scope.c

在linux下多媒体开发实例linux下多媒体开发

/*
 *       scope - a software oscilloscope
 *
 */

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <vga.h>
#include <sys/soundcard.h>
#ifndef NO_JOY
#include <linux/joystick.h>
#endif

/* global variables */
int quit_key_pressed;       /* set by handle_key() */
int snd;                    /* file descriptor for sound device */
unsigned char b1[1024];     /* buffer for sound data */
unsigned char b2[1024];     /* previous buffer for sound data */
unsigned char *buffer = b1; /* use pointers to buffers to avoid copies */
unsigned char *old = b2;    
unsigned char *tmp;         /* holder for swapping pointers */
int offset;                 /* vertical offset */
int sampling = 8000;        /* selected sampling rate */
int actual;                 /* actual sampling rate */
int mode = G640x480x16;     /* graphics mode */
int colour = 2;             /* colour */
int dma = 4;                /* DMA buffer divisor */
int point_mode = 0;         /* point v.s. line segment mode */
int verbose = 0;            /* verbose mode */
int v_points;               /* points in vertical axis */
int h_points;               /* points in horizontal axis */
int trigger = -1;           /* trigger level (-1 = disabled) */
int graticule = 0;          /* show graticule */
int file_read = 0;          /* reading from a file */
int joy_read = 0;           /* reading from a joystick */
char filename[255];         /* file name to read */

/* display command usage on standard error and exit */
void usage()
{
  fprintf(stderr,
	  "usage: scope -r<rate> -m<mode> -c<colour> -d<dma divisor>\n"
	  "             -d<trigger> -p -l -g -v -i<file>\n"
	  "Options:\n"
	  "-r <rate>        sampling rate in Hz\n"
	  "-m <mode>        graphics mode\n"
	  "-c <colour>      trace colour\n"
	  "-d <dma divide>  DMA buffer size divisor (1,2,4)\n"
	  "-t <trigger>     trigger level (0 - 255)\n"
	  "-p               point mode (faster)\n"
	  "-l               line segment mode (slower)\n"
	  "-g               draw graticule\n"
	  "-v               verbose output\n"
	  "-i <file>        read from file instead of /dev/dsp\n"
#ifndef NO_JOY
	  "-j <device>      read from joystick device\n"
#endif
	  );
  exit(1);
}

/* if verbose mode, show current parameter settings on standard out */
inline void show_info() {
  if (verbose) {
    printf("graphics mode: %d\n", mode);
    printf("       colour: %d\n", colour);
    if (!file_read && !joy_read)
      printf("  DMA divisor: %d\n", dma);
    if (point_mode)
      printf(" drawing mode: point\n");
    else
      printf(" drawing mode: line segment\n");
    if (graticule)
      printf("    graticule: on\n");
    else
      printf("    graticule: off\n");
    if (trigger == -1)
      printf("trigger level: disabled\n");
    else
      printf("trigger level: %d\n", trigger);
    if (!file_read && !joy_read) {
      printf("sampling rate: %d\n", sampling);
      printf("  actual rate: %d\n", actual);
    }
    if (file_read || joy_read)
      printf(" reading from: %s\n", filename);
    else
      printf(" reading from: /dev/dsp\n");
  }
}

/* handle command line options */
void parse_args(int argc, char **argv)
{
#ifndef NO_JOY
  const char     *flags = "r:m:c:d:t:plgvi:j:";
#else
  const char     *flags = "r:m:c:d:t:plgvi:";
#endif
  int             c;

  while ((c = getopt(argc, argv, flags)) != EOF) {
    switch (c) {
    case 'r':
      sampling = strtol(optarg, NULL, 0);
      break;
    case 'm':
      mode = strtol(optarg, NULL, 0);
      break;
    case 'c':
      colour = strtol(optarg, NULL, 0);
      break;
    case 'd':
      dma = strtol(optarg, NULL, 0);
      break;
    case 't':
      trigger = strtol(optarg, NULL, 0);
      break;
    case 'p':
      point_mode = 1;
      break;
    case 'l':
      point_mode = 0;
      break;
    case 'g':
      graticule = 1;
      break;
    case 'v':
      verbose = 1;
      break;
    case 'i':
      file_read = 1;
      strcpy(filename, optarg);
      break;
#ifndef NO_JOY
    case 'j':
      joy_read = 1;
      strcpy(filename, optarg);
      break;
#endif
    case '?':
      usage();
      break;
    }
  }
  if (joy_read && file_read) {
    fprintf(stderr, "scope: -i and -j options are mutually exclusive\n");
    exit(1);
  }
}

/* initialize screen data to zero level */
void init_data()
{
  int i;
  
  for (i = 0 ; i < 1024 ; i++) {
    buffer[i] = 128;
    old[i] = 128;
  }
}

/* draw graticule */
inline void draw_graticule()
{
  vga_clear();

  /* draw a frame */
  vga_setcolor(colour+1);
  vga_drawline(0, offset-1, h_points-1, offset-1);
  vga_drawline(0, offset+256, h_points-1, offset+256);
  vga_drawline(0, offset-1, 0, offset+256);
  vga_drawline(h_points-1, offset, h_points-1, offset+256);

  /* draw a tick mark where the trigger level is */
  if (trigger != -1) {
    vga_drawline(0, offset+trigger, 3, offset+trigger);
  }
}

/* initialize graphics screen */
void init_screen()
{
  vga_disabledriverreport();
  vga_init();
  vga_setmode(mode);
  v_points = vga_getydim();
  h_points = vga_getxdim();
  offset = v_points / 2 - 127;
  if (graticule)
    draw_graticule();
}

/* cleanup: restore text mode and close sound device */
void cleanup()
{
  /* restore text screen */
  vga_setmode(TEXT);

  /* close input device */
    close(snd);
}

/* initialize /dev/dsp */
void init_sound_card()
{
  int parm;
  int status;
  
  /* open DSP device for read */
  snd = open("/dev/dsp", O_RDONLY);
  if (snd < 0) {
    perror("scope: cannot open /dev/dsp");
    cleanup();
    exit(1);
  }
  
  /* set mono */
  parm = 1;
  status = ioctl(snd, SOUND_PCM_WRITE_CHANNELS, &parm);
  if (status < 0) {
    perror("scope: error from sound device ioctl");
    cleanup();
    exit(1);
  }

  /* set 8-bit samples */
  parm = 8;
  status = ioctl(snd, SOUND_PCM_WRITE_BITS, &parm);
  if (status < 0) {
    perror("scope: error from sound device ioctl");
    cleanup();
    exit(1);
  }
  
  /* set DMA buffer size */
  status = ioctl(snd, SOUND_PCM_SUBDIVIDE, &dma);
  if (status < 0) {
    perror("scope: error from sound device ioctl");
    cleanup();
    exit(1);
  }
  
  /* set sampling rate */
  parm = sampling;
  status = ioctl(snd, SOUND_PCM_WRITE_RATE, &parm);
  if (status < 0) {
    perror("scope: error from sound device ioctl");
  }
  ioctl(snd, SOUND_PCM_READ_RATE, &actual);
}

/* initialize input file */
void init_input_file()
{
  /* open file for read */
  snd = open(filename, O_RDONLY);
  if (snd < 0) {
    perror("scope: cannot open input file");
    cleanup();
    exit(1);
  }
}

#ifndef NO_JOY
/* initialize joystick */
void init_joystick()
{
  /* open device for read */
  snd = open(filename, O_RDONLY);
  if (snd < 0) {
    perror("scope: cannot open joystick device");
    cleanup();
    exit(1);
  }
}
#endif

/* dump image on screen to file scope.xbm in X bitmap format */
void screen_dump(void)
{
  int x, y, bit, bits;
  int x_max = vga_getxdim();
  int y_max = vga_getydim();
  int l = 0;
  FILE *fp;

  fp = fopen("scope.xbm", "w");
  if (fp == 0) {
    perror("scope: unable to open scope.xbm");
    cleanup();
    exit(1);
  }

  fprintf(fp, "#define scope_width %d\n", x_max);
  fprintf(fp, "#define scope_height %d\n", y_max);
  fprintf(fp, "static unsigned char scope_bits[] = {\n   ");

  for (y = 0 ; y < y_max ; y++) {
    for (x = 0 ; x < x_max; x+= 8) {
      l++;
      bits = 0;
      for (bit = 0 ; bit < 8 ; bit++) {
	if (vga_getpixel(x + bit, y) != 0)
	  bits += 1 << bit;
      }
      if (l == y_max*x_max/8)
	fprintf(fp, "0x%02x};\n", bits);
      else if (l % 12 ==  0)
	fprintf(fp, "0x%02x,\n   ", bits);
      else
	fprintf(fp, "0x%02x, ", bits);
    }
  }
  fclose(fp);
}

/* handle single key commands */
inline void handle_key()
{
  switch (vga_getkey()) {
  case 0:
  case -1:
    /* no key pressed */
    return;
    break;
  case 'q':
  case 'Q':
    quit_key_pressed = 1;
    return;
    break;
  case 'R':
    if (!file_read && !joy_read) {
      sampling = sampling * 10 / 9;
      ioctl(snd, SOUND_PCM_SYNC, 0);
      ioctl(snd, SOUND_PCM_WRITE_RATE, &sampling);
      ioctl(snd, SOUND_PCM_READ_RATE, &actual);
    }
    break;
  case 'r':
    if (!file_read && !joy_read) {
      sampling = sampling * 9 / 10;
      ioctl(snd, SOUND_PCM_SYNC, 0);
      ioctl(snd, SOUND_PCM_WRITE_RATE, &sampling);
      ioctl(snd, SOUND_PCM_READ_RATE, &actual);
    }
    break;
  case 'T':
    if (trigger != -1) {
      trigger += 10;
      if (trigger > 255)
	trigger = 255;
      if (graticule)
	draw_graticule();
    }
    break;
  case 't':
    if (trigger != -1) {
      trigger -= 10;
      if (trigger < 0)
	trigger = 0;
      if (graticule)
	draw_graticule();
    }
    break;
  case 'l':
  case 'L':
    if (point_mode == 1) {
      point_mode = 0;
      vga_clear();
      if (graticule)
	draw_graticule();
    }
    break;
  case 'p':
  case 'P':
    if (point_mode == 0) {
      point_mode = 1;
      vga_clear();
      if (graticule)
	draw_graticule();
    }
    break;
  case 'C':
    colour++;
    if (graticule)
      draw_graticule();
    break;
  case 'c':
    if (colour > 0) {
      colour--;
      if (graticule)
	draw_graticule();
    }
    break;
  case 'G':
    if (graticule == 0) {
      graticule = 1;
      draw_graticule();
    }
    break;
  case 'g':
    if (graticule == 1) {
      graticule = 0;
      vga_clear();
    }
    break;
  case ' ':
    /* pause until key pressed */
    while (vga_getkey() == 0)
      ;
    break;
  case 'd':
  case 'D':
    screen_dump();
    break;
  default:
    break;
  }
}

/* get data from sound card */
inline void get_data()
{
  unsigned char datum;
  int status;

  /* simple trigger function */
  if (trigger != -1) {
    /* positive trigger */
    if (trigger >128)
      do {
	read(snd, &datum, 1);
      } while (datum < trigger);
    else
      /* negative trigger */
      do {
	read(snd, &datum, 1);
      } while (datum > trigger);
  }
  /* now get the real data */  
  status = read(snd, buffer, h_points-2);
  if (status == 0) {
    fprintf(stderr, "scope: end of file\n");
    cleanup();
    exit(1);
  }
  if (status == 1) {
    perror("scope: error reading input");
    cleanup();
    exit(1);
  }
}

#ifndef NO_JOY
/* get data from joystick */
inline void get_joy_data()
{
  struct JS_DATA_TYPE js;
  int i, status;

  for (i = 0 ; i < h_points-1 ; i++) {
    status = read(snd, &js, JS_RETURN);
    if (status != JS_RETURN) {
      perror("scope: error reading joystick");
      cleanup();
      exit(1);
    }
    buffer[i] = js.y / 5; /* arbitrary scale factor */
  }
}
#endif

/* graph the data */
inline void graph_data()
{
  register int i;

  if (point_mode) {
    for (i = 1; i < h_points-1  ; i++) {
      /* erase previous point */
      vga_setcolor(0);
      vga_drawpixel(i, old[i] + offset);
      /* draw new point */
      vga_setcolor(colour);
      vga_drawpixel(i, buffer[i] + offset);
    }
  } else { /* line mode */
    for (i = 1; i < h_points-2  ; i++) {
      /* erase previous point */
      vga_setcolor(0);
      vga_drawline(i, old[i] + offset, i+1, old[i+1] + offset);
      /* draw new point */
      vga_setcolor(colour);
      vga_drawline(i, buffer[i] + offset, i+1, buffer[i+1] + offset);
      old[i] = buffer[i];
    }
  }
  /* swap the buffers for next time  */
  tmp = buffer;
  buffer = old;
  old = tmp;
}

/* main program */
int main(int argc, char **argv)
{
  parse_args(argc, argv);
  init_screen();
  init_data();  
  if (file_read)
    init_input_file();
#ifndef NO_JOY
  else if (joy_read)
    init_joystick();
#endif
  else
    init_sound_card();
  show_info();

  if (joy_read) {
#ifndef NO_JOY
    while (!quit_key_pressed) {
      handle_key();
      get_joy_data();
      graph_data();
    }
#endif
  } else {
    while (!quit_key_pressed) {
      handle_key();
      get_data();
      graph_data();
    }
  }

  cleanup();
  exit(0);
}