tests2/32_led.c

   1 /* example from http://barnyard.syr.edu/quickies/led.c */
   2
   3 /* led.c: print out number as if on 7 line led display. I.e., write integer
   4    given on command line like this:
   5       _   _       _
   6    |  _|  _| |_| |_
   7    | |_   _|   |  _| etc.
   8
   9    We assume the terminal behaves like a classical teletype. So the top
  10    lines of all digits have to be printed first, then the middle lines of
  11    all digits, etc.
  12
  13    By Terry R. McConnell
  14
  15 compile: cc -o led led.c
  16
  17 If you just want to link in the subroutine print_led that does all the
  18 work, compile with -DNO_MAIN, and declare the following in any source file
  19 that uses the call:
  20
  21 extern void print_led(unsigned long x, char *buf);
  22
  23 Bug: you cannot call repeatedly to print more than one number to a line.
  24 That would require curses or some other terminal API that allows moving the
  25 cursor to a previous line.
  26
  27 */
  28
  29
  30
  31 #include <stdlib.h>
  32 #include <stdio.h>
  33
  34 #define MAX_DIGITS 32
  35 #define NO_MAIN
  36
  37
  38 /* Print the top line of the digit d into buffer.
  39    Does not null terminate buffer. */
  40
  41 void topline(int d, char *p){
  42
  43    *p++ = ' ';
  44    switch(d){
  45
  46       /* all these have _ on top line */
  47
  48       case 0:
  49       case 2:
  50       case 3:
  51       case 5:
  52       case 7:
  53       case 8:
  54       case 9:
  55          *p++ = '_';
  56          break;
  57       default:
  58          *p++=' ';
  59
  60    }
  61    *p++=' ';
  62 }
  63
  64 /* Print the middle line of the digit d into the buffer.
  65    Does not null terminate. */
  66
  67 void midline(int d, char *p){
  68
  69    switch(d){
  70
  71       /* those that have leading | on middle line */
  72
  73       case 0:
  74       case 4:
  75       case 5:
  76       case 6:
  77       case 8:
  78       case 9:
  79          *p++='|';
  80          break;
  81       default:
  82          *p++=' ';
  83    }
  84    switch(d){
  85
  86       /* those that have _ on middle line */
  87
  88       case 2:
  89       case 3:
  90       case 4:
  91       case 5:
  92       case 6:
  93       case 8:
  94       case 9:
  95          *p++='_';
  96          break;
  97       default:
  98          *p++=' ';
  99
 100    }
 101    switch(d){
 102
 103       /* those that have closing | on middle line */
 104
 105       case 0:
 106       case 1:
 107       case 2:
 108       case 3:
 109       case 4:
 110       case 7:
 111       case 8:
 112       case 9:
 113          *p++='|';
 114          break;
 115       default:
 116          *p++=' ';
 117
 118    }
 119 }
 120
 121 /* Print the bottom line of the digit d. Does not null terminate. */
 122
 123 void botline(int d, char *p){
 124
 125
 126    switch(d){
 127
 128       /* those that have leading | on bottom line */
 129
 130       case 0:
 131       case 2:
 132       case 6:
 133       case 8:
 134          *p++='|';
 135          break;
 136       default:
 137          *p++=' ';
 138    }
 139    switch(d){
 140
 141       /* those that have _ on bottom line */
 142
 143       case 0:
 144       case 2:
 145       case 3:
 146       case 5:
 147       case 6:
 148       case 8:
 149          *p++='_';
 150          break;
 151       default:
 152          *p++=' ';
 153
 154    }
 155    switch(d){
 156
 157       /* those that have closing | on bottom line */
 158
 159       case 0:
 160       case 1:
 161       case 3:
 162       case 4:
 163       case 5:
 164       case 6:
 165       case 7:
 166       case 8:
 167       case 9:
 168          *p++='|';
 169          break;
 170       default:
 171          *p++=' ';
 172
 173    }
 174 }
 175
 176 /* Write the led representation of integer to string buffer. */
 177
 178 void print_led(unsigned long x, char *buf)
 179 {
 180
 181    int i=0,n;
 182    static int d[MAX_DIGITS];
 183
 184
 185    /* extract digits from x */
 186
 187    n = ( x == 0L ? 1 : 0 );  /* 0 is a digit, hence a special case */
 188
 189    while(x){
 190       d[n++] = (int)(x%10L);
 191       if(n >= MAX_DIGITS)break;
 192       x = x/10L;
 193    }
 194
 195    /* print top lines of all digits */
 196
 197    for(i=n-1;i>=0;i--){
 198       topline(d[i],buf);
 199       buf += 3;
 200       *buf++=' ';
 201    }
 202    *buf++='\n'; /* move teletype to next line */
 203
 204    /* print middle lines of all digits */
 205
 206    for(i=n-1;i>=0;i--){
 207       midline(d[i],buf);
 208       buf += 3;
 209       *buf++=' ';
 210    }
 211    *buf++='\n';
 212
 213    /* print bottom lines of all digits */
 214
 215    for(i=n-1;i>=0;i--){
 216       botline(d[i],buf);
 217       buf += 3;
 218       *buf++=' ';
 219    }
 220    *buf++='\n';
 221    *buf='\0';
 222 }
 223
 224 int main()
 225 {
 226    char buf[5*MAX_DIGITS];
 227    print_led(1234567, buf);
 228    printf("%s\n",buf);
 229
 230    return 0;
 231 }
 232
 233 #ifndef NO_MAIN
 234 int main(int argc, char **argv)
 235 {
 236
 237    int i=0,n;
 238    long x;
 239    static int d[MAX_DIGITS];
 240    char buf[5*MAX_DIGITS];
 241
 242    if(argc != 2){
 243       fprintf(stderr,"led: usage: led integer\n");
 244       return 1;
 245    }
 246
 247    /* fetch argument from command line */
 248
 249    x = atol(argv[1]);
 250
 251    /* sanity check */
 252
 253    if(x<0){
 254       fprintf(stderr,"led: %d must be non-negative\n",x);
 255       return 1;
 256    }
 257
 258    print_led(x,buf);
 259    printf("%s\n",buf);
 260
 261    return 0;
 262
 263 }
 264 #endif
 265
 266 /* vim: set expandtab ts=4 sw=3 sts=3 tw=80 :*/