[331] | 1 | /* example from http://barnyard.syr.edu/quickies/led.c */
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| 2 |
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| 3 | /* led.c: print out number as if on 7 line led display. I.e., write integer
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| 4 | given on command line like this:
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| 5 | _ _ _
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| 6 | | _| _| |_| |_
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| 7 | | |_ _| | _| etc.
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| 8 |
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| 9 | We assume the terminal behaves like a classical teletype. So the top
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| 10 | lines of all digits have to be printed first, then the middle lines of
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| 11 | all digits, etc.
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| 12 |
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| 13 | By Terry R. McConnell
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| 14 |
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| 15 | compile: cc -o led led.c
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| 16 |
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| 17 | If you just want to link in the subroutine print_led that does all the
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| 18 | work, compile with -DNO_MAIN, and declare the following in any source file
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| 19 | that uses the call:
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| 20 |
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| 21 | extern void print_led(unsigned long x, char *buf);
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| 22 |
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| 23 | Bug: you cannot call repeatedly to print more than one number to a line.
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| 24 | That would require curses or some other terminal API that allows moving the
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| 25 | cursor to a previous line.
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| 26 |
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| 27 | */
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| 28 |
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| 29 |
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| 30 |
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| 31 | #include <stdlib.h>
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| 32 | #include <stdio.h>
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| 33 |
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| 34 | #define MAX_DIGITS 32
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| 35 | #define NO_MAIN
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| 36 |
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| 37 |
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| 38 | /* Print the top line of the digit d into buffer.
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| 39 | Does not null terminate buffer. */
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| 40 |
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| 41 | void topline(int d, char *p){
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| 42 |
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| 43 | *p++ = ' ';
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| 44 | switch(d){
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| 45 |
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| 46 | /* all these have _ on top line */
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| 47 |
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| 48 | case 0:
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| 49 | case 2:
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| 50 | case 3:
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| 51 | case 5:
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| 52 | case 7:
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| 53 | case 8:
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| 54 | case 9:
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| 55 | *p++ = '_';
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| 56 | break;
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| 57 | default:
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| 58 | *p++=' ';
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| 59 |
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| 60 | }
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| 61 | *p++=' ';
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| 62 | }
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| 63 |
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| 64 | /* Print the middle line of the digit d into the buffer.
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| 65 | Does not null terminate. */
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| 66 |
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| 67 | void midline(int d, char *p){
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| 68 |
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| 69 | switch(d){
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| 70 |
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| 71 | /* those that have leading | on middle line */
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| 72 |
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| 73 | case 0:
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| 74 | case 4:
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| 75 | case 5:
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| 76 | case 6:
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| 77 | case 8:
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| 78 | case 9:
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| 79 | *p++='|';
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| 80 | break;
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| 81 | default:
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| 82 | *p++=' ';
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| 83 | }
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| 84 | switch(d){
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| 85 |
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| 86 | /* those that have _ on middle line */
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| 87 |
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| 88 | case 2:
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| 89 | case 3:
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| 90 | case 4:
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| 91 | case 5:
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| 92 | case 6:
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| 93 | case 8:
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| 94 | case 9:
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| 95 | *p++='_';
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| 96 | break;
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| 97 | default:
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| 98 | *p++=' ';
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| 99 |
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| 100 | }
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| 101 | switch(d){
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| 102 |
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| 103 | /* those that have closing | on middle line */
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| 104 |
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| 105 | case 0:
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| 106 | case 1:
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| 107 | case 2:
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| 108 | case 3:
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| 109 | case 4:
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| 110 | case 7:
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| 111 | case 8:
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| 112 | case 9:
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| 113 | *p++='|';
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| 114 | break;
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| 115 | default:
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| 116 | *p++=' ';
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| 117 |
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| 118 | }
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| 119 | }
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| 120 |
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| 121 | /* Print the bottom line of the digit d. Does not null terminate. */
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| 122 |
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| 123 | void botline(int d, char *p){
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| 124 |
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| 125 |
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| 126 | switch(d){
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| 127 |
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| 128 | /* those that have leading | on bottom line */
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| 129 |
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| 130 | case 0:
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| 131 | case 2:
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| 132 | case 6:
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| 133 | case 8:
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| 134 | *p++='|';
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| 135 | break;
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| 136 | default:
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| 137 | *p++=' ';
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| 138 | }
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| 139 | switch(d){
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| 140 |
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| 141 | /* those that have _ on bottom line */
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| 142 |
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| 143 | case 0:
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| 144 | case 2:
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| 145 | case 3:
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| 146 | case 5:
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| 147 | case 6:
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| 148 | case 8:
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| 149 | *p++='_';
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| 150 | break;
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| 151 | default:
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| 152 | *p++=' ';
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| 153 |
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| 154 | }
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| 155 | switch(d){
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| 156 |
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| 157 | /* those that have closing | on bottom line */
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| 158 |
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| 159 | case 0:
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| 160 | case 1:
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| 161 | case 3:
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| 162 | case 4:
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| 163 | case 5:
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| 164 | case 6:
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| 165 | case 7:
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| 166 | case 8:
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| 167 | case 9:
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| 168 | *p++='|';
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| 169 | break;
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| 170 | default:
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| 171 | *p++=' ';
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| 172 |
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| 173 | }
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| 174 | }
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| 175 |
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| 176 | /* Write the led representation of integer to string buffer. */
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| 177 |
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| 178 | void print_led(unsigned long x, char *buf)
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| 179 | {
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| 180 |
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| 181 | int i=0,n;
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| 182 | static int d[MAX_DIGITS];
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| 183 |
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| 184 |
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| 185 | /* extract digits from x */
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| 186 |
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| 187 | n = ( x == 0L ? 1 : 0 ); /* 0 is a digit, hence a special case */
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| 188 |
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| 189 | while(x){
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| 190 | d[n++] = (int)(x%10L);
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| 191 | if(n >= MAX_DIGITS)break;
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| 192 | x = x/10L;
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| 193 | }
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| 194 |
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| 195 | /* print top lines of all digits */
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| 196 |
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| 197 | for(i=n-1;i>=0;i--){
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| 198 | topline(d[i],buf);
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| 199 | buf += 3;
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| 200 | *buf++=' ';
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| 201 | }
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| 202 | *buf++='\n'; /* move teletype to next line */
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| 203 |
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| 204 | /* print middle lines of all digits */
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| 205 |
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| 206 | for(i=n-1;i>=0;i--){
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| 207 | midline(d[i],buf);
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| 208 | buf += 3;
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| 209 | *buf++=' ';
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| 210 | }
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| 211 | *buf++='\n';
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| 212 |
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| 213 | /* print bottom lines of all digits */
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| 214 |
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| 215 | for(i=n-1;i>=0;i--){
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| 216 | botline(d[i],buf);
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| 217 | buf += 3;
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| 218 | *buf++=' ';
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| 219 | }
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| 220 | *buf++='\n';
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| 221 | *buf='\0';
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| 222 | }
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| 223 |
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| 224 | int main()
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| 225 | {
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| 226 | char buf[5*MAX_DIGITS];
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| 227 | print_led(1234567, buf);
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| 228 | printf("%s\n",buf);
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| 229 |
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| 230 | return 0;
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| 231 | }
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| 232 |
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| 233 | #ifndef NO_MAIN
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| 234 | int main(int argc, char **argv)
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| 235 | {
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| 236 |
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| 237 | int i=0,n;
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| 238 | long x;
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| 239 | static int d[MAX_DIGITS];
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| 240 | char buf[5*MAX_DIGITS];
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| 241 |
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| 242 | if(argc != 2){
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| 243 | fprintf(stderr,"led: usage: led integer\n");
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| 244 | return 1;
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| 245 | }
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| 246 |
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| 247 | /* fetch argument from command line */
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| 248 |
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| 249 | x = atol(argv[1]);
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| 250 |
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| 251 | /* sanity check */
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| 252 |
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| 253 | if(x<0){
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| 254 | fprintf(stderr,"led: %d must be non-negative\n",x);
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| 255 | return 1;
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| 256 | }
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| 257 |
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| 258 | print_led(x,buf);
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| 259 | printf("%s\n",buf);
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| 260 |
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| 261 | return 0;
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| 262 |
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| 263 | }
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| 264 | #endif
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| 265 |
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| 266 | /* vim: set expandtab ts=4 sw=3 sts=3 tw=80 :*/
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