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 :*/
|
---|