
                        if (val == 1) { 
                                current_scale = &current_scale_1;
                                current_r = current_r_1;
                        } else if (val == 2) {
                                current_scale = &current_scale_2;
                                current_r = current_r_2;
                        }
                        break;
                case 'v':
                        val = atoi(optarg);
                        if (val == 1) { 
                                voltage_scale = &voltage_scale_1;
                        } else if (val == 2) {
                                voltage_scale = &voltage_scale_2;
                        } else if (val == 3) {
                                voltage_scale = &voltage_scale_3;
                        }
                        break;
                default: 
                        usage();
                }
        }
        argc -= optind;
        argv += optind;

        if (argc != 1 || current_scale == NULL || voltage_scale == NULL) 
                usage();

        d = open(argv[0], O_RDWR | O_NOCTTY | O_NONBLOCK, 0);
        if (d < 0) {
                err(1, "open %s", argv[0]);
        }
        fprintf(stderr, "o\n");

        if (tcgetattr(d, &ot) < 0) {
                err(1, "tcgetattr");
        }
        fprintf(stderr, "tg\n");

        quit = 0;

        if (signal(SIGINT, set_quit) == SIG_ERR) {
                err(1, "signal(SIGINT)");
        }
        if (signal(SIGQUIT, set_quit) == SIG_ERR) {
                err(1, "signal(SIGQUIT)");
        }
        if (signal(SIGPIPE, set_quit) == SIG_ERR) {
                err(1, "signal(SIGPIPE)");
        }
        if (signal(SIGTERM, set_quit) == SIG_ERR) {
                err(1, "signal(SIGTERM)");
        }

        t = ot;
        cfmakeraw(&t);
        t.c_cflag |= CLOCAL;
        t.c_cflag &= ~CRTSCTS;
        cfsetspeed(&t, B921600);

        if (tcsetattr(d, TCSANOW | TCSAFLUSH, &t) < 0) {
                err(1, "tcsetattr");
        }
        fprintf(stderr, "tty ready\n");
        FD_ZERO(&rfds);
        while (quit == 0) {
                FD_SET(d, &rfds);
                nfds = select(d+1, &rfds, NULL, NULL, NULL);
                if (nfds > 0 && FD_ISSET(d, &rfds)) {
                        bytes = read(d, buf, sizeof(buf));
                        if (bytes < 0 && errno != EAGAIN) {
                                warn("read");
                        }
                        for (i = 0; i < bytes; i++) {
                                switch(state) {
                                case INIT:
                                        /* look for an X mark */
                                        if (buf[i] == 'X')
                                                state = GPIO;
                                        break;
                                case GPIO:
                                        gpio[0] = buf[i];
                                        gpio[1] = '\0';
                                        val = strtol(gpio, &endp, 16);
                                        if (*endp != '\0') {
                                                fprintf(stderr,
                                                    "gpio error: %c\n",
                                                    *endp);
                                                state = INIT;
                                        } else {
                                                state = TENSION;
                                                tensioni = 0;
                                                printf("%2d ", val);
                                        }
                                        break;
                                case CURRENT:
                                        current[currenti] = buf[i];
                                        currenti++;
                                        if (currenti < 3)
                                                break;
                                        current[currenti] = '\0';
                                        val = strtol(current, &endp, 16);
                                        if (*endp != '\0') {
                                                fprintf(stderr,
                                                    "current error: %c\n",
                                                    *endp);
                                                state = INIT;
                                        } else {
                                                if (val == 4095) {
                                                        fprintf(stderr,
                                                          "current saturation\n"
                                                          );
                                                }
                                                state = MARK;
                                                current_a = val / current_scale->read * current_scale->result;
                                                printf("%8f ", current_a);
                                                /* correct for in our resistor */
                                                tension_v -= current_a * current_r;
                                                printf("%8f ", tension_v);
                                                printf("%8f\n", current_a * tension_v);
                                        }
                                        break;
                                case TENSION:
                                        tension[tensioni] = buf[i];
                                        tensioni++;
                                        if (tensioni < 3)
                                                break;
                                        tension[tensioni] = '\0';
                                        val = strtol(tension, &endp, 16);
                                        if (*endp != '\0') {
                                                fprintf(stderr,
                                                    "tension error: %c\n",
                                                    *endp);
                                                state = INIT;
                                        } else {
                                                if (val == 4095) {
                                                        fprintf(stderr,
                                                          "tension saturation\n"
                                                          );
                                                }
                                                state = CURRENT;
                                                currenti = 0;
                                                tension_v = val / voltage_scale->read * voltage_scale->result;
                                        }
                                        break;
                                case MARK:
                                        if (buf[i] != 'X') {
                                                fprintf(stderr,
                                                    "mark error: %c\n",
                                                    buf[i]);
                                                state = INIT;
                                        } else {
                                                state = GPIO;
                                        }
                                        break;
                                }
                        }
                } else if (nfds < 0) {
                        warn("select");
                }
        }
        if (tcsetattr(d, TCSANOW, &ot) < 0) {
                err(1, "restore tcsetattr");
        }
        exit(0);
}